External Cuneate Nucleus


In this paper we examined the neuronal activities of external cuneate nucleus, spinocerebellar Purkinje cells and interpositus nucleus during passive forelimb movements in anesthetized rats with the aim of identifying common or different patterns of activation across structures. This difference in the forelimb kinematics representation observed in external cuneate nucleus and spinocerebellar cortex compared with the interpositus nucleus is discussed with respect to the specific role that these structures may play also during active control of limb movements..  

A high density of calcitonin gene-related peptide-immunoreactive perikarya was found in the superior colliculus, the dorsal nucleus of the raphe, the trochlear nucleus, the lateral division of the marginal nucleus of the brachium conjunctivum, the motor trigeminal nucleus, the facial nucleus, the pons reticular formation, the retrofacial nucleus, the rostral hypoglossal nucleus, and in the motor dorsal nucleus of the vagus, whereas a high density of fibers containing calcitonin gene-related peptide was observed in the lateral division of the marginal nucleus of the brachium conjunctivum, the parvocellular division of the alaminar spinal trigeminal nucleus, the external cuneate nucleus, the nucleus of the solitary tract, the laminar spinal trigeminal nucleus, and in the area postrema.  

Immunostaining of human brain sections at the level of the medulla oblongata strengthened these data, showing for the first time a high density of immunoreactive neuronal cell bodies and fibers in the motor hypoglossal nucleus, the dorsal motor nucleus of the vagus, the nucleus of the solitary tract, the Roller nucleus, the ambiguus nucleus, the inferior olivary complex, and in the external cuneate nucleus.  

P2X7-positive neurons were found in the anterior olfactory nucleus, cerebral cortex, piriform cortex (Pir), lateral septal nucleus (LS), hippocampal pyramidal cell layers of CA1, CA3, CA4, pontine nuclei, external cuneate nucleus, and medial vestibular nucleus.  

Retrogradely labeled neurons in the external cuneate nucleus were more dorsally shifted in the reeler mice compared with their normal counterparts.  

It was seen heaviest in the pontine nuclei and moderate in the pontine reticulotegmental nucleus; however, it was seen less in the medial solitary nucleus, red nucleus, lateral reticular nucleus, inferior olivary nucleus, external cuneate nucleus and vestibular nuclear complex.  

Brain-behavior correlations indicated that the activity of the external cuneate nucleus strongly predicted the conditioned response in the renewal group.  

In situ hybridization analysis shows that at least four classic cadherins, cadherin 6 (Cad6), cadherin 8 (Cad8), cadherin11 (Cad11) and N-cadherin (Ncad), are expressed in the migratory streams of lateral reticular nucleus and external cuneate nucleus (LRN/ECN) neurons.  

C2 DRG injections produced anterograde labeling in the external cuneate nucleus, cuneate nucleus, nucleus X, central cervical nucleus, dorsal horn of upper cervical spinal segments, and cochlear nucleus.  

Labelled neurons in the tangential migratory streams form contralateral clusters in the external cuneate nucleus (ECN) and lateral reticular nucleus (LRN) in the myelencephalon, and bilateral clusters in the pontine grey nucleus (PGN) and reticulotegmental nucleus (RTN) in the metencephalon.  

In the brainstem, co-localisation of P2X(7)R-IR with VGLUT2-IR was widespread, but co-localisation with VGLUT1-IR was seen only in the external cuneate nucleus and spinocerebellar tract region of the ventral medulla.  

the tonic gravitational field experienced after landing potentiating the effects of increased phasic gravitational forces experienced during landing.The specificity of these results is demonstrated by an absence of direct gravity-related changes in Fos expression in other precerebellar structures such as the external cuneate nucleus, group X, and the dorsal column nuclei that transmit exteroceptive and proprioceptive signals to thalamic nuclei and somatosensory areas of the cerebral cortex.  

The principal brainstem areas of saccular nerve termination were lateral, particularly the spinal vestibular nucleus, the lateral portion of the superior vestibular nucleus, ventral nucleus y, the external cuneate nucleus, and cell group l.  

Saccular afferents projected strongly to the spinal vestibular nucleus, weakly to other vestibular nuclei, to the interstitial nucleus of the eighth nerve, the cochlear nuclei, the external cuneate nucleus, and nucleus y.The current findings reinforce the preponderance of literature.  

Neurones with inclusion bodies occur in the inferior olivary nuclear complex, lateral reticular nucleus, external cuneate nucleus, conterminal nucleus, interfascicular nucleus, nucleus of Roller, dorsal paramedian reticular nucleus, subventricular nucleus, arcuate nucleus, pontobulbar body and pontine grey.  

These results indicate that Pax-6 plays a role in the migration of medullary precerebellar neurons, although neurons generated in the lower rhombic lip can nevertheless migrate and settle to form the external cuneate nucleus in the absence of Pax-6..  

Owing to its anatomical connections, the external cuneate nucleus (ECU) plays a crucial role in processing proprioceptive input from the upper trunk and upper limbs.  

In addition, terminals were observed in the interstitial nucleus of the eighth nerve, nucleus Y, external cuneate nucleus, and lobules I, IV, V, IX, and X of the cerebellar vermis.  

DNPI immunoreactivity was much more intense than VGluT1 immunoreactivity in many brainstem and spinal cord regions, except the pontine nuclei, interpeduncular nucleus, cochlear nuclei, and external cuneate nucleus.  

Moderate levels of Y1 immunoreactivity were found the in the main olfactory bulb, dorsomedial part of suprachiasmatic nucleus, paraventricular hypothalamic nucleus, ventral nucleus of lateral lemniscus, pontine nuclei, mesencephalic trigeminal nucleus, external cuneate nucleus, area postrema, and nucleus tractus solitarius.  

In the brainstem, dense terminal fields were seen in deep layers of the medullary dorsal horn, in the external cuneate nucleus, and in group x.  

When compared with the opposite, unaffected, side, the ipsilateral cuneate nucleus (CN), external cuneate nucleus (ECN), and contralateral VPL showed reductions in volume: 44-51% in CN, 37-48% in ECN, and 32-38% in VPL.  

Immunoreactive fibres were observed in the following; the inferior central nucleus; the pontine gray nuclei; the K├Âlliker-Fuse nucleus; the motor trigeminal nucleus, the anteroventral cochlear nucleus; the abducens nucleus; the retrofacial nucleus; the superior, lateral, inferior, and medial vestibular nuclei; the lateral nucleus of the superior olive; the external cuneate nucleus; the nucleus of the trapezoid body; the postpyramidal nucleus of the raphe; the medial accessory inferior olive; the dorsal accessory nucleus of the inferior olive; the nucleus ambiguus; the principal nucleus of the inferior olive; the preolivary nucleus; the nucleus ruber; the substantia nigra; and in the area postrema.  

Using anesthetized adult rats, we studied the relationships between the activity of cells belonging to the external cuneate nucleus (ECN) and passive forelimb positions.  

The present experiments examined the capacity of external cuneate nucleus (ECN) neurones in the anaesthetized cat to respond to static and vibrotactile stretch of forearm extensor muscles.  

In particular, besides the external cuneate nucleus, thick-calibre neck muscle afferents project directly, to the vestibular nuclear complex.  

One was in the external cuneate nucleus, and the other was in the ventralmost part of the ophthalmic division of the TBNC.  

This injection resulted in anterograde labeling in the nucleus of the tractus solitarius (NTS), area postrema (AP) and external cuneate nucleus (ECu) with slightly ipsilateral predominance.  

The medial aspect of the NIA receives afferents from the lateral reticular nucleus, external cuneate nucleus, perihypoglossal nucleus, medial vestibular nucleus and inferior central raphe nucleus. Additional afferents to more lateral aspects of the NIA are derived from the lateral reticular nucleus, external cuneate nucleus, and the magnocellular, lateral and gigantocellular tegmental areas.  

Subcutaneous hindpaw injections of horseradish peroxidase conjugated to either wheat germ agglutinin or cholera toxin subunit B revealed aberrant expansions of gracile projections into the cuneate and, in one case, external cuneate nucleus within three months of the deafferentation.  

Bradykinin microinjections in different sites surrounding the Pa5 compromising the external cuneate nucleus, the trigeminal nucleus, the lateral and ventral spinal trigeminal tract and the dorsal trigeminal tract rostral and caudal to the Pa5 did not elicit significant pressor responses.  

For control purposes some stimulating points were placed in the external cuneate nucleus and restiform body. For six cells there was some possibility of current spread to the external cuneate nucleus or to the underlying reticular formation.  

This study reports the reactivities of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) in some of the nonneuronal elements in the external cuneate nucleus (ECN) of gerbils.  

Extratrigeminal projections were mainly to the external cuneate nucleus by way of a lateral descending trigeminal tract (lTTD; Dubbeldam and Karten [ 1978] J.  

The present study examined the synaptic organization of external cuneothalamic neurons and their relationships with primary afferents in the gerbil external cuneate nucleus (ECN) following an injection of horseradish peroxidase (HRP) into the anterodorsal cap of the ventrobasal thalamus in conjunction with a simultaneous injection of HRP into the contralateral brachial and cervical nerve plexuses.  

The present study examined the existence of catecholamine-, corticotropin-releasing factor (CRF)- and neurotensin (NT)-containing neurons in the external cuneate nucleus (ECN) of the gerbil using single label pre-embedding immunocytochemistry in an attempt to shed light on the increasing evidence for autonomic involvement of the ECN.  

We also recorded from neurons near the vestibular nuclei, mainly in the external cuneate nucleus.  

This study seeks to extend the observations of previous studies of projection of primary afferent fibres from the forelimb nerves and muscles to the external cuneate nucleus (ECN) of mammals using a neurotoxic lectin, Ricinus communis agglutinin (RCA) to achieve chemical ganglionectomy of the dorsal root ganglia.  

Using acetylcholinesterase histochemical and choline acetyltransferase immunocytochemical localization methods, this study has provided conclusive evidence for the existence of cholinergic neurons in the external cuneate nucleus of gerbils. By light microscopy, both acetylcholinesterase and choline acetyltransferase labelling was confined to the rostral portion of the external cuneate nucleus. It may thus be hypothesized that most, if not all, of the external cuneate nucleus cholinergic neurons are projection cells; such cells may give rise to axonal collaterals which synapse onto their own dendrites for possible feedback control. The preferential concentration of cholinergic components in the rostral external cuneate nucleus may be significant in the light of the highly organized somatotopy in the external cuneate nucleus and its extensive efferent projections to medullary autonomic-related nuclei.  

The central projections of extraocular muscle afferent neurons were found consistently in a restricted area of the external cuneate nucleus. The presence of a lateral trigeminal tract in the pigeon, through which the afferent axons course, which terminates exclusively in the ventral portion of the external cuneate nucleus may explain this finding..  

The dorsolateral medulla, including the nucleus reticularis parvicellularis, the cuneate nucleus, and the external cuneate nucleus, is an integrative region for a variety of sensory inputs. Neurons were located in the nucleus reticularis parvicellularis (24 cells, 60%), the cuneate nucleus (10 cells, 25%), and the external cuneate nucleus (6 cells, 15%). external cuneate nucleus neurons displayed response profiles intermediate between nucleus reticularis parvicellularis and cuneate nucleus.  

The synaptic organisation of the primary afferents from the brachial and cervical plexuses to the external cuneate nucleus of gerbils was compared following an intraneural injection of horseradish peroxidase into the musculocutaneous, median, ulnar and radial nerves of the brachial plexus or the main branches of the cervical plexus; 407 labelled primary afferent terminals from the brachial and 459 from the cervical plexus were studied.  

The present study examined the synaptic organization of cuneocerebellar neurons and their relationships with the primary afferents in the gerbil external cuneate nucleus following multiple injections of horseradish peroxidase over a widespread area in the cerebellum in conjunction with a simultaneous injection of horseradish peroxidase into the cervical or brachial nerve plexus. The external cuneate nucleus is topographically organized: the rostral portion receiving the primary afferents from the cervical plexus and the caudal portion primary afferents from the brachial plexus. This study attempted to correlate the synaptology with the topography and different cytoarchitecture in these two specific regions in the external cuneate nucleus. In the rostral external cuneate nucleus, synapses on cuneocerebellar neurons were more frequent on their primary dendrites as compared with those on the primary dendrites of the caudal cuneocerebellar neurons. This may have functional implications with regard to the afferent inputs to cuneocerebellar neurons in the rostral and caudal external cuneate nucleus..  

Our results showed the presence of HRP/ChAT double-labelled neurons in (1) the midline medulla: the periventricular gray beneath the 4th ventricle, C3 adrenergic area, raphe obscurus nucleus and medial longitudinal fasciculus, (2) the reticular formation: the medullary, lateral, intermediate, gigantocellular, lateral paragigantocellular and dorsal paragigantocellular reticular nuclei and gigantocellular reticular nucleus ventralis, and (3) sensory nuclei: the gracile nucleus, cuneate nucleus, external cuneate nucleus, spinal trigeminal nucleus interpolaris, prepositus hypoglossal nucleus and medial vestibular nucleus.  

The present study revealed the efferent projections from the external cuneate nucleus (ECN) to various medullary nuclei in the gerbil as demonstrated in fresh living brainstem slices by using in vitro anterogradely tracing with the dextran-tetramethyl-rhodamine-biotin.  

The present study is concerned with the connections of the external cuneate nucleus (ECN) in the gerbil following an injection of horseradish peroxidase (HRP) into the ventralis posterior pars oralis (VPLo) or adjacent nuclei of the thalamus.  

The projection from the external cuneate nucleus (ECN) to the cerebellum was studied in the gerbil following the retrograde transport of minute injections (0.05-0.1 microliter, 30% solution) or implantations of horseradish peroxidase (HRP) in various folia of the cerebellar cortex and deep nuclei.  

In particular, thick-calibre neck muscle afferents project directly to the external cuneate nucleus and to the vestibular nuclear complex.  

Wheat germ agglutinin-horseradish peroxidase was injected at three different levels in the spinal cord and in the external cuneate nucleus, and the terminal field distributions in lobules II and III of the cerebellar cortex were compared with the Purkinje cell compartmentation.  

In this study, the pattern of labelled mossy fiber terminals originating from the external cuneate nucleus was determined and compared with the Purkinje cell antigenic zebrin bands in the same sections.  

Terminal labeling was further found in a small zone immediately medial to the rostromedial border of the external cuneate nucleus.  

In the medulla terminal fields appear in the dorsal column nuclei including the external cuneate nucleus and group x near the descending vestibular nucleus.  

Derived states of each of the nine traits are characteristic of certain restricted groups of mammals; (1) mirroring of the complete SI body representation in isocortex (anthropoid primates); (2) loss of the accessory olfactory bulbs (sirenians, cetaceans, most bats, catarrhine primates); (3) Rindenkerne, clumps of cell bodies in layer 6 of cerebral cortex (sirenians); (4) posteriorly-pointing digits in the SI body representation (bats, both mega- and micro-); (5) equivalent tectopetal connections to the anterior colliculus of one side from both retinas, rather than predominantly from the contralateral retina (primates and megabats); (6) loss of lamination in dorsal cochlear nuclei (anthropoid primates, bats, seals, sirenians, cetaceans); (7) separation of claustrum from cerebral cortex (diprotodont marsupials, carnivores, artiodactyls, perissodactyls, hyracoids, cetaceans and primates), (8) presence of a complete secondary (SII) somatic sensory region of cerebral cortex (therians-all extant mammals other than monotremes), and (9) presence of a distinct external cuneate nucleus among the nuclei of the dorsal columns (all mammalian groups except monotremes and sirenians).  

The projections of muscle afferents from six regions (hand, forearm, arm, thorax, shoulder and neck) to the external cuneate nucleus (ECN) of gerbils were investigated using transganglionic transport of horseradish peroxidase (HRP).  

In the hindbrain, FLI was present in the contralateral rostral ventrolateral medulla and bilaterally in the cochlear nucleus, external cuneate nucleus, locus coeruleus and lateral parabrachial nucleus.  

A double label technique revealed that CGRP-IR mossy fibers arise from neurons located in the lateral reticular nucleus, external cuneate nucleus, inferior vestibular nucleus, and basilar pons.  

Neuronal nuclei, labeled for the expressed c-fos protein, were present and mapped in the following structures: motor cortex; basal ganglia (caudate-putamen, globus pallidus); thalamus (reticular, ventromedial and posterior nuclei); subthalamic nucleus; substantia nigra; tectum; red nucleus; pontine nuclei; inferior olive; external cuneate nucleus; cerebellar cortex; deep cerebellar nuclei. Axonal labeling, including terminal branches and boutons, was also found in most of the above structures with the exception of the globus pallidus, deep cerebellar nuclei, cerebellar cortex and external cuneate nucleus.  

Immunoreactive perikarya were detected in the main and accessory olfactory bulbs, cortical regions, the olfactory tubercle, the bed nucleus of the stria terminalis, the diagonal band of Broca, the nucleus accumbens, the septum, the neostriatum, several hypothalamic nuclei, the superior colliculus, the central gray, the substantia nigra, the medullary reticular formation, and the external cuneate nucleus.  

En passant swellings or terminals of neck primary afferents were found in the vicinity of neurones projecting to the thalamus in the dorsolateral part of the rostral cuneate nucleus, the ventral aspect of the external cuneate nucleus, and the border zone between the two. Putative synaptic contacts were found in the region between the dorsolateral part of the rostral cuneate nucleus and ventromedial external cuneate nucleus. Cutaneous afferents from the neck were associated with thalamic projecting cells located along the dorsolateral border of the rostral cuneate nucleus, and afferents from neck muscles were associated with thalamic projecting cells in the caudal third of the external cuneate nucleus and in nucleus x..  

Minor projections to the internal basilar nucleus, external cuneate nucleus, medial vestibular nucleus, ventral cochlear nucleus and trigeminal sensory nuclei were also found from some of the DRGs..  

Moderate projections were found to reach lobule VIa from the raphe pontis and external cuneate nucleus; lobules VIb,c from the raphe pontis, lateral reticular nucleus, and a group of cells in the lateral tegmentum; lobule VII from the spinal vestibular nucleus and a lateral tegmental cell group; and lobule VIII from the medial and spinal vestibular nuclei, nucleus intercalatus and Roller of the perihypoglossal nuclei, and the main cuneate nucleus.  

The median nerve projected to the internal basilar nucleus from C1-C6, the dorsal horn from C3-T2, Clarke's nucleus from T1-T6, the external cuneate nucleus, and a large central area throughout the length of the cuneate nucleus. The ulnar nerve projections were less extensive but also included the internal basilar nucleus from C1-C6, the medial region of the dorsal horn from C4-T1, Clarke's nucleus from T1-T6, the external cuneate nucleus, and the medial part of the cuneate nucleus.(ABSTRACT TRUNCATED AT 400 WORDS).  

The present study was carried out to analyze the topography of projections from external cuneate nucleus to the anterior and posterior lobes of the cerebellum and to investigate whether projections to the two lobes come from different cuneocerebellar neurons or from branching axons of the same cells.  

The main area of termination in the medulla was the external cuneate nucleus. Again, the external cuneate nucleus was the main area of termination within the medulla. Ascending proprioceptive fibers reached the external cuneate nucleus and group x.  

We investigated the spatial coding in neurons of the external cuneate nucleus (ECN) with natural neck and vestibular stimulations, and compared them to that of neurons in the descending and medial vestibular nuclei (DVN and MVN, respectively) obtained with vestibular stimulation.  

The neuronal density was highest (12,907 cells/mm3) in the gracile, and lowest in the external cuneate nucleus (5987 cells/mm3). The external cuneate nucleus had a larger relative volume (7.9%) occupied by nerve cell bodies compared with the two medial nuclei (5.1% and 5.8%). In the gracile and internal cuneate nuclei, the GABAergic neurones constituted 28% and 25% of the whole population, respectively, while the external cuneate nucleus was devoid of such cells.  

Dense or loose clusters of D-type cells were localized in the external edge of the laminar trigeminal nucleus, dorsal motor nucleus of the vagus, external cuneate nucleus, nucleus praepositus hypoglossi, central, pontine, and periaqueductal gray, superficial layer of the superior colliculus, and area medial to the retroflexus.  

Generated in the same primary precerebellar neuroepithelium, at embryonic days 12-13 (E12-E13) for the ION and E12-E14 for the LRN, the postmitotic cells take either the intraparenchymal (smms, for ION neurons) or the subpial migratory streams (mms, for LRN neurons and other populations, as those of the external cuneate nucleus, ECN).  

The Cun projections from the different DRGs appeared to overlap, and the same was true for the projections to the external cuneate nucleus.  

Injections of PHA-L into thoracic cord labeled fibers and varicosities in the medial cuneate and lateral gracile nuclei, as well as the external cuneate nucleus. In all regions of the DCn and in the external cuneate nucleus, fibers and varicosities labeled for PHA-L were seen in apposition to retrogradely labeled lemniscal cells.  

4) The terminal fields in the external cuneate nucleus were more extensive.  

The number of neurons in the ASH/TO mouse external cuneate nucleus was examined at 6, 15, 22, 25, 28 and 31 months of age.  

Brainstem projections from the DR nerve that were found only with the HRP method were found in the ipsilateral ventral part of the MCN together with a projection to the ipsilateral external cuneate nucleus.  

However, many cells in the dorsal column nuclei (including external cuneate nucleus) project up to these brain areas.  

Light microscopic studies demonstrated the presence of GABA-positive cells in the gracile nucleus, the internal cuneate nucleus and the lateral cervical nucleus but not in the external cuneate nucleus.  

Intensely-immunolabeled neuronal cell bodies were densely distributed in the main precerebellar nuclei sending mossy fibers to the cerebellum; in the pontine nuclei, pontine tegmental reticular nucleus of Bechterew, external cuneate nucleus, and lateral reticular nucleus of the medulla oblongata.  

Afferent terminals were found bilaterally in the nucleus of the solitary tract (nTS), area postrema (AP), the dorsal motor nucleus of the vagus (DMV), the external cuneate nucleus (ECN) and the principal subnucleus of the inferior olive (IOP).  

When it was present, small amounts of terminal labeling were found in the external cuneate nucleus (ECN) and the central cervical nucleus (CCN).  

As determined by retrograde labeling following these injections, kinesthetic thalamic subregions receive projections as follows: caudomedial from cells in the external cuneate nucleus and its medial tongue, rostromedial from cells in basal cuneate nucleus, and rostrolateral from cells in cell group z and the reticular division of cell group x.  

Two regions showed heavy projections to the cerebellum with no projections to the thalamus: the lateral portion of the external cuneate nucleus and the compact portion of cell group x. Four regions showed more equivalent projections to both target regions: basal cuneate, medial portion of the external cuneate nucleus, medial tongue extension of the external cuneate nucleus, and reticular portion of cell group x.  

The musculotopic organisation of projections to the external cuneate nucleus (ECN) from the neck muscles splenius (SP) and biventer cervicis (BC) was examined electrophysiologically.  

In the medulla, labeled binding sites were mainly concentrated within the dorsal motor nucleus of the vagus, the nucleus of the solitary tract, the external cuneate nucleus, the lateral reticular nucleus, the medial vestibular nucleus, the retrofacial nucleus, the linearis nucleus, the paragigantocellular nucleus and the nucleus raphe pallidus.  

In addition, they also project to several other brainstem nuclei; these include the contralateral nucleus gracilis, the ipsilateral main cuneate nucleus, the external cuneate nucleus and the presumptive nucleus z..  

Small injections of tritiated leucine and the autoradiographic method were used to demonstrate efferents from restricted portions of the external cuneate nucleus (NCE) to the cerebellum.  

Transport of radioactive leucine was used to demonstrate cerebellar projections from the external cuneate nucleus (NCE) and from adjacent portions of the main cuneate nucleus (NC), of the spinal trigeminal nucleus (N.tr.sp.V) and of the vestibular nuclei.  

In addition to the previously reported enkephalinergic cells, we found many methionine-enkephalin-Arg6-Gly7-Leu8 containing neurons; the rostral and caudal linear nucleus of raphe, the median raphe nucleus, entire length of the raphe magnus nucleus, the medial longitudinal fasciculus, the cuneate nucleus, the external cuneate nucleus, the gracile nucleus, and the area postrema.  

At more rostral medullary levels, fibers from all cervical dorsal roots also reach the external cuneate nucleus. Rostral cervical root fibers reach ventral and ventrolateral areas of the external cuneate nucleus and continue to its rostral pole; more caudal root fibers project to more dorsal and medial regions within the nucleus.  

The cardiac, respiratory, and renal responses of electrical stimulation and microinjection of excitatory amino acids into the external cuneate nucleus were investigated in 57 cats anesthetized with pentobarbital sodium, paralyzed, and artificially ventilated. Electrical stimulation at 232 histologically identified sites within the external cuneate nucleus could evoke changes in arterial blood pressure, heart rate, and efferent renal sympathetic nerve activity. An increase or decrease in all parameters measured could be elicited at different stimulus sites within the external cuneate nucleus. This suggests that the external cuneate nucleus contains cell bodies that may modulate components of various cardiac, respiratory and renal reflexes. It is proposed that the external cuneate nucleus may be involved in the integration of somato-autonomic reflex responses..  

Besides the CRFI cells in the paraventricular hypothalamic nucleus that project to the median eminence, CRFI cells were demonstrated in many brain regions, including the olfactory bulb, cerebral cortex, septal nuclei, hippocampus, amygdala, thalamic nuclei, medial hypothalamic nuclei, lateral hypothalamic area, perifornical area, central gray, cuneiform nucleus, inferior colliculus, raphe nuclei, mesencephalic reticular formation, laterodorsal tegmental nucleus, locus coeruleus, parabrachial nuclei, mesencephalic tract of the trigeminal nerve, pontine reticular formation, lateral superior olive, vestibular nuclei, prepositus hypoglossal nucleus, nucleus of the solitary tract, dorsal motor nucleus of the vagus, lateral reticular nucleus, nucleus of the spinal tract of the trigeminal nerve, external cuneate nucleus, inferior olive, and medullary reticular formation.  

Sequential thymidine radiograms from rats injected on day E15 and killed thereafter at daily intervals up to day E22 were analyzed to trace the migratory routes and settling patterns of neurons of the lateral reticular nucleus and the external cuneate nucleus. These cells begin to penetrate the parenchyma on day E20, and by days E21 and E22 two components of the external cuneate nucleus are identifiable-the dorsal and ventral external cuneate nuclei.  

5-HT-LI fibers are located in all cytoarchitectural subdivisions of the gracile and cuneate nuclei but are restricted to the medial half of the external cuneate nucleus.  

In this study the numbers and distribution of neurones projecting to these two regions were examined for the following nuclei: the rostral part of the main cuneate nucleus, the external cuneate nucleus, nucleus x, the principal sensory nucleus of the trigeminal nerve, and the oral, interpolar, and caudal subnuclei of the spinal nucleus of the trigeminal nerve. A thalamic projection from nucleus x and from the external cuneate nucleus was confirmed, and a distinct group of neurones projecting to the ventroposteromedial thalamus was distinguished near the ventromedial aspect of the principal sensory nucleus.  

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.  

Intense staining was also seen in possible mossy fiber endings in the granular layer of the cerebellar cortex and in neurons giving off mossy fibers such as those in the pontine nuclei, pontine tegmental reticular nucleus of Bechterew, lateral reticular nucleus of the medulla oblongata, and external cuneate nucleus..  

A few lagenar fibres terminated in the external cuneate nucleus.  

The present study also identified the cells of origin of two additional projections to the basilar pons: one from cells in the external cuneate nucleus and another from neurons of the medullary reticular formation..  

Labeled fiber terminals were identified in the dorsal horn and the central cervical nucleus in the spinal cord, and in the intermediate nucleus, cuneate nucleus, external cuneate nucleus and the caudal portion of the nucleus of the solitary tract (NTS) in the brainstem.  

Main cuneate nucleus neurons projecting to the cerebellum concentrate rostral to the obex, bordering the external cuneate nucleus and partially intermixing with the rostrally located cells projecting to the inferior olive.  

Injections in C1, 2, and 3 dorsal root ganglia resulted in axonal labeling in the nucleus intercalatus and the external cuneate nucleus, with a number of retrogradely labeled cells seen as well in the latter.  

A relatively dense, patchy, and discontinuous deposit of reaction product was also present in the external cuneate nucleus after muscle nerve exposure.  

In the lower brain stem of the dog, binding was evident in the external cuneate nucleus, the spinal trigeminal nucleus, and in the region of the solitary nucleus.  

In the cat, C5-C6 dorsal root ganglion cells related to phrenic afferents projecting directly to the ipsilateral external cuneate nucleus (ECN) were submitted to a double-labeling procedure using anterogradely transported Fast Blue and retrogradely transported Nuclear yellow.  

Single units were recorded extracellularly from the external cuneate nucleus and from the main cuneate nucleus in anesthetized monkeys.  

It was found that the "deep" input was confined to the pars triangularis of the main cuneate nucleus and to the ventromedial segment of the external cuneate nucleus.  

Using the method of transganglionic transport of horseradish peroxidase (HRP), the distribution of primary afferent projections was examined in the external cuneate nucleus (ECN) from different muscle groups in the forequarter of the cat.  

The wing representation, however, extended laterally throughout the external cuneate nucleus (CuE) and lateral regions of the descending trigeminal tract.  

No evidence of vagal afferent fibres was found in the reticular formation, the spinal tract of the trigeminal nerve, the external cuneate nucleus or the dorsal horns of the first and second cervical spinal segments.  

The present study, performed on anesthetized, spontaneously breathing cats, deals with the projection of group I and II muscle afferents of the phrenic nerve (PN) to the external cuneate nucleus (ECN).  

It is concluded that only muscle afferents terminate in the external cuneate nucleus. In the external cuneate nucleus, the distributions of afferents from individual muscles constitute integral parts of a segmental representation.  

The cerebellar projection of the external cuneate nucleus and the adjoining rostral part of the internal cuneate nucleus were investigated by means of anterograde transport of tritiated leucine.  

The results demonstrate a precise, musculotopic termination pattern in the external cuneate nucleus; thus, fibres from the intrinsic muscles of the paw terminate medially; those from forearm, arm, and shoulder muscles terminate progressively more laterally; and those from neck and thoracic muscles terminate in the ventrolateral and dorsolateral parts, respectively. Fibres from the neck muscles terminate slightly more laterally in the ventral region than do those from the limb muscles, but otherwise, and thus contrary to the case in the external cuneate nucleus, no topographic organization was detected.  

There is a muscle afferent projection to the ventrolateral main cuneate nucleus and a complex pattern of projection through the extent of the external cuneate nucleus.  

Dense accumulations of reaction product were present in circumscribed regions of the external cuneate nucleus (ECN) throughout its rostrocaudal extent.  

Fibers from those rostral (C2) or caudal (C8) cervical roots studied traverse the medulla as a single bundle, forming collaterals en route into the nucleus cuneatus and external cuneate nucleus at all levels. The second fiber group, larger, deeper, and more laterally situated, projects mainly to ventral and ventrolateral nucleus cuneatus (asomatotopically) and to the external cuneate nucleus.  

Axon collaterals of rubro-spinal neurones into the main sensory trigeminal nucleus, facial nerve nucleus, descending (inferior) vestibular nucleus, lateral reticular nucleus, external cuneate nucleus, gracile and main cuneate nuclei were identified.  

Within the brain stem, most afferents from the splenius terminate in the external cuneate nucleus.  

Threshold mapping for antidromic stimulation revealed termination in the main cuneate nucleus, the external cuneate nucleus and/or the LRN and also a branch projecting to more rostral levels in the brain.  

VIII, the rostral part of the external cuneate nucleus and in the reticular formation laterodorsal to the abducens nucleus.  

Horseradish peroxidase (HRP) was injected into the thalamic ventral tier of squirrel monkey and the brainstem was examined for the presence of HRP-reactive cells in the external cuneate nucleus (ECN), nuclei Z and X, and the mesencephalic nucleus of the trigeminal nerve (MNV).  

In addition, our data demonstrate a projection of gastrointestinal afferents to the lateral descending tract of the trigeminal nerve that appears to terminate in the external cuneate nucleus.  

Among the most prominent of these were neurons in the bed nucleus of stria terminalis, the central nucleus of the amygdala, the region of the dorsal raphe, locus ceruleus, the external cuneate nucleus, and the medullary reticular formation.  

Of these neurons, 99.2% were located in the ipsilateral external cuneate nucleus (ECN) and 0.8% in the ipsilateral main cuneate nucleus.  

The labeled central processes follow two distinct main routes: one to the external cuneate nucleus, which is known to project ipsilaterally to the cerebellum, the other to the central cervical nucleus (CCN) of the spinal cord.  

In the medulla oblongata HRP labeled structures were observed in the medial cuneate nucleus, in the rostral part of the external cuneate nucleus, and in the nucleus of the spinal tract of the trigeminal nerve.  

However, in the external cuneate nucleus and in the paramedian reticular nucleus there was a decrease in glucose utilization.  

Dorsolateral fibres arising from segments above at least T6 terminate in a clear-cut area at the lateral border of the external cuneate nucleus.  

The termination of a pathway recently discovered in monkey, from the external cuneate nucleus (ECN) to the thalamus, has been investigated with the degeneration method.  

Labeled fibers from both nerves were found to project bilaterally to the solitary complex, and ipsilaterally to the ventral region of the external cuneate nucleus and to the medial region of the nucleus praepositus hypoglossi, just dorsolateral to the medial longitudinal fasciculus.  

Neurons of the sensory relay nuclei, the gracilis, cuneatus, and solitarius are produced over a more extended period, with peaks on day E13; the exception was the external cuneate nucleus in which peak generation time was on day E15.  

246 neurons were found to respond to electrical stimulation of these muscle nerves and they were located mainly in the ipsilateral external cuneate nucleus (242; 98.3%) and the remaining 4 neurons were in the rostral tip of the main cuneate nucleus. The monosynaptically activated neurons showed somatotopic distribution in the nucleus; biventer cervicis responded neurons locate in the most lateral part, splenius locate in the middle and occipitoscapularis locate in the medial part of the external cuneate nucleus. It was concluded that the relay neurons of the external cuneate nucleus from biventer cervicis, splenius and occipitoscapularis neck muscles projected their axons to the ipsilateral cerebellum but not to ventral posterolateral (VPL) and ventral posteromedial (VPM) nucleus of the contralateral thalamus..  

Three cerebellar cortical regions are the main targets for the fibres from the external cuneate nucleus, viz.  

The regions of the nucleus ambiguus (AMB), dorsal motor nucleus of the vagus (DMV), nucleus tractus solitarius (NTS), and external cuneate nucleus (ECN) were systematically explored for units responding both to antidromic stimulation of the cardiac branches of the vagus (CBV) and to orthodromic stimulation of the carotid sinus and aortic depressor nerves.  

In the second series, in spinal unilaterally vagotomized animals, lesions of the nucleus ambiguus (AMB) selectively attenuated the ADN reflex vagal bradycardia but not the CSN response; on the other hand, lesions of the external cuneate nucleus (ECN) attenuated the reflex vagal bradycardia elicited by stimulation of the CSN, but did not alter the ADN response.  

Afferents from brachial levels terminate mainly in the cuneate nucleus and in the external cuneate nucleus.  

The role of the external cuneate nucleus (ECN) in the control of heart rate was systematically investigated in 26 chloralosed and 2 decerebrated, paralyzed, and artifically ventilated cats.  

Other precerebellar nuclei which send their cerebellipetal axons to the inferior cerebellar peduncle, such as the external cuneate nucleus, the lateral reticular nucleus and the arcuate nucleus, were normally preserved.  

Unilateral, intradural dorsal rhizotomies (C3-Cs) were performed on adult rats to study the patterns of synaptic organization of ascending dorsal root fibers in the external cuneate nucleus (ECN).  

The normal synaptic organization of the rat external cuneate nucleus (ECN) has been investigated.  

When horseradish peroxidase was injected into the NIA, labeled cells were found in the magnocellular and parvicellular LRN, the external cuneate nucleus (ECN), the pontine nuclei and the perihypoglossal nuclei.  

During the course of an investigation of the synaptic organization of the external cuneate nucleus (ECN) in the Sprague-Dawley albino rat, the ultrastructural morphology of nodes of Ranvier in the neuropil has been studied.  

Most neurons relaying neck activity were in group x of Brodal and Pompeiano (4), a few were in the external cuneate nucleus, and one was in the descending vestibular nucleus.  

In all cases, medullary nuclei known to project to the injected cortical regions of the cerebellum contained HRP-positive neurons mainly ipsilateral to the injection (e.g., external cuneate nucleus) or mainly contralateral to it (e.g., inferior olivary complex).  

The main projection from the external cuneate nucleus (ECN) is to the intermediate and, possibly, the small lateral part of lobule V and to the paramedian lobule on the ipsilateral side.  


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