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Nucleus Of Darkschewitsch


A large increase in nuclear Egr-1 immunolabeling was observed in several dorsomedial thalamic nuclei, and in a stream of neurons extending from below the mesencephalic central gray (overlapping the nucleus of Darkschewitsch at these levels) to just anterior to the nucleus of Edinger-Westphal. A more modest increase in neuronal nuclear Egr-1 was observed in the medial posterior hypothalamic area, the mesencephalic periventricular area, the ventral tegmental area, the inferior colliculus, the nucleus paramedianus of the midbrain, and the intercollicular nucleus. In those mammals, in which the boundaries of the nucleus of Edinger-Westphal are indistinct, the caudal part of the homologous field of urocortinergic neurons has been referred to as the nucleus of Edinger-Westphal. In pigeons, in which the nucleus of Edinger-Westphal is cytoarchitectonically well-defined, the caudal part of this urocortinergic field clearly does not include the nucleus of Edinger-Westphal..  

Thus, the highest density of cell bodies containing d-glutamate was observed in the dorsal raphe nucleus, the ventral part of the mesencephalic central gray, the superior colliculus, above the posterior commissure, and in the subparafascicular thalamic nucleus. A moderate density of immunoreactive cell bodies was observed in the dorsal part of the mesencephalic central gray, above the rostral linear nucleus of the raphe, the nucleus of Darkschewitsch, and in the medial habenular nucleus, whereas a low density was found below the medial forebrain bundle and in the posterior thalamic nuclear group.  

At 95 h, additional virus-labeled cell groups included the solitary, area postrema, pontine reticular, prepositus, dorsal raphe, tegmental, the subcoeruleus nuclei, the nucleus of Darkschewitsch, and the inferior olivary beta and ventrolateral subnuclei. Spinal cord tissue exhibited no labeling in the intermediolateral cell column, but scattered cells were found in the central cervical nucleus.  

Using a carbocyanine dye in postnatal rats, we have shown that the rostral part of the nucleus of Darkschewitsch (ND), consisting of a subnucleus of the so-called "area parafascicularlis prerubralis " and excluded from the rat's ND proper, projects ipsilaterally to the rostral part of the medial accessory olive.  

The intergeniculate leaflet (IGL) has widespread projections to the basal forebrain and visual midbrain, including the suprachiasmatic nucleus (SCN). These include the retinorecipient medial, lateral and dorsal terminal nuclei, the nucleus of Darkschewitsch, the oculomotor central gray, the cuneiform, and the lateral dorsal, pedunculopontine, and subpeduncular pontine tegmental nuclei. Intraocular CTB labeled a retinal terminal field in the medial terminal nucleus that extends dorsally into the pararubral nucleus, a location also containing cells projecting to the IGL. Distinct clusters of IGL-afferent neurons are also located in the medial vestibular nucleus. Vestibular projections to the IGL were confirmed by using anterograde tracer injection into the medial vestibular nucleus. Other IGL-afferent neurons are evident in Barrington's nucleus, the dorsal raphe, locus coeruleus, and retrorubral nucleus. Injection of a retrograde, trans-synaptic, viral tracer into the SCN demonstrated transport to cells as far caudal as the vestibular system and, when combined with IGL injection of CTB, confirmed that some in the medial vestibular nucleus polysynaptically project to the SCN and monosynaptically to the IGL, as do cells in other brain regions.  

Virus uptake involved exclusively orbicularis oculi motoneurons in the dorsolateral division of the facial nucleus. At 3-3.5 d, transneuronal transfer involved premotor interneurons of trigeminal, auditory, and vestibular reflex pathways (in medullary and pontine reticular formation, trigeminal nuclei, periolivary and ventral cochlear nuclei, and medial vestibular nuclei), motor pathways (dorsolateral quadrant of contralateral red nucleus and pararubral area), deep cerebellar nuclei (lateral portion of interpositus nucleus and dorsolateral hump ipsilaterally), limbic relays (parabrachial and Kölliker-Fuse nuclei), and oculomotor structures involved in eye-eyelid coordination (oculomotor nucleus, supraoculomotor area, and interstitial nucleus of Cajal). At 4 d, higher order neurons were revealed in trigeminal, auditory, vestibular, and deep cerebellar nuclei (medial, interpositus, and lateral), oculomotor and visual-related structures (Darkschewitsch, nucleus of the posterior commissure, deep layers of superior colliculus, and pretectal area), lateral hypothalamus, and cerebral cortex (particularly in parietal areas).  

Most intralaminar thalamic sites were also innervated by unique combinations of medullary and pontine reticular formation nuclei such as the subnucleus reticularis dorsalis, gigantocellular, dorsal paragigantocellular, lateral, parvicellular, caudal pontine, ventral pontine, and oral pontine reticular nuclei; the dorsomedial tegmental, subpeduncular tegmental, and ventral tegmental areas; and, the central tegmental field. In addition, most intralaminar injections resulted in retrograde cell body labeling in the substantia nigra, nucleus Darkschewitsch, interstitial nucleus of Cajal, and cuneiform nucleus. Details concerning the pathways from the spinal trigeminal, nucleus tractus solitarius, raphe magnus, raphe pallidus, and the rostral and caudal linear raphe nuclei to subsets of midline and intralaminar thalamic sites are discussed in the text.  

The rostral interstitial nucleus of the medial longitudinal fascicle (riMLF) contains premotor neurons essential for the generation of rapid vertical eye movements. The Alzheimer's disease (AD)-related cytoskeletal changes and beta-amyloid deposits in this nucleus were examined in 30 autopsy cases and compared to the involvement of three associated nuclei - Edinger-Westphal nucleus, nucleus of Darkschewitsch and interstitial nucleus of Cajal. In the Edinger-Westphal nucleus, in the nucleus of Darkschewitsch and most markedly in the interstitial nucleus of Cajal, the pathological changes were significantly less severe than those in the riMLF.  

The principal subcortical connections of area 7m were with the dorsal portion of the ventrolateral thalamic (VLc) nucleus, lateral posterior thalamic nucleus, lateral pulvinar, caudal mediodorsal thalamic nucleus and medial pulvinar, central lateral, central superior lateral, and central inferior intralaminar thalamic nuclei, dorsolateral caudate nucleus and putamen, middle region of the claustrum, nucleus of the diagonal band, zona incerta, pregeniculate nucleus, anterior and posterior pretectal nuclei, intermediate layer of the superior colliculus, nucleus of Darkschewitsch and dorsomedial parvicellular red nucleus (macaque cases only), dorsal, dorsolateral and lateral basilar pontine nuclei, nucleus reticularis tegmenti pontis, locus ceruleus, and superior central nucleus.  

After a single iontophoretic injection of PHA-L into a FEF site where intracortical microstimulation elicited eye movements, anterogradely labelled fibres and terminal-like elements were found in the thalamus in the anterior nuclei, intralaminar nuclei, lateral portion of the mediodorsal nucleus and posterior nuclear group. In the midbrain and pons, labelled fibres were located in the anterior pretectal area, Darkschewitsch nucleus, superior colliculus and dorsolateral portion of the central gray. In the thalamus, anterograde labelling was observed in these latter cases in the anterior nuclei, ventral nuclei, medial portion of the laterodorsal nucleus.  

Neuropathological examination revealed a degenerative process that severely affected the lower motor neurons, as well as the neurons of the pars compacta of the substantia nigra, the nucleus of Darkschewitsch, the nucleus interstitialis of Cajal, the colliculi superiores, and the pallidum.  

PHA-L was also placed into the dorsal raphe nuclei or nucleus of Darkschewitsch and interstitial nucleus of Cajal as controls. In a separate group of rats, the retrograde tracer cholera toxin beta-subunit (CTb) was injected into one of the intralaminar thalamic nuclei-lateral parafascicular, medial parafascicular, central lateral (CL), paracentral (PC), or central medial nucleus-or one of the midline thalamic nuclei-paraventricular (PVT), intermediodorsal (IMD), mediodorsal, paratenial, rhomboid (Rh), reuniens (Re), or caudal ventral medial (VMc) nucleus. All PAG regions (the four columns of the caudal two-thirds of the PAG plus rostral PAG) and the precommissural nucleus projected to the rostral PVT, IMD, and CL.  

In the present study, intensely labeled CGRP neurons were localized within several cranial nerve nuclei including the hypoglossal, facial, oculomotor, motor nucleus of the trigeminal nerve and nucleus ambiguus, as well as in the parabrachial nucleus, locus coeruleus and medullary and pontine reticular formation. In addition, lightly labeled CGRP neurons were identified within the deep cerebellar nuclei, the inferior olivary complex, lateral reticular nucleus, medial and lateral vestibular nuclei, nucleus Darkschewitsch, interstitial nucleus of Cajal, the central gray area adjacent to the third ventricle, and the zona incerta.  

In the forebrain, OFQ peptide and mRNA were prominent in the neocortex endopiriform nucleus, claustrum, lateral septum, ventral forebrain, hypothalamus, mammillary bodies, central and medial nuclei of the amygdala, hippocampal formation, paratenial and reticular nuclei of the thalamus, medial habenula, and zona incerta. In the brainstem, OFQ was prominent in the ventral tegmental area, substantia nigra, nucleus of the posterior commissure, central gray, nucleus of Darkschewitsch, peripeduncular nucleus, interpeduncular nucleus, tegmental nuclei, locus coeruleus, raphe complex, lateral parabrachial nucleus, inferior olivary complex, vestibular nuclear complex, prepositus hypoglossus, solitary nucleus, nucleus ambiguous, caudal spinal trigeminal nucleus, and reticular formation.  

The pupillary light reflex (PLR) is under the control of retinal ganglion cells projecting to the olivary pretectal nucleus (OPN). The OPN has a major projection to the Edinger-Westphal (EW) nucleus, which exerts its parasympathetic action on the iris musculature via the ciliary ganglion. The present study in rats aimed to elucidate the possible projections from the AON and PAG to the EW nucleus. The anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was iontophoretically injected into the interstitial nucleus of Cajal (INC), the nucleus of the posterior commissure (NPC), the nucleus of Darkschewitsch (ND) and the rostral part of the PAG. The INC, NPC and ND have small projections to the EW nucleus, whereas the rostral part of the PAG densely projects to the EW nucleus. Without exception INC, NPC, ND and PAG varicosities are presynaptic to dendritic profiles in the EW nucleus and contain electron dense mitochondria, round vesicles and make asymmetric synaptic contacts. The present observations allow the conclusion that the parasympathetic preganglionic neurons in the EW nucleus are not only controlled by the OPN-EW pathway but also by indirect pathways running via the AON and PAG.  

The goal of the present experiments was to examine the relationships of the nucleus of Darkschewitsch (ND) with the substantia nigra pars reticulata (SNr), the zona incerta (ZI), and the oculomotor nuclei by using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) as a retrograde and anterograde neuronal tracer injected into various sites of the cat's brain. A few small cells in the ND project bilaterally to the oculomotor nucleus.  

the nucleus of posterior commissure (NPC), the nucleus of Darkschewitsch (NDK) and the interstitial nucleus of Cajal (INC).  

The present study was carried out to determine whether, in the rat, the electric activation of the projection from the cerebellar lateral nucleus (LN) to the accessory oculomotor nuclei (AON; nucleus of posterior commissure, nucleus of Darkschewitsch, interstitial nucleus of Cajal) is capable of inducing c-fos expression.  

Faint projections were demonstrated to the nucleus of the posterior commissure and the nucleus of Darkschewitsch. The corticobulbar fibers left the pyramid along its entire extent; the principal trigeminal nucleus and the dorsolateral pontine tegmentum were supplied by additional fibers of the corticotegmental tract.  

Subsequent nuclei labeled with PRV after infection of the flocculus/paraflocculus, or nodulus/uvula, included the following: vestibular (e.g., z) and inferior olivary nuclei (e.g., dorsal cap), accessory oculomotor (e.g., Darkschewitsch n.) and accessory optic related nuclei, (e.g., the nucleus of the optic tract, and the medial terminal nucleus); noradrenergic, raphe, and reticular cell groups (e.g., locus coeruleus, dorsal raphe, raphe pontis, and the lateral reticular tract); other vestibulocerebellum sites, the periaqueductal gray, substantia nigra, hippocampus, thalamus and hypothalamus, amygdala, septal nuclei, and the frontal, cingulate, entorhinal, perirhinal, and insular cortices.  

LCGU increased (p < 0.05) in areas involved in motor function (motor cortex 39%, cerebellum approximately 110%, basal ganglia approximately 30%, substantia nigra approximately 37%, and in the following nuclei: subthalamic 47%, posterior hypothalamic 74%, red 61%, ambiguous 43%, pontine 61%), areas involved in sensory function (somatosensory 27%, auditory 32%, and visual cortex 42%, thalamus approximately 75%, and in the following nuclei: Darkschewitsch 22%, cochlear 51%, vestibular 30%, superior olive 23%, cuneate 115%), areas involved in autonomic function (dorsal raphe nucleus 30%, and areas in the hypothalamus approximately 35%, amygdala approximately 35%, and hippocampus 29%), and in white matter of the corpus callosum (36%) and cerebellum (52%). LCGU did not change with exercise in prefrontal and frontal cortex, cingulum, inferior olive, nucleus of solitary tract and median raphe, lateral septal and interpenduncular nuclei, or in areas of the hippocampus, amygdala, and hypothalamus.  

The nucleus of the optic tract (NOT) is associated with the generation of optokinetic nystagmus (OKN), whereas the olivary pretectal nucleus (ol), which lies embedded in the primate NOT, is believed to be essential for the pupillary light reflex. In this anatomical study of the pretectum, projections from NOT and ol to structures around the oculomotor nucleus were traced in the monkey, to determine which cell groups they innervated. 3[ H]-leucine injections were placed into NOT and ol, and labelled terminals were observed just outside the classical oculomotor nucleus (nIII), in the "C-group' and midline cell clusters, both of which contain small motoneurons of the extraocular eye muscles. In addition, there were strong projections to the lateral visceral cell column of the Edinger-Westphal complex (lvc), but not to the Edinger-Westphal nucleus (EW) itself. NOT efferents terminated over the ipsilateral medial accessory nucleus of Bechterew (nB), but not over the adjacent nucleus Darkschewitsch.  

Cells of the nucleus of Darkschewitsch (ND) are known to have reciprocal projections with the motor cortex (MX), in particular with the hand area of MX, and also to project to the rostral medial accessory olivary (MAO) nucleus (Onodera and Hicks, 1995a).  

Glutamate and aspartate immunoreactivity produced a strong labelling of many cell bodies and terminals in the nucleus of Darkschewitsch (ND). In the same cases, many cell bodies containing HRP reaction product also were found 1) ipsilaterally in the motor cortex, anterior pretectal nucleus, and a restricted area of the caudal part of the substantia nigra pars reticulata; 2) contralaterally in the anterior and posterior interposed cerebellar nuclei as well as in a portion of the lateral cerebellar nucleus; and 3) bilaterally in the zona incerta, the posterior pretectal nucleus, the pedunculopontine tegmental nuclei, the spinal trigeminal nucleus, the dorsal column nuclei, and the spinal cord.  

In this study an ultrastructural analysis was made of the efferent projections of the olivary pretectal nucleus in the rat. The anterograde tracer Phaseolus vulgaris leucoagglutinin was injected iontophoretically into the olivary pretectal nucleus. In the descending pathway special attention was paid to the fine structural features of the olivary pretectal nucleus efferents projecting to the Edinger-Westphal nucleus, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch and the periaqueductal gray. The projection to the superior colliculus and the pontine nucleus was also studied at the ultrastructural level. In the interstitial nucleus of Cajal and the superior colliculus the terminals are organized in glomerulus-like structures. In the ascending pathway the projection to the ventral part of the lateral geniculate nucleus was studied. To identify the projecting neurons in the interstitial nucleus of Cajal and the Edinger-Westphal nucleus, retrograde tracing experiments were performed. Therefore the beta subunit of cholera toxin conjugated with horseradish peroxidase was injected into the facial nucleus..  

The olivary pretectal nucleus is a primary visual centre sensitive to luminance changes. Since the olivary pretectal nucleus is a small nucleus, previous studies using degeneration, horseradish peroxidase and radioactive amino acid tracing were limited regarding to the exclusiveness of the projections from the olivary pretectal nucleus. In the present study the position of the olivary pretectal nucleus in the rat was first localized by physiological recording of the neurons upon luminance stimulation. This allows a much more precise localization of the olivary pretectal nucleus projections. Ascending and descending pathways originating from the olivary pretectal nucleus were observed. Ascending fibres project bilaterally to the intergeniculate leaflet, the ventral part of the lateral geniculate nucleus and ipsilaterally to the anterior pretectal nucleus. Descending fibres project bilaterally to the periaqueductal gray, the nucleus of Darkschewitsch, the interstitial nucleus of Cajal, the Edinger-Westphal nucleus and the intermediate gray layer of the superior colliculus. Also a contralateral projection to the oculomotor nucleus and an ipsilateral projection to the pontine nucleus and the nucleus of the optic tract were found. Furthermore, the contralateral olivary pretectal nucleus received a small projection. Retrograde tracing experiments using two fluorescent dyes revealed that the fibres projecting to the contralateral olivary pretectal nucleus and to the contralateral interstitial nucleus of Cajal are collaterals. The projection from the olivary pretectal nucleus to the facial nucleus which has been described to receive an input in cats could not be confirmed for the rat. The fact that the Edinger-Westphal nucleus, the interstitial nucleus of Cajal and the superior colliculus receive an input from the olivary pretectal nucleus suggests that this primary visual centre is not only involved in the pupillary light reflex, but also in controlling eye and head position and saccadic eye movements.  

BACKGROUND: Although the supranuclear pathways for vertical gaze control are not well defined, lesions of the mesencephalic reticular formation including the nucleus of Darkschewitsch, the rostral interstitial medial longitudinal fasciculus, the interstitial nucleus of Cajal, and the posterior commissure are known to produce vertical gaze palsies.  

The connections of the lateral terminal nucleus (LTN) of the accessory optic system (AOS) of the marmoset monkey were studied with anterograde 3H-amino acid light autoradiography and horseradish peroxidase retrograde labeling techniques. Results show a first and largest LTN projection to the pretectal and AOS nuclei including the ipsilateral nucleus of the optic tract, dorsal terminal nucleus, and interstitial nucleus of the superior fasciculus (posterior fibers); smaller contralateral projections are to the olivary pretectal nucleus, dorsal terminal nucleus, and LTN. A second, major bundle produces moderate-to-heavy labeling in all ipsilateral, accessory oculomotor nuclei (nucleus of posterior commissure, interstitial nucleus of Cajal, nucleus of Darkschewitsch) and nucleus of Bechterew; some of the fibers are distributed above the caudal oculomotor complex within the supraoculomotor periaqueductal gray. A third projection is ipsilateral to the pontine and mesencephalic reticular formations, nucleus reticularis tegmenti pontis and basilar pontine complex (dorsolateral nucleus only), dorsal parts of the medial terminal accessory optic nucleus, ventral tegmental area of Tsai, and rostral interstitial nucleus of the medial longitudinal fasciculus.  

There was only weak labeling in the nucleus accumbens and caudate putamen. In the mesencephalon, there was particularly strong labeling in the pars compacta and reticulata of the substantia nigra, central gray, and red nucleus, in the Darkschewitsch nucleus, and in the medial accessory oculomotor nucleus. Neurons of the medulla oblongata area postrema, nucleus tractus solitarius, reticular nucleus, nucleus cuneatus and several motor nuclei were strongly labeled.  

the nucleus of posterior commissure, the nucleus of Darkschewitsch and the interstitial nucleus of Cajal, was studied in adult rats. In addition, monosynaptic excitations induced by the stimulation of cerebellar lateral nucleus were abolished by microiontophoretic application of DNQX, but not of 2APV.  

Light microscopic analysis revealed that overlap of the anterograde and retrograde labeling was especially prominent in the nucleus of Darkschewitsch. It is concluded that the indirect cerebellar projection to the inferior olive via the nucleus of Darkschewitsch is disynaptic and excitatory..  

the nucleus of posterior commissure (NPC), the nucleus of Darkschewitsch (NDK) and the interstitial nucleus of Cajal (INC) and the putative neurotransmitters subserving this pathway have been studied in adult rats. Following an injection of horseradish peroxidase conjugated with wheat germ agglutinin in this cortical area, we observed corticofugal labeled fibers reaching the accessory oculomotor nuclei and terminating as a fine dust-like terminal labeling in the NDK, in the dorso-lateral division of the INC and in the NPC, as well as in the medial oculomotor accessory nucleus, the red nucleus, the superior colliculus and, even though to a lesser extent, in the mesencephalic reticular formation and the central gray.  

With the aim to evaluate a possible neocerebellar control on eye movements, the projections from the cerebellar lateral nucleus (LN) to the accessory oculomotor nuclei (i.e., the nucleus of posterior commissure, the nucleus of Darkschewitsch, and the interstitial nucleus of Cajal), the putative neurotransmitters subserving this pathway, and the nature of the synaptic influences exerted by these projections were studied in adult rats. Electrical stimulation of the contralateral LN elicited changes in firing rate of a significant fraction of cells belonging to the accessory oculomotor nuclei (36.4% in the nucleus of posterior commissure, 47.1% in the nucleus of Darkschewitsch, and 44.6% in the interstitial nucleus of Cajal).  

Labeled Me5 cell bodies were found throughout the Me5 nucleus from a level slightly caudal to the trigeminal motor nucleus to the level of the superior colliculus 5 mm further rostrally. Extensive central projections from labeled Me5 cells could be seen extending from the nucleus of Darkschewitsch rostrally to the C2 segment caudally. Trigeminal and hypoglossal motor nuclei received direct projections from Me5 cells, but not the facial motor nucleus. The most prominent Me5 projections appeared in the brainstem reticular formation, including the supratrigeminal nucleus. Smaller projections also extended into the main sensory trigeminal nucleus, trigeminal subnucleus oralis, and the nucleus of the solitary tract..  

An electron microscope study was carried out to clarify the ultrastructure of the nucleus of the posterior commissure (NPC) of rat which is thought to be related to the eye movements and oculomotor reflexes. Since the NPC, together with the nucleus of Darkschewitsch (ND) and the interstitial nucleus of Cajal (INC) belongs to the accessory oculomotor nuclei, a comparison of their ultrastructure was carried out..  

One target area, referred to as the external portion of the inferior colliculus, was represented as a semicircle of grain patches lateral and caudal to the central nucleus. In contrast, after high cervical injections, the pericentral portion dorsomedial to the rostral half of the central nucleus was labeled almost exclusively. Other than in the colliculi, weak pretectal projections were observed following dorsal column nuclear injections, while the nucleus of Darkschewitsch was labeled best following lumbosacral injections. This region might correspond to the lateral cervical nucleus, an aggregation of neurons that so far has only been demonstrated in higher mammals..  

In the off-axis animals there was a significant labeling of neurons: in the inferior, medial, and y-group subnuclei of the vestibular complex; in subnuclei of the inferior olive, especially the dorsomedial cell column; in midbrain nuclei, including the interstitial nucleus of Cajal, nucleus of Darkschewitsch, Edinger-Westphal nucleus, and dorsolateral periaqueductal gray; in autonomic centers including the solitary nucleus, area postrema, and locus coeruleus; and in reticular nuclei including the lateral reticular nucleus and the lateral parabrachial nucleus. Also, there was greater Fos expression in the dorsomedial cell column, the principal inferior olive subnuclei, inferior vestibular nucleus, the dorsolateral central gray, and the locus coeruleus in animals who had their heads restrained compared to animals whose heads were not restrained.  

Asymmetrical expression was apparent in the medial and inferior vestibular nuclei, the prepositus hypoglossi, the dorsolateral central gray, and the inferior olivary beta subnucleus. In addition, there was some Fos expression bilaterally in the olivary dorsomedial cell column, interstitial nucleus of Cajal and the Darkschewitsch nucleus.  

Rubro-spinal neurons of various sizes were distributed over the entire rostrocaudal extent of the contra-lateral nucleus; a few neurons were also located ipsilaterally, Unlike that of the opossum, the projection appeared to be somatotopically organised. In the ipsilateral periventricular grey, in addition, there was a distinct population of cells possibly corresponding to the nucleus of Darkschewitsch. Labeled cuneiform and midline cells, on the other hand, were quite numerous, extending both from a level just caudal to the trochlear nucleus to levels far beyond the rostral tip of the somatic oculomotor nucleus. Hypothalamo-spinal neurons were essentially restricted to dorsal regions: the hypothalamic paraventricular nucleus (PAV), the dorso-medial (DmHy) and dorso-intermediate cell groups as well as the lateral hypothalamic zone. Labeled neurons in the amygdala, colliculus superior and mesencephalic trigeminal nucleus were only found following cervical injections; all other mentioned areas and the posterior commissure complex projected to, at least, midthoracic level..  

Outside PAG, labelled cells and terminal labelling were observed in the cuneiform, parabrachial and intercollicular nuclei, in the deep and intermediate gray layers of the superior colliculus, in the anterior and posterior pretectal nuclei and in the nucleus of Darkschewitsch.  

The efferent and afferent connections of the dorsal part of the anterior pretectal nucleus, pars compacta (APc), were studied experimentally in the rat by using neurotracers. A restricted number of structures supply afferents to the anterior pretectal nucleus: the visual cortex (areas 17, 18 and 18a), ventral lateral geniculate nucleus and superficial layers of the superior colliculus. Additional afferents have been demonstrated originating from the Darkschewitsch nucleus, periaqueductal gray, zona incerta and anterior cingulate cortex. Efferent fibers are distributed to a sector of the deep mesencephalic nucleus just dorsolateral to the red nucleus, the basilar pontine gray, posterior and olivary pretectal nuclei, superficial layers of the superior colliculus, lateral posterior thalamic nucleus, ventral lateral geniculate nucleus and zona incerta. These anatomical observations indicate that the pars compacta of the anterior pretectal nucleus is closely related to visual centers, suggesting an involvement of this nucleus in visually mediated behavior..  

The cellular origin of the brainstem projections to the oculomotor nucleus in the rabbit has been investigated by using free (HRP) and lectin-conjugated horseradish peroxidase (WGA-HRP). Following injections of these tracers into the somatic oculomotor nucleus (OMC), retrogradely labeled cells have been observed in numerous brainstem structures. In particular, bilateral labeling has been found in the four main subdivisions of the vestibular complex, predominantly in the superior and medial vestibular nuclei and the interstitial nucleus of Cajal, while ipsilateral labeling was found in the rostral interstitial nucleus of the medial longitudinal fascicle (Ri-MLF), the Darkschewitsch and the praepositus nuclei. Neurons labeled only contralaterally have been identified in the following structures: mesencephalic reticular formation dorsolateral to the red nucleus, abducens internuclear neurons, group Y, several areas of the lateral and medial regions of the pontine and medullary reticular formation, ventral region of the lateral cerebellar nucleus and caudal anterior interpositus nucleus.  

The afferent and efferent connections of the cerebellar interpositus complex were studied in a capuchin monkey (Cebus apella) that had received a transcannular horseradish peroxidase implant into the caudal portion of the anterior interpositus nucleus and posterior interpositus nucleus. While the heaviest anterogradely labeled ascending projections were observed to the contralateral ventral posterolateral nucleus of the thalamus, pars oralis (VPLo), efferent projections were also observed to the contralateral ventrolateral thalamic nucleus (VLc) and central lateral (CL) nucleus of the thalamic intralaminar complex, magnocellular (and to a lesser extent parvicellular) red nucleus, nucleus of Darkschewitsch, zona incerta, nucleus of the posterior commissure, lateral intermediate layer and deep layer of the superior colliculus, dorsolateral periaqueductal gray, contralateral nucleus reticularis tegmenti pontis and basilar pontine nuclei (especially dorsal and peduncular), and dorsal (DAO) and medial (MAO) accessory olivary nuclei, ipsilateral lateral (external) cuneate nucleus (LCN) and lateral reticular nucleus (LRN), and to a lesser extent the caudal medial vestibular nucleus (MVN) and caudal nucleus prepositus hypoglossi (NPH), and dorsal medullary raphe.  

The highest labeling was found in the bulbus olfactorius (internal plexiform and granular layers) and in the caudal magnocellular nucleus of the hypothalamus. Strong labeling was observed in the Purkinje layer of the cerebellar cortex, the interpeduncular nucleus, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch and the suprachiasmatic nucleus. Interestingly, a low level of GAD mRNA was found in the caudate-putamen and nucleus accumbens, where the vast majority of nerve cells is known to contain GAD immunoreactivity. The comparison with cell counts performed by immunocytochemistry suggests that some brain areas, such as caudate-putamen and nucleus accumbens, contain a large number of GAD-immunoreactive cell bodies which express a low level of GAD mRNA.  

The mesencephalic projections of the medial cerebellar nucleus (MCN) were studied in the rat by using the method of anterograde transport of wheat germ agglutinin/horseradish peroxidase to establish connections of the nucleus with oculomotor-related nuclei as a basis for its proposed role in eye movement. The principal targets of projections were the supraoculomotor ventral periaqueductal gray (PAG) and lateral PAG, and paraoculomotor cell groups (nucleus of Darkschewitsch and medial accessory nucleus of Bechterew). Lesser projections were observed to the intermediate layer of the superior colliculus, nucleus of the posterior commissure, and prerubral field. The findings suggest that the caudal MCN in the rat, like the primate fastigial nucleus, is involved in the control of eye movement..  

It should be mentioned that the gigantocellular reticular nucleus contained labeled cells bilaterally with contralateral predominance. A few cells were labeled in the vestibular nuclei and nucleus prepositus hypoglossi bilaterally. Injections of WGA-HRP into the medial central nucleus showed a different pattern of labeling. It is noteworthy that no labeled cells were found in the dorsal thalamus, the hypothalamus (except for the lateral mamillary nucleus), the superior colliculus or the cerebellar nuclei..  

At necropsy, apart from bilateral infarction in the basis pontis, there was a single unilateral infarct selectively destroying the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on the right. The posterior commissure and its nucleus, the nucleus of Cajal, the nucleus of Darkschewitsch and the pontine tegmentum were spared.  

A morphoquantitative study was carried out to provide detailed information regarding the cytoarchitecture and neuronal morphology of the nucleus of Darkschewitsch (ND) of man. The cytoarchitectural features of the ND corresponded to the characters of the reticular formation so that the ND of man could be considered to be a typical reticular nucleus inside the central gray matter. The prevailing presence of multipolar neurons whose processes often spread outside the ND could suggest that the ND is a mainly projective nucleus..  

AGm projected to the anterior pretectal nucleus, the rostral interstitial nucleus of the medial longitudinal fasciculus, the medial accessory oculomotor nucleus of Bechterew, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the nucleus cuneiformis and subcuneiformis, intermediate and deep superior collicular layers, the paramedian pontine reticular formation (reticularis pontis oralis and caudalis, and reticularis gigantocellularis), and raphe centralis superior. The heaviest projections to the anterior pretectal nucleus were from the caudal portion of AGm.  

The common reciprocal connections were found in the ventral anterior-ventral lateral complex, principal ventromedial nucleus, rostral intralaminar nuclei, centromedian-parafascicular complex, lateral posterior nucleus, and suprageniculate nucleus. The common efferent projections were in the subthalamic nucleus, lateral habenular nucleus, pretectal nucleus, posterior commisure nucleus, nucleus of Darkschewitsch, pontine nucleus, nucleus reticularis tegmenti pontis, medial accessory inferior olive, and the superior colliculus.  

One group of cats received a WGA-HRP injection in the posterior interposed nucleus of the cerebellum and another group received an injection in the nucleus of Darkschewitsch. Following injection of WGA-HRP in the nucleus of Darkschewitsch, all WGA-HRP-labeled terminals were GABA-negative.  

Following minor concussive brain injury when there is an otherwise general suppression of CNS activity, the ventral tegmental nucleus of Gudden (VTN) demonstrates increased functional activity (32). Based upon retrograde HRP labeling, the principal afferents to the VTN region of the cmPRF originated from the medial and lateral mammillary nuclei, and lateral habenular nucleus, and to a lesser extent from the interpeduncular nucleus, lateral hypothalamus, dorsal tegmental nucleus, superior central nucleus, and contralateral nucleus reticularis pontis caudalis. Other afferents, which were thought to have been labeled through spread of HRP into the medial longitudinal fasciculus (MLF), adjacent paramedian pontine reticular formation, or uptake by transected fibers descending to the inferior olive, included the nucleus of Darkschewitsch, interstitial nucleus of Cajal, zona incerta, prerubral fields of Forel, deep superior colliculus, nucleus of the posterior commissure, nucleus cuneiformis, ventral periaqueductal gray, vestibular complex, perihypoglossal complex, and deep cerebellar nuclei. The majority of fibers ascended to terminate in the medial and lateral mammillary nuclei, interpeduncular complex (especially paramedian subnucleus), ventral tegmental area, lateral hypothalamus, and the medial septum in the basal forebrain. Some projections were also observed to nucleus reticularis pontis oralis and caudalis, superior central nucleus, and dorsal tegmental nucleus adjacent to the VTN....  

The posterior parietal cortex was found to be reciprocally connected with three different ipsilateral thalamic nuclei: the nucleus ventralis posterior inferior, the magnocellular part of the medial geniculate nucleus, and some intralaminar nuclei. The dorsolateral pontine nucleus is of particular interest because it is known to be related to smooth pursuit eye movements. Cortical area 7 also was seen to project to the accessory nucleus of Darkschewitsch, to all the vestibular nuclei, and to the nucleus propositus hypoglossi; the last two projections were found to be bilateral with a greater ipsilateral contribution.  

Bidirectional transport of lectin conjugated horseradish peroxidase was employed to investigate the relative distribution of the cerebellar and cortical connections of the nucleus of Darkschewitsch in the cat. Injection of horseradish peroxidase into the deep cerebellar nuclei produced terminal labeling which extended throughout the length of the contralateral nucleus of Darkschewitsch and into the perifascicular region. Injection of horseradish peroxidase into the pericruciate cortex produced both ipsilateral terminal labeling which extended throughout the length of the nucleus of Darkschewitsch and into the perifascicular region, and ipsilateral retrograde neuronal labeling. Labeled neurons displayed a variety of shapes and sizes, were more numerous in sections cut at rostral levels of the nucleus of Darkschewitsch, and were located both within and outside fields of terminal labeling. Comparison of the distribution of labeling following cerebellar and cortical injections indicates that convergence and overlap of input from these two sources occur in the nucleus of Darkschewitsch. These findings provide the morphological basis for integration of cerebellar and cortical information in this nucleus which may, in turn, influence output from neurons which project to the cortex or to the inferior olivary nucleus..  

Ascending projections from the medial pontine reticular formation, the mesencephalic reticular formation, and the median raphe nucleus were examined using the autoradiographic technique. The majority of the ascending fibers labeled after injections of [ 3H]-leucine into the nucleus pontis caudalis (RPC) course through the brainstem within the tracts of Forel (tractus fasciculorum tegmenti of Forel) and directly ventral to them. These include the abducens nucleus, the intermediate gray layer of the superior colliculus (SCi), the anterior pretectal nucleus (APN), the ventral lateral geniculate nucleus (LGNv), and regions of the central gray directly bordering the oculomotor nucleus, the interstitial nucleus of Cajal, and the nucleus of Darkschewitsch. Few, if any, fibers from RPC (or from nucleus pontis oralis-RPO) terminate within the oculomotor nucleus proper. These include major dopamine-containing cell groups (the retrorubral nucleus, the ventral tegmental area, and the substantia nigra-pars compacta) as well as the interpeduncular nucleus, the lateral mammillary nucleus, and the supramammillary nucleus.  

Ipsilateral projections originate from the striatum and the nucleus ventrolateralis thalami and reach the medulla oblongata. The ipsilateral nucleus praeopticus magnocellularis reaches the medulla spinalis. The rostral part of the nucleus tuberculi posterioris projects to the ipsilateral medulla oblongata; its caudal part projects further caudally. Tectal efferents and the efferents of the nucleus praetectalis profundus project bilaterally, the nucleus praetectalis superficialis, nucleus mesencephalicus nervi trigemini, torus semicircularis, nucleus Darkschewitsch, and nucleus fasciculi longitudinalis medialis project ipsilaterally to the medulla oblongata. The nucleus mesencephalicus nervi trigemini, nucleus fasciculi longitudinalis medialis, and tectal efferents reach the rostral medulla spinalis. The nucleus ruber projects mainly via the contralateral dorsolateral funiculus to the medulla spinalis. A largely crossed medullary projection arises in the nucleus dorsalis tegmenti pars anterior, a bilateral projection arises in the nucleus dorsalis tegmenti pars posterior, and an ipsilateral projection arises in the nucleus ventralis tegmenti pars anterior. The nucleus reticularis isthmi, superior, medius and inferior as well as the nucleus raphes exhibit spinal trajectories. The nucleus vestibularis magnocellularis projects bilaterally, the nucleus vestibularis medialis projects ipsilaterally spinalward. The supposed nucleus descendens nervi trigemini descends mainly contralaterally. A small spinal projection arises in the nucleus tractus solitarii.  

Patches of terminal labeling were located ipsilaterally in the lateral mesencephalic reticular formation near the parabigeminal nucleus and the ventrolateral pontine reticular formation. Patches of label like those in the pontine nuclei were located ipsilaterally in the reticularis tegmenti pontis nucleus in lFEF cases and bilaterally in sFEF cases. Small terminal patches were found in the nucleus of Darkschewitsch and dorsal and medial parts of the parvicellular red nucleus in most FEF cases. In the pretectal region, labeled terminal patches were consistently found in the nucleus limitans of the posterior thalamus, but we could not determine if label in the nucleus of the pretectal area and dorsal parts of the nucleus of the posterior commissure marked axon terminals or fibers of passage. In one sFEF case, very small patches of label were located in the supragenual nuclei anterior to the abducens nuclei and in the ipsilateral nucleus prepositus hypoglossi posterior to the abducens nucleus.  

HRP injections at the C2, T1 and S1 spinal levels and in the medullary lateral tegmental field revealed that the contralaterally projecting rubro-bulbospinal neurons are located not only in the caudal but also to a certain extent in the rostral red nucleus (RN). They further indicated that the contralateral RN projections to the caudal brainstem precerebellar nuclei (nucleus corporis pontobulbaris, lateral reticular nucleus, lateral cuneate nucleus) and the dorsal column nuclei are also somatotopically organized. These projections were derived from various rostral mesencephalic areas, including the nucleus of Darkschewitsch, the nucleus accessorius medialis of Bechterew, the interstitial nucleus of Cajal and the area of the rostral interstitial nucleus of the medial longitudinal fasciculus.  

These forebrain nuclei included the medial septum-vertical limb of the diagonal band nucleus, the lateral septum, the nucleus of the horizontal limb of the diagonal band, the medial preoptic area and the magnocellular preoptic nucleus/substantia innominata. Medial septal-vertical limb of the diagonal band injections produced dense cell labeling in: raphe obscurus, nucleus incertus, central gray-pars alpha, locus coeruleus, raphe pontis, median raphe, nucleus of Darkschewitsch, a compact cell group within the mesencephalic gray dorsolateral to the nucleus of Darkschewitsch and the supramammillary nucleus. Lateral septal injections produced the heaviest cell labeling in the A1 and A2 areas (of Dahlstrom and Fuxe), the lateral parabrachial nucleus, the Kolliker-Fuse nucleus, the ventral tegmental area and the supramammillary nucleus. The most heavily labeled nuclei were A1, locus coeruleus, laterodorsalis (dorsolateral tegmental nucleus of Castaldi), raphe pontis, median raphe, lateral parabrachial nucleus, ventral tegmental area, nucleus of Darkschewitsch and the supramammillary nucleus. Medial preoptic area injections produced pronounced labeling in: A1 and A2 areas, raphe magnus, locus coeruleus, laterodorsalis, lateral parabrachial nucleus, pedunculopontine nucleus, peripenduncular nucleus and the supramammillary nucleus. These included the medial parabrachial nucleus, the pedunculopontine nucleus, the dorsal raphe nucleus, the ventral tegmental area and the supramammillary nucleus. With the exception of the supramammillary nucleus, each of these cell groups was more heavily labeled with magnocellular preoptic/substantia innominata injections than with others of this series.  

In the accompanying paper we identified these nuclei in the pigeon as the nucleus lentiformis mesencephali--pars lateralis and pars medialis, the tectal gray, the area pretectalis, and pretectalis diffusus. These targets include the inferior olive, the cerebellum, the lateral pontine nucleus, the nucleus papillioformis, the nucleus of the basal optic root, the nucleus mesencephalicus profundus, pars ventralis, the nucleus principalis precommissuralis, and the stratum cellulare externum. We found that a few cells in the lentiformis mesencephali project to the medial pontine nucleus, but that a much heavier projection arises from the nucleus laminaris precommissuralis, which is medial to the nucleus lentiformis mesencephali, pars medialis. The nuclei that it projects to are the nucleus intercalatus thalami, the nucleus of the ventral supraoptic decussation, the nucleus posteroventralis, the ventral lateral geniculate nucleus, the nucleus dorsolateralis medialis, and the nucleus dorsolateralis anterior. It has ipsilateral ascending projections to the nucleus dorsolateralis anterior, pars magnocellularis, the nucleus lateralis anterior, and the nucleus ventrolateralis thalami. It has ipsilateral descending projections to the central gray, the nucleus of the basal optic root, pars dorsalis, the lateral pontine nucleus, and the deep layers of the optic tectum. It has contralateral projections to the area pretectalis, the nucleus Campi Foreli, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the cerebellum, and the Edinger-Westphal nucleus. It projects contralaterally to the pretectalis diffusus, and ipsilaterally to the nucleus of the ventral supraoptic decussation, the lateral pons, and the cerebellum.4.  

Group A monkeys had HRP injections or transcannular HRP gel implants into the oculomotor complex (OMC), the largest of which involved adjacent paraoculomotor nuclei (e.g., ventral periaqueductal gray, PAG; nucleus of Darkschewitsch, ND; medial accessory nucleus of Bechterew, MAB; dorsomedial parvicellular red nucleus, dmPRN). Whereas the smallest OMC injection only labeled a few cells in the dentate nucleus (DN), injections involving paraoculomotor nuclei produced labeling in all of the cerebellar nuclei except the basal interstitial nucleus (BIN). The pontine tegmental cases contained labeled cells in all cerebellar nuclei, but the DN was the most heavily labeled when the implant involved the nucleus reticularis tegmenti pontis (NRTP). Cases with injections into the caudal medial pontine tegmentum (nucleus reticularis pontis caudalis, NRPC), including the physiological paramedian pontine reticular formation (PPRF), but not NRTP, contained the largest number of labeled cells in the fastigial nucleus (FN) and lacked retrograde labeling in the DN. Dorsomedial basilar pontine cases contained almost no labeled cells in the FN, anterior interpositus nucleus (AIN), and posterior interpositus nucleus (PIN) but did contain DN labeling when the injection involved the NRTP. Group C monkeys had injections into the parvicellular red nucleus (PRN) and had their heaviest labeling in the DN, although the AIN and PIN also contained labeled cells.  

Afferent sources to all of these targets were observed in the interstitial nucleus of Cajal (INC), the region surrounding the fasciculus retroflexus (PF), and the nucleus of the fields of Forel (NFF). Spinal projecting cells were present in slightly greater numbers in the caudal two-thirds of the INC, whereas those projecting to the vestibular complex were more numerous in the rostral two-thirds of this nucleus. Each type of afferent source was also seen in the nucleus of the posterior commissure and the posterior ventral lateral hypothalamic area. Unique sources of afferents to the inferior olive were observed in the parvicellular red nucleus (ipsilateral to the injections) and the anterior and posterior pretectal nuclei. A large number of labeled neurons was seen in the nucleus of Darkschewitsch after injections of tracer into the inferior olive, but this projection did not appear to be unique, as small numbers of labeled cells were also seen after injections into the cervical spinal cord. The Edinger-Westphal nucleus and the adjacent somatic oculomotor nucleus contained cells which projected separately to the spinal cord or the vestibular complex, and the superior colliculus contained cells which projected separately to the contralateral spinal cord or the contralateral inferior olive. In this study, it was also noted that neurons in the medial terminal nucleus of the accessory optic tract projected to the ipsilateral inferior olive or to the contralateral vestibular complex.  

A sparse bilateral projection from the interstitial nucleus of Cajal was demonstrated. No retrogradely labelled cells were found in the nucleus of Darkschewitsch and the nucleus of the posterior commissure..  

In both species retrogradely labelled cells were observed: ipsilaterally in the corpus striatum, lateral amygdala, ventral and dorsal thalamus and nucleus of Darkschewitsch--bilaterally in the pretectal nucleus, dorsal tegmentum and nucleus reticularis medius--contralaterally in the tectum opticum and area octavo lateralis. Besides these nuclei the nucleus isthmi was bilaterally labelled. The tecto-isthmic projection was highly topographic forming a layered terminal field lateral to the nucleus isthmi. The nucleus isthmi identified here is proposed to be homologe to that of other vertebrates..  

Terminal labeling in the rostral midbrain, except that observed in the nucleus of Darkschewitsch, was substantially less than that observed at more caudal midbrain levels. Structures receiving the strongest input from the spinal cord included the central gray, nucleus cuneiformis, the deep and intermediate layers of the superior colliculus, and the intercollicular nucleus. Other structures receiving afferent input from the lumbosacral spinal cord included the anterior and posterior pretectal nuclei, red nucleus, Edinger-Westphal nucleus, interstitial nucleus of Cajal, and the mesencephalic reticular formation.  

A preponderance of immunoreactivity was localized in reticular, limbic, and hypothalamic areas including: 1) in the forebrain: the bed nucleus of the stria terminalis; lateral preoptic, dorsal, anterior, lateral and posterior hypothalamic areas; amygdaloid, periventricular, arcuate, supraoptic, suprachiasmatic, ventromedial, dorsomedial, paraventricular, lateral and medial mammillary, and lateral septal nuclei; the nucleus of the diagonal band of Broca and nucleus accumbens septi; 2) in the midbrain: the periaqueductal gray, interpeduncular, dorsal and ventral tegmental, pretectal, and Edinger-Westphal nuclei; and 3) in the hindbrain: the superior central and parabrachial nuclei, nucleus incertus, locus coeruleus, and nucleus reticularis gigantocellularis. Other areas containing SLI included the striatum (caudate nucleus and putamen), zona incerta, infundibulum, supramammillary and premammillary nuclei, medial and dorsal lateral geniculate nuclei, entopeduncular nucleus, lateral habenular nucleus, central medial thalamic nucleus, central tegmental field, linear and dorsal raphe nuclei, nucleus of Darkschewitsch, superior and inferior colliculi, nucleus ruber, substantia nigra, mesencephalic nucleus of V, inferior olivary nucleus, inferior central nucleus, nucleus prepositus, and deep cerebellar nuclei.  

Retrogradely labeled cells were observed in numerous oculomotor-related structures, including the prerubral field (rostral interstitial nucleus of the medial longitudinal fasciculus), nucleus of Darkschewitsch, nucleus of the posterior commissure, deep superior colliculus, supraoculomotor ventral periaqueductal gray, contralateral paramedian pontine reticular formation, pontine raphe and dorsal medial pontine tegmentum medial to the abducens nucleus (purported to contain omnipause neurons), cell group Y, and the perihypoglossal complex (nucleus prepositus hypoglossi). Other sources of afferents to the region included the zona incerta, lateral and medial habenular nuclei, medial hypothalamus, medial mammillary nucleus, nucleus cuneiformis, medial medullary reticular formation, and the medial and lateral cerebellar nuclei.  

Following injection of wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the spinal enlargements, the lateral cervical nucleus (LCN), the dorsal column nuclei (DCN), or the spinal trigeminal nucleus, anterograde labeling was observed in several regions of the mid-brain. (1) Injection of tracer into the spinal enlargements resulted in dense terminal labeling in the parabrachial nucleus (PBN) and the periaqueductal gray matter (PAG); moderate termination was observed in the intercollicular nucleus (Inc), the intermediate and deep gray layers of the superior colliculus (SGI, SGP), the posterior pretectal nucleus (PTP), and the nucleus of Darkschewitsch (D); and scattered terminal fibers were seen in the cuneiform nucleus (CNF) and the pars compacta of the anterior pretectal nucleus (PTAc). (2) Terminal labeling after injection of tracer into LCN was found mainly in Inc, SGI, and SGP, but sparse labeling was also observed in the nucleus of the brachium of the inferior colliculus (BIN), PAG, PBN, PTP, and D. (3) The projection from DCN terminated densely in the external and pericentral nuclei of the inferior colliculus (ICX, ICP), Inc, SGI, SGP, PTP, PTAc, the nucleus ruber, and D, and weak terminal labeling was seen in BIN, PAG, and PBN. Comparisons of the anterograde labeling following injections involving both the gracile nucleus and the cuneate nucleus with that after injection restricted to the gracile nucleus alone suggested a somatotopic termination pattern in Inc, the superior colliculus, and the pretectal nuclei. (4) The patterns of projection from the laminar and alaminar parts of the spinal trigeminal nucleus differed: injection of tracer into the caudal part of the alaminar spinal trigeminal nucleus (nucleus interpolaris) resulted in dense anterograde labeling in SGI and SGP, moderate termination in Inc, and minor projections to PBN, PAG, and PTP, whereas after tracer injection into the laminar trigeminal nucleus (nucleus caudalis) terminal labeling was present only in PBN and PAG. Following injection of tracer into the midbrain terminal areas retrogradely labeled neurons were found in the spinal cord, LCN, DCN, and the spinal trigeminal nucleus, with the majority of labeled cells situated on the side contralateral to the injection site.(ABSTRACT TRUNCATED AT 400 WORDS).  

Histologically the active region was identified as overlying the nucleus of Darkschewitsch, and it was suggested that this nucleus was the origin of a pathway which via the rostral parts of the medial accessory olive projected to the C2 zone of the posterior as well as the anterior cerebellar cortex..  

It was shown that stimulation of nucleus reticularis parvocellularis of the medulla oblongata as well as interstitial nucleus of Cajal, nucleus Darkschewitsch, periaqueductal gray and pretectal area evokes in facial motoneurons monosynaptic excitatory postsynaptic potentials accompanied by single action potentials. Functional role of the midbrain structures as intermediate relays transmitting descending signals to the facial nucleus is discussed..  

Retrogradely labelled neurons in cortical areas 4 and 6 were found after injections located in the interstitial nucleus of Cajal (INC), nucleus of Darkschewitsch (ND), and in the caudal parafascicular (Pf) and subparafascicular (sPf) nuclei (perifascicular region, PF). Injections that were more caudal and within the parvi- and magnocellular red nucleus (RNp and RNm) labelled cells not only in areas 4 and 6 but also in portions of adjacent areas 3a, 3b, 5a, and 7. Cortical regions involving the representation of the neck musculature were shown to project principally ipsilaterally to lamina IV of the SC as well as to the anterior pretectal nucleus.(ABSTRACT TRUNCATED AT 400 WORDS).  

The present paper demonstrates that the lateral and medial subdivisions of the rat facial motor nucleus (NVII) receive differing mesencephalic and metencephalic projections. In order to study brain projections to facial nucleus, horseradish peroxidase (HRP) was injected iontophoretically into the entire facial nucleus or the following subdivisions: lateral, dorsolateral, medial, intermediate, and ventral. In the mesencephalic region, the retrorubral nucleus was found to project to the contralateral medial subdivision of NVII, while the red nucleus was found to project to the contralateral lateral subdivision of NVII. Other mesencephalic projections to the facial nucleus arose from the deep mesencephalic nucleus, oculomotor nucleus, central gray including interstitial nucleus of Cajal and nucleus Darkschewitsch, superior colliculus and substantia nigra (reticular). In the mesencephalic region, the Kölliker-Fuse nucleus, parabrachial nucleus, and the ventral nucleus of the lateral lemniscus projected mainly to the ipsilateral lateral subdivision of NVII. In addition, the trapezoid, pontine reticular, vestibular, and motor trigeminal nuclei were observed to have predominantly ipsilateral connections to the facial nucleus. The medullary reticular nucleus, ambiguus nucleus, spinal trigeminal nucleus and parvocellular reticular nucleus projected to both lateral and medial subdivisions of NVII with an ipsilateral predominance. The gigantocellular and paragigantocellular reticular nuclei, raphe magnus, external cuneate nucleus and the nucleus of the solitary tract also projected to the facial motor nucleus.  

Injection of tracer into the nucleus interpolaris or nucleus oralis (in the latter cases with involvement of the nucleus principalis) resulted in dense anterograde labeling in the deep and intermediate gray layers of the contralateral superior colliculus, extending throughout the rostrocaudal extent of the colliculus with the exception of its caudalmost part, which was not labeled. Minor projections to the intercollicular nucleus, posterior pretectal nucleus and nucleus of Darkschewitsch were found. Injection of tracer into the nucleus caudalis yielded a completely different result; terminal labeling in the midbrain was now present only in the periaqueductal gray matter, in its rostral and middle parts. The retrograde labeling observed after injection of tracer into the midbrain terminal areas showed that the cells of origin were located mainly in the alaminar spinal trigeminal nucleus, and the highest density of labeled neurons was found in the rostral part (subnucleus y) of the nucleus oralis. The retrograde labeling in the nucleus principalis was very sparse and almost exclusively involved peripherally located neurons. In the nucleus caudalis the overwhelming majority of the retrogradely labeled neurons were situated in its marginal layer.  

The frontal eye field also projects to the ipsilateral pretectal nuclei, subthalamic nucleus, nucleus of the posterior commissure, superior colliculus (especially layer four), zona incerta, rostral interstitial nucleus of the medial longitudinal fasciculus, nucleus Darkschewitsch, dorsomedial parvocellular red nucleus, interstitial nucleus of Cajal, basilar pontine nuclei, and bilaterally to the paramedian pontine reticular formation and the nucleus reticularis tegmenti pontis.  

Data obtained from injections of HRP into areas 6a alpha or 6a beta revealed that labeled thalamic neurons were distributed in a longitudinal band extending from the rostral part of the ventral anterior nucelus (VA) through the caudal part of the mediodorsal nucleus (MD). A few labeled cells were also located in the suprageniculate nucleus. The band of labeled cells also extended into the hypothalamus, zona incerta, amygdala, claustrum, periaqueductal gray of the midbrain, and the nucleus of Darkschewitsch.  

A light and electron microscope study was carried out to elucidate the cytoarchitectural organization of the nucleus of Darkschewitsch (ND) in the cat.  

Experiments were performed to study the projection of the group y of the vestibular nuclei and the dentate and fastigial nuclei of the cerebellum to the interstitial nucleus of Cajal (INC) in cats by using retrograde axonal transport of horseradish peroxidase (HRP) and electrophysiological methods; and to study the vestibular responses of such projection neurons. Following injections of HRP into the unilateral INC, with partial involvement of the surrounding reticular formation, including the nucleus of Darkschewitsch (ND), many retrogradely labeled neurons were found in the dorsal part of the group y nucleus contralateral to the injection site. Labeled cells were also seen in the contralateral dentate nucleus, frequently in its caudal-ventral part, and in the contralateral fastigial nucleus at all rostrocaudal levels, but most frequently in its caudal part.  

The effects of stimulation of the interstitial nucleus of Ramón y Cajal, as well as the nucleus of Darkschewitsch, inferior olive and nucleus reticularis tegmenti pontis on the neuronal activity of the lateral vestibular nucleus of Deiters were studied by means of an intracellular recording technique. Mono-, oligo- and/or polysynaptic inhibitory postsynaptic potentials were also evoked by stimulation of nucleus reticularis tegmenti pontis, as well as the rostral and particularly, caudal parts of the inferior olive. A topical correlation between Deiters' nucleus and the brainstem nuclei mentioned above was found. The presence of inhibitory and excitatory interaction of these structures with Deiters' nucleus was established..  

The largest contingent of afferents arises from the following centers: the cingulate and somatosensory cortices, central amygdaloid nucleus, ventromedial hypothalamic nucleus, posterior thalamic nucleus, anterior pretectal nucleus, peripeduncular area, deep and intermediate layers of the superior colliculus, dorsal and ventral parabrachial nuclei, principal and interpolar trigeminal subnuclei, and cuneate nucleus. Other centers less systematically or more sparsely labeled were the lateral hypothalamic area, ventrobasal complex, lateral geniculate nucleus pars ventralis, medial geniculate nucleus, interstitial nucleus of Cajal, Darkschewitsch nucleus, perirubral fields, cuneiform, tegmental pedunculopontine, and deep mesencephalic reticular nuclei, pontine reticular nucleus pars oralis, lateral and interpositus cerebellar nuclei, and gracile nucleus. It has been thus possible to distinguish a ventral zone (ventral sector of pars caudalis and pars ventralis) in which the somesthetic (somatosensory cortex, trigeminal complex, and dorsal column nuclei (DCN), collicular, and cerebellar projections terminate, from a dorsal zone (pars dorsalis) to which a limbic input (cingulate cortex and ventromedial hypothalamic nucleus) is directed.  

Attempts were made to determine brainstem and cerebellar afferent and efferent projections of the superior vestibular nucleus (SVN) and cell group 'y' ('y') in the cat using axoplasmic tracers. Controls were provided by unilateral HRP injections involving the oculomotor nuclear complex (OMC), the interstitial nucleus of Cajal (INC) and the deep cerebellar nuclei (DCN). Large injections of SVN almost invariably involved 'y' and dorsal parts of the lateral vestibular nucleus (LVN). SVN receives sparse projections from the ipsilateral INC, the contralateral central cervical nucleus (CCN) and virtually no projections from the reticular formation. SVN projects via the medial longitudinal fasciculus (MLF) to the ipsilateral trochlear nucleus (TN), the inferior rectus subdivision of the OMC, the INC, the nucleus of Darkschewitsch (ND) and the rostral interstitial nucleus of the MLF (RiMLF).  

Experiments in 5 monkeys revealed 3 major sources of input: (1) bilateral projections from the so-called frontal eye field (FEF), which is situated in the frontal cortex around the arcuate sulcus; (2) the intermediate and deep layers of mainly the contralateral superior colliculus; and (3) ipsilateral projections from brainstem structures such as the accessory oculomotor nuclei (nucleus interstitialis of Cajal, nucleus of Darkschewitsch, and nucleus of the posterior commissure), the mesencephalic reticular formation, the vestibular nuclei, the nucleus prepositus hypoglossi, and the cerebellar fastigial nucleus.  

Afferent and efferent connections of the medial preoptic area including medial preoptic nucleus (MP) and periventricular area at the MP level were examined using WGA-HRP as a marker. Previously reported reciprocal connections with lateral septum, bed nucleus of the stria terminalis, medial amygdaloid nucleus, lateral hypothalamic nucleus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, arcuate nucleus, supramammillary nucleus, central gray at the mesencephalon, raphe dorsalis, raphe medianus, and lateral parabrachial nucleus have been confirmed. In addition, we found reciprocal connections with septo-hypothalamic nucleus, amygdalo-hipocampal nucleus, subiculum, parafascicular thalamic nucleus, posterior thalamic nucleus at the caudo-ventral subdivision, median preoptic nucleus, lateral preoptic nucleus, anterior hypothalamic nucleus, periventricular area at the caudal hypothalamic level, dorsomedial hypothalamic nucleus, posterior hypothalamic nucleus, dorsal and ventral premammillary nucleus, lateral mammillary nucleus, peripeduncular nucleus, periventricular gray, ventral tegmental area, interpeduncular nucleus, nucleus raphe pontis, nucleus raphe magnus, pedunculo-pontine tegmental nucleus, gigantocellular reticular nucleus and solitary tract nucleus. The areas which had only efferent connections from MP were accumbens, caudate putamen, ventral pallidum, substantia innominata, lateral habenular nucleus, paratenial thalamic nucleus, paraventricular thalamic nucleus, mediodorsal thalamic nucleus, reuniens thalamic nucleus, median eminence, medial mammillary nucleus, subthalamic nucleus, pars compacta of substantia nigra, oculomotor nucleus, red nucleus, laterodorsal tegmental nucleus, reticular tegmental nucleus, cuneiform nucleus, nucleus locus coeruleus, and dorsal motor nucleus of vagus among which substantia innominata and median eminence were previously reported. Efferent connections to the nucleus of Darkschewitsch, interstitial nucleus of Cajal, dorsal tegmental nucleus, ventral tegmental nucleus, vestibular nuclei, nucleus raphe obsculus were very weak or abscent in the ventral approach while they were observed in dorsal approach. Previously reported afferent connections from dorsal tegmental nucleus, cuneiform nucleus, and nucleus locus ceruleus were not detected in this study.(ABSTRACT TRUNCATED AT 400 WORDS).  

WGA-HRP injections into the LD or LP labeled also a considerable number of neurons in the dorsal raphe nucleus and the dorsal tegmental nucleus bilaterally with homolateral predominance, but the nucleus of Darkschewitsch contained labeled neurons only after the LD injection..  

Projections of the medial terminal nucleus (MTN) of the accessory optic system, the ventral tegmental area of Tsai, and the substantia nigra of the rabbit and the rat have been studied by the method of retrograde axonal transport of horseradish peroxidase. The MTN projects heavily to the ipsilateral nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system and to a portion of the contralateral ventral tegmental area of Tsai that we have termed the visual tegmental relay zone (VTRZ). Further, the MTN sends projections to the ipsilateral mesencephalic (deep mesencephalic nucleus, pars medialis) and pontine (nucleus reticularis pontis oralis) reticular formations; the contralateral dorsolateral division of the basal pontine complex; the superior and lateral vestibular nuclei (contralateral in rat; bilateral in rabbit); and the ipsi- and contralateral interstitial nucleus of Cajal, nucleus of Darkschewitsch, and supraoculomotor-periaqueductal gray. The nucleus parabrachialis pigmentosus sends a small contralateral projection to the VTRZ and a moderate-sized bilateral projection to the supraoculomotor-periaqueductal gray. The nucleus paranigralis sends a moderate number of axons to the ipsilateral deep mesencephalic nucleus, pars medialis, and the nucleus reticularis pontis oralis and provides a strong bilateral projection to the supraoculomotor-periaqueductal gray. The pars compacta of the substantia nigra provides a sparse input to the ipsilateral deep mesencephalic nucleus, pars medialis, and nucleus reticularis pontis oralis, and to the contralateral VTRZ and sends a moderate number of axons, bilaterally, to the supraoculomotor-periaqueductal gray.The pars reticulata of the substantia nigra sends an ipsiateral projection of moderate size to the intermediate and deep layers of the superior colliculus, sparse ipsilateral projections to the deep mesencephalic nucleus, pars medialis, and nucleus reticularis pontis oralis, and a sparse bilateral projection to.  

Injections of combined lectin-conjugated and unconjugated horseradish peroxidase were made in the dorsal (d) and ventral (v) divisions of the paramedian reticular nucleus (PRN), a precerebellar relay nucleus, of the cat. The interstitial nucleus of Cajal projects bilaterally to the dPRN and predominantly to the ipsilateral side. The vPRN receives only a unilateral projection from the ipsilateral nucleus of Cajal. Major afferent projections to the vPRN arise from the ipsilateral nucleus of Darkschewitsch and the intermediate layer of the contralateral superior colliculus.  

The major differences in distribution patterns were as follows: Injections of HRP into the lateral or ventrolateral portions of the ventroanterior and ventrolateral nuclear complex of the thalamus (VA-VL) produced retrogradely labeled neurons consistently in area 4 gamma (lateral part of the anterior and posterior sigmoid gyri, lateral sigmoid gyrus and the lateral fundus of the cruciate sulcus), the medial division of posterior thalamic group (POm), suprageniculate nucleus (SG) and anterior pretectal nucleus ipsilaterally, and in the nucleus Z of the vestibular nuclear complex bilaterally. fu (posterior part of the bank), fundus of the presylvian sulcus (area 6a beta), medial part of the nucleus lateralis posterior of thalamus and nucleus centralis dorsalis ipsilaterally, and in the entopeduncular nucleus (EPN) and medial pretectal nucleus bilaterally. After HRP injections into the ventral medial nucleus (VM), major labeled neurons were observed in the gyrus proreus, area 6a beta (mainly in the medial bank of the presylvian sulcus), and EPN ipsilaterally, and in the medial pretectal nucleus and substantia nigra bilaterally. Following HRP injections into the centre médian nucleus (CM), major labeled neurons were found in the areas 4 gamma, 6a beta, and the orbital gyrus ipsilaterally, and in the EPN, rostral and rostrolateral parts of the thalamic reticular nucleus, locus ceruleus, nucleus reticularis pontis oralis et caudalis and nucleus prepositus hypoglossi bilaterally. The contralateral intercalatus nucleus also possessed labeled neurons.  

In the Parkinsonian cases, the rostral part of the nucleus of Edinger Westphal disclosed Lewy bodies in 3% of the neurons, neurofibrillary degeneration in 2% of the neurons, and a 54% neuronal loss. In Alzheimer's disease, 2% of Edinger Westphal neurons contained neurofibrillary degeneration, whereas in senile dementia of Alzheimer's type only rare neurofibrillary degeneration was evident in this nucleus. Neuronal loss was not apparent in the nucleus of Edinger Westphal in either of the Alzheimer's cases. The pathologic changes observed in this presumably cholinergic nucleus resemble in some respects changes reported in the cholinergic centers of the basal forebrain in these diseases. In addition, the central gray matter and pretectal region in Parkinson's disease contained a patchy increase in astroglia, some with scant reactive cell bodies; however, Lewy bodies were limited to that part of the central gray matter corresponding to the nucleus of Darkschewitsch. A few neurofibrillary tangles were present in the nucleus of Darkschewitsch in both diseases..  

Projections from the midbrain and caudal diencephalon to the inferior olivary nucleus (ION) in the rat were investigated by using anterograde and retrograde tracing techniques. Particular attention was directed to studying the projection from the red nucleus (RN) to the ION. No labeled cells were noted in the RN or the nucleus of Darkschewitsch (ND).  

The main terminal area was situated at the level of transition between the superior and inferior colliculus on the side contralateral to the injection site and comprised the intercollicular nucleus and part of the external and pericentral nuclei of the inferior colliculus and of the nucleus of the brachium of the inferior colliculus, but there were also projections to the caudal half of the deep and intermediate gray layers of the superior colliculus, the anterior and posterior pretectal nuclei, the nucleus of Darkschewitsch and nucleus ruber. Injections restricted to either the gracile nucleus or the cuneate nucleus revealed a somatotopic termination pattern in the intercollicular nucleus, superior colliculus and pretectal nuclei.  

In 33 cats the projections of different parts of the mesencephalon to the facial nucleus were studied with the aid of the autoradiographical tracing method. The dorsomedial facial subnucleus, containing motoneurons innervating ear muscles, receives afferents from 4 different mesencephalic areas: a, the most rostral mesencephalic reticular formation; b, the nucleus of Darkschewitsch and/or the ventral part of the rostral PAG; c, the interstitial nucleus of Cajal and/or the mesencephalic tegmentum dorsomedial to the red nucleus. The lateral mesencephalic tegmentum close to the parabigeminal nucleus. The mesencephalic tegmentum just dorsolateral to the red nucleus and perhaps from the dorsolateral red nucleus itself. The intermediate facial subnucleus containing motoneurons innervating the muscle around the eye, receives afferents from two different mesencephalic areas: The dorsal part of the rostral as well as caudal red nucleus (but not from its caudal pole) and from the dorsally adjoining mesencephalic tegmentum including the area of the nucleus of Darkschewitsch and the interstitial nucleus of Cajal. The nucleus of the optic tract and/or the olivary pretectal nucleus. The nucleus raphe dorsalis and perhaps the nucleus centralis superior.  

Afferents to the ventral tegmental nucleus of Gudden (VT) were investigated in mice, rats, and cats. Fewer labeled cells were observed in the prefrontal cortex, the basal forebrain, various hypothalamic nuclei, the interpeduncular nucleus, nucleus of the posterior commissure, nucleus of Darkschewitsch and interstitial nucleus of Cajal, vestibular nucleus, and nucleus praepositus hypoglossi. Scant but consistent labeling occurred in the cingular, retrosplenial, and insular cortices, within the medial forebrain bundle, fields of Forel, zona incerta, ventral tegmental area of Tsai, substantia nigra, pretectal area, periaqueductal gray, dorsal tegmental nucleus, locus ceruleus, and raphe complex.  

Fluid HRP injections or transcannular solid polyacrylamide HRP gel implants were made into the oculomotor nucleus (OMN) and adjacent nuclei to label retrogradely corticofugal neurons that project to this region, and cortical HRP gel implants were made in various areas of the frontal lobe to label anterogradely the trajectories and terminations of cortico-paraoculomotor projections and thus to confirm the retrograde findings. Both retrograde and anterograde studies confirmed that the prearcuate cortex in the concavity of the arcuate sulcus, including the frontal eye field, and, to a lesser extent, suprarcuate rostral dorsal area 6 cortex and the dorsomedial convexity (area 9), project to the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) in the dorsal region of the prerubral field, nucleus of Darkschewitsch (ND), medial accessory nucleus of Bechterew (NB) and dorsomedial parvocellular red nucleus (dmPRN). The premotor area 6 and motor area 4 cortex, on the other hand, give rise to projections that target a larger portion of the parvocellular red nucleus, extending rostrally into the ventral region of the prerubral field, and a rather intense projection to the ND. The interstitial nucleus of Cajal (IC) was distinguished more by its light, or lack of, projections from the frontal cortex.  

After injecting horseradish peroxidase into the facial nucleus regions containing orbicularis oculi motoneurons, labeled neuronal cell bodies were found in the lateral medullary reticular formation, pretectal olivary nucleus, sensory trigeminal nuclei, lateral and medial parabrachial nuclei, ventromedial reticular formation medial to the facial nucleus, red nucleus and its surroundings, anterior horn of the upper cervical cord, medullary raphe nuclei, oculomotor nucleus and its surroundings, nuclei of Darkschewitsch, Cajal and Edinger-Westphal, ventral part of the midbrain central gray, pontine tegmentum, lateral vestibular nucleus and deep layers of the superior colliculus..  

The projections of the medial terminal nucleus (MTN) of the accessory optic system have been studied in the rabbit and rat following injection of 3H-leucine or 3H-leucine/3H-proline into the MTN and the charting of the course and terminal distribution of the MTN efferents. The largest projection is to the ipsilateral nucleus of the optic tract and dorsal terminal nucleus (DTN) of the accessory optic system. Labeled axons course through the midbrain reticular formation and the superior fasiculus, posterior fibers of the accessory optic system, to reach the nucleus of the optic tract and the DTN in both rabbit and rat. Axons also run forward to traverse the lateral thalamus and to distribute to rostral portions of the nucleus of the optic tract in rat only. A second, large projection is to the contralateral dorsolateral portion of the nucleus parabrachialis pigmentosus of the ventral tegmental area together with an adjacent segment of the midbrain reticular formation. This fiber projection courses within the posterior commissure and along its path to the VTRZ, provides terminals to the interstitial nucleus of Cajal and the nucleus of Darkschewitsch, both bilaterally. A third, large MTN projection distributes ipsilaterally to the deep mesencephalic nucleus, pars medialis, and the oral pontine reticular formation. Further, this projection also supplies input to the medial nucleus of the periaqueductal gray matter, bilaterally in the rabbit and rat, and in the rabbit also to the ipsilateral superior and lateral vestibular nuclei. A fifth projection of the MTN utilizes the medial longitudinal fasciiculus to reach the rostral medulla, in which its axons distribute ispilaterally to the dorsal cap, its ventrolateral outgrowth, and the beta nucleus of the inferior olivary complex.  

Following HRP injections in various parts of the inferior olive, many cells were labeled ipsilaterally in the nucleus of Darkschewitsch, the nucleus accessorius medialis of Bechterew, the nucleus of the fields of Forel, and the subnucleus dorsomedialis and ventrolateralis of the parvocellular red nucleus. Some labeled cells also occurred ipsilaterally in the suprarubral reticular formation and a few labeled cells in the interstitial nucleus of Cajal. That is, the nucleus of Darkschewitsch was found to project to the rostral half of the medial accessory olive and the dorsomedial cell column. The nucleus accessorius medialis of Bechterew was found to project to the ventral lamella and the lateral part of the dorsal lamella as well as to small rostromedial part of the caudal half of the medial accessory olive. The subnucleus dorsomedialis and ventrolateralis of the parvocellular red nucleus projected to the rostral and caudal halves, respectively, of the medial part of the dorsal lamella. The subnucleus ventrolateralis of the parvocellular red nucleus also sent fibers to the lateral part of the ventrolateral outgrowth. The nucleus of the fields of Forel, suprarubral reticular formation, and interstitial nucleus of Cajal appeared to project to the caudal half of the medial accessory olive, the medial part of the ventrolateral outgrowth, the rostral part of the dorsal cap, and the caudal part of the dorsal accessory olive..  

Labeled nuclei included (from caudal to rostral): dorsal and ventral parabrachial nuclei; Kolliker-Fuse nucleus; dorsolateral tegmental nucleus; A7 (lateral pontine tegmentum medial to lateral lemniscus); median and dorsal raphe nuclei; distinct group of cells oriented mediolaterally in the dorsal pontine tegmentum below the central gray; B9 (ventral midbrain tegmentum dorsal to medial lemniscus); retrorubral nucleus; nucleus of Darkschewitsch, interfascicular nucleus; rostral and caudal linear nuclei; ventral tegmental area; medial part of substantia nigra, pars compacta; and the supramammillary nucleus. With the exception of the ventral parabrachial nucleus, Kolliker-Fuse, A7, B9 and substantia nigra, pars compacta, each of the nuclei mentioned above sent strong projections along the medial forebrain bundle to the rostral forebrain. With the exception of the dorsal raphe nucleus, projections to the most anterior regions of the medial forebrain bundle (level of the anterior commissure) essentially only arose from presumed dopamine-containing nuclei-retrorubral nucleus (A8 area), interfascicular nucleus, rostral and caudal linear nuclei, substantia nigra pars compacta, and ventral tegmental area.  

The main terminal areas were the periaqueductal gray matter, the intercollicular nucleus, the posterior pretectal nucleus and the nucleus of Darkschewitsch. In addition, there was a sparse projection to the cuneiform nucleus and the anterior pretectal nucleus.  

The results show large projections to the lateral and ventrolateral parts of the periaqueductal gray (PAG1), the posterior pretectal nucleus (PP) and the nucleus of Darkschewitsch (D). More moderate projections go to the medial division of the periaqueductal gray (PAGm), the cuneiform nucleus (CF), the mesencephalic reticular formation (MRF), lateral part of the deep layer of the superior colliculus (SP) and magnocellular medial geniculate nucleus (GMmc), while scattered spinal fibers are present in the dorsal part of the periaqueductal gray (PAGd), the external inferior collicular nucleus (IX), the intermediate layer of the superior colliculus (SI), the lateral part of the red nucleus (NR) and in the Edinger-Westphal portion of the oculomotor nucleus (3). In addition a few fibers are present in the interstitial nucleus of Cajal (CA) and anterior pretectal nucleus (PAc).  

Effects of stimulation of the Cajal interstitial nucleus and Darkschewitsch nucleus on the activity of neurons of the lateral vestibular nucleus of Deiters was studied in experiments on cats anesthetized with nembutal.  

The nucleus of Darkschewitsch (ND) of the cat was observed electron microscopically after surgical ablation of the motor cortex and horseradish peroxidase (HRP) injection into the inferior olive of the same animals.  

reticularis parvocellularis, the interstitial nucleus of Cajal and the nucleus of Darkschewitsch.  

Results showed that the interstitial nucleus of Cajal (INC) projected mainly to the spinal cord, with only a modest termination within the inferior olive. The nucleus of Darkschewitsch and the rostromedial portion of the red nucleus projected heavily to the inferior olive but not to the spinal cord.  

When the injections were placed in the lateral part of the motor area of the hand or arm regions, silver grains were manifested in the nucleus of Darkschewitsch (ND) in its whole rostrocaudal extent, and they were observed also in the ventrolateral part of the anterior pretectal nucleus (PA) and in the caudal portion of the posterior pretectal nucleus (PP).  

The small injections were centered in the nucleus raphe magnus, nucleus reticularis gigantocellularis, or nucleus medullae oblongatae centralis. The five labeled midbrain nuclei were the periaqueductal gray, nucleus cuneiformis, deep layers of the superior colliculus, nucleus of Darkschewitsch, and the interstitial nucleus of Cajal. In addition, the parvocellular division of the red nucleus and the posterior pretectal nucleus contained large numbers of cells when the injection spread into the inferior olive.  

Afferents of the nucleus raphe magnus (NRM) were retrogradely labelled by using a transcannula HRP gel technique in conjunction with tetramethylbenzidine neurohistochemistry to determine the sources of inputs to the nucleus which could potentially influence the descending antiociceptive raphe-spinal system. Large numbers of HRP-labelled neurons were seen in the frontal cortex, dorsomedial nucleus of the hypothalamus, zona incerta, nucleus parafascicularis prerubralis (NPfPr), pretectum, dorsal and lateral periaqueductal gray, nucleus cuneiformis (NC), deep superior colliculus (dSC), a paraoculomotor cell group which may be the medial accessory nucleus of Bechterew, dorsal column nuclei, and spinal trigeminal nucleus. Smaller numbers of labelled cells were also observed in the preoptic area, nucleus of Darkschewitsch, ventral peri(third)ventricular gray, nucleus reticularis pontis oralis and caudalis, medial and lateral vestibular nuclei, and a subdivision of the hypoglossal nucleus. The results are compared with control HRP gel implants in the inferior olive, spinal cord, nucleus reticularis paragigantocellularis, and medial facial nucleus.  

In cases with injections placed in the lateral part of area 4, dense accumulations of label were present in the lateral part of the ventral anterior nucleus (VA), the central part of the ventral lateral nucleus (VL), the ventral half of the ventral posterior inferior nucleus (VPI), the caudal part of the central lateral nucleus (CL), and the centrum medianum (CM). Lighter label was also present in the lateral part of the cytoarchitectonically distinct VL region bordering the ventrobasal complex (VB), as well as in the ventrolateral part of the mediodorsal nucleus (MD), and in the lateral posterior nucleus (LP). Projections from both the lateral and medial parts of area 4 were also noted in the subthalamic nucleus, zona incerta, and nucleus of Darkschewitsch.  

In the midbrain the periaqueductal gray, the nucleus of Darkschewitsch and the posterior pretectal nucleus contained fairly dense labeling. Labeling was more scattered in the cuneiform nucleus, the mesencephalic reticular formation, the superior colliculus and in the magnocellular part of the medial geniculate body..  

This study describes the cytoarchitecture and neuronal morphology of the interstitial nucleus of Cajal (INC) in the cat. In addition, the efferent projections of this nucleus to the spinal cord and inferior olive were studied by retrograde labelling with horseradish peroxidase (HRP). Caudally, the nucleus consists of a small number of loosely aggregated neurons lying lateral to the ventral periaqueductal gray matter at a rostrocaudal level corresponding to the rostral one-fifth of the somatic cell columns of the oculomotor nucleus. Rostrally, the INC increases in size and reaches its maximum development in its rostral half, where it lies ventrolateral to the nucleus of Darkschewitsch (ND). Following injections of HRP into the inferior olive only small to medium-sized neurons were labelled in the nucleus, the majority of which are located in rostral levels of the INC. A substantial olivary projection was observed to originate in the nucleus of Darkschewitsch (ND) and the nucleus parafascicularis (NPF). Smaller numbers of neurons were also observed in the rostral parvocellular red nucleus (RN) and mesencephalic reticular formation (MRF)..  

Autoradiographic experiments showed that the incertofugal fiber systems reach ipsilaterally to the thalamus (lateral dorsal, central lateral, ventral lateral geniculate, parafascicular, subparafascicular and reuniens nuclei, and posterior nuclear complex), to the hypothalamus (dorsal, lateral and posterior hypothalamic areas), to the tectum (medial pretectal area, deep pretectal and pretectal nuclei, superior colliculus and periaqueductal gray) and to the midbrain tegmentum, pons and medulla oblongata (subcuneiform, cuneiform and red nuclei, nuclei of the posterior commissure and Darkschewitsch, interstitial nucleus of Cajal, pedunculopontine tegmental nucleus, oral and caudal pontine reticular nuclei, nucleus raphe magnus, gigantocellular reticular nucleus, pontine gray and inferior olivary complex).  

The medial accessory nucleus of Bechterew, a vertically oriented cell group in the rostral lateral oculomotor nucleus (OMN), contiguous dorsally with the nucleus of Darkschewitsch (ND) and ventrally with the parvocellular red nucleus, is separated from the interstitial nucleus of Cajal (IC) by a small paraoculomotor fascicle (POF) that forms the anatomical limits of the OMN. The functional role of this largely overlooked nucleus is yet to be determined.  

The retrograde transport of fluorescent substances was used in order to investigate divergent axon collaterals of neurons in the nucleus prepositus hypoglossi (Ph). Fast blue (FB) was injected into the flocculus, paraflocculus and/or the vermis, while nuclear yellow (NY) was injected into the oculomotor nucleus alone or combined with injections in the nucleus of Darkschewitsch, the interstitial nucleus of Cajal and the medial longitudinal fascicle. Double-labeled neurons were seen in the rostral Ph following FB injections into the flocculus and the paraflocculus and NY injections restricted to the oculomotor nucleus. The present findings demonstrate that many neurons in the rostral Ph give collateral branches to the cerebellum and to the oculomotor nucleus..  

Fibers from the dentate (DN), anterior interpositus (AIN) and posterior interpositus (PIN) nuclei were distributed contralaterally, while those from the fastigial nucleus (FN) bilaterally. In the pretectum, the DN fibers terminated ventrally in the reticular part of the anterior pretectal nucleus and the posterior pretectal nucleus. THe AIN fibers terminated ventrally in the compact part of the anterior pretectal nucleus and the posterior pretectal nucleus. The nucleus of the posterior commissure received cerebellar fibers chiefly from the DN, and additionally from the FN. The nucleus of Darkschewitsch and the interstitial nucleus of Cajal received fibers from all cerebellar nuclei.  

The rostral interstitial nucleus of the medial longitudinal fasciculus in known to participate in the generation of fast vertical eye movements in the monkey. A cell group homologous to this nucleus has been identified in the human brain. In man the nucleus lies dorsomedial to the anterior pole of the red nucleus, rostral to the interstitial nucleus of Cajal, and lateral to the nucleus of Darkschewitsch. Reconstructions of lesions in patients with different types of vertical gaze paralysis show that destruction of the rostral interstitial nucleus of the MLF bilaterally leads to an impairment of fast vertical eye movements. We propose that the nucleus participates in the production of vertical saccades and quick phases of nystagmus in man.  

The present study demonstrated that there are three main origins of the cerebellotectal projections in regard to the locations of the cell bodies: (1) the caudal half approximately of the fastigial nucleus (NM) including the subnucleus medialis parvocellularis (SMP), (2) the ventral and lateral parts of the posterior interpositus nucleus (NIP), and (3) the ventral part of the dentate nucleus (NL) including the subnucleus lateralis parvocellularis (SLP).  

Retrogradely labelled cells are present in the ventral part of the central grey, the nucleus of Darkschewitsch (especially its ventral part), the Edinger-Westphal nucleus, the interstitial nucleus of Cajal and the reticular formation between the red nucleus and the central grey. The projection is ipsilateral and the heaviest contribution of afferents is derived from the interstitial nucleus of Cajal.  

These were located adjacent to the central gray and extended from the rostral red nucleus to the posterior thalamus. After injections in the caudo-medial parafascicular and subparafascicular nuclei and rostral nucleus of Darkschewitsch, deposits of grains were observed in the rostral pole of the medial accessory olive and adjacent ventral lamella of the principal olive. More caudal injections which involved the interstitial nucleus of Cajal as well as the nucleus of Darkschewitsch and rostral red nucleus resulted in the dense labeling of the entire principal olive (except the dorsal cap), the entire medial accessory olive (except subnucleus beta and the caudo-medial pole) and the caudo-dorsal accessory olive. Injections centered in the caudal magnocellular red nucleus and extending into the rostral parvocellular division labelled the dorsal lamella of the principal olive almost exclusively. When only the caudal part of the red nucleus was involved in the injection, the olive was entirely clear of grains. The deep layers of the superior colliculus were found to project strongly to the contralateral medial accessory olive immediately beside subnucleus beta and weakly to the same area ipsilaterally. Injections in the caudate nucleus, entopeduncular nucleus and ventral anterior and ventral lateral thalamic nuclei, did not result in any labeling in the olive..  

Small microelectrophoretic injections of tritiated proline and leucine practically confined to the ZI were found to label a widespread, predominantly ipsilateral system of descending and ascending fibers distributed to reticular structures of the brain stem (mesencephalic reticular formation, nucleus tegmenti pedunculopontinus pars compacta, parabrachial area, nuclei reticularis pontis oralis, pontis caudalis, gigantocellularis and medullae oblongatae, pars ventralis), precerebellar nuclei (nucleus reticularis tegmenti pontis, pontine nuclei and inferior olivary complex), the middle and deep layers of the superior colliculus, the pretectum (anterior, posterior and medial pretectal nuclei), perioculomotor nuclei (interstitial nucleus of Cajal, nucleus of Darkschewitsch and nuclei of th posterior commissure), the parvocellular portion of the red nucleus, the central gray substance, the nucleus tegmenti dorsalis lateralis, the ventral horn of the cervical spinal cord, non-specific thalamic nuclei (parafascicular, centralis medius, paracentralis, centralis lateralis and ventromedial thalamic nuclei, nucleus reuniens), basal ganglia (entopeduncular nucleus and globus pallidus), hypothalamic structures (posterior hypothalamic nucleus, dorsal and lateral hypothalamic areas), and a subpallidal district of the substantia innominata.  

In the nucleus of Darkschewitsch peak production time was on day E12 and 13, extending to day E15; in the Edinger-Westphal nucleus the time span was the same but with a pronounced between days E13; finally, the neurons of the parabigeminal nucleus were produced between days E13 and E15 with a peak on day E14. In the red nucleus the neurons were produced on days E13 and E14 with a caudal-to-rostral gradient: the cells of the magnocellular division preceding slightly but significantly the cells of the parvocellular division. The neurons of the interpeduncular nucleus originated between days E13 and E15; the peak in its ventral portion was on day E13, in its dorsal portion on days E14 and E15.  

The retrograde transport of horseradish peroxidase (HRP) was employed in 35 cats to trace the sources of descending afferents to the inferior olivary nucleus. The majority of HRP-labeled cells were located in the ipsilateral mesencephalon, from the rostral pole of the red nucleus to the caudomedial border of the thalamus. Among the heavily labeled nuclear groups were the the parvocellular red nucleus, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, and the caudomedial extremity of the subparafascicular nucleus. Occasional cells were also labeled in the reticular formation lateral to the interstitial nucleus of Cajal in the caudomedial parafascicular nucleus, in the nucleus of the fields of Forel, and in the central gray. Elsewhere in the midbrain, there were HRP-labeled cells in the deep layers of the superior colliculus (IV and VI), predominantly on the side contralateral to the injection and in the nucleus of the optic tract, and in the anterior and posterior pretectal nuclei, ipsilaterally. Certain areas previously reported to project to the inferior olive were devoid of labeled cells; these included the basal ganglia, the rostral raphe nuclei, and the nucleus of Edinger-Westphal.  

Two were placed ventromedial to the caudal half of the abducens nucleus (VIn), two were placed further laterally and ventral to the rostral half of the nucleus, and two were placed rostral to the nucleus. Injections placed caudomedial to VIn resulted in a characteristic concentration of labeled cells in the ipsilateral nucleus cuneiformis and rostral half of the contralateral superior colliculus (SC). Injections placed rostral to VIn in PARF produced cell labeling in the nucleus campi Foreli.  

A comparison of neurogenesis in different components of the visuomotor and visual pathways of the rat indicates that the motor neurons of the extraocular muscles, the abducens, trochlear and oculomotor nuclei, and neurons of the nucleus of Darkschewitsch are produced first. Next in line are source neurons of efferents to the bulb and the spinal cord: those of the Edinger-Westphal nucleus and the intermediate magnocellular zone of the superior colliculus. These are followed by the relay neurons of the dorsal nucleus of the lateral geniculate body.  

Cerebellar efferent fibers terminate contralaterally in both divisions of the red nucleus, and bilaterally in the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the oculomotor nucleus, and the central gray. Rather there are longitudinally oriented strips of terminal labeling which extend through all divisions of the ventral lateral nucleus, i.e., the VLps, the VLc, the VLo, as well as nucleus X, the oral division of the ventral posterolateral nucleus (VPLo), the central lateral nucleus (CL), and the most caudal region of the ventral anterior nucleus (VA).  

These projections originate in the periventricular somatostatin-immunoreactive perikarya of the hypothalamus and form three main pathways: (1) along the stria medullaris thalami and the fasciculus retroflexus into the interpeduncular nucleus; (2) along the medial forebrain bundle into the mammillary body; and (3) via the periventricular gray and the bundle of Schütz into the midbrain tegmentum. Densely arranged immunoreactive fibers and/or basket-like fiber terminals are observed within the following afferent systems: somatic afferent systems (nucleus spinalis nervi trigemini, substantia gelatinosa dorsalis of the entire spinal cord), and visceral afferent systems (nucleus solitarius, regio intermediolateralis and gelatinosa gelatinosa of the sacral spinal cord). Perikarya of the third afferent neuron are influenced by somatostatin-immunoreactive projections into the auditory system (nucleus dorsalis lemnisci lateralis, nucleus corporis trapezoidei). Furthermore, a somatostatin-immunoreactive fiber projection is found in the ventral part of the medial accessory olivary nucleus, in nuclei of the limbic system (nucleus habenularis medialis, nucleic supramamillaris and mamillaris lateralis) and in the formatio reticularis (nucleus Darkschewitsch, nuclei tegmenti lateralis and centralis, nucleus parabrachialis lateralis, as well as individual perikarya of the reticular formation).  

First, there are targets of a major ipsilateral descending pathway which include: the dorsal cap of Kooy of the inferior olivary complex, the dorsolateral and dorsomedial regions of the griseum pontis, the mesencephalic reticular formation which lies immediately dorsal and lateral to the red nucleus, the medial terminal nucleus and the superficial layers of the superior colliculus. A second category of targets receive their pretectal input from a large ascending bundle which projects ipsilaterally to: the reticular and lateral nuclei of the thalamus, the zona incerta, the central lateral and paracentral intralaminar nuclei of the thalamus and bilaterally to the ventral lateral geniculate nucleus. Pretectofugal fibers projecting to nuclei in this third category terminate ipsilaterally within the nucleus of Darkschewitsch, bilaterally within the nucleus of the posterior commissure and the interstitial nucleus of Cajal, and contralaterally within the somatic cell column of the oculomotor and trochlear nuclei.  

The same PPRF neurons also responded to medium frequency stimulation of excitatory pulse trains released from the medial vestibular nuclei, mainly in cats with enucleated nucleus interstitialis of Cajal and nucleus Darkschewitsch (NiC, ND) (inhibitory interneurons). The special PPRF neurons selectively respond to the cyclic stimuli of second order vestibular nucleus origin with release of the pontine PGO waves.  

Bilateral simultaneous stimulation elicited straight downward binocular movements from a core of tissue about 40 mm3 on each side which included the fields of Forel, zona incerta, subthalamic nucleus, oral pole of the red nucleus, fasciculus retroflexus and 'area tegmentalis'. The so-called rostral interstitial nucleus of the medial longitudinal fasciculus and the nucleus campi Foreli appear to be destroyed. These structures are known to receive an input from the paramedian pontine reticular formation and project on to the oculomotor nerve nucleus.  

The superior vestibular nucleus sends commissural fibres to the superior, medial, and descending nuclei and to Deiters' complex. The cell group A projects to the contralateral superior nucleus and to the Deiter's complex. The medial nucleus projects to the contralateral superior and descending nuclei, Deiters' complex, as well as strongly to the medial nucleus. The descending nucleus projects commissurally to the superior nucleus, the medial nucleus and the Deiters' complex, as well as heavily to the descending nucleus. The nucleus Deiters ventralis, the nucleus Deiters dorsalis, the cell group B and the trangential nucleus do not project to any other vestibular nuclei. Furthermore, the medial nucleus projects to the superior and descending nuclei and the Deiters' complex on the same side. The descending nucleus projects to the superior and medial nuclei on the same side. Finally, the superior nucleus, the medial nucleus, the descending nucleus, and the Deiters' compelx receive fibres from the ipsilateral nucleus of Darkschewitsch and the nucleus ectomammillaris, as well as bilaterally from the pontine but mainly from the bulbar reticular formation..  

The afferents to the oculomotor nucleus were examined in the macaque monkey by means of horseradish peroxidase. The demonstration of afferents from the contralateral interstitial nucleus of Cajal, and from the nearby rostral interstitial nucleus of the medial longitudinal fasciculus, predominantly ipsilateral to the injection site, confirms the significant role of these two regions as premotor structures. HRP label in the pretectal area was strictly confined to the olivary nucleus and the corresponding pathway seems to concern the Edinger-Westphal nucleus in particular. A purely crossed internuclear pathway emanating from the abducens nucleus could be established, and evidence for the presence of intranuclear connections within the oculomotor complex itself was found. Ipsilateral afferents from the superior vestibular nucleus and bilateral connections from the medial vestibular nucleus and the y-group were prominent. A projection, showing some rostrocaudal organization within the oculomotor nucleus, arises from the ipsilateral perihypoglossal complex, and other afferents originated from the underlying medullary reticular formation. No evidence was found for the existence of afferents from the paramedian pontine reticular formation, the nucleus Darkschewitsch, the nuclei of the posterior commissure, the lateral tegmentum and the dentate nucleus..  

Laminar projections into the parvocellular red nucleus were found bilaterally from the somatotopic representation areas of the precentral cortex and three main divisions of premotor cortex (ventral, dorsal, and medial). Homolateral projections were found from the limb areas of the precentral motor cortex to the magnocellular portion of the red nucleus and direct evidence for the overlap between corticorubral projections and corresponding areas of origin of the rubrospinal tract was obtained.  

The cell group lies ventral to nucleus of Darkschewitsch (nD), rostral to the interstitial nucleus of Cajal (iC) and the tractus retroflexus (TR). It receives inputs from areas which control eye movements, PPRF and the vestibular nuclei, and sends efferents to the oculomotor nucleus. In an attempt to be anatomically specific the name rostral interstitial nucleus of the medial longitudinal fasciculus (rostral iMLF) has been used..  

Techniques of intra-axonal transport were utlizied to elucidate the organization of diencephalic and midbrain projections to the inferior olivary nucleus of the Virginia opossum. Retrograde transport of horseradish peroxidase injected into the olive suggests that terminals within it arise from the subparafascicular nucleus of the caudal thalamus, the nucleus of Darkschewitsch, the fields of Forel, the interstitial nucleus of Cajal, the periaqueductal grey, the caudal pretectal nucleus, the tegmentum dorsomedial to the red nucleus, the red nucleus (minimal), the nucleus linearis, as well as the dorsolateral midbrain tegmentum and tectum (Henkel et al., '75). Ventromedial areas of the midbrain, including the ventral periaqueductal grey, the interstitial nucleus of Cajal, part of the red nucleus and the tegmentum dorso-medial to it, provide a substantial and topographically organized projection to the principal nucleus of the olive, as well as minor inputs to the accessory nuclei. Secondly, neurons within the subparafascicular nucleus, the nucleus of Darkschewitsch and the fields of Forel project most heavily to parts of the medial accessory nucleus, although they also provide input to the other major subdivisions of the olive. Third, axons from the dorsolateral tegmentum and tectum completely avoid the principal nucleus, while supplying small regions of the accessory nuclei..  

Multiple-unit recordings were obtained from the interstitial nucleus of Cajal, nucleus of Darkschewitsch and the superior colliculus of the cat during acquisition of classically conditioned pupillary dilation. However, only the acquisition functions for the accessory oculomotor nuclei, i.e., interstitial nucleus of Cajal and nucleus of Darkschewitsch, were significantly correlated with the acquisition of conditioned pupillary dilation.  

Secretion in response to 2-DG and feeding behaviour were entirely blocked after making a lesion in a large ventromedial area of the meso diencephalic transition comprising the ventral tegmental area of Tsai, the ventral tegmental decussation, the red nucleus, a ventral portion of the central grey matter, the interstitial nuclei of Darkschewitsch and of Cajal, the pre-rubral fields, the reticular part of substantia nigra, the internal portion of the cerebral peduncle and the ventral part of the mesencephalic reticular formation.  


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