Topographical projections from the thalamus to the putamen in the cat

Thalamic projections to the putamen (Put) in the cat were studied by the retrograde horseradish peroxidase method. Major thalamic projections to the Put originate from the midline and intralaminar nuclear regions including the centre médian-parafascicular complex (CM-Pf). The other thalamic projections to the Put arise mainly from the suprageniculate nucleus (Sg), magnocellular division of the medial geniculate nucleus (MGm), caudomedial part of the lateroposterior nucleus (LP) and ventrolateral part of the ventromedial nucleus (VM). The VM projects to the rostral Put, while the posterior thalamic regions (Sg, MGm, LP) project to the caudal Put.     

Distribution of the tecto-thalamic projection neurons in the hereditary microphthalmic rat

Summary Tecto-thalamic projections in the hereditary bilaterally microphthalmic rat were studied by means of WGA-HRP injection into the dorsal lateral geniculate nucleus (LGNd) and the lateroposterior thalamic nucleus (LP). Histological study in the mutant rats showed that whereas LGNd and superficial layers of the superior colliculus (SC) suffered from a remarkable reduction in size, LP had no histological changes as compared to the normal animals. Unilateral injection of the tracer into the microphthalmic LGNd showed that WGA-HRP positive neurons were present mostly in the ipsilateral str. griseum superficiale (SGS) of the SC. However, the number of labeled SGS neurons of the microphthalmic animals was about 3% of the normal. Although cell bodies of the normal tecto-LGNd neurons in the SGS were spindle-form in shape and issued one or two proximal dendrites from each pole, the microphthalmic tecto-LGNd neurons showed an irregular contour and their dendrites were not so intensively labeled. Unilateral injections of WGA-HRP into the LP revealed that the tecto-LP neurons were mainly distributed in the ipsilateral str. opticum of the colliculus. (SO) in both normal and microphthalmic animals. However, the number of labeled SO cells in the microphthalmic rat was about one-half of the normal. Furthermore, the size of labeled tecto-LP neurons was smaller than that of the normal ones, and they showed irregular round to oval cell bodies with equivocally labeled dendrites, in contrast to the normal tecto-LP neurons with polygonal cell bodies extending three or more dendrites in a radial fashion. These results indicate that there exist the tecto-LGNd and -LP projection neurons in the microphthalmic rat and that their laminally segregated projection is fundamentally preserved. However, the number of the tecto-thalamic projection neurons, especially of the tecto-LGNd cells, was markedly diminished in the mutant tectum compared to normals.Abbreviations CST cortico-spinal tract - DRN dorsal raphe nucleus - DTN dorsal tegmental nucleus - LGNd pars dorsalis of the lateral geniculate nucleus - LLN nucleus of the lateral lemniscus - LM medial lemniscus - LP lateroposterior thalamic nucleus - MGN medial geniculate nucleus - MRF midbrain reticular formation - OT optic tract - P pretectal area - PAG periaqueductal gray - PB parabigeminal nucleus - PN pontine nuclei - PCS superior cerebellar peduncle - SGS superficial gray layer of the superior colliculus - SO stratum opticum of the superior colliculus - SN substantia nigra - Vm motor nucleus of the trigeminar nerve - Vs sensory nucleus of the trigeminar nerve     

Connections of the anterior ectosylvian visual area (AEV)

Summary We have previously described a visual area situated in the cortex surrounding the deep infolding of the anterior ectosylvian sulcus of the cat (Mucke et al. 1982). Using orthograde and retrograde transport methods we now report anatomical evidence that this anterior ectosylvian visual area (AEV) is connected with a substantial number of both cortical and subcortical regions. The connections between AEV and other cortical areas are reciprocal and, at least in part, topographically organized: the rostral AEV is connected with the bottom region of the presylvian sulcus, the lower bank of the cruciate sulcus, the rostral part of the ventral bank of the splenial sulcus, the rostral portion of the lateral suprasylvian visual area (LS) and the lateral bank of the posterior rhinal sulcus; the caudal AEV is connected with the bottom region of the presylvian sulcus, the caudal part of LS, the ventral part of area 20 and the lateral bank of the posterior rhinal sulcus. Subcortically, AEV has reciprocal connections with the ventral medial thalamic nucleus (VM), with the medial part of the lateralis posterior nucleus (LPm), as well as with the lateralis medialis-suprageniculate nuclear (LM-Sg) complex. These connections are also topographically organized with more rostral parts of AEV being related to more ventral portions of the LPm and LM-Sg complex. AEV also projects to the caudate nucleus, the putamen, the lateral amygdaloid nucleus, the superior colliculus, and the pontine nuclei. It is concluded that AEV is a visual association area which functionally relates the visual with both the motor and the limbic system and that it might play a role in the animal's orienting and alerting behavior.Abbreviations Ac aqueductus cerebri - AEs anterior ectosylvian sulcus - ALLS anterolateral lateral suprasylvian area - AMLS anteromedial lateral suprasylvian area - ASs anterior suprasylvian sulcus - Cd caudate nucleus - CL central lateral nucleus - Cl claustrum - Cos coronal sulcus - Crs cruciate sulcus - DLS dorsal lateral suprasylvian area - GI stratum griseum intermediale - GP stratum griseum profundum - IC inferior colliculus - LAm lateral amygdaloid nucleus - LGNd dorsal nucleus of lateral geniculate body - LGNv ventral nucleus of lateral geniculate body - Llc nucleus lateralis intermedius, pars caudalis - LM nucleus lateralis medialis - LPl nucleus lateralis posterior, pars lateralis - LPm nucleus lateralis posterior, pars medialis - Ls lateral sulcus - MD nucleus mediodorsalis - MG medial geniculate body - MSs middle suprasylvian sulcus - Ndl nucleus dorsolateralis pontis - Nl nucleus lateralis pontis - Np nucleus peduncularis pontis - Npm nucleus paramedianus pontis - Nrt nucleus reticularis tegmenti pontis - Nv nucleus ventralis pontis - Ped cerebral peduncle - PEs posterior ectosylvian sulcus - Pg periaqueductal gray - PLLS posterolateral lateral suprasylvian area - PMLS posteromedial lateral suprasylvian area - PSs presylvian sulcus - Pul pulvinar - Put putamen - R red nucleus - Sg suprageniculate nucleus - SN substantia nigra - Sps splenial sulcus - Syls sylvian sulcus - T trapezoid body - VA ventral anterior nucleus - VL ventral lateral nucleus - VLS ventral lateral suprasylvian area - VM ventral medial nucleus - VPL ventral posterolateral nucleus - VPM ventral posteromedial nucleus Sponsored by Max-Planck-Society during part of the studySponsored by Thyssen FoundationSponsored by Alexander von Humboldt-Foundation     

Topographic projections from the basal ganglia to the nucleus tegmenti pedunculopontinus pars compacta of the cat with special reference to pallidal projections

Summary Projections from the basal ganglia to the nucleus tegmenti pedunculopontinus pars compacta (TPC) were studied by using anterograde and retrograde tracing techniques with horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) in the cat. Following WGA-HRP injections into the medial TPC area, a substantial number of retrogradely labeled cells were seen in the entopeduncular nucleus (EP) and medial half of the substantia nigra pars reticulata (SNr), whereas following WGA-HRP injections into the lateral TPC area, labeled cells were marked in the caudal half of the globus pallidus (GP) and lateral half of the SNr. To confirm the retrograde tracing study, WGA-HRP was injected into the EP or the caudal GP, and anterograde labeling was observed in the TPC areas. Terminal labeling was located in the medail TPC area in the EP injection case, while terminal labeling was observed in the lateral TPC area in the caudal GP injection case. Projections from the striatum to the pallidal complex (the EP and the caudal GP) were also studied autoradiographically by injecting amino acids into various parts of the caudate nucleus and the putamen. Terminal labeling was distributed over the whole extent of the EP and the rostral GP following injections into the rostral striatum (the head of the caudate nucleus or the rostral part of the putamen), while terminal labeling was distributed over the caudal GP following injections into the caudal striatum (the body of the caudate nucleus or the caudal part of the putamen). From these findings, we conclude that there exists a medio-lateral topography in the projection from the basal ganglia to the TPC: The EP receives afferent projections from the rostral striatum and projects to the medial TPC area, whereas the caudal GP receives projections from the caudal striatum and sends fibers to the lateral TPC area.Abbreviations BC brachium conjunctivum - CD caudate nucleus - CP cerebral peduncle - DBC decussation of the brachium conjunctivum - EP entopeduncular nucleus - GP globus pallidus - IC internal capsule - ICo inferior colliculus - LH lateral habenular nucleus - ML medial lemniscus - PN pontine nuclei - PUT putamen - SCo superior colliculus - SI substantia innominata - SN substantia nigra - SNc substantia nigra pars compacta - SNr substantia nigra pars reticulata - STN subthalamic nucleus - TH thalamus - TPC nucleus tegmenti pedunculopontinus pars compacta     

Topographic organization of the auditory thalamocortical system in the albino rat

Summary The organization of the auditory thalamocortical connections was studied in rats. Retrograde transport of horseradish peroxidase conjugated to wheat germ agglutinin following injections into parietal, occipital and temporal cortex was used. The medial geniculate body, the suprageniculate, the lateral part of the nucleus posterior thalami, the posterior part of the nucleus lateralis thalami, and the nucleus ventroposterior project to the investigated part of the neocortex. Corresponding to different patterns of labeling, five areas of auditory neocortex were distinguished: 1. The rostral area is innervated by neurons of the nucleus ventroposterior, the lateral part of the nucleus posterior thalami, and the medial division of the medial geniculate body. 2. The dorsal area is innervated by neurons of the suprageniculate, the posterior part of the nucleus lateralis thalami and the rostral region of the dorsal division of the medial geniculate body. 3. The caudal area is innervated by neurons of the posterior part of the nucleus lateralis thalami, the suprageniculate, the medial division, the caudal region of the dorsal division and the ventrolateral nucleus of the medial geniculate body. 4. The ventral area is innervated by neurons of the suprageniculate, the medial division, the caudal region of the dorsal division, and the ventrolateral nucleus of the medial geniculate body. 5. The core area of the temporal cortex is exclusively connected to the caudal region of the medial division and the ventral division of the medial geniculate body.The findings of the present study indicate topographic organizations of the ventral division of the medial geniculate body and of the corea area. Four segments (a-d) of the ventral division each show a different set of topographic axes. They correspond to sets of topographic axes in the core area of the auditory cortex. These topographies characterize the segments which are each exclusively connected to one of the four fields of the core area.Abbreviations AC Auditory Cortex - c Caudal - d Dorsal - FR Fissura rhinalis, Rhinal Fissure - l Lateral - LTP Nucleus lateralis thalami, pars posterior - m Medial - MGB Medial geniculate body - MGBd Medial geniculate body, dorsal division - MGBm Medial geniculate body, medial division - MGBmc Medial geniculate body, caudal third of MGBm - MGBv Medial geniculate body, ventral division - MGBvl Medial geniculate body, ventrolateral nucleus - NPT Nucleus posterior thalami, pars lateralis - r Rostral - SG Suprageniculatum - VP Nucleus ventroposterior     

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     

Some topographical connections of the striate cortex with subcortical structures in Macaca fascicularis

Summary Subcortical connections of the striate cortex with the superior colliculus (SC), the lateral pulvinar (Pl), the inferior pulvinar (Pi) and the dorsal lateral geniculate nucleus (LG) were studied in the macaque monkey, Macaca fascicularis, following cortical injections of tritiated proline and/or horseradish peroxidase. All four structures were shown to receive topographically organized projections from the striate cortex. The exposed surface of the striate cortex was found to be connected to the rostral part of the SC and the caudal part of the LG. Injections of the exposed striate cortex close to its rostral border resulted in label in adjoining parts of the Pl and Pi. The ventral half and dorsal half of the calcarine fissure were connected with the medial and lateral parts of the SC, the ventrolateral and dorsomedial portions of the Pl and Pi and the lateral and medial parts of the LG, respectively. Injections located at the lateral posterior extreme of the calcarine fissure resulted in label at the optic disc representation in the LG. The horseradish peroxidase material demonstrated that LG neurons in all laminae and interlaminar zones project to the striate cortex.Abbreviations BIC brachium of the inferior colliculus - BSC brachium of the superior colliculus - C cerebellum - CG central grey - i interlaminar zone(s) of the dorsal lateral geniculate nucleus - IC inferior colliculus - ICc central nucleus of the inferior colliculus - LG dorsal lateral geniculate nucleus - m magnocellular layer(s) of the dorsal lateral geniculate nucleus - MG medial geniculate body - p parvocellular layer(s) of the dorsal lateral geniculate nucleus - P pulvinar complex - Pi inferior pulvinar - PG pregeniculate nucleus - Pl lateral pulvinar - Pm medial pulvinar - s superficial layer(s) of the dorsal lateral geniculate nucleus - SC superior colliculus - sgs stratum griseum superficiale of the superior colliculus - R reticular nucleus of the thalamus - VP ventroposterior group - 17 Area 17 Supported by NEI Grants EY-07007 (J. Graham) and EY-02686 (J.H. Kaas)     

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     

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     

Differential projection of the posterior paralaminar thalamic nuclei to the amygdaloid complex in the rat

The thalamic paralaminar nuclei that border the medial and ventral edges of the medial geniculate body, viz. the suprageniculate nucleus (SG), the posterior intralaminar nucleus (PIN), the medial division of the medial geniculate nucleus (MGm), and the peripeduncular nucleus (PP), are regarded as important extralemniscal relay nuclei for sensory stimuli and as an important link for the direct transmission of sensory stimuli to the amygdala. Each of these thalamic nuclei receives a unique pattern of afferent input but an unresolved question is, how each of these thalamic nuclei project to the amygdala and whether there are zones of convergence and/or non-overlapping regions within amygdaloid target nuclei. Small injections of PHA-L or Miniruby, which were made into single thalamic nuclei at different rostrocaudal levels, revealed a non-uniform distribution of anterogradely labeled axons within the amygdaloid complex. Injections into the SG, MGm, and rostral PIN predominantly labeled axons in the laterodorsal and lateroventral portions of the lateral nucleus of the amygdala (LA). Axons from the MGm were located rather in the dorsal part of the LA, whereas SG-derived axons were concentrated in the ventrolateral part of the LA. Injections into the PP labeled axons predominantly in the medial part of the LA, whereas after injections into the caudal PIN axons were seen in the entire LA. In addition, the PIN projects heavily to the anterior basomedial nucleus and medial division of the central nucleus, whereas this projection is virtually absent from the other thalamic nuclei. The lateral part of the central nucleus and the basal nucleus of the amygdala are spared by axons from the thalamic paralaminar nuclei. The present results suggest that, despite a considerable degree of convergence of the thalamoamygdaloid projection in the lateral nucleus, each thalamic nucleus plays a unique role in the transmission of sensory stimuli to the amygdala and in the modulation of intraamygdaloid circuits.     

Efferent connections of "posterodorsal" auditory area in the rat cortex: implications for auditory spatial processing

We examined efferent connections of the cortical auditory field that receives thalamic afferents specifically from the suprageniculate nucleus (SG) and the dorsal division (MGD) of the medial geniculate body (MG) in the rat [Neuroscience 117 (2003) 1003]. The examined cortical region was adjacent to the caudodorsal border (4.8-7.0 mm posterior to bregma) of the primary auditory area (area Te1) and exhibited relatively late auditory response and high best frequency, compared with the caudal end of area Te1. On the basis of the location and auditory response property, the cortical region is considered identical to "posterodorsal" auditory area (PD). Injections of biocytin in PD revealed characteristic projections, which terminated in cortical areas and subcortical structures that play pivotal roles in directed attention and space processing. The most noticeable cortical terminal field appeared as dense plexuses of axons in area Oc2M, the posterior parietal cortex. Small terminal fields were scattered in area frontal cortex, area 2 that comprises the frontal eye field. The subcortical terminal fields were observed in the pontine nucleus, the nucleus of the brachium inferior colliculus, and the intermediate and deep layers of the superior colliculus. Corticostriatal projections targeted two discrete regions of the caudate putamen: the top of the middle part and the caudal end. It is noteworthy that the inferior colliculus and amygdala virtually received no projection. Corticothalamic projections terminated in the MGD, the SG, the ventral zone of the ventral division of the MG, the ventral margin of the lateral posterior nucleus (LP), and the caudodorsal part of the posterior thalamic nuclear group (Po). Large terminals were found in the MGD, SG, LP and Po besides small terminals, the major component of labeling. The results suggest that PD is an auditory area that plays an important role in spatial processing linked to directed attention and motor function. The results extend to the rat findings from nonhuman primates suggesting the existence of a posterodorsal processing stream for auditory spatial perception.     

Laminar origin of the tecto-thalamic projections in the albino rat

Cells of origin of the tecto-LP (lateroposterior nucleus of the thalamus) projection and the tecto-LGNd (dorsal nucleus of the lateral geniculate body) projection were studied in the albino rat by means of retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). Tecto-LGNd neurons with small spindle form were located in the stratum griseum superficiale of the superior colliculus (SC), whereas tecto-LP neurons with polygonal shape were found in the stratum opticum of the SC.     

Ultrastructure and synaptic associations of auditory thalamo-amygdala projections in the rat

Summary Projections from the acoustic thalamus to the lateral nucleus of the amygdala (AL) have been implicated in the formation of emotional memories. In order to begin elucidating the cellular basis of emotional learning in this pathway, the ultrastructure and synaptic associations of acoustic thalamus efferents terminating in AL were studied using wheat-germ agglutinated horse-radish peroxidase (WGA-HRP) and Phaseolus vulgaris Leucoagglutinin (Pha-L) as ultrastructural anterograde axonal markers. The tracers were injected into those areas of the thalamus (medial division of the medial geniculate body and posterior intralaminar nucleus, MGM/PIN) known both to project to AL and to receive afferents from the inferior colliculus. Terminals labeled with WGA-HRP or Pha-L in AL contained mitochrondria and many small, round clear vesicles and 0–3 large, dense-core vesicles. Most labeled terminals formed asymmetric synapses on unlabeled dendrites; of these the majority were on dendritic spines. These data demonstrate that projections from the acoustic thalamus form synapses in AL and provide the first characterization of the ultrastructure and synaptic associations of sensory afferent projections to the amygdala.Abbreviations ABL basolateral nucleus of the amygdala - ABM basomedial nucleus of the amygdala - ABV ventral basolateral nucleus of the amygdala - ACE central nucleus of the amygdala - ACO cortical nucleus of the amygdala - AM medial nucleus of the amygdala - APT anterior pretectal area - AST amygdalo-striatal transition area - AL lateral nucleus of the amygdala - CI internal capsule - CG central gray - CP cerebral peduncle - CPU caudateputamen - EN endopiriform area - GP globus pallidus - I intercalated nucleus of the amygdala - OT optic tract - PIN posterior intralaminar nucleus - PIR piriform cortex - POM medial posterior thalamic complex - PP peripeduncular area - PR perirhinal cortex - SC superior colliculus - SG suprageniculate nucleus - RN red nucleus     

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)     

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。     

Response properties of single units in areas of rat auditory thalamus that project to the amygdala

Projections from the auditory thalamus to the amygdala have been implicated in the processing of the emotional signficance of auditory stimuli. In order to further our understanding of the contribution of thalamoamygdala projections to auditory emotional processing, acoustic response properties of single neurons were examined in the auditory thalamus of chloral hydrate-anesthetized rats. The emphasis was on the medial division of the medial geniculate body (MGm), the suprageniculate nucleus (SG), and the posterior intralaminar nucleus (PIN), thalamic areas that receive inputs from the inferior colliculus and project to the lateral nucleus of the amygdala (AL). For comparison, recordings were also made from the specific thalamocortical relay nucleus, the ventral division of the medial geniculate body (MGv). Responses latencies were not statistically different in MGv, MGm, PIN, and SG, but were longer in the posterior thalamic region (PO). Overall, frequency tuning functions were narrower in MGv than in the other areas but many cells in MGm were as narrowly tuned as cells in MGv. There was some organization of MGv, with low frequencies represented dorsally and high frequencies ventrally. A similar but considerably weaker organization was observed in MGm. While the full range of frequencies tested (1–30 kHz) was represented in MGv, cells in MGm, PIN, and SG tended to respond best to higher frequencies (16–30 kHz). Thresholds were higher in PIN than in MGv (other areas did not differ from MGv). Nevertheless, across the various areas, the breadth of tuning was inversely related to threshold, such that more narrowly tuned cells tended to have lower thresholds. Many of the response properties observed in MGm, PIN, and SG correspond with properties found in AL neurons and thus add support to the notion that auditory responses in AL reflect thalamoamygdala transmission.     

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     

Contralateral corticofugal projections to cat visual thalamus

Summary Contralateral corticofugal projections from visual cortical areas to thalamic nuclei were demonstrated in the cat using anterograde transport of tritiated proline. Thalamic nuclei receiving projections from contralateral visual cortex include both subdivisions of the lateral-posterior nucleus, the posterior nucleus of Rioch, and the posterior nuclear complex.Abbreviations BIC brachium of the inferior colliculus - BN nucleus of the brachium of the inferior colliculus - BSC brachium of the superior colliculus - C dorsal lateral geniculate nucleus, C laminae - CG central gray matter - D nucleus of Darkschewitz - FR fasciculus retroflexus - FTC central tegmental field - H habenula - IPN interpeduncular nucleus - LGNd dorsal lateral geniculate nucleus, A laminae - LGNv ventral lateral geniculate nucleus - LP lateral posterior complex - LPi interjacent division of lateral posterior complex - LPl lateral division of lateral posterior complex - LPm medial division of lateral posterior complex - M mammillary body - MGM magnocellular division of medial geniculate nucleus - MGN medial geniculate nucleus - MGP parvocellular division of medial geniculate nucleus - MIN medial interlaminar division of lateral geniculate nucleus - MML medial medullary lamina - NOT nucleus of the optic tract - OT optic tract - P cerebral peduncle - PA anterior pretectal nucleus - PC nucleus of the posterior commissure - PM medial pretectal nucleus - PO posterior nuclear group - PoC posterior commissure - POi intermediate division of posterior nuclear complex - POL pretectal olivary nucleus - POm medial division of posterior nuclear complex - PPT posterior pretectal nucleus - PUL pulvinar - RN red nucleus - RNR posterior nucleus of Rioch - SG suprageniculate nucleus - SGI stratum griseum intermedium of superior colliculus - SGP stratum griseum profundum of superior colliculus - SCSl lower division of stratum griseum superficiale of superior colliculus - SGSu upper division of stratum griseum superficiale of superior colliculus - SN substantia nigra - SO stratum opticum of superior colliculus - TC tectal commissure - III III nerve - IIIN nucleus of III nerve     

The superior colliculus neurons which project to the dorsal and ventral lateral geniculate nuclei in the cat

Summary Cells in the cat superior colliculus which project to the ventral and dorsal lateral geniculate nuclei (VLG and DLG) have been labeled by retro-grade transport of horseradish peroxidase (HRP). We studied the depth, area, and morphology of each labeled neuron quantitatively. Our measurements show that the projection neurons to both VLG and DLG vary in laminar position, size, and morphology. Labeled cells projecting to both nuclei were concentrated within the superficial gray layer, but were also scattered through the optic layer and, after DLG injections, in the intermediate gray layer as well. Labeled cells in both groups varied greatly in size, ranging from 49–344 m² cross-sectional area (mean 143 m²) for the VLG group and from 31–398 m² (mean 165 m²) for the DLG group. The labeled cells also varied in morphology after both VLG and DLG injections. The majority had a granule or vertical fusiform morphology. There were fewer with a stellate morphology and almost none with a horizontal morphology. At least three types of superior colliculus cells thus appear to project to the ventral and dorsal lateral geniculate nuclei. These cell types likely give rise to distinct functional channels to these nuclei.Abbreviations A lamina A of the dorsal lateral geniculate nucleus - A1 lamina A1 of the dorsal lateral geniculate nucleus - C lamina C of the dorsal lateral geniculate nucleus - CM central medial nucleus - CMM medial mammillary nucleus - CP cerebral peduncle - D nucleus of Darkschewitsch - FCT central tegmental tract - H habenular nuclei - HPM medial habenulo-peduncular tract - LP lateral posterior nucleus - MG medial geniculate nucleus - MIN medial intralaminar nucleus - NCP nucleus of the posterior commissure - NR reticular nucleus - OT optic tract - P pulvinar nucleus - PC posterior commissure - R red nucleus - SG suprageniculate nucleus - SN substantia nigra - VLA ventral anterolateral nucleus - VLG ventral lateral geniculate nucleus - VPL ventral posterolateral nucleus - VPM ventral postero-medial nucleus This study was supported by USPHS Research Grant EY02973 from the National Eye Institute, a New Faculty Research Grant from the State of Tennessee, and USPHS Postdoctoral Training Grant GM-00202     

Retinofugal projections in the house musk shrew, Suncus murinus.

Retinofugal projections in the house musk shrew (Suncus murinus) were studied with the WGA-HRP method. After WGA-HRP injection into the vitreous cavity of one eye, terminal labeling was seen in the suprachiasmatic nucleus, dorsal and ventral lateral geniculate nuclei, pretectum and superficial layer of the superior colliculus. The terminal labeling in the suprachiasmatic nucleus was more marked on the side ipsilateral to the injection than on the contralateral side, whereas that in other regions was seen mainly on the contralateral side. A retino-intergeniculate leaflet projection was observed. No unequivocal terminal labeling was found in the lateroposterior thalamic nucleus.