In situ hybridization showed that rln3a was expressed in neurons of the Lateral Lemniscus of the midbrain and of the griseum centrale (GC) of the hindbrain, while low amounts of rln transcripts were found in neurons of the periventricular nucleus of the posterior tuberculum of the diencephalon and the GC. 
We investigated the anatomical location of the pedunculopontine nucleus (PPN) in the human brain using diffusion tensor imaging.
Here we fitted a statistical model to single-cell rate responses of the dorsal nucleus of the Lateral Lemniscus.
Neurons in the dorsal nucleus of the Lateral Lemniscus (DNLL) receive excitatory and inhibitory inputs from the superior olivary complex (SOC) and convey GABAergic inhibition to the contralateral DNLL and the inferior colliculi.
Results revealed that this subunit was expressed throughout the auditory system with the level being high in the layers I-V of the auditory cortex, medial geniculate nucleus, dorsomedial and lateral parts of the inferior colliculus, and the molecular and fusiform cell layers of the dorsal cochlear nucleus. Regional distributions of the receptor subunit revealed clear boundaries of some auditory subnuclei including the dorsal and ventral cochlear nuclei and the lateral superior olivary nucleus. Differences in immunoreactivity were found between the central nucleus and the dorsal cortex of the inferior colliculus and between the dorsal and ventral parts of the ventral nucleus of the Lateral Lemniscus, although no clear boundaries were observed. No differences in immunoreactivity were found between the core and the belt areas of the auditory cortex and among the subdivisions of the medial geniculate nucleus.
This suggests that there exists a single mechanism for the derivation of residue pitch from binaurally created components and from spectral components, and that this mechanism operates at or after the level of the dorsal nucleus of the Lateral Lemniscus (brainstem) or the inferior colliculus (midbrain), which receive inputs from the medial superior olive where temporal information from the two ears is first combined..
In the intermediate nucleus of the Lateral Lemniscus, most FG-positive cells expressed VGLUT2, and a few FG-positive cells expressed both VGLUT1 and 2. In the ventral cochlear nucleus, almost all FG-positive cells expressed VGLUT1&2. On the other hand in the dorsal cochlear nucleus, the vast majority of FG-positive cells expressed only VGLUT2. Our data suggest that (1) the most likely sources of VGLUT2 terminals in the IC are the intermediate nucleus of the Lateral Lemniscus, the dorsal cochlear nucleus, the medial and lateral superior olive, and the IC itself, (2) VGLUT1 terminals in the IC originate only in the ipsilateral auditory cortex, and (3) VGLUT1&2 terminals in IC originate mainly from the VCN with minor contributions from the SOC and the lateral lemniscal nuclei..
The first section is concerned with how neurons in the dorsal nucleus of the Lateral Lemniscus (DNLL), the nucleus ventral to the IC, respond to species-specific signals and how they compare to responses of IC neurons evoked by the same signals.
Compared with 95 cases without the CTT lesion, the changes in the pontine reticular formation were more closely associated with the CTT lesion than those in the inferior olivary nucleus.
Distinct pathways carry monaural and binaural information from the lower auditory brainstem to the central nucleus of the inferior colliculus (ICC). One pattern was identified by inputs from the cochlear nucleus and ventral nucleus of the Lateral Lemniscus in isolation, and these injection sites were correlated with monaural responses. A third pattern had inputs from a variety of olivary and lemniscal sources, notably the contralateral lateral superior olive and dorsal nucleus of the Lateral Lemniscus.
PV expression characterized the superior olivary nuclei, whereas GAD immunoreactivity characterized many neurons in the nucleus of the Lateral Lemniscus and some neurons in the torus semicircularis. In the auditory midbrain, the distribution of CR, PV, and CB characterized divisions within the central nucleus of the torus semicircularis. All three calcium-binding proteins were expressed in nucleus medialis of the thalamus.
Then we consider the physiological role of each of these conductances from the perspective of the principal neuron in the medial nucleus of the trapezoid body (MNTB). These are: the medial superior olive (MSO), the lateral superior olive (LSO), the superior paraolivary nucleus (SPN) and the nuclei of the Lateral Lemniscus (NLL).
The four groups are octopus cells in the cochlear nucleus, their connections with the ventral nucleus of the Lateral Lemniscus (VNLL) and the superior paraolivary nucleus (SPON), and the connections of the VNLL and SPON with the IC.
In the intermediate nucleus of the Lateral Lemniscus (INLL), some neurons display a form of spectral integration in which excitatory responses to sounds at their best frequency are inhibited by sounds within a frequency band at least one octave lower. Most retrogradely labeled cells were located in the ipsilateral medial nucleus of the trapezoid body (MNTB) and contralateral anteroventral cochlear nucleus. Consistent labeling, but in fewer numbers, was observed in the ipsilateral lateral nucleus of the trapezoid body (LNTB), contralateral posteroventral cochlear nucleus, and a few other brainstem nuclei.
LLI extends from a caudal position ventrolateral to the principal sensory trigeminal nucleus (LLIc) to a rostral position medial to the ventrolateral parabrachial nucleus (LLIr). The cochlear nucleus angularis (NA) and the third-order nucleus laminaris (NL) project on OS predominantly ipsilaterally, on LLV and LLI predominantly contralaterally, and on LLD contralaterally only. In this the projections are similar to those in the barn owl (Takahashi and Konishi [ 1988] J Comp Neurol 274:212-238), in which time and intensity pathways remain separate as far as the central nucleus of the inferior colliculus (MLd).
In the model, IC neurons have physiologically plausible inputs, receiving excitation from the ipsilateral medial superior olive (MSO) and long-lasting inhibition from both ipsilateral and contralateral MSOs, relayed through the dorsal nucleus of the Lateral Lemniscus.
Fast glutamatergic and GABAergic transmission in the central nucleus of the inferior colliculus (ICC), a major auditory midbrain structure, is mediated respectively by alpha-amino-3-hydroxy-5-methylisoxazole-4 propionic acid (AMPA) and gamma-aminobutyric acid (GABA)(A) receptors.
Neuropathological study of one autopsied case with the FUS mutation revealed multiple system degeneration in addition to upper and lower motor neuron involvement: the globus pallidus, thalamus, substantia nigra, cerebellum, inferior olivary nucleus, solitary nucleus, intermediolateral horn, Clarke's column, Onuf's nucleus, central tegmental tract, medial lemniscus, medial longitudinal fasciculus, superior cerebellar peduncle, posterior column, and spinocerebellar tract were all degenerated.
Estrogen receptors alpha and beta (ERalpha, ERbeta) were localized predominantly in the ventral cochlear nucleus, nucleus of the trapezoid body, the lateral- and medio-ventral periolivary nuclei, the dorsal lateral lemniscus, and the inferior colliculus. The medial geniculate nucleus was negative for both ERalpha and ERbeta whereas the auditory cortex was positive for ERalpha. The lateral superior olive, the ventral lateral lemniscus and the central nucleus of the inferior colliculus expressed only ERbeta.
Further it is proposed that specific inhibitory circuitry in the auditory brainstem, centered on the dorsal nucleus of the Lateral Lemniscus (DNLL), contributes to this selective filtering.
The STT began at the posterolateral medulla and ascended to the ventral posterior-lateral (VPL) nucleus of the thalamus, through the pontine tegmentum posterolateral to the ML, and through the mesencephalic tegmentum posterior to the ML. STT-related thalamocortical fibers originated from the VPL nucleus of the thalamus and ascended through the posterior limb of the internal capsule and the posterior portion of the corona radiata, terminating at the primary somatosensory cortex.
Specifically, we investigated the transformation that takes place between the first two stages of the gerbil auditory pathway that are sensitive to differences in the arrival time of a sound at the two ears (interaural time differences; ITDs): the medial superior olive (MSO), where ITD tuning originates, and the dorsal nucleus of the Lateral Lemniscus (DNLL), to which the MSO sends direct projections.
In rats, most neurons in the inferior colliculus (IC) exhibit binaural responses which are affected by axonal projections from both the contralateral dorsal nucleus of the Lateral Lemniscus (DNLL) and the contralateral IC.
The presence and nature of a descending projection from the ventral nucleus of the Lateral Lemniscus (LLV) to the cochlear nuclei (NA, NM) and the third-order nucleus laminaris (NL) was investigated in a songbird using tract tracing and GAD immunohistochemistry.
In rodents, the superior paraolivary nucleus (SPON) is a prominent and well-defined cell group of the superior olivary complex that sends significant but often neglected GABAergic projections to the IC. Our results demonstrate that: (1) the SPON innervates densely all three subdivisions of the ipsilateral IC: central nucleus (CNIC), dorsal cortex (DCIC) and external cortex (ECIC).
The intermediate nucleus of the Lateral Lemniscus (INLL) is a major input to the inferior colliculus (IC), the auditory midbrain center where multiple pathways converge to create neurons selective for specific temporal features of sound. INLL receives excitatory projections from the cochlear nucleus and inhibitory projections from the medial nucleus of the trapezoid body (MNTB), so it must perform some form of integration.
Here we report early projection specificity for multiple converging inputs to the rat central nucleus of the inferior colliculus (ICC). Afferents arising from the dorsal cochlear nucleus (DCN), the dorsal nucleus of the Lateral Lemniscus (DNLL), and the lateral superior olive (LSO) establish discernible axonal layers a week prior to experience.
Here we report early projection specificity for multiple converging inputs to the rat central nucleus of the inferior colliculus (ICC). Afferents arising from the dorsal cochlear nucleus (DCN), the dorsal nucleus of the Lateral Lemniscus (DNLL), and the lateral superior olive (LSO) establish discernible axonal layers a week prior to experience.
NB-2 was strongly expressed in the ventral cochlear nucleus (VCN), ventral acoustic stria, lateral and medial superior olivary complex (SOC), superior paraolivary nucleus, medial nucleus of the trapezoid body (MNTB), ventrolateral lemniscus, and central nucleus of the inferior colliculus (CIC).
Injections were made into the central nucleus of the inferior colliculus (ICC), the dorsal nucleus of the Lateral Lemniscus (DNLL), the intermediate nucleus of the Lateral Lemniscus (INLL), or the ventral nucleus of the Lateral Lemniscus (VNLL). The ICC receives both ipsilateral and contralateral projections from the DNLL and the lateral superior olive, major ipsilateral projections from the INLL, VNLL, medial superior olive, and superior paraolivary nucleus, and major contralateral projections from both dorsal and ventral cochlear nucleus. The INLL, in contrast, receives its major projections from the ipsilateral VNLL, lateral superior olive, medial superior olive, superior paraolivary nucleus, and medial nucleus of the trapezoid body, but does not receive a heavy projection from the contralateral lateral superior olive. It receives a major contralateral projection from the ventral cochlear nucleus, but a much lighter projection from the contralateral dorsal cochlear nucleus. The VNLL receives projections from the ipsilateral medial nucleus of the trapezoid body and the contralateral ventral cochlear nucleus, but does not receive projections from the medial or lateral superior olives, the superior paraolivary nucleus, or the dorsal cochlear nucleus.
Double-labeling experiments revealed nNOS/ChAT-positive cells in (1) the diencephalon: the preoptic and suprachiasmatic nuclei, the habenula, the dorsal thalamus, and the nucleus of the medial longitudinal fasciculus; (2) the mesencephalon: the optic tectum, the mesencephalic portion of the trigeminal nucleus, the oculomotor and trochlear nuclei, and the Edinger-Westphal nucleus; and (3) the rhombencephalon: the secondary gustatory nucleus, the nucleus isthmi, the Lateral Lemniscus nucleus, the cerebellum, the reticular formation, different nuclei of the octaval column, the motor zone of the vagal lobe, and the trigeminal, facial, abducens, glosso-pharyngeal, vagal, and hypobranchial motor nuclei. The percentage of double-labeled cells was different in each studied nucleus, indicating a selective distribution pattern.
Previously, we described a cell group expressing tuberoinfundibular peptide of 39 residues (TIP39) in the lateral pontomesencephalic tegmentum, and referred to it as the medial paralemniscal nucleus (MPL). To identify this nucleus further in rat, we have now characterized the MPL cytoarchitectonically on coronal, sagittal, and horizontal serial sections. The MPL is bordered by the intermediate nucleus of the Lateral Lemniscus nucleus laterally, the oral pontine reticular formation medially, and the rubrospinal tract ventrally, whereas the A7 noradrenergic cell group is located immediately mediocaudal to the MPL. The MPL has afferent neuronal connections distinct from adjacent brain regions including major inputs from the auditory cortex, medial part of the medial geniculate body, superior colliculus, external and dorsal cortices of the inferior colliculus, periolivary area, lateral preoptic area, hypothalamic ventromedial nucleus, lateral and dorsal hypothalamic areas, subparafascicular and posterior intralaminar thalamic nuclei, periaqueductal gray, and cuneiform nucleus. In addition, injection of the anterograde tracer biotinylated dextran amine into the auditory cortex and the hypothalamic ventromedial nucleus confirmed projections from these areas to the distinct MPL.
Moreover, chemical block of glutamate transmissions in the contralateral inferior colliculus markedly reduced the ipsilaterally driven FFRs, which, however, were significantly enhanced by blocking the contralateral dorsal nucleus of the Lateral Lemniscus. Thus, FFRs in inferior colliculus to ipsilateral stimulation were facilitated by excitatory projections from the contralateral inferior colliculus but suppressed by inhibitory projections from the contralateral dorsal nucleus of the Lateral Lemniscus..
We used broadband noise stimuli to investigate the interaural-delay sensitivity of low-frequency neurons in two midbrain nuclei: the inferior colliculus (IC) and the dorsal nucleus of the Lateral Lemniscus.
It has been shown that immunoreactivity to calbindin, parvalbumin, and calretinin in neurons and neuropil of nuclei of cochlear and superior olivary complexes, in nucleus of lateral lemniscus, and in spiral ganglion neurons coincides topographically with the high CO activity.
The spatial organization of projections from the ventral cochlear nucleus (VCN) to the ventral nucleus of the Lateral Lemniscus (VNLL) and from the VNLL to the central nucleus of the inferior colliculus (CNIC) was investigated by using neuroanatomical tracing methods in the gerbil.
The results indicate an activation-dependent accumulation of manganese in the neural circuit composed of the cochlear nucleus, the superior olivary complex, the Lateral Lemniscus, and the inferior colliculus.
lateral lemniscus, central nucleus of IC, dorsal cortex of IC), they generally exhibited similar threshold versus phase duration, threshold versus pulse rate, and pitch versus pulse rate curves.
Axonal projections from the dorsal nucleus of the Lateral Lemniscus (DNLL) distribute contralaterally in a pattern of banded layers in the central nucleus of the inferior colliculus (IC). A lipophilic carbocyanine dye, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), was placed in the dorsal tegmental commissure of Probst to label decussating DNLL axons that end in the central nucleus of the contralateral IC. The distribution of labeled fibers across the central nucleus of the IC was analyzed in digital images by comparing the pattern of labeling with a sine model of periodic distribution of banded layers.
Although the intended target was the central nucleus of the inferior colliculus (ICC), the electrode array was implanted into different locations across patients (i.e., ICC, dorsal cortex of inferior colliculus, lateral lemniscus).
ChAT-immunoreactive (IR) cells comprise several prominent groups, including the pedunculopontine tegmental nucleus, laterodorsal tegmental nucleus, and parabigeminal nucleus, as well as the cranial nerve somatic motor and parasympathetic nuclei. Among auditory nuclei, the majority of ChAT-IR cells are in the superior olive, particularly in and around the lateral superior olive, the ventral nucleus of the trapezoid body and the superior paraolivary nucleus. A discrete group of ChAT-IR cells is located in the sagulum, and additional cells are scattered in the nucleus of the brachium of the inferior colliculus. A group of ChAT-IR cells lies dorsal to the dorsal nucleus of the Lateral Lemniscus. A few ChAT-IR cells are found in the cochlear nucleus and the ventral nucleus of the Lateral Lemniscus.
In the adult hindbrain, the cytoplasmic Math5-lacZ reporter is expressed within the ventral cochlear nucleus (VCN), in a subpopulation of neurons that project to medial nucleus of the trapezoid body (MNTB), lateral superior olive (LSO), and lateral lemniscus (LL). These cells were identified as globular and small spherical bushy cells based on their morphology, abundance, distribution within the cochlear nucleus (CN), co-expression of Kv1.1, Kv3.1b and Kcnq4 potassium channels, and projection patterns within the auditory brainstem.
Double labeling with anti-KCNQ5 antibodies and anti-synaptophysin or anti-syntaxin, which mark synaptic endings, or anti-microtubule-associated protein 2 (MAP2) antibodies, which mark dendrites, were used to analyze the subcellular distribution of KCNQ5 in neurons in the cochlear nucleus, superior olivary complex, nuclei of the Lateral Lemniscus, and inferior colliculus. Punctate KCNQ5 immunoreactivity virtually disappeared from the cochlear nucleus after cochlea removal, which strongly supports localization of this channel in excitatory endings of the auditory nerve.
In songbirds, nucleus Uvaeformis (Uva) is the sole thalamic input to the telencephalic nucleus HVC (used as a proper name), a sensorimotor structure essential to learned song production that also exhibits state-dependent responses to auditory presentation of the bird's own song (BOS). Using in vivo extracellular and intracellular recordings in urethane-anesthetized zebra finches, we characterized the auditory properties of Uva and examined its influence on auditory activity in HVC and in the telencephalic nucleus interface (NIf), the main auditory afferent of HVC and a corecipient of Uva input. We found robust auditory activity in Uva and determined that Uva is innervated by the ventral nucleus of lateral lemniscus, an auditory brainstem component.
Octopus cells, neurons in the most posterior and dorsal part of the mammalian ventral cochlear nucleus, convey the timing of synchronous firing of auditory nerve fibers to targets in the contralateral superior paraolivary nucleus and ventral nucleus of the Lateral Lemniscus.
We recorded from ITD-sensitive neurons in the dorsal nucleus of the Lateral Lemniscus (DNLL) while presenting pure tones at different ITDs embedded in noise.
The dorsal nucleus of the Lateral Lemniscus (DNLL) receives afferent inputs from many brain stem nuclei and, in turn, is a major source of inhibitory inputs to the inferior colliculus (IC).
The ventral division of the medial geniculate nucleus (MGv) receives almost all of its ascending input from the ipsilateral central nucleus of the inferior colliculus (CNIC). The results indicate that two parallel pathways arising in the CNIC remain largely separate in the medial geniculate nucleus of the gerbil.
Despite preserved cell differentiation, the Reln(rl-Orl) phenotype comprises laminar abnormalities of cell position in auditory cortex and dorsal cochlear nucleus. CO activity increased in the granular cell layer of dorsal cochlear nucleus, trapezoid body nucleus, intermediate lateral lemniscus, central and external inferior colliculus, and pyramidal cell layer of primary auditory cortex. On the contrary, CO activity decreased in the superficial molecular layer of dorsal cochlear nucleus as well as in the medioventral periolivary nucleus.
In the present study, we injected the retrograde transynaptic tracer pseudorabies virus into single tensor tympani (TT) muscles, and identified transynaptically labeled cochlear nucleus neurons at multiple survival times. Motoneurons controlling TT were located ventral to the ipsilateral motor trigeminal nucleus and extended rostrally towards the medial aspect of the Lateral Lemniscus. At those times, labeling was also detected bilaterally in the medial nucleus of the trapezoid body and periolivary cell groups in the superior olivary complex.
Axonal projections from the lateral superior olivary nuclei (LSO), as well as from the dorsal cochlear nucleus (DCN) and dorsal nucleus of the Lateral Lemniscus (DNLL), converge in frequency-ordered layers in the central nucleus of the inferior colliculus (IC) where they distribute among different synaptic compartments. Thus, well before hearing onset in ferret (P28-30), three different afferent projections have segregated into banded compartments along layers in the central nucleus of the ferret IC.
We performed in vivo recordings in Mongolian gerbils of neurons of the dorsal nucleus of the Lateral Lemniscus (DNLL), a GABAergic brainstem nucleus that targets the auditory midbrain, and show that these DNLL neurons exhibit inhibition that persists tens of milliseconds beyond the stimulus offset, so-called persistent inhibition (PI).
In addition, a functional test of TTX diffusion around the BC indicated that the inactivation did not affect other known parts of eyeblink circuits, such as the cerebellar interposed nuclei, the middle cerebellar peduncle or the contralateral red nucleus.
After blocking the massive GABAergic projection from the dorsal nucleus of the Lateral Lemniscus (DNLL) to the contralateral central nucleus of the inferior colliculus (ICC) in anesthetized rats, a reactive increase in the efficacy of other inhibitory circuits in the ICC (separable because of the dominant ear that drives each circuit) was demonstrated with physiological measures-single-neuron activity and a neural-population-evoked response.
During postnatal development, ascending and descending auditory inputs converge to form fibrodendritic layers within the central nucleus of the inferior colliculus (IC). Previous studies in our laboratory have shown that unilateral or bilateral cochlear ablation at postnatal day 2 (P2) disrupts the development of afferent bands from the dorsal nucleus of the Lateral Lemniscus (DNLL) to the IC. The present results suggest that cochlear ablation after DNLL bands have formed may affect the maintenance of banded DNLL projections within the central nucleus of the IC..
We investigated in young rats (P10-P14) the effects of taurine on the neuronal responses and synaptic transmissions in the central nucleus of the inferior colliculus (ICC) with a brain slice preparation and with whole-cell patch-clamp recordings.
Notably, particularly high levels of Cbln mRNAs were expressed in some nuclei and neurons, whereas their postsynaptic targets often lacked or were low for any Cbln mRNAs, as seen for cerebellar granule cells/Purkinje cells, entorhinal cortex/hippocampus, intralaminar group of thalamic nuclei/caudate-putamen, and dorsal nucleus of the Lateral Lemniscus/central nucleus of the inferior colliculus.
Recordings were made from single neurons in the rat's ventral nucleus of the Lateral Lemniscus (VNLL) to determine responses to amplitude-modulated (AM) tones.
The ventral nucleus of the Lateral Lemniscus (VNLL) has been implicated in the processing of such temporal features of a sound. The presence of neurons with band-pass rMTFs in the VNLL suggests that this nucleus plays a role in converting the temporal code for modulation frequency used in lower structures into a rate-based code for use higher in the auditory pathway.
Ultimately, we wanted to determine if the pontine nuclei could be a component of the descending auditory system from the inferior colliculus to the cochlear nucleus.
The highest density of fibers containing thiamine was observed in the pulvinar nucleus and in the region extending from the pulvinar nucleus to the caudate nucleus. Thus, immunoreactive fibers were found in nuclei close to the midline (centrum medianum/parafascicular complex), in the ventrolateral thalamus (medial geniculate nucleus, inferior pulvinar nucleus), and in the dorsolateral thalamus (lateral posterior nucleus, pulvinar nucleus).
Both cues are initially processed in the superior olivary complex (SOC), which projects to the dorsal nucleus of the Lateral Lemniscus (DNLL) and the auditory midbrain. The large number of ITD-sensitive low-frequency neurons implicates a substantial role for the DNLL in ITD processing and promotes this nucleus as a suitable model for further studies on ITD-coding..
Both groups had labeled cells in the nuclei of the Lateral Lemniscus and the superior paraolivary nucleus. The injection sites for both group 1 and group 2 were located in the central nucleus, but those for group 1 tended to be located laterally relative to those for group 2, which were located more medially and caudally. The injection sites for group 3 cases lay outside the central nucleus of the IC. The two regions of the central nucleus of the IC, distinguished on the basis of connectivity, are likely to subserve different functions..
Responses to monaural and binaural tone bursts were recorded from neurons in the rat's ventral nucleus of the Lateral Lemniscus (VNLL).
Interaural time differences, a cue for azimuthal sound location, are first encoded in the superior olivary complex (SOC), and this information is then conveyed to the dorsal nucleus of the Lateral Lemniscus (DNLL) and inferior colliculus (IC).
Anterograde projections could be traced into all cranial motor and sensory nuclei involved in phonation, that is, the nucleus ambiguus, facial, hypoglossal and trigeminal motor nuclei, the motorneuron column in the ventral gray substance innervating the extrinsic laryngeal muscles, the nucleus retroambiguus, solitary tract and spinal trigeminal nuclei. Projections were also found into a number of auditory nuclei, namely the nucleus cochlearis-complex, superior olive, ventral and dorsal nuclei of the Lateral Lemniscus and inferior colliculus. Furthermore, there were projections into the reticular formation of the lateral and dorsocaudal medulla and lateral pons, into nucleus gracilis, inferior and medial vestibular nuclei, lateral reticular nucleus, ventral raphe, pontine gray, superior colliculus, PAG and mediodorsal thalamic nucleus.
The central nucleus of the inferior colliculus (ICC) receives inputs from all parts of the auditory brainstem and transmits the information to the forebrain.
Here we report on response properties and the roles of inhibition in three brain stem nuclei of Mexican-free tailed bats: the inferior colliculus (IC), the dorsal nucleus of the Lateral Lemniscus (DNLL) and the intermediate nucleus of the Lateral Lemniscus (INLL). In each nucleus, we documented the response properties evoked by both tonal and species-specific signals and evaluated the same features when inhibition was blocked.
On MRI, the lesion was thought to involve the spinothalamic tract, medial lemniscus and inferior olivary nucleus. Ambiguus nucleus was in the lesion and solitary nucleus near the lesion.
Neurons immunopositive for TH but not DBH or PNMT were observed in the dorsal cortex and dorsal horn of the central nucleus of the IC and ventral and intermediate lemniscus. In the central nucleus of the IC and dorsal lateral lemniscus many lightly labeled TH neurons were also DBH positive.
Auditory-only sites were located in the most dorsal and medial sites in nucleus centralis. Bimodal sites were identified within both nucleus centralis and nucleus ventrolateralis. The greatest number of retrogradely filled cell bodies was found in the descending octaval nucleus following injection at auditory-only recording sites in nucleus centralis. In contrast, retrogradely filled cell bodies were found in both the descending octaval nucleus and the lateral line nucleus medialis following injection at bimodal sites in nucleus centralis or nucleus ventrolateralis.
The synaptic pharmacology of the ventral nucleus of the Lateral Lemniscus (VNLL) was investigated in brain slices obtained from rats of 14-37 days old using intracellular recording techniques.
In both strains, the highest number of urocortin 1-positive neurons was observed in the Edinger-Westphal nucleus and lateral superior olive. Urocortin 1-positive neurons were detected in the dorsal nucleus of the Lateral Lemniscus of DBA/2J mice, but were absent in the C57BL/6J strain. Further, we found that in both mouse strains, urocortin 1 in the Edinger-Westphal nucleus and choline acetyltransferase are not coexpressed. We show that the urocortin 1-positive neurons of this brain area form a separate population of cells that we propose to be called the non-preganglionic Edinger-Westphal nucleus..
In the mammalian brain, such interaural time differences (ITDs) are encoded in the auditory brain stem; first by the medial superior olive (MSO) and then transferred to higher centers, such as the dorsal nucleus of the Lateral Lemniscus (DNLL), a brain stem nucleus that gets a direct input from the MSO.
The function of the ventral nucleus of the Lateral Lemniscus (VNLL), a secondary processing site within the auditory brain stem, is unclear. Our data suggest it is a result of an intrinsic circuit activated by the octopus cell pathway originating in the contralateral cochlear nucleus; this pathway is known to convey exquisitely timed and broadly tuned onset information.
The mammalian cochlear nucleus (CN) has been a model structure to study the relationship between physiological and morphological cell classes. The main axon used the IAS and followed one of two routes occasionally giving off olivary complex collaterals on their way to the contralateral ventral nucleus of the Lateral Lemniscus (VNLL).
In anaesthetized animals with unilateral electrical stimulation of the cochlear nerve, increased expression of c-Fos was detected in the ipsilateral ventral cochlear nucleus (VCN), in the dorsal cochlear nucleus bilaterally (DCN), in the ipsilateral lateral superior olive (LSO) and in the contralateral inferior colliculus (IC).
Projections of the nucleus reticularis tegmenti pontis (NRTP) to the cerebellar paramedian lobule were examined in the rabbit by means of the double fluorescent retrograde tract-tracing method.
In rats exposed to 400 ppm for 12 weeks, predominant lesions were in the parietal cortex area 1 (necrosis) and posterior colliculus (neuronal loss, microgliosis, hemorrhage), and occasional necrosis was present in the putamen, thalamus, and anterior olivary nucleus. Carbonyl sulfide specifically targeted the auditory system including the olivary nucleus, nucleus of the Lateral Lemniscus, and posterior colliculus. Consistent with these findings were alterations in the amplitude of the brainstem auditory evoked responses (BAER) for peaks N3, P4, N4, and N5 that represented changes in auditory transmission between the anterior olivary nucleus to the medial geniculate nucleus in animals after exposure for 2 weeks to 400 ppm COS.
The highest transcript and protein levels were found in the external nucleus of the inferior colliculus and paraolivary nucleus. More moderate levels of transcript and protein were measured in the ventral, intermediate, and dorsal nuclei of the Lateral Lemniscus, lateral and medial ventral posterior olivary nuclei, rostral periolivary region, lateral periolivary nucleus, caudal periolivary region, ventral and dorsal trapezoid nuclei, medial superior olive, and the lateral superior olive.
Overall, the developmental progression of projections follows that of terminal mitoses in various nuclei, suggesting the consistent use of a developmental timetable at a given nucleus, independent of that of other nuclei.
Strong HCN1 staining was present on octopus and bushy cells of the ventral cochlear nucleus, principal neurons of the lateral and medial superior olive, and neurons of the ventral nucleus of the Lateral Lemniscus. No HCN1 staining was observed in the dorsal cochlear nucleus and the medial nucleus of the trapezoid body (MNTB). In contrast, HCN2 staining was strongest in the MNTB and the dorsal nucleus of the Lateral Lemniscus. Strong HCN2 antibody labelling was also observed in bushy cells of the ventral cochlear nucleus. In the central nucleus of the inferior colliculus only a subpopulation of neurons showed HCN1 or HCN2 immunolabelling.
The central nucleus of the inferior colliculus (ICC) is a major site of synaptic interaction in the central auditory system.
Biotin was detected in cells of the spiral ganglion, somata and proximal dendrites of cells in the cochlear nuclei, superior olivary nuclei, medial nucleus of the trapezoid body, and nucleus of the Lateral Lemniscus. Biotin was further found in pontine nuclei and fiber tracts, the substantia nigra pars reticulata, lateral mammillary nucleus, and a small number of hippocampal interneurons.
Some units resembled the response of constant latency neurons found in the ventral nucleus of the Lateral Lemniscus of bats.
Three main relay nuclei are located between the auditory nerve and the primary auditory cerebral cortex: 1- the cochlear nucleus, 2- the contralateral inferior colliculus and 3- the contralateral medial geniculate body. Some fibers of this main ascending pathway branch off to other nuclei such as the nuclei of the superior olivary complex and the nucleus of the Lateral Lemniscus.
The vast majority of TIP39-containing neurons are localized in two regions, the subparafascicular area at the thalamic-midbrain junction, and the medial paralemniscal nucleus in the rostral pons. Following bilateral lesions of the medial subparafascicular area including the subparafascicular nucleus, TIP39-immunoreactive fibers almost completely disappeared from forebrain regions including the anterior limbic cortical areas, the shell and cone portions of the nucleus accumbens, the lateral septum, the bed nucleus of the stria terminalis, the amygdaloid nuclei, the fundus striati, the subiculum, the thalamic paraventricular nucleus, and the hypothalamic paraventricular, dorsomedial and arcuate nuclei. Following lesions of the medial paralemniscal nucleus, TIP39-immunoreactive fibers disappeared from the medial geniculate body, the periaqueductal gray, the deep layers of the superior colliculus, the external cortex of the inferior colliculus, the cuneiform nucleus, the nuclei of the Lateral Lemniscus, the lateral parabrachial nucleus, the locus coeruleus, the subcoeruleus area, the medial nucleus of the trapezoid body, the periolivary nuclei, and the spinal cord, suggesting that these regions receive TIP39-containing fibers from the medial paralemniscal nucleus, and unilateral lesions demonstrated that the projections are ipsilateral. The projections of the TIP39-containing cells in the subparafascicular area suggest their involvement in limbic and endocrine functions, while the projections of the TIP39-containing cells in the medial paralemniscal nucleus suggest their involvement in auditory and nociceptive functions..
Significant decreases in 2-DG uptake were found in the ipsilateral anteroventral and posteroventral cochlear nucleus, with respect to the exposed left ears. Exposed animals also showed significant increases in the ipsilateral nucleus of the Lateral Lemniscus, central nucleus of inferior colliculus and medial geniculate body. No significant changes in uptake were observed in the ipsilateral dorsal cochlear nucleus, superior olivary complex, auditory cortex and any contralateral structures.
Moreover, together with the lesions seen in the motor cerebellothalamocortical feedback loop (pontine nuclei, deep cerebellar nuclei and cerebellar cortex, ventral lateral nucleus of the thalamus), they also account for the somatomotor deficits that were observed in the young woman (gait, stance, and limb ataxia, falls, and impaired writing).
The immunocytochemical results demonstrated a significant increase in exposed animals of FLI in auditory brain structures such as the Lateral Lemniscus, central nucleus of inferior colliculus, and auditory cortex, as well as in some nonauditory brain structures such as the locus coeruleus, lateral parabrachial nucleus, certain subregions of the hypothalamus, and amygdala.
None of the cell populations in the cochlear nucleus projects to all brainstem targets, and none of the targets receives inputs from all cell types. The projections of nine distinguishable cell types in the cochlear nucleus-seven in the ventral cochlear nucleus and two in the dorsal cochlear nucleus-are described in this review. Fusiform cells in the dorsal cochlear nucleus appear to be important for the localization of sounds based on spectral cues and send direct excitatory projections to the inferior colliculus. Giant cells in the dorsal cochlear nucleus also project directly to the inferior colliculus; some of them may convey inhibitory inputs to the contralateral cochlear nucleus as well..
These included octopus cells and spherical bushy cells of the cochlear nucleus and principal neurons of the medial nucleus of the trapezoid body. In addition, we found high levels of Kv1.1 in neurons of the columnar subdivision of the ventral nucleus of the Lateral Lemniscus and in ventral periolivary cell groups. Neurons with high levels of Kv1.1 were differentially distributed in the intermediate nucleus of the Lateral Lemniscus and in the inferior colliculus, suggesting that these structures contain functionally distinct cell populations, some of which may be involved in high-precision temporal processing..
In the central nucleus of the inferior colliculus (IC), afferent projections are aligned with dendritic arbors of disk-shaped cells, forming fibrodendritic layers. One feature that may serve as a guide for study of the intrinsic organization of the IC layers is the segregation of certain inputs to bands and patches within the layers of the central nucleus. In this study, we used Phaseolus leucoagglutinin as an anterograde tracer to examine the projections from the dorsal nucleus of the Lateral Lemniscus to the contralateral IC in adult ferrets.
The central nucleus of the inferior colliculus but not the surrounding regions contained parvalbumin-positive neuronal somata and fibres. Calbindin-positive neurons and fibres were concentrated in the dorsal aspect of the central nucleus and in structures surrounding it: the dorsal cortex, the Lateral Lemniscus, the ventrolateral nucleus, and the intercollicular region.
In the present study, gerbils were deafened at postnatal day 9, an age at which there is no deafferentation-induced cell death of ventral cochlear nucleus neurons.
We studied how lemniscal feedback affects ascending transmission of cutaneous neurons of the middle cuneate nucleus.
Seven weeks after hatching, ir-GHRH cells were also identified in the nucleus of the Lateral Lemniscus and the cerebellum.
This study evaluated how neurons in the dorsal nucleus of the Lateral Lemniscus (DNLL) in Mexican free-tailed bats respond to both tone bursts and species-specific calls.
Synaptic responses were elicited by applying a current pulse to the Lateral Lemniscus just below the central nucleus of the inferior colliculus.
The investigation was carried out by means of extracellular single-unit recordings in the ventroposterior lateral nucleus of the thalamus in rats anesthetized with pentobarbital.
The medial division of the ventral nucleus of the Lateral Lemniscus (VNLLm) contains a specialized population of neurons that is sensitive to interaural temporal disparities (ITDs), a potent cue for sound localization along the azimuth.
In the diencephalon, TRHir neurons were observed in the anterior parvocellular preoptic nucleus, the suprachiasmatic nucleus, the lateral hypothalamic nucleus, the rostral parts of the anterior tuberal nucleus and torus lateralis, and the posterior tuberal nucleus. Some TRHir neurons were also observed in the central posterior thalamic nucleus and in the habenula. The mesencephalon contained TRHir cells in the rostrodorsal tegmentum, the Edinger-Westphal nucleus, the torus semicircularis, and the nucleus of the Lateral Lemniscus. Further TRHir neurons were observed in the interpeduncular nucleus. In the rhombencephalon, TRHir cells were observed in the nucleus isthmi and the locus coeruleus, rostrally, and in the vagal lobe and vagal motor nucleus, caudally. In the forebrain, TRHir fibers were abundant in several regions, including the medial and caudodorsal parts of the dorsal telencephalic area, the ventral and commissural parts of the ventral telencephalic area, the preoptic area, the posterior tubercle, the anterior tuberal nucleus, and the posterior hypothalamic lobe. The medial and lateral mesencephalic reticular areas and the interpeduncular nucleus were richly innervated by TRHir fibers. In the rhombencephalon, the secondary gustatory nucleus received abundant TRHir fibers. TRHir fibers moderately innervated the ventrolateral and ventromedial reticular area and richly innervated the vagal lobe and Cajal's commissural nucleus.
The data support our hypothesis that the BI component in wave P4 results from a binaural reduction in dischargings of axons ascending in the LL, with this reduction due to contralateral inhibition of the discharge activity of the inhibitory-excitatory units in the lateral nucleus of the SO.
The ventral nucleus of the Lateral Lemniscus (VNLL) is a major source of input to the inferior colliculus. The VNLL has generally been viewed as a monaural nucleus, with its neurons responding primarily to stimulation of the contralateral ear.
EI neurons are first created in the lateral superior olive (LSO), but they also dominate the dorsal nucleus of the Lateral Lemniscus (DNLL) and regions of the IC.
Brain slice studies of neurons in the central nucleus of the inferior colliculus (ICC) indicate that excitatory responses evoked by electrical stimulation of the Lateral Lemniscus consist of two components, an early, rapid response mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and a later, a slower one mediated by N-methyl-D-aspartate (NMDA) receptors.
The synaptic mechanisms underlying excitation in the rat's central nucleus of the inferior colliculus (ICC) were examined by making whole-cell patch clamp recordings in brain slice preparations of the auditory midbrain.
However, it is difficult to place these data into the proper quantitative perspective due to our lack of knowledge of the number of neurons contained within each auditory nucleus.
In brief, very high levels of Y1R-LI were seen in the islands of Calleja, the anterior olfactory nucleus, the molecular layer of the dentate gyrus, parts of the habenula, the interpeduncular nucleus, the mammillary body, the spinal nucleus of the trigeminal, caudal part, the paratrigeminal nucleus, and superficial layers of the dorsal horn. High levels were found in most cortical areas, many thalamic nuclei, some subnuclei of the amygdaloid complex, the hypothalamus and the nucleus of the stria terminalis, the nucleus of the solitary tract, the parabrachial nucleus, and the inferior olive.
These neurons resided in the posteroventral and anteroventral cochlear nucleus, the dorsal cochlear nucleus, the lateral superior olive, the medial nucleus of the trapezoid body, the dorsal and ventral nucleus of the Lateral Lemniscus, and the central nucleus of the inferior colliculus. Moreover, effects of electrical stimulation were identified in the medial vestibular nucleus and the lateral parabrachial nucleus.
However in five brain regions, dizocilpine injected HSP70 Tg mice displayed significantly altered LCGU compared to dizocilpine injected WT mice (anterior thalamic nucleus +27%, dorsal CA1 stratum lacunosum molecularae +22%, dorsal CA1 stratum oriens + 14%, superior olivary body -26%, and the nucleus of the Lateral Lemniscus -16%).
The results confirm abundant AT(1) binding in regions involved in cardiovascular and drinking regulation: the nucleus of the solitary tract, ventrolateral medulla, subfornical organ, organum vasculosum of the lamina terminalis, median eminence, and several hypothalamic structures. Novel AT(1) binding sites were discovered in the pituitary, retrorubral field, periolivary region, dorsolateral nucleus of the Lateral Lemniscus, dorsal raphe, and laterodorsal tegmental nuclei.
The responses of single neurons in the posterior part of the ventral nucleus of the Lateral Lemniscus were recorded to stimulation with binaurally correlated and binaurally uncorrelated noise. Neurons in the posterior part of the ventral nucleus of the Lateral Lemniscus encode the interaural level difference of binaurally correlated and binaurally uncorrelated noise with equal accuracy and precision. This nucleus therefore supplies higher auditory centers with an undegraded interaural level difference signal for sound stimuli that lack a coherent interaural time difference.
The ventromedial periolivary nucleus and the rostral periolivary nucleus showed c-Fos activation in isolated conditions and were strongly activated following sound stimulation.
Positive cells were seen in the dorsal and ventral nuclei of the Lateral Lemniscus, the rostral periolivary region, the lateroventral and medioventral periolivary nuclei, the dorsal periolivary region, the superior paraolivary nucleus, and the external cortex and dorsal cortex of the inferior colliculus.
In the mustached bat, they also occur in the central nucleus of the inferior colliculus (ICC). All combination-sensitive units were in the intermediate nucleus of the NLL (INLL), which in bats is a hypertrophied structure that projects strongly to combination-sensitive neurons in the ICC.
Auditory input to the torus, that arising directly from the dorsal medullary nucleus, is present only in the laminar nucleus. The principal and magnocellular nuclei receive their input from the lateral line nucleus of the medulla. All three nuclei of the torus also have reciprocal connections with the superior olive and the nucleus of the Lateral Lemniscus. The laminar and magnocellular nuclei have reciprocal connections with the ventral thalamus, and all three nuclei of the torus receive descending input from the anterior entopeduncular nucleus. Based on our identification of toral nuclei and these results we assign a major function for the detection of water-borne sounds to the laminar nucleus and a major function for the detection of near field disturbances in water pressure to the principal and magnocellular nuclei..
Notably, Kv3.1 mRNA was not expressed in neurons of the medial and lateral superior olive and a subpopulation of neurons in the ventral nucleus of the Lateral Lemniscus. The intensity of Kv3.1 immunoreactivity varied across the tonotopic map in the medial nucleus of the trapezoid body with neurons responding best to high-frequency tones most intensely labeled.
The nucleus paragigantocellularis lateralis (PGL) is located in the rostral ventrolateral medulla (RVLM), a brainstem region that regulates homeostatic functions, such as blood pressure and cardiovascular reflexes, respiration. In the present study, we examined anatomic relationships of the human nucleus paragigantocellularis lateralis using a bidirectional lipophilic fluorescent tracer, 1,1'-dioctadecyl-3,3.3',3'-tetramethylindocarbocyanine perchlorate (DiI), in nine postmortem human fetal midgestational brainstems. The areas which were labeled by diffusion of DiI from the nucleus paragigantocellularis lateralis included the arcuate nucleus (ARC) of the medulla, caudal raphe (nucleus raphe obscurus and pallidus), hilum and amiculum of the inferior olive, bilateral "reticular formation" (including the nucleus paragigantocellularis lateralis, nucleus gigantocellular-is and the intermediate reticular zone (IRZ)). vestibular and cochlear nuclei, cells and fibers at the floor of the fourth ventricle with morphologic features of tanycytes, parabrachial nuclei (PBN), medial lemniscus, lateral lemniscus, inferior cerebellar peduncle and cerebellar white matter, central tegmental tract, and the capsule of the red nucleus. This pattern of DiI labeling bears many similarities with the pattern of connections of the nucleus paragigantocellularis lateralis previously demonstrated by tract-tracing methods in experimental animals, and is consistent with the role of the nucleus paragigantocellularis lateralis in central regulation of homeostatic functions. In contrast to the animal studies, however, we did not demonstrate connections of the nucleus paragigantocellularis lateralis with the nucleus of the tractus solitarius (nTS) (only connections with the rostral subdivision were examined), locus coeruleus, or the periaqueductal gray (PAG) in the human midgestational brainstem.
To test this, we measured ITD tuning across frequency in neurons from the superior olivary complex, the dorsal nucleus of the Lateral Lemniscus, the inferior colliculus, the auditory thalamus, and the auditory cortex. For some neurons in each nucleus, the ITD tuning width did become systematically narrower by the expected 1/frequency relationship.
Although EI properties are first formed in a lower nucleus and imposed on some IC cells via an excitatory projection, many other EI neurons are formed de novo in the IC. By reversibly inactivating the dorsal nucleus of the Lateral Lemniscus (DNLL) in Mexican free-tailed bats with kynurenic acid, we show that the EI properties of many IC cells are formed de novo via an inhibitory projection from the DNLL on the opposite side. These features suggest that the circuitry linking the DNLL with the opposite central nucleus of the IC is important for the processing of IIDs that change over time, such as the IIDs generated by moving stimuli or by multiple sound sources that emanate from different regions of space..
We have investigated the somatosensory and auditory representations in the nucleus basalis of the barn owl. In pigeons and finches, the nucleus basalis contains a representation of the beak and an auditory area. In the barn owl, the nucleus basalis also contains a complete somatotopic map of the head and body (as in the budgerigar), with a tonotopically organized auditory area in close proximity to the representation of the facial ruff and the preaural area. Recordings within and around the nucleus basalis revealed predominantly (about 80%) contralateral responses to somatic stimulation. Towards more rostral positions in nucleus basalis, responses from the head and beak predominated ventrally. Some penetrations yielded predominantly monaural responses with a fairly broad dynamic range, similar to those recorded from the ventral nucleus of the Lateral Lemniscus (LLV) and the cochlear nucleus angularis, whereas other penetrations contained predominantly binaural responses sensitive to interaural time differences (ITD). The physiological responses could be predicted on the basis of auditory projections to the nucleus basalis. An injection of biotinylated dextran amine (BDA) in the auditory region of nucleus basalis retrogradely labeled cells in both the caudal and rostral parts of the intermediate lateral lemniscal nucleus (LLIc and LLIr), and a few cells in the anterior part of the dorsal lateral lemniscal nucleus (LLDa, previously known as nucleus ventralis lemnisci lateralis, pars anterior, or VLVa) and in the posterior part of the dorsal lateral lemniscal nucleus (LLDp, previously known as nucleus ventralis lemnisci lateralis, pars posterior, or VLVp). A large injection of cholera toxin B-chain (CTB) into the nucleus basalis also produced dense retrograde labeling of a previously unidentified nucleus on the lateral aspect of the rostral pons, that we here call nucleus pontis externus (PE). An injection of CTB into PE produced dense retrograde labeling of the contralateral dorsal column nuclei and anterograde labeling of the ipsilateral lateral and dorsolateral nucleus basalis.
Telencephalic GAL-ir neurons were found in the olfactory bulb, cerebral cortex, lateral and medial septum, diagonal band of Broca, nucleus basalis of Meynert, bed nucleus of stria terminalis, amygdala, and hippocampus. In the midbrain, GAL-ir neurons appeared in the pretectal olivary nucleus, oculomotor nucleus, the medial and lateral lemniscus, periaqueductal gray, and the interpeduncular nucleus. In the medulla oblongata, GAL-ir neurons appear in the anterodorsal and dorsal cochlear nuclei, salivatory nucleus, A5 noradrenergic cells, gigantocellular nucleus, inferior olive, solitary tract nucleus, dorsal vagal motor and hypoglossal nuclei. Only GAL-ir fibers were seen in the lateral habenula nucleus, substantia nigra, parabrachial complex, cerebellum, spinal trigeminal tract, as well as the motor root of the trigeminal and facial nerves.
The ventral nucleus of the Lateral Lemniscus (VNLL) is a prominent neuronal group that lies within the auditory pathway connecting the auditory lower brainstem and midbrain.
We have studied by in situ hybridization for GAD65 mRNA in thick sections and by semiquantitative postembedding immunocytochemistry in consecutive semithin sections, the expression of gamma-aminobutyric acid (GABA) and glycine in cell bodies and axosomatic puncta of the rat ventral nucleus of the Lateral Lemniscus (VNLL), a prominent monaural brainstem auditory structure.
Here we describe, using in situ hybridization, the subunit expression patterns of GABA(A) receptors in the rat cochlear nucleus, superior olivary complex, and dorsal and ventral nuclei of the Lateral Lemniscus. In the dorsal cochlear nucleus, fusiform (pyramidal) and giant cells express alpha1, alpha3, beta3 and gamma2L. Dorsal cochlear nucleus interneurons, particularly vertical or tuberculoventral cells and cartwheel cells, express alpha3, beta3 and gamma2L. In the ventral cochlear nucleus, octopus cells express alpha1, beta3, gamma2L and delta. Both dorsal and ventral cochlear nucleus granule cells express alpha1, alpha6, beta3 and gamma2L; unlike their cerebellar granule cell counterparts, they do not express beta2, gamma2S or the delta subunit genes. The delta subunit's absence from cochlear nucleus granule cells may mean that tonic inhibition mediated by extrasynaptic GABA(A) receptors is less important for this cell type. In both the dorsal and ventral nuclei of the Lateral Lemniscus, alpha1, beta3 and gamma2L are the main subunit messenger RNAs; the ventral nucleus also expresses the delta subunit.
High concentrations of Y1 immunoreactivity were found in the claustrum, piriform cortex (superficial layer), arcuate hypothalamic nucleus, interpeduncular nucleus, paratrigeminal nucleus, and lamina II of the spinal trigeminal nucleus and entire spinal cord. 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. Low levels of Y1 immunostaining were distributed widely throughout layers II-III of the cerebral cortex (i.e., orbital, cingulate, frontal, parietal, insular, and temporal regions), nucleus accumbens core, amygdalohippocampal and amygdalopiriform areas, dentate gyrus, CA1 and CA2 fields of hippocampus, principal and oral divisions of the spinal trigeminal nucleus, islands of Calleja and presubiculum.
The cochlear nucleus angularis (NA) of the barn owl (Tyto alba) was analyzed using Golgi, Nissl, and tract tracing techniques. NA forms a column of cells in the dorsolateral brainstem that partly overlaps with, and is rostral and lateral to, the cochlear nucleus magnocellularis (NM). Neurons in each of these four classes projected to the inferior colliculus and dorsal nucleus of the Lateral Lemniscus..
Olivary projections are the predominant afferents to the central nucleus of the inferior colliculus. Electron microscopic observations of axonal endings in the central nucleus suggest that the ipsilateral medial superior olive and contralateral lateral superior olive make excitatory synapses. In contrast, the axons from the ipsilateral lateral superior olive to the central nucleus contain glycine and have a morphology consistent with inhibitory synapses.
Based on current literature, the afferents of the superior olivary complex (SOC) are described including those from the cochlear nucleus, inferior colliculus, thalamus, and auditory cortex. New data are provided that show a differential distribution of serotoninergic afferents within the SOC: serotoninergic fibers were relatively sparse in the lateral and medial superior olives and the medial nucleus of the trapezoid body and were most numerous in periolivary regions. These include: cochlear nucleus afferents to periolivary (lateral nucleus of the trapezoid body, LNTB) cells that project to the inferior colliculus; cortical afferents to periolivary (ventral nucleus of the trapezoid body, VNTB) cells that project to the cochlear nucleus; and serotoninergic and noradrenergic afferents to periolivary (LNTB and VNTB) cells that project to the cochlear nucleus. The circuits include those that are part of the ascending auditory system (to the inferior and superior colliculi, lateral lemniscus, and medial geniculate nucleus), the descending auditory system (to the cochlea and cochlear nucleus), and the middle ear reflex circuits..
It was found that injections made into the ventrolateral pons around the ventral nucleus of the Lateral Lemniscus and superior olive could block periaqueductally elicited vocalization.
In the diencephalon, labeled cells were present in all the mid-line and intralaminar thalamic nuclei; the lateral posterior, pulvinar and suprageniculate nuclei; the ventral nucleus of the lateral geniculate body and the medial geniculate body. Additionally, Met-enk-li cells were seen in every hypothalamic nucleus except in the supraoptic. In the rhombencephalon, labeled cells were seen in the majority of the nuclei in the latero-dorsal pontine tegmentum, the nuclei of the Lateral Lemniscus, the trapezoid, vestibular medial, vestibular inferior and cochlear nuclei, the prepositus hypoglossal, the nucleus of the solitary tract and the dorsal motor nucleus of the vagus, the infratrigeminal nucleus and the caudal part of the spinal trigeminal nucleus and in the rhombencephalic reticular formation. The distribution of fibers included additionally the substantia nigra, all the trigeminal nerve nuclei, the facial nucleus and a restricted portion of the inferior olive.
In a previous paper (Reed and Blum, 1999), we examined the connectional hypotheses put forward by Markovitz and Pollak (1994) to explain the steady-state behavior of cells in the dorsal nucleus of the Lateral Lemniscus (DNLL). We found that the steady-state outputs of the four major binaural types of cells found in the DNLL (EI, EI/F, EE/I, and EE/FI) could be accounted for by known connectional patterns using only one or two cells per nucleus and quite simple hypotheses on cell behavior. The model auditory nerve fibers ramp up linearly (usually in 2 ms) to full firing and the anteroventral cochlear nucleus cells have primary-like discharge patterns.
To better understand the development of the dorsal nucleus of the Lateral Lemniscus (DNLL), intrinsic membrane properties and synaptic responses of DNLL neurons in brain slice preparations were examined.
The lesion was suspected of affecting ipsilateral side of the spinal trigeminal nerve tract and the nucleus, the intraaxial infranuclear facial nerve fiber, the Lateral Lemniscus adjacent to the superior olivary nucleus and the central gustatory tract. Our case suggests that the central gustatory pathway projecting from the nucleus of the solitary tract to the parabrachial nucleus, presumed to be pontine taste area, ascends ipsilaterally and is located laterally from the medial lemniscus..
The central nucleus of the inferior colliculus (IC) is the site of convergence for nearly all ascending monaural and binaural projections. Several of these inputs, including inhibitory connections from the dorsal nucleus of the Lateral Lemniscus (DNLL), are highly ordered and organized into series of afferent bands or patches.
In young adult guinea pigs, the high-affinity specific binding of [ (3)H]AMPA was measured in the cochlear nucleus (CN), the superior olivary complex (SOC), and the auditory midbrain at 2-147 postlesion days. In the midbrain, transient elevations and/or deficits in binding were evident in the dorsal nucleus of the Lateral Lemniscus as well as in the central and dorsal nucleus of the inferior colliculus. A persistent deficit was evident in the intermediate nucleus of the Lateral Lemniscus.
In the mustached bat, we have discovered a population of such FM selective cells in an area interposed between the central nucleus of the inferior colliculus (ICC) and the nuclei of the Lateral Lemniscus (NLL). We believe this area to be the ventral extent of the external nucleus of the inferior colliculus (ICXv). The primary site of retrograde transport was the nucleus of the central acoustic tract in the brainstem. Thus, the ICXv appears to be a part of the central acoustic tract, an extralemniscal pathway linking the auditory brainstem directly to a multimodal nucleus of the thalamus..
alpha7 mRNA and protein are expressed in selected regions of the cochlear nucleus (CN), inferior colliculus (IC), medial superior olive, lateral superior olive, ventral nucleus of the Lateral Lemniscus and superior paraolivary nucleus. Of particular interest is the octopus cell region of the posteroventral cochlear nucleus (PVCN).
The purpose of this study is to determine whether long-term potentiation (LTP) can be induced in the central nucleus of the inferior colliculus (ICC) by electrical stimulation of the Lateral Lemniscus.
AI, AAF, DP and VP project to all three subdivisions of the inferior colliculus, namely the dorsal cortex, external cortex and central nucleus ipsilaterally and to the dorsal and external cortex contralaterally. In addition, AAF and particularly DP and VP project to paralemniscal regions around the dorsal nucleus of the Lateral Lemniscus (DNLL), to the DNLL itself and to the rostroventral aspect of the superior olivary complex. Moreover, DP and VP send axons to the dorsal lateral geniculate nucleus.
Upon reaching the midbrain, the medial lemniscus turns dorsally to terminate heavily in a lateral division of the torus semicircularis, in the ventral optic tectum, and in the lateral subnucleus of the nuc. Lesser projections also reach the posterior periventricular portion of the posterior tubercle with a few fibers terminating along the ventral, posterior margin of the ventromedial (VM) nucleus of the thalamus. Both direct and indirect spinocerebellar fibers can be followed through the dorsolateral fasciculus, with or without relay in the lateral funicular nucleus and terminating in a restricted portion of the granule cell layer of the ipsilateral corpus cerebelli.
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.
Biotin injections into physiologically identified auditory sites in nucleus centralis (NC) in the torus semicircularis show a medial column of retrogradely filled neurons in the medulla mainly in a dorsomedial division of a descending octaval nucleus (DO), dorsal and ventral divisions of a secondary octaval nucleus (SO), and the reticular formation (RF) near the Lateral Lemniscus. Biotin-filled neurons are also located at midbrain-pretectal levels in a medial pretoral nucleus. Terminal fields are identified in the medulla (ventral SO, RF), isthmus (nucleus praeeminentialis), midbrain (nucleus of the Lateral Lemniscus, medial pretoral nucleus, contralateral NC, tectum), diencephalon (lateral preglomerular, central posterior, and anterior tuber nuclei), and telencephalon (area ventralis).
Binaural responses of single neurons in the rat's central nucleus of the inferior colliculus (ICC) were recorded before and after local injection of excitatory amino acid receptor antagonists (either 1,2, 3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[ f]quinoxaline-7-sulfonamide disodium [ NBQX], (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid [ CPP], 6-cyano-7-nitroquinoxaline-2,3-dione [ CNQX], or (+/-)-2amino-5-phosphonovaleric acid [ APV]) into the dorsal nucleus of the Lateral Lemniscus (DNLL).
Previous studies in the macaque monkey have identified a thalamic nucleus, the posterior portion of the ventral medial nucleus (VMpo), as a dedicated lamina I spinothalamocortical relay for pain and temperature sensation. This region, which we identify as VMpo, is located posteromedial to the ventral posterior lateral (VPL) and ventral posterior medial (VPM) nuclei, ventral to the anterior pulvinar and centre médian nuclei, lateral to the limitans and parafascicular nuclei and dorsal to the medial geniculate nucleus. CGRP immunoreactivity is also present over small, non-clustered neurons in the calbindin-negative area that separates VMpo from the VPL and VPM nuclei, which we denote as the posterior nucleus (Po).
Extratelencephalic projections of rostral HA traveled in the septomesencephalic tract (TSM) and gave rise to nuclear-specific terminal fields in the precerebellar medial spiriform nucleus of the posterior thalamus, the red nucleus in the mesencephalon, the medial pontine nucleus in the pons, and the subtrigeminal, external cuneate, cuneate, gracile, and inferior olivary nuclei in the medulla. There was also a sparse projection to the dorsal thalamic nucleus intermedius ventralis anterior, which supplies the somatosensory input to the rostral Wulst, and distinct projections to the intercollicular region surrounding the central nucleus of the inferior colliculus, where they partly overlapped the projections of the dorsal column nuclei.
The purpose of the present study was to determine the development of the projection from the dorsal nucleus of the Lateral Lemniscus (DNLL) to the IC in rat prior to the onset of hearing (postnatal day 12/13).
While GAD neurons were numerous and preferably localized in the dorsal (DLL) and ventral (VLL) nuclei, neurons expressing these peptides were less numerous and localized primarily in the intermediate (ILL) nucleus of the Lateral Lemniscus. The ILL nucleus was shown to project to the inferior colliculus and to express Fos rapidly in response to peripheral acoustic stimulation, suggesting that the ILL nucleus may take part in non-GABAergic relay of acoustic information in the Lateral Lemniscus..
Whole-cell patch-clamp recordings were made from neurons in the rat's dorsal nucleus of the Lateral Lemniscus (DNLL) in a brain slice preparation.
In the hindbrain, CR-IR was first observed in the rostromedial regions of the cochlear nucleus magnocellularis and the nucleus laminaris, and in the dorsal regions of the nucleus angularis and in the nucleus of the Lateral Lemniscus.
The main target of CRN axons is the contralateral pontine reticular formation, where collaterals terminate in the caudal pontine reticular nucleus (PnC) and, to a lesser degree, in the ventrolateral tegmental area, the oral pontine reticular nucleus, and the rostral and medial paralemniscal regions. Other targets of CRN axons include the lateral paragigantocellular nucleus of both sides, the ipsilateral facial motor nucleus and PnC, and the contralateral intercollicular tegmentum and superior colliculus.
Several studies have been performed in which both the time-dependent and steady state output of cells in the dorsal nucleus of the Lateral Lemniscus (DNLL) have been measured in response to binaural sound stimulation.
The ventral nucleus of the Lateral Lemniscus (VNLL) is a major auditory nucleus that sends a large projection to the inferior colliculus. Neurons sensitive to ITDs were mostly of the onset type and were embedded in the fiber tract medial to the main part of the nucleus. The sustained neurons were located on the periphery of the main nucleus as well as in the fiber tract.
In the present study, we correlated asymmetries in the outputs of the dorsal nucleus of the Lateral Lemniscus (DNLL) to the two inferior colliculi (ICs), with asymmetries in the inputs to DNLL from the two lateral superior olives (LSOs).
Considering both the density of labeled neurons per region and their intensity of labeling, the distribution of prepronociceptin messenger RNA-containing neurons can be summarized as follows: the highest level of prepronociceptin messenger RNA expression was detected in the septohippocampal nucleus, bed nucleus of the stria terminalis, central amygdaloid nucleus, and in selective thalamic nuclei such as the parafascicular, reticular, ventral lateral geniculate and zona incerta. High to moderate levels of prepronociceptin messenger RNA expression were detected in the lateral, ventral and medial septum, and were evident in brainstem structures implicated in descending antinociceptive pathways (e.g., the gigantocellular nucleus, raphe magnus nucleus, periaqueductal gray matter), and also observed in association with auditory relay nuclei such as the inferior colliculi, lateral lemniscus nucleus, medioventral preolivary nucleus and lateral superior nucleus. A moderate level of prepronociceptin messenger RNA expression was observed in the medial preoptic nucleus, ventromedial preoptic nucleus, periventricular nucleus, pedonculopontine tegmental nucleus, solitary tract nucleus and spinal trigeminal nucleus. A weak level of prepronociceptin messenger RNA expression was present in some areas, such as the cerebral cortex, endopiriform cortex, hippocampal formation, medial amygdaloid nucleus, anterior hypothalamic area, medial mammillary hypothalamic nuclei, retrorubral field and substantia nigra pars compacta. No labeled cells could be found in the caudate-putamen, nucleus accumbens and ventral tegmental area.
FM-FM neurons are common in high-frequency regions of the central nucleus of the inferior colliculus (ICC) and may be created there. In the anteroventral cochlear nucleus, labeling in the anterior and marginal cell divisions occurred in regions thought to respond to low-frequency sounds. Labeling in the intermediate nucleus of the Lateral Lemniscus and the magnocellular part of the ventral nucleus of the Lateral Lemniscus together comprised nearly 40% of all labeled cells. If the spectral integration of FM-FM neurons is created at the level of the ICC, these results suggest that neurons of the anteroventral cochlear nucleus or monaural nuclei of the Lateral Lemniscus may provide the essential low-frequency input.
The physiological properties including current-voltage relationships, firing patterns, and synaptic responses of the neurons in the ventral nucleus of the Lateral Lemniscus (VNLL) were studied in brain slices taken through the young rat's (17-37 days old) auditory brain stem.
The dorsal nucleus of the Lateral Lemniscus (DNLL) is an auditory structure of the brainstem. Single, small iontophoretic injections of biotinylated dextran amine were made at different loci in the central nucleus of the inferior colliculus (CNIC).
Binaural evoked responses were recorded with glass micropipettes from the central nucleus of the rat's inferior colliculus (ICC) before and after transection of the commissure of Probst (CP) with a microsurgical knife. After recordings were made, both anterograde and retrograde tract tracing methods were used to verify that the CP was completely transected and that all crossed projections from the dorsal nucleus of the Lateral Lemniscus (DNLL) to ICC were destroyed.
After perfusion of these cats, histological examination of the brainstem revealed complete ablation of both ICs, neuronal loss in the nucleus of the Lateral Lemniscus and the superior olivary complex and preservation of the cochlear nucleus. Our results suggest that retrograde degeneration of neuronal cells of the brainstem, which project to the IC from the nucleus of the Lateral Lemniscus and superior olivary complex except the cochlear nucleus, affect the peak amplitudes of the ABR over the long-term..
AT2 mRNA is detected beginning at E15 in the subthalamic and hypoglossus nuclei; at E17 in the pedunculopontine nucleus, cerebellum, motor facial nucleus, and the inferior olivary complex; at E19 in the thalamus, bed nucleus of the supraoptic decussation, interstitial nucleus of Cajal, nuclei of the Lateral Lemniscus, locus coeruleus, and supragenual nucleus; and at E21 in the lateral septal and medial amygdaloid nuclei, medial geniculate body, and the superior colliculus. Certain structures express AT2 mRNA strongly but transiently during embryonic life, such as the differentiating lateral hypothalamic area at E13, the superior olivary complex at E19 and E21, and the red nucleus at E15 and E17.
Compared to controls, experimental animals showed significantly (P<0.05) more FLI in the dorsal and external cortex of the IC, as well as in the medial part of the medial geniculate body (MGB), perigeniculate area, and dorsal cochlear nucleus. No significant increase of FLI was observed in the central nucleus of the IC, ventral and dorsal parts of the MGB, dorsal nucleus of the Lateral Lemniscus, or ventral cochlear nucleus.
Anatomical and electrophysiological specializations for conveying precise timing, including calyceal synaptic terminals and matching axonal conduction times, are evident in several of the major ascending auditory pathways through the ventral cochlear nucleus and its nonmammalian homologues.
The dorsal nucleus of the Lateral Lemniscus (DNLL) is a distinct auditory neuronal group located ventral to the inferior colliculus (IC).
The conventional view, based largely on studies in cats, holds that the dorsal nucleus of the Lateral Lemniscus (DNLL) is tonotopically organized with a dorsal (low-frequency) to ventral (high-frequency) representation. Many fewer neurons labeled following middle-frequency stimulation, and these tended to be more uniformly distributed throughout the nucleus. Still fewer neurons labeled after low-frequency stimulation and these tended to be scattered mostly in the dorsal half of the nucleus.
Both retrograde and anterograde labelings were mainly found in: 1) the deep cerebellar nuclei; 2) the Lateral Lemniscus and paralemniscal nuclei, deep gray, and white intermediate layers of the superior colliculus, tegmental (laterodorsal and microcellular) nuclei, and central gray; and 3) the septohypothalamic nucleus, and lateral and posterior hypothalamic areas. The FR-labeled terminal-like elements were found in: 1) Crus 2 of the ansiform lobule, and the simple, 2, and 3 cerebellar lobules; 2) the subcoeruleus, deep mesencephalic, and Edinger-Westphal nuclei; and 3) the premammillary, lateral, and medial mammillary nuclei, retrochiasmatic part of the supraoptic nucleus, and the zona incerta. The FB-labeled neurons were found in: 1) the parapedunculopontine tegmental and cuneiform nuclei, caudal linear nucleus of the raphe, and adjacent area of the cerebral peduncle; 2) the thalamic posterior nuclear group and subparafascicular, parafascicular, and gelatinosus thalamic nuclei; 3) the parastrial amygdaloid and subthalamic nuclei; and 4) the olfactory tubercle, granular, and agranular insular cortex, parietal and lateral orbital cortices.
The aim of the present study was to characterize the discharge properties of single neurons in the dorsal nucleus of the Lateral Lemniscus (DNLL) of the rat. The DNLL units were arranged according to a mediolateral sensitivity gradient with the lowest threshold units in the most lateral part of the nucleus. The DNLL exhibits a loose tonotopic organization, where there is a concentric pattern with high BF units located in the most dorsal and ventral parts of the DNLL and lower BF units in the middle part of the nucleus..
Here we have studied age-dependent changes in the expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) and N-methyl-D-aspartate (NMDA) receptor subunits in the cochlear nucleus complex (CN), the superior olivary complex (SOC), the nuclei of the Lateral Lemniscus, and the inferior colliculus of the developing rat. In the lateral superior olive, the medial nucleus of the trapezoid body, and the ventral nucleus of the Lateral Lemniscus, the distribution of AMPA receptor subunits changed drastically with age.
In some brain areas, induced expression manifested a clear tonotopic organization, i.e., in dorsal, posteroventral, and anteroventral cochlear nuclei, and in the medial nucleus of the trapezoid body. The dorsal nucleus of the Lateral Lemniscus had a crude tonotopy.
In the adult rat brain, NTT4 is strongly expressed in the olfactory bulb, cerebral cortex, striatum, hippocampus, thalamus, substantia nigra, pontine nucleus, cerebellum, and spinal cord.
A total of 40 neurons from of the central nucleus of the mouse inferior colliculus (IC) were recorded intracellularly from brain slices to determine input properties by electrical stimulation of the ipsilateral lateral lemniscus (LL), commissure of Probst (CP), and commissure of the IC (CoIC) together with cellular morphology (in 25 neurons) by biocytin injection and staining. Axon collaterals of a given neuron often ran in several directions to provide multiple input to adjacent isofrequency laminae, the lateral nucleus of the IC, the brachium of the IC, the LL, the CP, and the IC commissure.
Neurons that respond to unmodulated tones with a sustained discharge are found in the dorsal nucleus (DNLL), intermediate nucleus (INLL) and multipolar cell division of the ventral nucleus (VNLLm). Neurons that respond only at the onset of a tone make up a small proportion of cells in DNLL, INLL and VNLLm, but are the only type found in the columnar division of the ventral nucleus (VNLLc).
Extracellular recordings were obtained from single neurons in the multipolar and columnar divisions of the ventral nucleus (VNLLm and VNLLc), the intermediate nucleus (INLL) and the dorsal nucleus of the Lateral Lemniscus (DNLL). The ability of NLL neurons to synchronize their discharge to the pattern of an SFM signal is intermediate between that of neurons in the cochlear nucleus and in the inferior colliculus.
Morphine suppressed responses to TP stimulation in both tooth pulp specific (TPS) and wide dynamic range (WDR) neurons with TP input recorded from the nucleus ventralis posteromedialis (VPM). Furthermore, in nociceptive neurons with TP input recorded from nucleus centralis lateralis (CL) and parafascicularis (Pf) of the intralaminar nuclei, intravenous morphine suppressed responses both to stimulation of the mesencephalic reticular formation (MRF) as well as TP stimulation.
Brainstem afferents to the PDVR originate in the dorsal interpeduncular nucleus, the nucleus of the Lateral Lemniscus and parabrachial nucleus. The dorsomedial anterior thalamic nucleus receives projections mainly from limbic structures, whereas the medial posterior thalamic nucleus is the target of projections from structures with a clear sensory significance (optic tectum, torus semicircularis, nuclei of the lateral and spinal lemniscus, superior olive and trigeminal complex). As a result, the PDVR appears as an associative centre that receives visual, auditory, somatosensory and olfactory information from several telencephalic and non-telencephalic centres, and a multimodal projection from the medial posterior thalamic nucleus.
Anatomical pathway tracing uncovered a bilateral array of both first- and second-order medullary nuclei and a perilemniscal nucleus.
The central nucleus of the inferior colliculus (ICC) receives direct inputs, bilaterally, from all auditory brain stem nuclear groups.
Vestibulospinal neurons are located in the descending, magnocellular, and tangential octaval nuclei, as well as in the medial octavolateralis nucleus of the lateral line system. Additionally, axons of cells of the trigeminal system and the nucleus of the Lateral Lemniscus project caudally into the spinal cord. In the midbrain, descending spinal projections arise from cells of the medial longitudinal fasciculus and the red nucleus. We also provide further evidence that a red nucleus is present in the brains of bony fishes and is therefore a primitive vertebrate character antedating the evolution of tetrapods..
Neurons in the central nucleus of the inferior colliculus (ICc) typically respond with phase-locked discharges to low rates of sinusoidal amplitude-modulated (SAM) signals and fail to phase-lock to higher SAM rates. Previous studies have shown that comparable phase-locking to SAM occurs in the dorsal nucleus of the Lateral Lemniscus (DNLL) and medial superior olive (MSO) of the mustache bat.
Neurons in VLVp receive excitatory input from the contralateral nucleus angularis, and inhibitory input from the contralateral VLVp.
Five possible sources for the inhibition are considered: the auditory nerve, intrinsic circuits in the cochlear nucleus, medial and lateral nuclei of the trapezoid body inhibition to the medial superior olive, dorsal nucleus of the Lateral Lemniscus (DNLL) inhibition to the ICC, and intrinsic circuits in the ICC itself..
The dorsal nucleus of the Lateral Lemniscus (DNLL) is a binaural nucleus whose neurons are excited by stimulation of the contralateral ear and inhibited by stimulation of the ipsilateral ear.
Extracellular recordings were made with microelectrodes from single neurons in the rat's dorsal nucleus of the Lateral Lemniscus (DNLL) and response characteristics were determined for monaural and binaural acoustic stimulation. The responses of DNLL neurons could be distinguished on the basis of monaural and binaural response characteristics from those in surrounding areas including the sagulum, paralemniscal zone and the intermediate nucleus of the Lateral Lemniscus..
One class of cerebrospinal projection nuclei (represented by the nucleus of the medial longitudinal fascicle, the intermediate reticular formation, and the magnocellular octaval nucleus) showed a robust regenerative response after both types of lesions as determined by retrograde tracing and/or in situ hybridization for GAP-43. A second class (represented by the nucleus ruber, the nucleus of the Lateral Lemniscus, and the tangential nucleus) showed a regenerative response only after proximal lesion.
We have recorded from principal cells of the medial nucleus of the trapezoid body (MNTB) in the cat's superior olivary complex using either glass micropipettes filled with Neurobiotin or horseradish peroxidase for intracellular recording and subsequent labeling or extracellular metal microelectrodes relying on prepotentials and electrode location. These include the lateral superior olive (LSO), ventral nucleus of the Lateral Lemniscus, medial superior olive, dorsomedial and ventromedial periolivary nuclei, and the MNTB itself.
[ i] In young adult guinea pigs, the effects of unilateral ossicle removal and unilateral cochlear ablation were determined on [ 14C]glycine or [ 14C]GABA release and uptake measured in subdivisions of the cochlear nucleus (CN), the superior olivary complex, and the auditory midbrain, after 2 or 5, 59, and 145 postlesion days. [ iii] Transient elevations of release occurred at 59 days in the ipsilateral posteroventral CN ([ 14C]glycine) and bilaterally in the ventral nucleus of the Lateral Lemniscus ([ 14C]GABA) after ossicle removal, and bilaterally in the medial superior olive ([ 14C]glycine) after cochlear ablation. [ iv] In the medial nucleus of the trapezoid body, [ 14C]GABA release was depressed bilaterally 5 days after ossicle removal, but was elevated at 145 days contralaterally after ossicle removal and ipsilaterally after cochlear ablation. [ v] In the contralateral central nucleus of the inferior colliculus, [ 14C]GABA release was elevated persistently after ossicle removal.
In contrast to the ease of finding tonotopicity in other nuclei, both anatomical and electrophysiological methods have failed to demonstrate a clear and simple tonotopic map within the ventral nucleus of the Lateral Lemniscus (VLL). Since the same organization of ascending frequencies present in the cochlea is maintained in these fibers as well as in all main auditory nuclei, demonstration of a similar organization of frequencies in VLL would be evidence of the cochleo- or tono-topicity of this nucleus.
Results show an attenuation of Fos expression following TMR in the dorsal and ventral cochlear nuclei, ventral nucleus of the Lateral Lemniscus and medial geniculate nucleus. In contrast, Fos expression following TMR was unchanged in the locus coeruleus, the laterodorsal tegmental nucleus, the supramammilary nucleus, and the ventromedial hypothalamic nucleus.
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