Tachykinin immunoreactivity in terminals of trigeminal afferent fibers in adult and fetal monkey thalamus

Summary Immunocytochemistry of fetal and adult monkey thalamus reveals a dense concentration of tachykinin immunoreactive fibers and terminals in the dorsolateral part of the VPM nucleus in which the contralateral side of the head, face and mouth is represented. The immunoreactive fibers enter the VPM nucleus from the thalamic fasciculus and electron microscopy reveals that they form large terminals resembling those of lemniscal axons and terminating in VPM on dendrites of relay neurons and on presynaptic dendrites of interneurons. Double labeling strategies involving immunostaining for tachykinins after retrograde labeling of brainstem neurons projecting to the VPM failed to reveal the origin of the fibers. The brainstem trigeminal nuclei, however, are regarded as the most likely sources of the VPM-projecting, tachykinin positive fibers.Abbreviations AB ambiguus nucleus - AN abducens nucleus - C cuneate nucleus - CD dorsal cochlear nucleus - CL central lateral nucleus - CM centre médian nucleus - D dendrite - DR dorsal raphe - DV dorsal vagal nucleus - EC external cuneate nucleus - FM medial longitudinal fasciculus - FN facial nucleus - G gracile nucleus - Gc gigantocellular reticular formation - HN hypoglossal nucleus - ICP inferior cerebellar peduncle - IO inferior olivary complex - LC locus coeruleus - LL lateral lemniscus - LM medial lemniscus - M5 motor trigeminal nucleus - NS solitary nucleus - OS superior olivary complex - P dendritic protrusion - Pb parabrachial nucleus - Pc parvocellular reticular formation - PLa anterior pulvinar nucleus - Pp prepositus hypoglossi nucleus - Ps presynaptic region - Py pyramidal tract - P5 principal sensory trigeminal nucleus - R reticular nucleus - RF reticular formation - RL lateral reticular nucleus - S5 spinal trigeminal nucleus - T terminal - T5 spinal trigeminal tract - VL lateral vestibular nucleus - VM medial vestibular nucleus - VMb basal ventral medial nucleus - VPI ventral posterior inferior nucleus - VPL ventral posterior lateral nucleus - VPM ventral posterior medial nucleus - VR ventral raphe - VS superior vestibular nucleus - VSp spinal vestibular nucleus - ZI zona incerta - 5 trigeminal nerve - 6 abducens nerve - 7 facial nerve     

Nucleus ventroposterior inferior (VPI) as the vestibular thalamic relay in the rhesus monkey I. Field potential investigation

Summary In order to investigate the thalamic relay of the vestibulo-cortical pathway, field potentials were recorded in the rhesus thalamus under pentobarbital anesthesia. Short latency responses (2.5 msec on the average) upon stimulation in isolation of the vestibular nerve were recorded in the inferior ventroposterior nucleus (VPI). These potentials were abolished after transection of the vestibular nerve but were not affected by total cerebellectomy. Projection of VPI neurons to the primary vestibular cortex was demonstrated by antidromic stimulation. Field potentials with latencies of those observed in the vestibular cortex (about 5 msec) in response to vestibular nerve stimulation were recorded in other areas of the thalamus (ventrobasal, ventrolateral, posterior group, including magnocellular medial geniculate nuclei). Thus, the VPI rather than the other nuclei with long latency responses is likely to be the thalamic relay in the vestibulo-cortical path. The close topographical relationship between vestibular and somatic areas in the cortex is parallelled in the thalamus, the VPI being closely related to VPL and VPM nuclei.1 Abbreviations used in this Communication AI primary auditory projection area - BCI brachium colliculi inferioris - CM ncl. centrum medianum - IPS intraparietal sulcus, the lower bank of the anterior end of which contains the primary vestibular field - LM medial lemniscus - mc magnocellular - MG medial geniculate body - PO posterior group - SI primary somatosensory cortex - V.c.pc. ncl. ventrocaudalis parvocellularis. - VL ncl. ventralis lateralis - VPI ncl. ventroposterior inferior - VPL ncl. ventroposterior lateralis - VPM ncl. ventroposterior medialis Guest researcher from Abteilung Neurologie, Universität Ulm, W.-Germany.     

The termination of the spinothalamic tract in the cat an experimental study with silver impregnation methods

Summary The termination of the spinothalamic tract (STT) in the cat has been studied light microscopically in Fink-Heimer and Nauta impregnated sections. Following lesions of the STT at various rostrocaudal levels of the spinal cord the degenerating fibres in the thalamus and subthalamus were mapped, mainly in transverse sections. The cervicothalamic tract was not injured by the lesions.The spinothalamic fibres enter the diencephalon through the mesencephalic reticular formation and terminate in the following regions: the medial portion of the magnocellular part of the medial geniculate body (MGmc), the ventrolateral portion of the medial part of the posterior nuclear complex (PO_m), the caudolateral and medial parts of the zona incerta (ZI), the nucleus centralis medialis (CeM), the nucleus parafascicularis (Pf), the lateral part of the nucleus centralis lateralis (CL), the medial and rostrolateral parts of the nucleus ventralis lateralis (VL). To reach these regions the fibres pass through the nucleus centrum medianum (CM), the nucleus subparafascicularis (SPf) and the nucleus paracentralis (Pc). The fibres that terminate in the VL pass through Forel's field H₁ and the external medullated lamina (EML). Conclusive results were not obtained concerning a termination in the CM. The spinothalamic fibres do not pass through nor terminate in the nucleus ventralis posterolateralis (VPL) and the nucleus reticularis (R). The VPL, defined as that portion of the ventral thalamus that receives terminal fibres from the dorsal column nuclei, has been found to extend rostrally only as far as Horsley-Clarke level anterior 10.5. The results strongly support the view that all the spinothalamic fibres terminate ipsilateral to their course in the ventral quadrant of the spinal cord. No signs of a somatotopical organization of the termination of the STT were found.List of Abbreviations Cd nucleus caudatus - CeM nucleus centralis medialis - CG circumaqueductal gray substance - CL nucleus centralis lateralis thalami - CM nucleus centrum medianum thalami - CP commissura posterior - CTT cervicothalamic tract - EML external medullated lamina - H₁ Forel's field H₁ - HP tractus habenulopeduncularis - LCN nucleus cervicalis lateralis - LG corpus geniculatum laterale - LP nucleus lateralis posterior thalami - MD nucleus medialis dorsalis thalami - MG corpus geniculatum mediale - MGmc corpus geniculatum mediale, pars magnocellularis - MGp corpus geniculatum mediale, pars principalis - ML medial lemniscus - MRF mesencephalic reticular formation - OT optic tract - Pc nucleus paracentralis thalami - Pf nucleus parafascicularis thalami - PO posterior group of thalamic nuclei - PO₁ lateral part of PO - PO_m medial part of PO - R nucleus reticularis thalami - SG nucleus suprageniculatus - STT spinothalamic tract - VA nucleus ventralis anterior - VL nucleus ventralis lateralis thalami - VM nucleus ventralis medialis thalami - VPI nucleus ventralis posterior inferior - VPL nucleus ventralis posterior lateralis thalami (VPL₁ + VPL_m) - VPL₁ lateral part of VPL - VPL_m medial part of VPL - VPM nucleus ventralis posterior medialis thalami - VPMpc parvocellular part of VPM - ZI zona incerta     

A horseradish peroxidase study of afferent connections of the globus pallidus in Macaca mulatta

Summary The high tonic discharge rates of globus pallidus neurons in awake monkeys suggest that these neurons may receive some potent excitatory input. Because most current electrophysiological evidence suggests that the major described pallidal afferent systems from the neostriatum are primarily inhibitory, we used retrograde transport of horseradish peroxidase (HRP) to identify possible additional sources of pallidal afferent fibers. The appropriate location was determined before HRP injection by mapping the characteristic high frequency discharge of single pallidal units in awake animals. In animals with injections confined to the internal pallidal segment, retrograde label was seen in neurons of the pedunculopontine nucleus, dorsal raphe nucleus, substantia nigra, caudate, putamen, subthalamic nucleus, parafascicular nucleus, zona incerta, medial and lateral subthalamic tegmentum, parabrachial nuclei, and locus coeruleus. An injection involving the external pallidal segment and the putamen as well resulted in additional labeling of cells in centromedian nucleus, pulvinar, and the ventromedial thalamus.Abbreviations AC anterior commissure - CG central grey - CM centromedian nucleus - CN caudate nucleus - DM dorsomedial nucleus - DR dorsal raphe nucleus - DSCP decussation of superior cerebellar peduncle - GPe globus pallidus, external segment - GPi globus pallidus, internal segment - LC locus coeruleus - LL lateral lemniscus - MG medial geniculate nucleus - ML medial lemniscus - NVI abducens nucleus - OT optic tract - Pbl lateral parabrachial nucleus - Pbm medial parabrachial nucleus - Pf parafascicular nucleus - PPN pedunculopontine nucleus - PuO oral pulvinar nucleus - RN red nucleus - SCP superior cerebellar peduncle - SI substantia innominata - SNc substantia nigra, pars compacta - SNr substantia nigra, pars reticulata - STN subthalamic nucleus - TMT mamillothalamic tract - VA ventral anterior nucleus - VLc ventral lateral nucleus, pars caudalis - VLm ventral lateral nucleus, pars medialis - VLo ventral lateral nucleus, pars oralis - VPI ventral posterior inferior nucleus - VPM ventral posterior medial nucleus - VPLc ventral posterior lateral nucleus, pars caudalis - ZI zona incerta     

Subcortical afferent and efferent connections of the superior colliculus in the rat and comparisons between albino and pigmented strains

Summary Subcortical connections of the superior colliculus were investigated in albino and pigmented rats using retrograde and anterograde tracing with horseradish peroxidase (HRP), following unilateral injection of HRP into the superior colliculus. Afferents project bilaterally from the parabigeminal nuclei, the nucleus of the optic tract, the posterior pretectal region, the dorsal part of the lateral posterior-pulvinar complex and the ventral nucleus of the lateral lemniscus; and ipsilaterally from the substantia nigra pars reticulata, the pars lateralis of the ventral lateral geniculate nucleus, the intergeniculate leaflet, the zona incerta, the olivary pretectal nucleus, the nucleus of the posterior commissure, the lateral thalamus, Forel's field H₂, and the ventromedial hypothalamus. Collicular efferents terminate ipsilaterally in the anterior, posterior and olivary pretectal nuclei, the nuclei of the optic tract and posterior commissure, the ventrolateral part of the dorsal lateral geniculate nucleus, the pars lateralis of the ventral lateral geniculate nucleus, the intergeniculate leaflet, and the zona incerta; and bilaterally in the parabigeminal nuclei and lateral posterior-pulvinar complex (chiefly its dorsal part). The general topographical patterns of some of the afferent and efferent projections were also determined: the caudal and rostral parts of the parabigeminal nucleus project to the caudal and rostral regions, respectively, of the superior colliculus; caudal superior colliculus projects to the most lateral, and lateral superior colliculus to the most caudal part of the terminal field in the dorsal lateral geniculate nucleus; caudolateral superior colliculus projects to the caudal ventrolateral part of the ventral lateral geniculate nucleus, while rostromedial parts of the colliculus project more rostrally and dorsomedially. Following comparable injections in pigmented and albino animals, fewer retrogradely labelled cells were found in subcortical structures in the albino than in the pigmented rats. The difference was most marked in nuclei contralateral to the injected colliculus. Thus, the effects of albinism on the nervous system may be more widespread than previously thought.M. R. C. Scholar     

Ascending projections from the nucleus of the brachium of the inferior colliculus in the cat

Summary Ascending projections from the nucleus of the brachium of the inferior colliculus (NBIC) in the cat were studied by the autoradiographic tracing method. Many fibers from the NBIC ascend ipsilaterally in the lateral tegmentum along the medial border of the brachium of the inferior colliculus. At midbrain levels, fibers from the NBIC end in the superior colliculus, the pretectum, the central gray and the peripeduncular tegmental region bilaterally with ipsilateral predominance. NBIC fibers to the superior colliculus are distributed densely to laminae VI an III throughout the whole rostrocaudal extent of the colliculus. In the pretectum, NBIC fibers terminate in the anterior and medial nuclei and the nucleus of the posterior commissure. NBIC fibers to the dorsal thalamus are distributed largely ipsilaterally. Many NBIC fibers end in the dorsal and medial divisions of the medial geniculate body, but few in the ventral division. The NBIC also sends fibers to the suprageniculate, limitans and lateralis posterior nuclei and the lateral portion of the posterior nuclear complex; these regions of termination of NBIC fibers constitute, as a whole, a single NBIC recipient sector. Additionally, the NBIC sends fibers to the centralis lateralis, medialis dorsalis, paraventricular and subparafascicular nuclei of the thalamus.Abbreviations APtC Pars compacta of anterior pretectal nucleus - APtR Pars reticulata of anterior pretectal nucleus - BIC Brachium of infertior colliculus - CG Central gray - CL Nucleus centralis lateralis - CP Cerebral peduncle - D Dorsal division of medial geniculate body - IC Inferior colliculus - LG Lateral geniculate body - LP Nucleus lateralis posterior - Lim Nucleus limitans - M Medial division of medial geniculate body - MD Nucleus medialis dorsalis - ML Medial lemniscus - NBIC Nucleus of brachium of inferior colliculus - NPC Nucleus of posterior commissure - PN Pontine nuclei - Ppr Peripeduncular region - Pt Pretectum - Pbg Parabigeminal nucleus - Pol Lateral portion of posterior nuclear complex - Pom Medial portion of posterior nuclear complex - Pul Pulvinar - Pv Nucleus paraventricularis - R Red nucleus - SC Superior colliculus - Sg Nucleus suprageniculatus - Spf Nucleus subparafascicularis - V Ventral division of medial geniculate body - VPL Nucleus ventralis posterolateralis - VPM Nucleus ventralis posteromedialis - II,III,IV,VI Tectal laminae     

An analysis of potentially converging inputs to the rostral ventral thalamic nuclei of the cat

Summary Potentially convergent inputs to cerebellar-receiving and basal ganglia-receiving areas of the thalamus were identified using horseradish peroxidase (HRP) retrograde tracing techniques. HRP was deposited iontophoretically into the ventroanterior (VA), ventromedial (VM), and ventrolateral (VL) thalamic nuclei in the cat. The relative numbers of labeled neurons in the basal ganglia and the cerebellar nuclei were used to assess the extent to which the injection was in cerebellar-receiving or basal ganglia-receiving portions of thalamus. The rostral pole of VA showed reciprocal connections with prefrontal portions of the cerebral cortex. Only the basal ganglia and the hypothalamus provided non-thalamic input to modulate these cortico-thalamo-cortical loops. In VM, there were reciprocal connections with prefrontal, premotor, and insular areas of the cerebral cortex. The basal ganglia (especially the substantia nigra), and to a lesser extent, the posterior and ventral portions of the deep cerebellar nuclei, provided input to VM and may modulate these corticothalamo-cortical loops. The premotor cortical areas connected to VM include those associated with eye movements, and afferents from the superior colliculus, a region of documented importance in oculomotor control, also were labeled by injections into VM. The dorsolateral portion of the VA-VL complex primarily showed reciprocal connections with the medial premotor (area 6) cortex. Basal ganglia and cerebellar afferents both may modulate this cortico-thalamo-cortical loop, although they do not necessarily converge on the same thalamic neurons. The cerebellar input to dorsolateral VA-VL was from posterior and ventral portions of the cerebellar nuclei, and the major potential brainstem afferents to this region of thalamus were from the pretectum. Mid- and caudo-lateral portions of VL had reciprocal connections with primary motor cortex (area 4). The dorsal and anterior portions of the cerebellar nuclei had a dominant input to this corticothalamo-cortical loop. Potentially converging brainstem afferents to this portion of VL were from the pretectum, especially pretectal areas to which somatosensory afferents project.List of Abbreviations AC central amygdaloid nucleus - AL lateral amygdaloid nucleus - AM anteromedial thalamic nucleus - AV anteroventral thalamic nucleus - BC brachium conjunctivum - BIC brachium of the inferior colliculus - Cd caudate nucleus - CL centrolateral thalamic nucleus - CM centre median nucleus - CP cerebral peduncle - CUN cuneate nucleus - DBC decussation of the brachium conjunctivum - DR dorsal raphe nuclei - EC external cuneate nucleus - ENTO entopeduncular nucleus - FN fastigial nucleus - FX fornix - GP globus pallidus - GR gracile nucleus - IC internal capsule - ICP inferior cerebellar peduncle - IP interpeduncular nucleus - IVN inferior vestibular nucleus - LD lateral dorsal thalamic nucleus - LGN lateral geniculate nucleus - LH lateral hypothalamus - LP lateral posterior thalamic complex - LRN lateral reticular nucleus - LVN lateral vestibular nucleus - MB mammillary body - MD mediodorsal thalamic nucleus - MG medial geniculate nucleus - ML medial lemniscus - MLF medial lengitudinal fasciculus - MT mammillothalamic tract - MVN medial vestibular nucleus - NDBB nucleus of the diagonal band of Broca - NIA anterior nucleus interpositus - NIP posterior nucleus interpositus - OD optic decussation - OT optic tract - PAC paracentral thalamic nucleus - PPN pedunculopontine region - PRO gyrus proreus - PRT pretectal region - PT pyramidal tract - PTA anterior pretectal region - PTM medial pretectal region - PTO olivary pretectal nucleus - PTP poterior pretectal region - Pul pulvinar nucleus - Put putamen - RF reticular formation - RN red nucleus - Rt reticular complex of the thalamus - S solitary tract - SCi superior colliculus, intermediate gray - SN substantia nigra - ST subthalamic nucleus - VA ventroanterior thalamic nucleus - VB ventrobasal complex - VL ventrolateral thalamic nucleus - VM ventromedial thalamic nucleus - III oculomotor nucleus - IIIn oculomotor nerve - 5S spinal trigeminal nucleus - 5T spinal trigeminal tract - VII facial nucleus     

Extent of the ipsilateral representation in the ventral posterior medial nucleus of the monkey thalamus

Summary Single and multiunit mapping was used to determine the extent of the representation of ipsilateral structures in the ventral posterior medial (VPM) nucleus of the thalamus in cynomolgus monkeys. The extent of the VPM occupied by terminations of afferent fibers arising in the ipsilateral principal trigeminal nucleus was also determined by anterograde transport of horseradish peroxidase. Both methods indicate that most of the medial half of VPM is occupied by the ipsilateral representation. This is much larger than previously suspected. Units in the medial half of VPM have small, well localized receptive fields on the ipsilateral side of the lower lip, tongue and palate, in the ipsilateral cheek pouch and on the ipsilateral teeth. The representation is largest for the ipsilateral side of the tongue and the cheek pouch. Most units in the lateral half of VPM have small, contralateral receptive fields. Few units in VPM have bilateral receptive fields. VPM is clearly distinguishable by cytochrome oxidase (CO) staining. Anteroposteriorly elongated, CO-positive aggreations correspond to elongated aggregations of units with the same or closely similar receptive fields, especially in the medial, ipsilateral representation.Abbreviations CL Central lateral nucleus - CM Centre médian nucleus - DCN Dorsal cochlear nucleus - DIT Dorsal ipsilateral trigeminal tract - IO Inferior olivary nuclei - ML Medial lemniscus - MV Motor trigeminal nucleus - PRV Principal sensory trigeminal nucleus - SO Superior olivary nuclei - SPV Spinal trigeminal nucleus - Ves Vestibular nuclei - VMb Basal ventral medial nucleus - VPI Ventral posterior inferior nucleus - VPL Ventral posterior lateral nucleus - VPM Ventral posterior medial nucleus - IV Trochlear nucleus - VI Abducens nucleus     

The vestibulothalamic projections in the cat studied by retrograde axonal transport of horseradish peroxidase

Summary Horseradish peroxidase (HRP) was injected or iontophoretically ejected in various thalamic nuclei in 63 adult cats. In 11 other animals HRP was deposited outside the thalamic territory. The number and distribution of labelled cells within the vestibular nuclear complex (VC) were mapped in each case. To a varying degree all subgroups of VC appear to contribute to the vestibulothalamic projections. Such fibres are distributed to several thalamic areas. From the present investigation it appears that generally speaking, there exist three distinct vestibulothalamic pathways with regard to origin as well as to site of termination of the fibres. One projection appears to originate mainly in caudal parts of the medial (M) and descending (D) vestibular nuclei and in cell group z. This pathway terminates chiefly in the contralateral medial part of the posterior nucleus of the thalamus (POm) including the magnocellular part of the medial geniculate body (Mgmc), the ventrobasal complex (VB) and the area of the ventral lateral nucleus (VL) bordering on VB. A second projection originates mainly in the superior vestibular nucleus (S) and in cell group y and terminates mainly in the contralateral nucleus centralis lateralis (CL) and the adjoining nucleus paracentralis (Pc). A third, more modest, pathway originates chiefly in the middle M and D, with a minor contribution from S and cell group y, and terminates in the contralateral ventral nucleus of the lateral geniculate body (GLV). There is some degree of overlap between the origin of these three vestibulothalamic pathways.Abbreviations B.c. brachium conjunctivum - CeM nucleus centralis medialis thalami - CL nucleus centralis lateralis thalami - CM nucleus centrum medianum - D nucleus vestibularis descendons - f cell group f - g cell group g - GLD corpus geniculatum laterale dorsalis - GLV corpus geniculatum laterale ventralis - i.e. nucleus intercalatus - L nucleus vestibularis lateralis - LD nucleus lateralis dorsalis thalami - LIM lamina medullaris interna - Lim nucleus limitans - LP nucleus lateralis posterior thalami - M nucleus vestibularis medialis - MD nucleus medialis dorsalis thalami - MGmc corpus geniculatum mediale, pars magnocellularis - MGp corpus geniculatum mediale, pars principalis - N.cu.e. nucleus cuneatus externus - N.f.c. nucleus fasciculi cuneati - N.mes. V nucleus mesencephalicus nervi trigemini - NR nucleus ruber - N.tr.s. nucleus tractus solitarius - N. VII nervus facialis - N. VIII nervus statoacusticus - PC pedunculus cerebri - Pc nucleus paracentralis thalami - Pf nucleus parafascicularis - p.h. nucleus prepositus hypoglossi - PO posterior thalamic group - PO1 lateral part of PO - POm medial part of PO - Prt nucleus pretectalis - Pul pulvinar - R nucleus reticularis thalami - S nucleus vestibularis superior - Sg nucleus suprageniculatus - SN substantia nigra - Sv nucleus supravestibularis - Tr.s. tractus solitarius - VA nucleus ventralis anterior thalami - VL nucleus ventralis lateralis thalami - VPL nucleus ventralis posterior lateralis - VPL1 lateral part of VPL - VPLm medial part of VPL - VPM nucleus ventralis posterior medialis - x cell group x - y cell group y - z cell group z - V nucleus motorius nerve trigemini - X nucleus dorsalis nerve vagi - XII nucleus nervi hypoglossi     

Localized responses in the midsuprasylvian gyrus of the cat following stimulation of the central lateral nucleus in thalamus

Summary Evoked responses were mapped in the cerebral cortex following low intensity electrical stimulation in serial penetrations of the medial and intralaminar nuclei of the thalamus of the cat. A projection was found from one of the intralaminar nuclei, the central lateral nucleus (CL) to the midsuprasylvian gyrus, mainly areas 5 and 7. The projection is suggested to be direct, since the evoked responses had a short latency initial positivity. The most characteristic type of response consisted of this early positivity followed by two successive negativities. The earlier, so called first negativity followed high frequency stimulation and was recorded in a smaller area of the cortex than the later, so called second negativity. The first negativity is suggested to depend on monosynaptic depolarization and activation of cortical cells. The second negativity failed at frequencies higher than 10 Hz and was strongly depressed by the administration of barbiturates; it is suggested to depend on polysynaptic depolarization and cellular activity. In electrode penetrations of the cortex both negativities reversed at the border between cortical layers II and III, indicating a superficial termination of thalamic afferents in the cortex. The cortical evoked response to CL stimulation was facilitated by light mechanical and low intensity electrical stimulation of the periphery, as well as by electrical stimulation of the tooth pulp. The possible significance and function of this projection is discussed in relation to arousal, attention and pain.Abbreviations AV anteroventral nucleus - CM centre médian nucleus - CL central lateral nucleus - GL lateral geniculate nucleus - LD lateral dorsal nucleus - LG lateral gyrus - LP lateral posterior complex - MD mediodorsal nucleus - MSSG midsuprasylvian gyrus - OT optic tract - PAC paracentral nucleus - PF parafascicular nucleus - PP pes pedunculi - VA ventroanterior nucleus - VL ventrolateral complex - VMB basal ventromedial nucleus - VMH ventromedial hypothalamic nucleus - VPL ventroposterolateral nucleus - VPM ventroposteromedial nucleus     

Projections from the rostral mesencephalic reticular formation to the spinal cord

Summary Eye and head movements are strongly interconnected, because they both play an important role in accurately determining the direction of the visual field. The rostral brainstem includes two areas which contain neurons that participate in the control of both movement and position of the head and eyes. These regions are the caudal third of Field H of Forel, including the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) and the interstitial nucleus of Cajal with adjacent reticular formation (INC-RF). Lesions in the caudal Field H of Forel in monkey and man result in vertical gaze paralysis. Head tilt to the opposite side and inability to maintain vertical eye position follow lesions in the INC-RF in cat and monkey. Projections from these areas to extraocular motoneurons has previously been observed. We reported a study of the location of neurons in Field H of Forel and INC-RF that project to spinal cord in cat. The distribution of these fiber projections to the spinal cord are described. The results indicate that: 1. Unlike the neurons projecting to the extra-ocular muscle motoneurons, the major portion of the spinally projecting neurons are not located in the riMLF or INC proper but in adjacent areas, i.e. the ventral and lateral parts of the caudal third of the Field H of Forel and in the INCRF. A few neurons were also found in the nucleus of the posterior commissure and ventrally adjoining reticular formation. 2. Neurons in caudal Field H of Forel project, via the ventral part of the ventral funiculus, to the lateral part of the upper cervical ventral horn. This area includes the laterally located motoneuronal cell groups, innervating cleidomastoid, clavotrapezius and splenius motoneurons. At lower cervical levels labeled fibers are distributed to the medial part of the ventral horn. Projections from the caudal Field H of Forel to thoracic or more caudal spinal levels are sparse. 3. Neurons in the INC-RF, together with a few neurons in the area of the nucleus of the posterior commissure, project bilaterally to the medial part of the upper cervical ventral horn, via the dorsal part of the ventral funiculus. This area includes motoneurons innervating prevertebral flexor muscles and some of the motoneurons of the biventer cervicis and complexus muscles. Further caudally, labeled fibers are distributed to the medial part of the ventral horn (laminae VIII and adjoining VII) similar to the projections of Field H of Forel. A few INC-RF projections were observed to low thoracic and lumbosacral levels. It is argued that the neurons in the caudal Field H of Forel, which project to the spinal cord are especially involved in the control of those fast vertical head movements which occur in conjunction with saccadic eye movements. In contrast the INC-RF projections to the spinal cord are responsible for slower, smaller movements controlling the position of the head in the vertical plane.Abbreviations Aq aquaduct of Sylvius - BIC brachium of the inferior colliculus - CGL lateral geniculate body - CGLd lateral geniculate body (dorsal part) - CGLv lateral geniculate body (ventral part) - CGM medial geniculate body - CGMd medial geniculate body, dorsal part - CGMint medial geniculate body, interior division - CGMp medial geniculate body, principal part - CM centromedian thalamic nucleus - CP posterior commissure - CS superior colliculus - D nucleus of Darkschewitsch - EW nucleus Edinger-Westphal - F fornix - FR/fRF fasciculus retroflexus - Hab habenular nucleus - HPA posterior hypothalamus area - HT hypothalamus - IN interpeduncular nucleus - INC interstitial nucleus of Cajal - LD nucleus lateralis dorsalis of the thalamus - LHA lateral hypothalamic area - LP lateral posterior nucleus - LV lateral ventricle - MB mammillary body - MC nucleus medialis centralis of the thalamus - MD nucleus medialis dorsalis of the thalamus - ML medial lemniscus - MTN medial terminal nucleus - ND nucleus of Darkschewitsch - NOT nucleus of the optic tract - NOTL lateral nucleus of the optic tract - NOTM medial nucleus of the optic tract - OL olivary pretectal nucleus - OT optic tract - PAG periaqueductal gray - PC pedunculus cerebri - PCN/NPC nucleus of the posterior commissure - PP posterior pretectal nucleus - PTA anterior pretectal nucleus - PTM medial pretectal nucleus - Pul pulvinar nucleus of the thalamus - PV posterior paraventricular nucleus of the thalamus - PVG periventricular gray - R reticular nucleus of the thalamus - riMLF rostral interstitial nucleus of the MLF - RN red nucleus - SM stria medullaris - SN substantia nigra - ST subthalamic nucleus - STT stria terminalis - SUB subiculum - VB ventrobasal complex of the thalamus - VTA ventral tegmental area of Tsai - ZI zona incerta - III oculomotor nucleus On leave of absence from Dept. Anatomy Erasmus University, Rotterdam, The Netherlands     

Segregation of lemniscal inputs and motor cortex outputs in cat ventral thalamic nuclei: application of a novel technique

Summary A double labeling method that permits accurate delineation of the terminals of medial lemniscal fibers was used to determine whether thalamic neurons projecting to motor cortex in the cat are in a position to be contacted by such terminals. Thalamic neurons in the VL nucleus were retrogradely labeled by injections of fluorogold placed in the cytoarchitectonically defined area 4, while lemniscal axons and their terminal boutons were anterogradely labeled, in a Golgi-like manner, from injections of Fast Blue placed under physiological control in different parts of the contralateral dorsal column nuclei. In additional experiments, spinothalamic fibers were similarly labeled by injections of Fast Blue in the spinal cord. The results reveal that there is no significant overlap in the distributions of lemniscal terminals and motor cortex-projecting neurons and that no somata or proximal dendrites of motor cortex-projecting neurons are in a position to receive lemniscal terminals. Spinothalamic terminals, on the other hand, end in clusters around motor cortex-projecting neurons in the VL nucleus as well as in other nuclei and are a more likely route for short latency somatosensory inputs to the motor cortex.Abbreviations AD anterodorsal nucleus - AM anteromedial nucleus - AP area postrema - AV anteroventral nucleus - C cuneate nucleus - CeM central medial nucleus - CL central lateral nucleus - CM centre médian nucleus - EC external cuneate nucleus - G gracile nucleus - L limitans nucleus - LD lateral dorsal nucleus - LP lateral posterior nucleus - MGM magnocellular medial geniculate nucleus - MD mediodorsal nucleus - MTT mamillothalamic tract - MV medioventral nucleus - Pc paracentral nucleus - Pf parafascicular nucleus - Po posterior nuclei - R reticular nucleus - RF fasciculus retroflexus - S solitary nucleus - SG suprageniculate nucleus - T spinal trigeminal nucleus - VA ventral anterior nucleus - VIN vestibular nuclei - VL ventral lateral nucleus - VMb basal ventral medial nucleus - VMp principal ventral medial nucleus - VPL ventral posterior lateral nucleus - VPM ventral posterior medial nucleus - ZI zona incerta - 1,2,3a,3b,4 fields of cerebral cortex - C4, C5, C6 spinal cord segments - 5SP,5ST spinal trigeminal nucleus and tract - 10, 12 vagal and hypoglossal nuclei     

A ventral lateral geniculate nucleus projection to the dorsal thalamus and the midbrain in the cat

Summary Retrograde tracing experiments using horseradish peroxidase (HRP) have been utilized for demonstrating the origin of efferent projections of the ventral lateral geniculate nucleus (LGNv) in the cat. HRP-positive cells identifiable as origins of thalamic projections were found in LGNv after injections of HRP into the lateral central intralaminar nucleus. The labeled cells appeared concentrated in the medial part of the internal division of LGNv, consisting of medium-sized multipolar cells. Contralaterally, fewer labeled cells were present in the corresponding part of LGNv. In the case of injections of HRP into the midbrain (pretectum and superior colliculus), labeled cells in LGNv were distributed almost exclusively in its external division, composed of mainly small cells. Little overlap of the distribution of HRP-positive cells was seen in LGNv between the thalamic and midbrain injection cases.Abbreviations Ad Dorsal anterior nucleus - Am Medial anterior nucleus - Av Ventral anterior nucleus - BSC Brachium of superior colliculus - Cg Central gray - Cl Lateral central nucleus - Ld Dorsal lateral nucleus - LGNd Dorsal lateral geniculate nucleus - LGNv Ventral lateral geniculate nucleus - Lp Posterior lateral nucleus - Md Dorsal medial nucleus - NIII Oculomotor complex - NOT Nucleus of the optio tract - NPC Nucleus of posterior commissure - OT Optic tract - P Posterior nucleus (Rioch 1929) - Pc Paracentral nucleus - Po Posterior group of thalamic nuclei - Pt Parataenial nucleus - PTa Anterior pretectal nucleus - PTm Medial pretectal nucleus - PTp Posterior pretectal nucleus - Pul Pulvinar - R Red nucleus - Rt Thalamic reticular nucleus - Sg Suprageniculate nucleus - Va Anterior ventral nucleus - VI Lateral ventral nucleus - Vm Medial ventral nucleus - Vpl Posterolateral ventral nucleus - Vpm Posteromedial ventral nucleus - Zi Zona incerta - II Layer of superior colliculus - III Layer of superior colliculus - IV (Kanaseki and Sprague, 1974)     

Efferent fiber projections of the habenula and the interpeduncular nucleus. An experimental study in the opossum and cat

Summary A study of efferent fiber connections of the habenula and the inter-peduncular nucleus was conducted using anterograde degeneration techniques. Lesions were placed in the habenula of the opossum and the habenula and interpeduncular nucleus of the cat. Degeneration was studied by means of the Nauta and Fink-Heimer techniques.Fibers from the habenular nucleus of the opossum extended caudally and were traced bilaterally to the interpeduncular nucleus, dorsal tegmental nucleus of Gudden, deep (ventral) tegmental nucleus of Gudden, nucleus centralis superior and nucleus reticularis tegmenti pontis. Rostrally fibers were traced to the preoptic and septal region and the anterior and lateral hypothalamus.The medial and lateral habenular nuclei of the cat projected differentially to portions of the interpeduncular nucleus and the tegmental nuclei of Gudden. The medial habenular nucleus sent fibers to the paramedian subnucleus of the interpeduncular nucleus and to the deep tegmental nucleus; whereas the lateral habenular nucleus distributed to the apical and central subnuclei of the interpeduncular nucleus and the dorsal tegmental nucleus.Fibers from both the medial and lateral habenular nuclei were found to project bilaterally to the nucleus paraventricularis anterior, nucleus ventralis anterior, anterior medialis and anterior dorsalis of the thalamus, and the septal area.Fibers from the interpeduncular nucleus of the cat were represented bilaterally. Those passing rostral went to the lateral habenular nucleus, nucleus centromedianus and parafascicularis of the thalamus, and to the septal area. Those directed caudally projected to the nucleus centralis superior, and the dorsal and deep tegmental nucleus of Gudden.Abbreviations AC anterior commissure - AD nucleus anterior dorsalis - AM nucleus anterior medialis - AV nucleus anterior ventralis - BC brachium conjunctivum - CC corpus callosum - CD caudate nucleus - CI internal capsule - CL nucleus centralis lateralis - CM nucleus centromedianus - CP cerebral peduncle - DT dorsal tegmental nucleus (of Gudden) - EN entopeduncular nucleus - Fx fornix - GC central gray - GL lateral geniculate nucleus - GM medial geniculate nucleus - GP globus pallidus - HbPt habenulopeduncular tract - HVM ventromedial hypothalamic nucleus - IC inferior colliculus - IP interpeduncular nucleus - LHb lateral habenular nucleus - LL lateral lemniscus - LMN lateral mammillary nucleus - LP nucleus lateralis posterior - MD nucleus medialis dorsalis - MHb medial habenular nucleus - ML medial lemniscus - MMN medial mammillary nucleus - MP mammillary peduncle - NCM nucleus centralis medialis - OC optic chiasm - OT optic tract - Pf nucleus parafascicularis - Pul pulvinar - PUT putamen - RE nucleus reuniens - RN red nucleus - RPO preoptic area - RTP nucleus reticularis tegmenti pontisv (von Bechterew) - S stria medullaris - SC superior colliculus - SN substantia nigra - SPT septal area - VA nucleus ventralis anterior - VL nucleus ventralis lateralis - VM nucleus ventralis medialis - VPL nucleus ventralis posterolateralis - VPM nucleus ventralis posteromedialis - VT deep tegmental nucleus (of Gudden) - II optic nerve     

Widely distributed GABA-mediated afferent inhibition processes within the ventrobasal thalamus of rat and their possible relevance to pathological pain states and somatotopic plasticity

Summary We have recently described extensive inhibitory interactions between inputs to the ventroposterolateral (VPL) (Roberts and Wells 1990, 1991) and ventropos-teromedial (VPM) (Salt 1989) portions of the ventrobasal nucleus of the thalamus (VB). We wished to determine whether (i) the inhibition observed in the VPL was operating at the thalamic level, (ii) was dependant on GABA receptors, (iii) was demonstrable on neurons of the ventro-posteromedial nucleus of the thalamus (VPM) and (iv) was operant on test responses evoked by natural stimuli. Conditioning stimulation of sciatic nerve afferents caused inhibition of air jet evoked test responses of single VB neurons in urethane-anaesthetized rats. Both VPM and VPL neurons were subject to inhibition by conditioning stimulation of hindlimb afferents, indicating the widespread nature of the inhibitory process. This inhibition was reduced by the iontophoretic application of SR95531, a GABA_A receptor antagonist. We conclude that there is a widely distributed inhibitory system operating in the somatic thalamus which involves both the medial and lateral portions of the nucleus and is, at least in part, mediated by GABA_A receptors. The possible involvement of inhibitory processes and intrinsic membrane properties of thalamic neurones in the somatotopic plasticity of the sensory thalamus following deafferentation and in deaf-ferentation pain is discussed.     

Connections between the supratemporal and its rostral areas, and the posterior thalamic region in the monkey: a retrograde HRP study.

Connections between the anterior half of the superior temporal gyrus (Ts) and the supratemporal plane (STP) in the Sylvian fissure, and the posterior thalamic region in the monkey were studied after retrograde transport of horseradish peroxidase (HRP). HRP injections into the Ts resulted in labeled cells in the posterodorsal division of the principal medial geniculate complex (GMpd), the suprageniculate and limitans nuclei, and the medial part of the medial nucleus of the pulvinar complex. HRP injections into the rostral Ts led to labeling in the posterior extremity of the GMpd, whereas injections into the caudal Ts resulted in labeling in the rostral GMpd. HRP injections into the area of transition between the Ts and STP led to labeling in the ventral part of the ventral division of the principal medial geniculate complex (GMv) and in the GMpd. HRP injections into the rostral STP led to labeling in the lateral part of the GMv, the anterodorsal division of the principal medial geniculate complex (GMad), and the lateral division of the posterior nucleus (Pol). HRP injections into the more caudal part of the STP yielded labeling in the more dorsomedial part of the GMv, Pol, and GMad. HRP injections into the lip of the STP yielded labeling in the GMv, Pol, GMad, and GMpd.     

大鼠上丘的传出投射——ARG法和WGA-HRP法研究

本实验将~3H-Leucine 或 WGA-HRP 定位注(导)入大鼠一侧上丘内,观察了上丘传出纤维的终止部位。上丘浅层的传出纤维下行终止于二叠体旁核(以同侧核的背、腹群为主)、同侧桥核的背外侧部;其上行投射终止于内侧膝状体、膝上核、顶盖前区后核、丘脑外侧后核(以上均为两侧性,以同侧为主)、同侧的内及外侧视束核和外侧膝状体的背侧及腹侧核。另外,在两侧视束和视束交叉处均有标记颗粒。上丘中、深层的传出纤维终止于同侧中央灰质、Darkschewitsch 核、Cajal 中介核、楔形核以及对侧上丘;上行终止于内测膝状体,膝上核、顶盖前区前核、丘脑外侧后核(以上均为两侧性,以同侧为主)、束旁核、未定带、丘脑腹侧核(以上均为同侧);下行终止于同侧的有二叠体旁区和二叠体旁核,桥核的背外侧部、下丘外侧部、桥脑和延髓网状结构、下橄榄核的外侧部;终止于对侧的有二叠体旁核、桥脑和延髓网状结构内侧部、下橄榄核的内侧副核、脊髓颈段前角。     

Brain stem projections to the pulvinar-lateralis posterior complex of the cat

Summary The present experiments were undertaken to define the areas of projection of pretectum and superior colliculus to the pulvinar and n. lateralis posterior, respectively, and to define other brain stem structures projecting to these thalamic nuclei in cats. For this purpose the technique of retrograde transport of horseradish peroxidase (HRP) has been used.After injection of the enzyme in the pulvinar, neurons were labeled in all subdivisions of the pretectal area. The majority of the labeled cells were located in the n. pretectalis posterior and n. tractus opticus although cells filled with HRP were present also in the n. pretectalis anterior pars compacta and area pretectalis medialis. Neurons projecting to the pulvinar were also found in the periaqueductal gray, reticular formation and locus coeruleus.When HRP was injected in the n. lateralis posterior, labeled neurons were present in the II and III subdivisions of the second layer of the superior colliculus. The location of these cells shifted from medial to lateral as the injections were shifted from posterior to anterior within the lateralis posterior. Neurons projecting to this nucleus were also present in the intermediate layers of the superior colliculus, lateral hypothalamus and parabigeminal nucleus.The possible role of the pretectal area and superior colliculus in mediating somesthetic input to the pulvinar and lateralis posterior, respectively, and the role of these structures in the control of ocular movements, are discussed.Abbreviations APM area pretectalis medialis - Cu nucleus cuneiformis - CS nucleus centralis superior - fr fasciculus retroflexus - Gp pontine gray - Hb nucleus habenulae - IC inferior colliculus - LC locus coeruleus - LGB lateral geniculate body - LP lateralis posterior - MGB medial geniculate body - nPA_c nucleus pretectalis anterior pars compacta - nPA_r nucleus pretectalis anterior pars reticularis - nPC nucleus posterior commissurae - nPP nucleus pretectalis posterior - nTO nucleus tractus opticus - PAG periaqueductal gray - PB nucleus parabigeminalis - Pi pulvinar inferior - PO nucleus posterior of the thalamus - Pul pulvinar - Pt pretectum - RF reticular formation - Rtp tegmental reticular nucleus - SC superior colliculus Supported by H. de Jur Foundation and USPHS Grant TWO 2718Present address: Max-Planck-Institut für biophysikalische Chemie, Postfach 968, D-3400 Göttingen, Federal Republic of Germany     

Projections of the bed nucleus of the stria terminalis to the mesencephalon,pons, and medulla oblongata in the cat

Summary Injections of HRP in the nucleus raphe magnus and adjoining medial reticular formation in the cat resulted in many labeled neurons in the lateral part of the bed nucleus of the stria terminalis (BNST) but not in the medial part of this nucleus. HRP injections in the nucleus raphe pallidus and in the C2 segment of the spinal cord did not result in labeled neurons in the BNST. Injections of ³H-leucine in the BNST resulted in many labeled fibers in the brain stem. Labeled fiber bundles descended by way of the medial forebrain bundle and the central tegmental field to the lateral tegmental field of pons and medulla. Dense BNST projections could be observed to the substantia nigra pars compacta, the ventral tegmental area, the nucleus of the posterior commissure, the PAG (except its dorsolateral part), the cuneiform nucleus, the nucleus raphe dorsalis, the locus coeruleus, the nucleus subcoeruleus, the medial and lateral parabrachial nuclei, the lateral tegmental field of caudal pons and medulla and the nucleus raphe magnus and adjoining medial reticular formation. Furthermore many labeled fibers were present in the solitary nucleus, and in especially the peripheral parts of the dorsal vagal nucleus. Finally some fibers could be traced in the marginal layer of the rostral part of the caudal spinal trigeminal nucleus. These projections appear to be virtually identical to the ones derived from the medial part of the central nucleus of the amygdala (Hopkins and Holstege 1978). The possibility that the BNST and the medial and central amygdaloid nuclei must be considered as one anatomical entity is discussed.Abbreviations AA anterior amygdaloid nucleus - AC anterior commissure - ACN nucleus of the anterior commissure - ACO cortical amygdaloid nucleus - AL lateral amygdaloid nucleus - AM medial amygdaloid nucleus - APN anterior paraventricular thalamic nucleus - AQ cerebral aqueduct - BC brachium conjunctivum - BIC brachium of the inferior colliculus - BL basolateral amygdaloid nucleus - BNSTL lateral part of the bed nucleus of the stria terminalis - BNSTM medial part of the bed nucleus of the stria terminalis - BP brachium pontis - CA central nucleus of the amygdala - Cd caudate nucleus - CI inferior colliculus - CL claustrum - CN cochlear nucleus - CP posterior commissure - CR corpus restiforme - CSN superior central nucleus - CTF central tegmental field - CU cuneate nucleus - D nucleus of Darkschewitsch - EC external cuneate nucleus - F fornix - G gracile nucleus - GP globus pallidus - HL lateral habenular nucleus - IC interstitial nucleus of Cajal - ICA internal capsule - IO inferior olive - IP interpeduncular nucleus - LC locus coeruleus - LGN lateral geniculate nucleus - LP lateral posterior complex - LRN lateral reticular nucleus - MGN medial geniculate nucleus - MLF medial longitudinal fascicle - NAdg dorsal group of nucleus ambiguus - NPC nucleus of the posterior commissure - nV trigeminal nerve - nVII facial nerve - OC optic chiasm - OR optic radiation - OT optic tract - P pyramidal tract - PAG periaqueductal grey - PC cerebral peduncle - PO posterior complex of the thalamus - POA preoptic area - prV principal trigeminal nucleus - PTA pretectal area - Pu putamen - PUL pulvinar nucleus - R red nucleus - RF reticular formation - RM nucleus raphe magnus - RP nucleus raphe pallidus - RST rubrospinal tract - S solitary nucleus - SC suprachiasmatic nucleus - SCN nucleus subcoeruleus - SI substantia innominata - SM stria medullaris - SN substantia nigra - SO superior olive - SOL solitary nucleus - SON supraoptic nucleus - spV spinal trigeminal nucleus - spVcd spinal trigeminal nucleus pars caudalis - ST stria terminalis - TRF retroflex tract - VC vestibular complex - VTA ventral tegmental area of Tsai - III oculomotor nucleus - Vm motor trigeminal nucleus - VI abducens nucleus - VII facial nucleus - Xd dorsal vagal nucleus - XII hypoglossal nucleus     

Lack of collateral thalamocortical projections to fields of the first somatic sensory cortex in monkeys

Summary Retrograde axoplasmic transport of differently colored fluorescent dyes was used to determine the distributions and relative proportions of cells in the ventrobasal complex of the monkey thalamus that project to each of the architectonic fields of the first somatic sensory cortex.Fast Blue was injected into portions of area 3a identified by first recording short latency, multiunit responses to electrical stimulation of Group I afferents in a muscle nerve of the forelimb or hindlimb. Nuclear Yellow was later injected into a part of area 2 responding to maximal electrical stimulation of the same nerve. In experiments that served as controls, Fast Blue was injected into area 3b and Nuclear Yellow into area 1.The results confirm the division of the ventrobasal complex into: (i) a central core with an inner part projecting to area 3b and a surrounding part projecting to area 1; (ii) a peripheral shell projecting to areas 3a and 2 (Jones et al. 1982). A far greater proportion of VB cells projects to areas 3b or 3a than to areas 1 or 2. In portions of the ventrobasal complex projecting to two areas, no cells were double labelled provided that the injections of blue and yellow dyes did not overlap. The results, thus, show a lack of collateral thalamocortical projections to the fields of the postcentral gyrus and, when taken in conjunction with other data, imply the independent relay of modality specific information through the thalamus.Abbreviations CL central nucleus - CM centre médian nucleus - LP lateral posterior nucleus - MG medial geniculate complex - mc magnocellular medial geniculate nucleus - Pla anterior pulvinar nucleus - Po posterior complex - SI first somatic sensory area - VB ventrobasal complex - VLc caudal ventral lateral nucleus - VPI ventral posterior inferior nucleus - VPLc caudal ventral posterior lateral nucleus - VPLo oral ventral posterior lateral nucleus - VPM ventral posterior medial nucleus - 1, 2, 3a, 3b, 4, 5 fields of cerebral cortex Supported by grant number NS10526 from the National Institutes of Health, United States Public Health Service