Quantitative studies on the supraoptic nucleus in the rat. II. Afferent fiber connections

Summary A quantitative electron microscopic study of synaptic terminal degeneration was performed in the supraoptic nucleus (NSO) after a variety of major transections or ablations, destroying or interrupting in different combinations the afferent pathways known from earlier and own light microscopic degeneration studies. Solutions of a set of equations, expressing the percentage degenerations in synaptic profiles after different combinations in which the several pathways are interrupted by the various interferences, enabled the authors to give the following percentage numbers for afferent synapses from different sources.32.7% of supraoptic afferents originate from the brain stem probably representing the monoaminergic innervation of this nucleus. The medial basal hypothalamus (21.0%), amygdala (13.5%), septum (13.5%), hippocampus (8.5%) and olfactory tubercle and further rostral cortical region (17.0%) are the other main sites of origin of supraoptic nucleus afferents. There are no supraoptic afferents from the optic nerve, superior cervical ganglion or fimbria hippocampi.Abbreviations A nucleus accumbens - AB nucleus amygdaloideus basalis - AC nucleus amygdaloideus centralis - AL nucleus amygdaloideus lateralis - AM nucleus amygdaloideus medialis - ATV area tegmenti ventralis (Tsai) - C caudate-putamen - CA commissura anterior - CC corpus callosum - CFV commissura fornicvis ventralis - CO chiasma opticum - CP commissura posterior - D nucleus tractus diagnolis - DM nucleus dorsomedialis - DS decussationes supraoptica - F columna fornicis - FH fimbria hippocampi - FLM fasciculus longitudinalis medialis - FP fornix praecommissuralis - FS fornix superior - G globus pallidus - GD gyrus dentatus - HI hippocampus - IC capsula interna - IP nucleus interpeduncularis - LM lemniscus medialis - M medial forebrain bundle (MFB) - MM nucleus medialis thalami, pars medialis - NA nucleus arcuatus - R nucleus rhomboideus - RE nucleus reuniens - RV nucleus ruber - S stria medullaris thalami - SD nucleus dorsalis septi - SF nucleus fimbrialis septi - SG substantia grisea centralis - SL nucleus lateralis septi - SM nucleus medialis septi - SN substantia nigra - ST nucleus interstitialis striae terminalis - T tractus olfactorius lateralis - TD tractus diagonalis (Broca) - TO tractus opticus - TSTH tractus striohypothalamicus - TU tuberculum olfactorium - VM nucleus ventromedialis     

Afferent fiber connections from lower brain stem to hypothalamus studied by the horseradish peroxidase method with special reference to noradrenaline innervation

Summary Attempts were made to determine the afferent projections to the anterior hypothalamus including the preoptic area from the lower brain stem by means of the horseradish peroxidase method combined with monoamine oxidase staining to identify noradrenaline (NA) neurons. In addition to this technique, a histofluorescence analysis was performed. NA fibers in the medial part of the anterior hypothalamus were mainly supplied by A1 and A2 NA neuron groups, while the lateral part and periventricular zone received NA terminals from both pontine and medulla oblongata NA neuron groups. Furthermore, the present study indicated that there were direct projections to the anterior hypothalamus from non-noradrenergic neurons in the lower brain stem: nuclei raphe dorsalis, centralis superior, cells in the mesencephalic and pontine central gray matter, nuclei parabrachialis lateralis and medialis, cells around fasciculus longitudinalis medialis.Abbreviations CA Commissura anterior - CO Chiasma opticum - DP Decussatio pyramidum - DPCS Decussatio pedunculorum cerebellarium superiorum - F Columna fornicis - FLM Fasciculus longitudinalis medialis - FMT Fasciculus mamillothalamicus - GCM Griseum centrale mesencephali - GCP Griseum centrale pontis - LL Lemniscus lateralis - LM Lemniscus medialis - PCM Pedunculus cerebellaris medius - PCS Pedunculus cerebellaris superior - TO Tractus opticus - TS Tractus solitarius - TVme Tractus mesencephalicus nervi trigemini - V Ventriculus tertius - VTS Tractus spinalis nervi trigemini - am nucleus ambiguus - B Barrington nucleus - com nucleus commissuralis - cp nucleus caudatus putamen - cs nucleus centralis superior - ct nucleus corporis trapezoidei - cu nucleus cuneatus - dX nucleus dorsalis nervi vagi - Gd nucleus tegmentalis dorsalis (von Gudden) - gr nucleus gracilis - Gv nucleus tegmentalis ventralis (von Gudden) - ha nucleus hypothalamicus anterior - hl nucleus hypothalamicus lateralis - hpe nucleus periventricularis (hypothalami) - hvm nucleus ventromedialis hypothalami - lc nucleus locus coeruleus - oi nucleus olivaris inferior - p nucleus pontis - pa nucleus paraventricularis - pbl nucleus parabrachialis lateralis - pbm nucleus parabrachialis medialis - ph nucleus praepositus hypoglossi - pol nucleus preopticus lateralis - pom nucleus preopticus medialis - pop nucleus preopticus periventricularis - rd nucleus raphe dorsalis - re nucleus reuniens - rl nucleus reticularis lateralis - rm nucleus raphe magnus - ro nucleus raphe obscrus - sc nucleus suprachiasmaticus - so nucleus supraopticus - st nucleus interstitialis striae terminalis - td nucleus tractus diagonalis (Broca) - ts nucleus tractus solitarii - Vme nucleus mesencephalicus nervi trigemini - Vmo nucleus motorius nervi trigemini - Vts nucleus tractus spinalis nervi trigemini - XII nucleus nervi hypoglossi     

Neocortical layers I and II of the hedgehog (Erinaceus europaeus). II. Thalamo-cortical connections

Summary This study examines the thalamo-cortical projections to the most superficial neocortical layers in the hedgehog (Erinaceus europaeus) after small injections of horseradish peroxidase and horseradish peroxidase conjugated to wheat germ agglutinin in the somato-sensory cortex. The injections were limited to layers I, II and upper parts of layer III/IV. Retrogradely labeled cells were plotted in serial sections through the thalamus. Injections in the somato-sensory cortex gave a pattern of elongated columns of labeled cells, extending rostro-caudally in the nucleus ventralis thalami. In the neocortex, labeled fibers extended for considerable distances running horizontally in layer I. Complementary observations demonstrate the thalamic origin of certain, coarse ascending bundles observed previously in Golgi preparations of the hedgehog. It is concluded that a major cortical input to layer I originates in the hedgehog in the principal thalamic (relay) nuclei. After injections in the somato-sensory cortex, retrogradely labeled cells were also found in the nucleus ventro-medialis thalami and very few in a zone medial to the nucleus ventralis thalami corresponding to the intralaminar thalamic nuclei. The contributions of this latter system seem to be limited in comparison with other mammals.Abbreviations A hucleus amygdaloideus - Abol bulbus olfactorius accessorius - Al nucleus amygdaloideus lateralis - Am nucleus anterior medialis thalami - Av nucleus anterior ventralis thalami - Bol bulbus olfactorius - Bst nucleus interstitialis striae terminalis - Ca commissura anterior - Cc corpus callosum - Cen cortex entorhinalis - Ch Chiasma opticum - Ci capsula interna - Cp commissura posterior - Cpu nucleus caudatus putamen - Cs colliculus superior - Fmp fasciculus medialis prosencephali - Fmt fasciculus mamillothalamicus - For formatio reticularis - Fr fasciculus retroflexus - Fx columna fornicis - Gd gyrus dentatus - Gla nucleus geniculatus lateralis, pars dorsalis - Glv nucleus geniculatus lateralis, pars ventralis - Gm nucleus geniculatus medialis - Ha nucleus anterior hypothalami - Hb nucleus habenulae - Hdv nucleus dorsomedialis hypothalami - Hia hippocampus, pars anterior - Hip hippocampus - Hl nucleus lateralis hypothalami - Hvm nucleus ventromedialis hypothalami - Lm lemniscus medialis - Noa nucleus olfactorius anterior - Npm nucleus preopticus medialis - Ped crus cerebri - Pf nucleus parafascicularis - Pre pretectum - Pt nucleus paratenialis - Pv nucleus periventricularis - R nucleus reticularis thalami - Rcn regio cingularis (Brodmann) - Re nucleus reuniens - Rhi regio hippocampica (Brodmann) - Re nucleus reuniens - Rhi regio hippocampica (Brodmann) - Ro regio occipitalis (Brodmann) - Rol regio olfactoria (Brodmann) - Rpc regio precentralis (Brodmann) - Rrs regio retrosplenialis (Brodmann) - Rt regio temporalis (Brodmann) - Rti radiatio thalamica - Rt regio temporalis (Brodmann) - Rti radiatio thalamica - Rtn regio insularis (Brodmann) - S subiculum - Sf sulcus frontalis - Sm stria medullaris thalami - Sn substantia nigra - Srh sulcus rhinalis - St stria terminalis - Td tractus diagonalis (Broca) - Tl nucleus lateralis thalami - Tlp nucleus lateralis thalami, pars posterior - Tm nucleus medialis thalami - To tractus opticus - Tol tractus olfactorius lateralis - Tuo tuberculum olfactorium - Tv nucleus ventralis thalami - Tvd nucleus ventralis thalami, pars dorsalis - Tvm nucleus ventromedialis thalami - wm white matter of the cerebral cortex     

The distribution of zinc in the forebrain and midbrain of the lizard Gekko gecko

Summary The distribution of zinc in the forebrain and midbrain of the lizard Gekko gecko was studied with the recently modified Timm method. Areas with a high intensity of staining are almost exclusively found in the telencephalon, although also some structures in the diencephalon display notable staining. Cortical areas that stain heavily are the deep zone of the subcortical layer of the small-celled medial cortex, the longitudinal association bundle that encompasses the large-celled medial cortex, and the dorsal cortex. Of the subcortical areas, particularly the anterior septal nucleus shows a high intensity of staining. Moderate to dense Timm staining is further observed in the ventral part of the anterior lateral cortex, the lateral septal nucleus, the striatum, the amygdaloid complex, and the dorsal ventricular ridge. Staining in the diencephalon is primarily confined to the stria terminalis and the ventromedial hypothalamic nucleus, whereas in the midbrain weak staining is observed in the ventral tegmental area and the periventricular layers of the tectum and the tegmentum. The presence of zinc in the gekkonid brain is discussed in relation to connections and neurotransmitters as studied in the same species. Moreover, similarities in pattern of staining for zinc in mammals and reptiles and possible evolutionary implications are mentioned.Abbreviations Acc nucleus accumbens - Alh area lateralis hypothalami - Amc nucleus centralis amygdalae - Ame nucleus externus amygdalae - Aml nucleus lateralis amygdalae - Anm nucleus marginalis amygdalae - Bmfb bed nucleus of the medial forebrain bundle - Cgld corpus geniculatum laterale pars dorsalis - Cglv corpus geniculatum laterale, pars ventralis - Cgp corpus geniculatum pretectale - cpa commissura pallii anterior - cso commissura supraoptica - Cxd cortex dorsalis - Cxla cortex lateralis, pars anterior - Cxlp cortex lateralis, pars posterior - Cxml cortex medialis, large-celled part - Cxms cortex medialis, small-celled part - Dlh nucleus dorsolateralis hypothalami - Dll nucleus dorsolateralis thalami, large-celled part - Dls nucleus dorsolateralis thalami, small-celled part - Dm nucleus dorsomedialis thalami - DVR dorsal ventricular ridge - Ent nucleus entopeduncularis - Hab ganglion habenulae - lfb lateral forebrain bundle - lfbv lateral forebrain bundle, ventral peduncle - Lte nucleus lentiformis thalami, pars extensa - Ltp nucleus lentiformis thalami, pars plicata - Mp nucleus medialis posterior - Mt nucleus medialis thalami - NdB nucleus of the diagonal band of Broca - Nsa nucleus septalis anterior - Nsd nucleus septalis dorsalis - Nsl nucleus septalis lateralis - Nsm nucleus septalis medialis - Nsph nucleus sphericus - oph organon periventriculare hypothalami - Ph nucleus periventricularis hypothalami - Ppo periventricular preoptic area - Rot nucleus rotundus - Rub nucleus ruber - Sped nucleus suprapeduncularis - st stria terminalis - Str striatum - tect tectum - topt tractus opticus - Torc nucleus centralis of the torus semicircularis - Torl nucleus laminaris of the torus semicircularis - tsh tractus septohypothalamicus - Vltv nucleus ventrolateralis thalami, pars ventralis - Vmh nucleus ventromedialis hypothalami - Vmt nucleus ventromedialis thalami - VTA ventral tegmental area - III nucleus nervi oculomotorii     

Distribution of serotonin-immunoreactivity in the central nervous system of the rat—Cell bodies and terminals

The localization and distribution of serotonin (5-hydroxytryptamine, 5-HT) has been studied with the indirect immunofluorescence technique using a highly specific and well-characterized antibody to 5-HT. In neuron systems 5-HT was found to be primarily present with a distribution similar to that observed in basic mappings carried out with the formaldehyde-induced fluorescence method. In addition to the nine areas originally described, several other areas in the mesencephalon and rhombencephalon appeared to contain widely distributed 5-HT-positive perikarya. In the median eminence 5-HT fluorescent mast cells could be visualized. No 5-HT-positive nerve cell bodies could be observed either in the telencephalon or diencephalon.Our results also demonstrate a widespread occurrence of 5-HT-positive nerve terminals throughout the central nervous system. Dense populations of serotonin-immunoreactive nerve terminals are present in the following areas, from rostral to caudal: various parts of the medial forebrain bundle; the ventromedial part of the nucleus suprachiasmaticus: the most ventrolateral part of the caudatus-putamen complex; an area between the rostral part of the nucleus reuniens and the fornix: at that same level of the latter area, a region just ventral of the fornix; the dorsolateral part of the nucleus periventricularis thalami; an area lateral of the claustrum, close to the cortex piriformis; the nucleus amygdaloideus basalis; the dorsomedial part of the nucleus medialis thalami pars medialis, only in the rostral part; the inner part of the nucleus ventromedialis hypothalami; the ventral part of the nucleus mamillaris medialis; the radiatio thalami superior; the nucleus subthalamicus; the caudal part of the nucleus amygdaloideus medialis posterior; the area pretectalis radialis; the dorsal part of the nucleus ventralis corporis geniculati lateralis; the ventromedial part of the substantia nigra reticularis; an area ventral of the decussatio supramammillaris; the substantia nigra pars lateralis; the dorsolateral part of the nucleus reticularis pontis oralis; some parts of the nucleus origines nervi trigemini; the ventromedial part of the nucleus origines nervi facialis; the medial part of the nucleus tractus solitarius and the medial part of the cornu ventrale of the spinal cord. There are only a few areas where no serotonin-immunoreactivity could be found. Within several areas, as, e.g., hippocampus, nucleus caudatus, medial forebrain bundle, the density of serotoninergic fibers appeared to show considerable local differences. Within the same nuclei or area the amount can differ considerably.This immunohistochemical procedure makes it possible to study the distribution of serotonin-containing nerves and their processes in considerable detail. The finding that serotonin-containing neurons are present in many nuclei that also include catecholamine-containing neurons makes it necessary to reconsider the terminology of the monoaminergic cell groups.     

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     

The primary visual system of flatfish: an evolutionary perspective

Summary The retinal projections of two species of flatfish (Scophthalmus maximus, Scophthalmidae; Platichthys flesus, Pleuronectidae) were investigated by autoradiography and by a HRP technique. Contralateral projections to five hypothalamic centres (area optica preoptica ventralis, nucleus opticus preopticus parvocellularis posterior pars lateralis, n. suprachiasmaticus, n. opticus hypothalami ventromedialis and area optica hypothalami posterior), thirteen thalamo-pretectal centres (nucleus opticus dorsolateralis (partes medialis, ventralis and lateralis), n. opticus ventrolateralis, n. opticus commissurae posterioris (partes dorsalis and ventralis), n. opticus accessorius, n. geniculatus lateralis mesencephali, nn. opticus pretectalis dorsalis, medialis and ventralis and n. corticalis), three layers of the optic tectum (stratum opticum pars externa, stratum fibrosum et griseum superficiale, stratum album centrale), and a single target in the tegmentum (n. opticus tegmenti mesencephali dorsalis), were identified in both species. Interspecific variation of the contralateral visual projections is relatively small. Ipsilateral visual projections of fibres which recross the midline in the minor and transverse commissures were also identified; in S. maximus this ipsilateral contingent is poorly developed and concerns principally hypothalamic structures, while in P. flesus the ipsilateral projections are considerably more extensive and involve both hypothalamic and thalamo-pretectal primary visual centres. No differences in the projections from the fixed and from the migrated eye were observed in either species. The findings are discussed in the general context of the existing literature on the visual projections of teleosts, in an attempt to characterize the primary visual system of the Pleuronectiformes in an evolutionary context.List of Abbreviations AOHp Area optica hypothalami posterior - AOPv Area optica preoptica ventralis - CER Cerebellum - Com. H Commissura horizontalis - Com. M Commissura minor - Com. T Commissura transversalis - Cp Commissura posterioris - FDtro Fasciculus dorsalis tractus optici - FHtro Fasciculus hypothalami tractus optici - FOCM Fasciculus opticus commissurae minor - FOCT Fasciculus opticus commissurae transversalis - FOHpv Fasciculus opticus hypothalami posterior pars ventralis - FVLtro Fasciculus ventrolateralis tractus optici - FVLtroi Fasciculus ventrolateralis optici ipsilateralis - FVMtro Fasciculus ventromedialis tractus optici - FVMtroi Fasciculus ventromedialis tractus optici ipsilateralis - FVtro Fasciculus ventralis tractus optici - Hyp Hypophysis cerebri - IS Interlobular sulcus - LO Lobus opticus - LOd Lobus opticus dorsalis - LOv Lobus opticus ventralis - LON left optic nerve - NC Nucleus corticalis - NDLi Nucleus diffusus lobi inferioris - NDM Nucleus dorsomedialis - NE Nucleus entopeduncularis - NG Nucleus glomerulosus - NGL Nucleus geniculatus lateralis - NGLM Nucleus geniculatus lateralis mesencephali - NOA Nucleus opticus accessorius - NOCPpd Nucleus opticus commissurae posterions pars dorsalis - NOCPpv Nucleus opticus commissurae posterioris pars ventralis - NODL Nucleus opticus dorsolateralis - NODLpl Nucleus opticus dorsolateralis pars lateralis - NODLpm Nucleus opticus dorsolateralis pars medialis - NODLpv Nucleus opticus dorsolateralis pars ventralis - NOHvl Nucleus opticus hypothalamicus ventrolateralis - NOPd Nucleus opticus pretectalis dorsalis - NOPL Nucleus opticus pretectalis lateralis - NOPm Nucleus opticus pretectalis medialis - NOPPpl Nucleus opticus preopticus parvocellularis posterior pars lateralis - NOPv Nucleus opticus pretectalis ventralis - NOTMd Nucleus opticus tegmenti mesencephali dorsalis - NOTMdl Nucleus opticus tegmenti mesencephali dorsalis pars lateralis - NOTMdm Nucleus opticus tegmenti mesencephali dorsalis pars medialis - NOVL Nucleus opticus ventrolateralis - NPG Nucleus preglomerulosus - NPMg Nucleus preopticus magnocellularis - NPP Nucleus preopticus parvocellularis posterior - NPPa Nucleus preopticus parvocellularis anterior - NPs Nucleus pretectalis superficialis - NRL Nucleus recessus lateralis - NSC Nucleus suprachiasmaticus - NVM Nucleus ventromedialis - RON right optic nerve - sac stratum album centrale - sfgs stratum fibrosum et griseum superficiale - sfpv stratum fibrosum periventriculare - sgc stratum griseum centrale - sgpv stratum griseum periventriculare - sm stratum marginale - soe stratum opticum pars externa - soi stratum opticum pars interna - SV saccus vascularis - Tel telencephalon - TL Torus longitudinalis - TM Tegmentum mesencephali - TO Tectum opticum - TROA Tractus opticus accessorius - TROdm Tractus opticus dorsomedialis - TROdmd Tractus opticus dorsomedialis dorsalis - TROdme Tractus opticus dorsomedialis pars externa - TROdmi Tractus opticus dorsomedialis pars interna - TROdmv Tractus opticus dorsomedialis ventralis - TROdmvd Tractus opticus dorsomedialis ventralis pars dorsalis - TROdmvv Tractus opticus dorsomedialis ventralis pars ventralis - TROM Tractus opticus marginalis - TROvl Tractus opticus ventrolateralis - TROvld Tractus opticus ventrolateralis dorsalis - TROvle Tractus opticus ventrolateralis pars externa - TROvli Tractus opticus ventrolateralis pars interna - TROvldd Tractus opticus ventrolateralis dorsalis pars dorsalis - TROvldv Tractus opticus ventrolateralis dorsalis pars ventralis - TROvlv Tractus opticus ventrolateralis pars ventralis - TS Torus semicircularis - v ventricle - VC Valvula cerebelli - I Nervus olfactorius - II Nervus opticus - V Nervus trigeminus - VII Nervus facialis - VIII Nervus octavolateralis - IX Nervus glossopharyngeus - X Nervus vagus     

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     

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     

Thalamic projections to the posterior sylvian and posterior ectosylvian gyri of the sheep brain, revealed with the retrograde transport of horseradish peroxidase

Summary The auditory area of the sheep cerebral cortex was studied on the basis of its afferents from the medial geniculate nucleus, traced with the horseradish peroxidase retrograde transport method. The results show that the medial geniculate nucleus projects only to the anterior parts of the posterior ectosylvian gyrus and the posterior sylvian gyrus. A small area of the posterior ectosylvian gyrus receives afferents exclusively from the ventral part of the medial geniculate nucleus, while the anterior part of the posterior sylvian gyrus receives also afferents from the posterior nucleus of the thalamus and the pulvinar. In addition, it was found that the medial part of the medial geniculate nucleus projects in a sparse way to the auditory cortex. The middle part of the posterior ectosylvian gyrus receives afferents from the posterior nucleus of the thalamus, the suprageniculate nucleus and the pulvinar, while the posterior part of the posterior ectosylvian gyrus together with the posteriormost part of the posterior sylvian gyrus receive afferents from the pulvinar. Finally, the area located between the anterior and the posteriormost part of the posterior sylvian gyrus receives afferents from both the posterior nucleus of the thalamus and the pulvinar.Abbreviations Ad nucleus anterior dorsalis - Am nucleus anterior medialis - Av nucleus anterior ventralis - BCI nucleus of the brachium colliculi inferioris - bci brachium colliculi inferioris - Cg substantia grisea centralis - ci capsula interna - Cm nucleus centralis medialis - EC sulcus ectomarginalis - EN sulcus entomarginalis - Ep epiphysis - ES sulcus ectosylvius - fd columna fornicis descendens - FS fissura sylvia - Hl nucleus habenularis lateralis - Hm nucleus habenularis medialis - Iv nucleus interventralis - Ld nucleus lateralis dorsalis - LGN nucleus geniculatus lateralis - LGNd nucleus geniculatus lateralis, pars dorsalis - LGNv nucleus geniculatus lateralis, pars ventralis - lme lamina medullaris thalami externa - Lp nucleus lateralis posterior - Lt nucleus lateralis thalami - MA sulcus marginalis - Md nucleus medialis dorsalis - MGN nucleus geniculatus medialis - MGNd nucleus geniculatus medialis, pars dorsalis - MGNm nucleus geniculatus medialis, pars magnocellularis - MGNv nucleus geniculatus medialis, pars ventralis - MIN medial interlaminar nucleus - mt fasciculus mamillothalamicus - ml lemniscus medialis - Mv nucleus medialis ventralis - ot tractus opticus - p putamen - pc pedunculus cerebri - Pl nucleus paralemniscalis - Po nucleus posterior - Pp nucleus paraventricularis posterior - Pta nucleus praetectalis anterior - Ptp nucleus praetectalis posterior - Pul pulvinar - R nucleus ruber - rf fasciculus retroflexus - Rh nucleus rhomboidalis - RH sulcus rhinalis lateralis - Rt nucleus reticularis thalami - Sg nucleus suprageniculatus - SN substantia nigra - SP sulcus cinguli - SS sulcus suprasylvius - Sth nucleus subthalamicus - Va nucleus ventralis anterior - Vl ventrolateral nuclear complex - Vll pars lateralis of the ventrolateral nuclear complex - Vm nucleus ventralis medialis - Vp nucleus ventralis posterior - Vpl nucleus ventralis posterior, pars lateralis - Vpm nucleus ventralis posterior, pars medialis - W Wernicke's field     

Electrophysiological investigation of the archistriato-hypothalamic pathway in the pigeon (Columba livia)

The connection from the limbic part of the avian archistriatum (Am+Ap) to the hypothalamus by way of the tractus occipito-mesencephalicus, pars hypothalami (HOM) was investigated electrophysiologically by means of electrical stimulation in the archistriatum and extracellular single unit recording in the hypothalamus. A powerful activating influence of Am on the hypothalamus could be demonstrated, which involved not only the established termination region of HOM in the posterior hypothalamus, but also the lateral and anterior hypothalamus, the stratum cellulare internum (SCI) and externum (SCE). The response patterns in the medial region differ in a characteristic manner from those in the lateral and posterior regions. Whereas neurons in the medial hypothalamus have small amplitudes (0.2 mV) and are evoked with relatively long latencies (>8 ms), responses in the remaining regions appear to have higher amplitudes (up to 1 mV) and faster conduction velocities.The results are not in conflict with the presence of the postulated [25] direct anatomical pathway, but monosynaptic transmission was proven neither for the projection to the medial nor for that to the lateral region. The spontaneous activity of some neurons in LHy, SCI and SCE was inhibited by Am stimulation. It is concluded that the HOM-tract includes several pathways mediating slow and fast, monosynaptic and polysynaptic excitatory and inhibitory effects. These observations on the archistriato-hypothalamic connections in the pigeon compare with those on amygdalo-hypothalamic projections via stria terminalis in the rat and contrast with the more complex organization of these pathways encountered in higher mammals.Abbreviations Aa Archistriatum anterior - AHM Nucleus anterior medialis hypothalami - Ai Archistriatum intermedium - Aid Archistriatum intermedium, pars dorsalis - AL Ansa lenticularis - Am Archistriatum mediale - Ap Archistriatum posterior - CO Chiasma opticum - CoS Nucleus commissuralis septi - DA Tractus archistriatalis dorsalis - DIP Nucleus dorsointermedius posterior thalami - DLL Nucleus dorsolateralis anterior thalami. pars lateralis - DLM Nucleus dorsolateralis anterior thalami. pars medialis - DLP Nucleus dorsolateralis posterior thalami - DMA Nucleus dorsomedialis anterior thalami - DMP Nucleus dorsomedialis posterior - TA Tractus-frontoarchistriatalis - FPL Fasciculus prosencephali lateralis - GLv Nucleus geniculatus lateralis, pars ventralis - HOM Tractus occipitomesencephalicus, pars hypothalami - IPS Nucleus interstitio-pretecto-subpretectalis - LA Nucleus lateralis anterior thalami - LHy Hypothalamus lateralis - nST Nucleus striae terminalis - OM Tractus occipitomesencephalicus - Ov Nucleus ovoidalis - PA Paleostriatum augmentatum - pB Commissura anterior, pars bulbaris - PP Paleostriatum primitivum - PPc Nucleus principalis precommissuralis - PVM Nucleus periventricularis magnocellularis - QF Tractus quintofrontalis - Rt Nucleus rotundus - SCE Stratum cellulare externum - SCI Stratum cellulare internum - SL Nucleus septalis lateralis - SM Nucleus septalis medialis - SP Nucleus subpretectalis - SPC Nucleus superficialis parvocellularis - SPM Nucleus spiriformis lateralis - SRt Nucleus subrotundus - T Nucleus triangularis - TIO Tractus isthmo-opticus - Tn Nucleus taeniae - TOv Tractus nuclei ovoidalis - TrO Tractus opticus - TSM Tractus septomesencephalicus - TT Tractus tectothalamicus - TU Nucleus tuberis - V Ventriculus     

The thalamic connections with medial area 6 (supplementary motor cortex) in the monkey (macaca fascicularis)

Summary 1. The interrelationship of medial area 6 (supplementary motor area) with the thalamus was investigated by means of anterograde and retrograde tracing methods. Nine monkeys were prepared for autoradiography or histochemistry with the marker HRP conjugated to the lectin wheat germ agglutinin. Three of the monkeys received injections into the precentral cortex for comparison. 2. Previous observations were confirmed that the thalamic relays to the motor areas are organized as crescent-shaped lamellae which transgress cytoarchitectonic boundaries. The thalamic VA-VL complex receiving fibres from areas 4 and medial area 6 also sends fibres to these same areas. 3. The thalamic relay to medial area 6 comprised the following subdivisions: VLo, VLc, area X of Olszewski, VLm and, to a smaller extent VA. 4. Labeling (mostly anterograde only) was also prominent in some thalamic compartments outside the motor thalamus: R, CL, CM-Pf, MD, LP, PULo. 5. It was noted that rostral and caudal injections into the medial area 6 resulted in different thalamic labeling: The rostral portion was found to be related mainly with VApc, area X and VLc, the central portion with VLo, and the caudal portion with VLc/VLo. This structural inhomogeneity may reflect also a functional rostro-caudal differentiation of the medial area 6. 6. The thalamic territory projecting to the precentral cortex is separate from the above relay and includes principally VPLo. 7. The present anatomical labeling study is in agreement with the conclusion of Schell and Strick (1984) that the SMA, especially its central portion, is an important target of basal ganglia outflow via the thalamic relay VLo. In addition consistent labeling was also found in thalamic subdivisions (area X, VLc) which had been found to receive cerebellar fibres.Abbreviations AD Nucleus anterior dorsalis - AM Nucleus anterior medialis - AV Nucleus anterior ventralis - ARG Autoradiography - CL Nucleus centralis lateralis - CM Centre median nucleus - Comm. post. Commissura posterior - CLS Nucleus centralis superior lateralis - For Fornix - GM Nucleus geniculatus medialis - In p.c. Nucleus interstitialis of the posterior commissure - LD Nucleus lateralis dorsalis - Li Nucleus limitans - LP Nucleus lateralis posterior - MDmc Nucleus medialis dorsalis, pars magnocellularis - MDmf Nucleus medialis dorsalis, pars multiformis - MDpc Nucleus medialis dorsalis, pars parvocellularis - NRmc Nucleus ruber magnocellularis - NRpc Nucleus ruber parvocellularis - Pcn Nucleus paracentralis - Pf Nucleus parafascicularis - Pul.i. Nucleus pulvinaris inferior - Pul.l. Nucleus pulvinaris lateralis - Pul.m. Nucleus pulvinaris medialis - Pul.o. Nucleus pulvinaris oralis - R Nucleus reticularis thalami - SMA Supplementary motor area - STh Nucleus subthalamicus - VAmc Nucleus ventralis anterior, pars magnocellularis - VApc Nucleus ventralis anterior, pars parvocellularis - VLc Nucleus ventralis lateralis, pars caudalis - VLm Nucleus ventralis lateralis, pars medialis - VLo Nucleus ventralis lateralis, pars oralis - VLps Nucleus ventralis lateralis, pars postrema; - VPI Nucleus ventralis posterior inferior - VPLo Nucleus ventralis posterior lateralis, pars oralis - VPM Nucleus ventralis posterior medialis - WGA-HRP Horseradish peroxidase conjugated to the lectin wheat germ agglutinin; - X Area X - ZI Zona incerta     

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     

An autoradiographic study of efferent connections of the globus pallidus in Macaca mulatta

Summary Radioactive amino acids were injected into restricted regions of the globus pallidus of rhesus macaques to allow identification of the organization and courses of efferent pallidal projections. The previously identified projection of the internal pallidal segment (GPi) to ventral thalamic nuclei showed a topographic organization, with the predominant projection from ventral GPi being to medial and caudal ventralis anterior (VA) and lateralis (VL) and from dorsal GPi to lateral and rostral VA and VL. Pallidal efferent fibers also extended caudally and dorsally into pars caudalis of VL, but they spared the portion of pars oralis of VL shown by others to receive input from the cerebellum. In addition to centromedian labeling in all animals, the parafascicular nucleus was also labeled when isotope was injected into dorsal GPi. The medial route from GPi to the midbrain tegmentum was more substantial than has been shown before, and along this route there was an indication that some fibers terminated in the prerubral region. The projection to the pedunculopontine nucleus was extensive, and fibers continued caudally into the parabrachial nuclei.Pallidal projections to the thalamus seem to be topographically organized but spare thalamic regions that interact with area 4. Caudally directed efferent fibers follow multiple routes and extend more caudally than to the pedunculopontine nuclei.Abbreviations Cd caudate nucleus - CM centromedian nucleus - CT central tegmental tract - DPCS decussation of superior cerebellar peduncle - F fornix - FLM medial longitudinal fasciculus - GPe globus pallidus, pars externa - GPi globus pallidus, pars interna - HbL lateral habenular nucleus - HbM medial habenular nucleus - Is interstitial nucleus - LM medial lemniscus - MD dorsomedial nucleus - PbL lateral parabrachial nucleus - PbM medial parabrachial nucleus - PCS superior cerebellar peduncle - Pf parafascicular nucleus - PPN pedunculopontine nucleus - Put putamen - R reticular nucleus - Rmg red nucleus, pars magnocellularis - Rpc red nucleus, pars parvocellularis - S stria medullaris - SI substantia innominata - SNc substantia nigra, pars compacta - SNr substantia nigra, pars reticulata - St subthalamic nucleus - ST stria terminalis - THI habenulointerpeduncular tract - TM tuberomamillary nucleus - TMT mamillothalamic tract - VA nucleus ventralis anterior - VAmg nucleus ventralis anterior, pars magnocellularis - VAp nucleus ventralis anterior, pars principalis - VI nucleus ventralis intermedius - VLc nucleus ventralis lateralis, pars caudalis - VLm nucleus ventralis lateralis, pars medialis - VLo nucleus ventralis lateralis, pars oralis - VPL nucleus ventralis posterior lateralis - X area X Supported by National Institutes of Health, grant RR00166, Rehabilitation Services Administration, grant 16-P-56818, and PHS grant NS10804     

Physiologic and anatomic investigation of a visual cortical area situated in the ventral bank of the anterior ectosylvian sulcus of the cat

Summary In this paper a cortical area is described that covers approximately the posterior two-thirds of the ventral bank of the anterior ectosylvian sulcus of the cat and is called anterior ectosylvian visual area (AEV).In cats anesthetized with a combination of N₂O and barbiturate we explored this area by recording extracellularly the responses of AEV neurons to visual and electric stimulation as well as by injecting HRP into physiologically verified points. AEV neurons were found to be highly sensitive to small light stimuli moving rapidly in a particular direction through their large receptive fields. The properties of 74 neurons were quantitatively analyzed. Increasing the length of the stimulus within the receptive field to more than 2 deg strongly inhibited the responses, whereas increasing the speed of the stimulus movement up to 72–120 deg/s enhanced the neuronal responsiveness. Although the majority of neurons responded to a wide range of possible directions, one clearly preferred direction could usually be found for each neuron. There was a predominance of preferred directions toward the contralateral hemifield. Anatomic and electrophysiologic connectivity studies showed that AEV receives its main afferent inputs from the lateral suprasylvian visual area (LS) and from the tecto-recipient zone of the nucleus lateralis posterior (LP)-pulvinar complex.Although these studies suggested some topographical organization within the projection from LS to AEV, the large receptive fields in AEV, the great majority of which included the central area, did not reveal a clear retinotopic order. It is concluded that AEV is a specific visual area and that functionally the extrageniculate inputs predominate.Abbreviations AEs anterior ectosylvian sulcus - ALLS anterolateral lateral suprasylvian area - AMLS anteromedial lateral suprasylvian area; - Cl Claustrum - DLS dorsal lateral suprasylvian area - LGNd dorsal nucleus of lateral geniculate body - LGNv ventral nucleus of lateral geniculate body - LM nucleus lateralis medialis - LP1a nucleus lateralis posterior, pars lateralis - LPm nucleus lateralis posterior, pars medialis - Ls lateral sulcus - MGmc magnocellular division of medial geniculate body - MGpc parvocellular division of medial geniculate body - MSs middle suprasylvian sulcus - NP nucleus posterior of Rioch - PLLS postero-lateral lateral suprasylvian area - PLs posterolateral sulcus - PMLS posteromedial lateral suprasylvian area - Pu putamen - Pul pulvinar - Sg suprageniculate nucleus - VLS ventral lateral suprasylvian area Sponsored by Max-Planck-Gesellschaft and IBRODept. of Anatomy, School of Medicine, Iwate Medical University, Morioka 020, JapanSponsored by Alexander von Humboldt-FoundationDept. of Physiology, University Medical School, Szeged, Hungary     

Habenular projections in the monitor lizard (Varanus benegalensis)

Summary The efferent connections of the medial (MHb) and the lateral (LHb) habenular nuclei in the monitor lizard were studied using experimental degeneration techniques. The MHb was found to project to the interpeduncular nucleus and the parvocellular nucleus of the superior raphe via the core portion of the habenulo-peduncular tract (HPT). The LHb fibers form the mantle portion of the HPT and curve laterally to collect again in the ventral tegmentum. From here, they follow either (1) the medial forebrain bundle to terminate in hypothalamus, ventromedial thalamus, preoptic area, and septum, or (2) they continue caudally to terminate in the superior raphe and the paramedian reticular formation, or (3) they decussate and follow in smaller numbers the ascending and descending pathways on the other side. Some fibers enter the midline and reach the periventricular zone of the midbrain. Short range projections exist to the dorsomedial thalamic nucleus and the paramedian central gray and pretectum. The habenular projections are bilateral, however, much smaller on the contralateral side. Although distinct terminal fields were not found in the substahtia nigra and the central gray of the isthmic region, the overall pattern of habenular pathways is strikingly similar to those found in mammals which confirms a long presumed phylogenetic stability of habenular connections.Abbreviations AC anterior commissure - DLA nucleus dorsolateralis anterior thalami - DM nucleus dorsomedialis thalami - EP entopeduncular nucleus - GLd nucleus geniculatus lateralis, pars dorsalis - GLv nucleus geniculatus lateralis, pars ventralis - GPT nucleus geniculatus praetectalis - Hb habenula - HbC habenular commissure - HPT habenulo-peduncular tract - Hy hypothalamus - IP interpeduncular nucleus - LFB lateral forebrain bundle - LHb lateral habenular nucleus - LHy nucleus lateralis hypothalami - MFB medial forebrain bundle - MHb medial habenular nucleus - N neostriatum - NIII oculomotor nucleus - nIII oculomotor nerve - nIV trochlear nerve - Pa paleostriatum - PC posterior commissure - PD nucleus posterodorsalis - PHy nucleus paraventricularis hypothalami - Ra raphe nuclei - Re nucleus reuniens - Rt nucleus rotundus - Ru nucleus ruber - RMS nucleus magnocellularis raphe superior - RPS nucleus parvocellularis raphe superior - SAP stratum album periventriculare - SGP stratum griseum periventriculare - Se septum - SMe stria medullaris - SRF superior reticular formation - TO nucleus opticus tegmenti - VHy nucleus ventralis hypothalami - VL nucleus ventrolateralis thalami - VM nucleus ventromedialis thalami Supported by a postdoctoral fellowship to H. Distel from the Alfred Sloan Foundation and by the Alexander von Humboldt Stiftung     

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     

The distribution of serotonin in the brain of Apteronotus leptorhynchus: an immunohistochemical study

The immunohistochemical distribution of serotonin (5-HT) cells, fiber tracts and terminal fields was mapped in the brain of the gymnotiform electric fish. Two major types of 5-HT cells were found: the small paraventricular organ (PVO) cells of the diencephalon, and the large raphe cells of the brain stem. Six diencephalic nuclei were identified: the nucleus preopticus periventricularis, anterior division, nucleus posterioris periventricularis, nucleus recessus lateralis medial subdivisions 1, 2 and 3, and nucleus recessus posterioris. In the brainstem, raphe centralis, between the arms of the medial longitudinal fasciculus (MLF), the raphe medialis, lateral to MLF, and the diffuse raphe posterioris, were described. Five 5-HT fiber tracts were identified. The tract rising from PVOs projected rostrally through the medial forebrain bundle (MFB). The central tegmental bundle arising from the raphe centralis-medialis complex projected rostrally and also joined the MFB. The lateral tegmental tract, the ventrolateral and the subtrigeminal tracts arose from brain stem raphe groups and innervated the brainstem nuclei. The densest 5-HT innervation occurred in the hypothalamus in the neuropil of the PVOs and in the brainstem in the interpeduncular nucleus, cranial nerve nuclei V motor, V tractus spinalis, VII, X sensory and lateral inferior olive. Electrosensory nuclei including the electrosensory lateral line lobe, the nucleus praeminentialis, dorsal torus semicircularis, optic tectum, nucleus electrosensorius and prepacemaker nucleus received light to medium 5-HT innervation. Serotonergic terminal fields appeared to be conserved across phyla with additional innervation evident in specialized sensory regions such as the electrosensory nuclei of gymnotiform and mormyriform fish.     

Distribution of serotonin- and dopamine-immunoreactivity in the brain of the teleost Clarias gariepinus

The distribution of serotonergic and dopaminergic cell bodies and varicose fibres in the brain of the teleost Clarias gariepinus was studied immunohistochemically using antisera against formaldehyde-conjugated serotonin and dopamine. Many serotonergic and dopaminergic fibres innervated the areas dorsalis telencephali pars medialis and pars lateralis dorsalis, as well as the area ventralis telencephali pars ventralis. In the diencephalon, a large number of serotonergic and some dopaminergic fibres were found in the preoptic nucleus, innervating the cells of this nucleus. In addition, serotonergic and dopaminergic fibres were observed in the pituitary stalk and in all regions of the pituitary gland. Moreover, the diencephalon contained the highest number of serotonin- or dopamine-immunoreactive cell bodies. These cells were confined to the same periventricular nuclei as the nucleus ventromedialis thalami, the nucleus posterior periventricularis, the nucleus lateralis tuberis, the nuclei recessus lateralis and recessus posterioris. Most cells of these nuclei were in contact with the cerebrospinal fluid of the third ventricle. The brainstem contained serotonergic cell bodies in the raphe nuclei and a few serotonergic and dopaminergic fibres. The torus semicircularis was densely innervated by serotonergic fibres and, to a lesser extent, dopaminergic fibres. In the midbrain of Clarias gariepinus, no dopaminergic homologue of the substantia nigra was observed. The results are discussed both in a comparative and a physiological context. In this regard, special attention has been paid to the contribution of hypothalamic monoamines in the regulation of gonadotropin secretion as an essential step in the neuro-endocrine control of reproduction.     

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