Cholinergic projections to the anterior thalamic nuclei in the rat: a combined retrograde tracing and choline acetyl transferase immunohistochemical study

Retrograde transport of horseradish peroxidase (HRP) was combined with choline acetyltransferase (ChAT) immunohistochemistry to study cholinergic projections to the anterior thalamic nuclei in the rat. Small iontophoretic injections of HRP placed into different subdivisions of the anterior thalamic nuclear complex resulted in distinct patterns of retrograde labelling in two major cholinergic cell groups of the mesopontine tegmentum, the laterodorsal tegmental nucleus (LDTg), in which a majority of the labelled cells was located, and the pedunculopontine tegmental nucleus (PPT). After injections into the posterior subdivision of the anteroventral thalamic nucleus (AVp), double-labelled neurons were present predominantly in the ipsilateral LDTg while a smaller number was found in the PPT. In the ipsilateral LDTg, 60–70% of ChAT-positive neurons were HRP-labelled, and 90–95% of the HRP-labelled neurons were ChAT-positive. In the contralateral LDTg, 30–40% of ChAT-positive neurons were HRP-labelled. After injections in the medial subdivision of the anteroventral thalamic nucleus (AVm), the pattern of labelling in LDTg was similar to that detected after injections in the AVp. The number of double-labelled neurons in the LDTg and PPT was much lower after injections into AVm than after injections into AVp. When injections were confined to the anterodorsal thalamic nucleus (AD), no HRP-labelled cells were present in the LDTg or PPT. These results show that the LDTg and PPT are the sources of the cholinergic input to the rat anterior thalamus. The major projection from LDTg and PPT is to the AVp, whereas there is a lighter cholinergic projection to the AVm. The AD does not receive a projection from cholinergic cells in the mesopontine tegmentum.Abbreviations AChE Acetylcholinestrase - AD anterodorsal thalamic · nucleus - AM anteromedial thalamic nucleus - ATN anterior thalamic nuclei - AVm medial subdivision of the anteroventral thalamic nucleus - AVp posterior subdivision of the anteroventral thalamic nucleus - CG central gray - ChAT choline acetyltransferase - DAB diaminobenzidine tetrahydrochloride - DR dorsal raphé nucleus - f fornix - HRP horseradish peroxidase - ic internal capsule - LD laterodorsal thalamic nucleus - LDTg laterodorsal tegmental nucleus - ml medial lemniscus - mlf medial longitudinal fasciculus - mt mamillothalamic tract - NRS normal rabbit serum - PPT pedunculopontine tegmental nucleus - PT paratenial thalamic nucleus - Re reuniens thalamic nucleus - Rh rhomboid thalamic nucleus - RPn raphé pontis nucleus - scp superior cerebellar peduncle - sm stria medullaris thalami - st stria terminalis - TAAB glutaraldehyde - TRN thalamic reticular nucleus - VL ventrolateral thalamic nucleus - VM ventromedial thalamic nucleus - xscp decussation of superior cerebellar peduncle     

GABAergic projections from the thalamic reticular nucleus to the anteroventral and anterodorsal thalamic nuclei of the rat

We have studied GABAergic projections from the thalamic reticular nucleus to the anterior thalamic nuclei of the rat by combining retrograde labelling with horseradish peroxidase and GABA-immunohistochentistry. Small iontophoretic injections of the tracer into subnuclei of the anterior thalamic nuclear complex resulted in retrograde labelling of cells in the rostrodorsal pole of the ipsilateral thalamic reticular nucleus. All of these cells were also GABA-positive. The projections were topographically organized. Neurons located in the most dorsal part of the rostral reticular nucleus projected to the dorsal half of both the posterior subdivision and the medial subdivision of the anteroventral thalamic nucleus, and to the rostral portion of the anterodorsal thalamic nucleus. Immediately ventral to this group of neurons, but still within the dorsal portion of the reticular nucleus, a second group of neurons, extending from the dorsolateral to the dorsomedial edge of the nucleus, projected to the ventral parts of the posterior and medial subdivisions of the anteroventral nucleus. Following injection of tracer into the dorsal part of the rostral anteroventral nucleus, retrograde labelled GABA-containing cell bodies were also found in the ipsilateral anterodorsal nucleus.     

含后叶加压素的视上核神经元及含P物质的中缝背核神经元至下丘脑室旁核投射的研究

用HRP逆行追踪与免疫细胞化学结合的方法,对某些投射至大鼠下丘脑室旁核的神经元的化学性质进行了研究.结果显示在视上核内存在三种标记细胞:HRP单标细胞、后叶加压素免疫反应阳性单标细胞和HRP后叶加压素双标细胞.双标细胞为大、中型椭圆形或圆形细胞,约占HRP标记细胞总数的22%.在中缝背核投射至室旁核的神经元中,部分为P物质免疫反应阳性,双标细胞为中小型梭形细胞,约占HRP标记细胞总数的20%.上述结果提示:视上核有后叶加压素能神经元、中缝背核有P物质能神经元投射到室旁核.     

Direct projections of the hypothalamic nuclei to the thalamic mediodorsal nucleus in the cat

Direct projections of the hypothalamic nuclei to the thalamic mediodorsal nucleus (MD) were studied using retrograde and anterograde transport of horseradish peroxidase (HRP) and wheat germ agglutinin (WGA)-HRP. HRP and WGA-HRP were injected into the MD, thalamic paraventricular, lateral habenular and hypothalamic nuclei. The results indicate that the MD, particularly its medial part, receives a moderate amount of hypothalamic afferents, and that most of these afferents originate in the medial part of the lateral hypothalamic nucleus at anterior levels, while a limited number are derived from the dorsal, dorsomedial, ventromedial and anterior hypothalamic and lateral preoptic nuclei.     

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     

大鼠中缝背核接触脑脊液神经元化学性质的研究

用CB-HRP追踪与免疫细胞化学结合的方法,对大鼠中缝背核接触脑脊液神经元(简称触液神经元)的化学性质进行了研究.将CB-HRP注入第三脑室后,中缝背核内观察到CB-HRP标记细胞,标记细胞分布于中缝背核的背侧部和腹侧部.在CB-HRP与P物质或5-羟色胺免疫细胞化学结合的切片上,中缝背核内出现三种标记细胞:HRP单标细胞,P物质或5-羟色胺免疫反应阳性单标细胞,HRP/SP或HRP/5-HT双标细胞,双标细胞为中、小型梭形或圆形细胞.上述结果提示:中缝背核存在SP能和5-HT能触液神经元.     

Cortical projections of the anterior thalamic nuclei in the cat

Summary Unilateral stereotaxic lesions were made in the anterior thalamic nuclei of the cat, and the ensuing terminal degeneration traced to the medial cortex by the methods of Nauta-Gygax and Fink-Heimer. The anterodorsal nucleus projects to the retrosplenial, postsubicular and presubicular areas. These projections appear to be organized in the dorsoventral direction. The posterior portion of the retrosplenial area receives no fibers from the anterodorsal nucleus. Fibers from this nucleus are distributed largely in layer I and in layer III and the deep portion of layer II of the posterior limbic cortex. The anteroventral nucleus sends fibers to the cingular area and parts of the retrosplenial, postsubicular and presubicular areas. These projections appear to be organized in a topical manner mediolaterally. When the lesion involves the parvocellular part of the nucleus, degeneration spreads to the lower lip, bank and fundus of the splenial sulcus. There appears to be an anteroposterior organization in the cortical projections of the anteroventral nucleus. Fibers from the anteroventral nucleus are distributed most profusely in layers IV and III and in the superficial portion of layer I of the posterior limbic cortex. The anteromedial nucleus sends fine fibers to the anterior limbic region and to the cingular, retrosplenial, postsubicular and presubicular areas. The cortical projections of the anteromedial nucleus appear to be topographically organized in the dorsoventral direction. Fibers from the anteromedial nucleus are distributed largely in cortical layers V and VI of the anterior and posterior limbic regions.Abbreviations used in Figures a anterior - AD anterodorsal nucleus - AM anteromedial nucleus - AMD dorsolateral part of anteromedial nucleus - AMV ventromedial part of anteromedial nucleus - AV anteroventral nucleus - AVM magnocellular part of anteroventral nucleus - AVP parvocellular part of anteroventral nucleus - CC corpus callosum - Cg cingular area - CM medial central nucleus - Il infralimbic area - LA anterior limbic region - LD dorsal lateral nucleus - MD dorsal medial nucleus - Of orbitofrontal region - p posterior - Pr presubicular area - Prag precentral agranular area - Ps postsubicular area - Pt paratenial nucleus - Pv anterior paraventricular nucleus - R reuniens nucleus - Rs retrosplenial area - Rt thalamic reticular nucleus - SC cruciate sulcus - SM stria medullaris - Sm submedial nucleus - SS splenial sulcus - VA ventral anterior nucleus - VL ventral lateral nucleus - VM ventral medial nucleus     

Evidence for collateral projections to the retrosplenial granular cortex and thalamic reticular nucleus from glutamate and/or aspartate-containing neurons of the anterior thalamic nuclei in the rat

 Small, stereotaxically guided injections of true blue (TB) were made into the retrosplenial granular cortex (RSg) and of diamidino yellow (DY) into the dorsal portion of the rostral pole of the thalamic reticular nucleus (TRN) in 16 adult rats to determine whether axons projecting from the anterior thalamic nuclear complex (ATN) to the TRN are branches of axons also projecting to the RSg. Following injections of the fluorescent dyes, serial coronal sections of the brain revealed single retrogradely labelled, and large numbers of double retrogradely labelled neuronal cell bodies in the ipsilateral anteroventral and anterodorsal nuclei and smaller numbers in the anteromedial nucleus of the ATN complex. In a se- cond series of six adult rats with similar double injections of TB and DY, two sections in three were immunoreacted, one with antiserum against glutamate and one with antiserum against aspartate, using indirect immunofluorescence with rhodamine to detect reactive cells. The great majority of both single and double retrogradely labelled cell bodies were also immunoreactive for aspartate or glutamate. In addition, a moderate to small number of non-immunolabelled neurons projecting to the TRN and/or to the RSg were also found in all three nuclei of the ATN complex. These results are compatible with the possibility that large numbers of neurons in the ATN send axonal branches to both the RSg and the TRN, and that many such neurons use glutamate and/or aspartate as transmitters. The findings also suggest that the projections from the ATN might be heterogeneous with respect to transmitter phenotype. Received: 27 June 1996 / Accepted: 5 February 1997     

大鼠中缝背核及中缝正中核内的VIP、GABA样触液神经元

本文将ＣＢ－ＨＲＰ注入侧脑室，用ＣＢ－ＨＲＰ逆行迫踪与免疫细胞化学相结合的方法，对大鼠脑干内的中缝背核及中缝正中核的远位触液神经元进行了定性研究。结果表明：中缝背核内存在ＶＩＰ样、ＧＡＢＡ样免疫反应阳性的触液神经元；中缝正中核内亦存在少量ＶＩＰ样、ＧＡＢＡ样免疫反应阳性触液神经元。它们的形态和数量各异。本文首次报道中缝背核和中缝正中核内远位触液神经元的化学性质，为探索其机能意义提供了形态学依据。     

New central projections of neuropeptide FF: colateral branching pathways in the brainstem and hypothalamus in the rat

Neuropeptide FF (NPFF), a morphine modulatory peptide, has been identified within discrete autonomic regions in the brainstem and hypothalamus. Triple fluorescence labelling was employed to identify collateral branching projections of NPFF neurons located within the nucleus tractus solitarius (NTS) and in the region of the hypothalamus between the dorsomedial and ventromedial hypothalamus. Injections of two retrograde tracers, rhodamine- and fluorescein-labelled latex microspheres into the pontine parabrachial nucleus (PBN) and the ventrolateral medulla resulted in labelling of NPFF neurons in the NTS that contained one (double-labelled) or both (triple-labelled) tracers. Within the NTS, most double- and triple-labelled NPFF neurons were localized at the level of the area postrema or just rostral to it and within the medial and dorsomedial subdivisions of the nucleus. Injections of tracers into the PBN and hypothalamic paraventricular nucleus revealed double- and triple-labelled NPFF neurons, a majority of which were located in a zone between the dorsomedial and ventromedial hypothalamus. These results indicate that NPFF neurons in the brainstem and hypothalamus may simultaneously transmit signals to their target nuclei in the brainstem and forebrain. This coordinated signalling may lead to synchronized responses of NPFF target sites and provide insights into the role of this peptide in cardiovascular and nociceptive responses.     

大鼠中脑导水管周围灰质向三叉神经脊束核尾侧亚核的5-羟色胺能投射

大鼠中脑导水管周围灰质(PAG)向三又神经脊束核尾侧亚核(Sp 5 C)投射的起源细胞在其吻、中、尾三个部分的分布不同,且由尾段向吻段有从腹侧向背侧移行的趋势。尾段的HRP逆标细胞主要位于PAG的腹外侧区、内侧区腹侧部;中段的标记细胞较多,主要见于腹外侧区、背侧区和背外侧区腹侧部,尚可见一些顺行标记的终末;吻段的标记细胞主要位于背外侧区,在上丘深层、Cajal氏中介核、Darkschewitsch氏核内,也可见标记细胞。标记细胞和终末均主要位于注射侧的PAG内。PAG向Sp 5 C投射的5-羟色胺(5-HT)样神经元主要位于PAG的中、尾段的腹外侧区和内侧区腹侧部。中段的双标细胞占全部双标细胞数的57％,尾段占41％,吻段占2％。在背中缝核(DR)内,亦可见到一些双标细胞。PAG内的双标细胞占其HRP标记细胞总数的37％,但仅占5-HT样阳性细胞总数的4.5％。标记细胞主要为中型(20—30μm)梭形及三角形,小型(<20μm)梭形和大型(>30μm)多角形细胞较少见。     

Developmental changes of calretinin immunoreactivity in the anterior thalamic nuclei of the guinea pig

This study describes for the first time the distribution of the calcium-binding protein calretinin (CR) in the anterior thalamic nuclei (ATN) of the guinea pig during development. Brains from animals ranging from 40th embryonic day (E40) to 80th postnatal day (P80) were used in the study. No CR-immunoreactive (CR-ir) perikarya were present among the ATN at E40, but thick bundles of fibers containing CR were crossing the anteromedial nucleus (AM). The first CR-ir neurons appeared at E50 in the lateral part of the AM. At E60, the bundles of fibers disappeared and the whole area of AM displayed closely packed CR-ir perikarya. At this stage, CR also appeared in neurons of the anteroventral nucleus (AV), particularly in its lateral part and along its dorsal border. Moreover, from E50 short and thin bundles of fibers were observed in the medial part of the AV. The ATN of newborns (P0) already showed an adult-like CR distribution pattern – perikarya in the AM and AV were distributed more homogenously and their number was slightly decreased in comparison to E60. The anterodorsal nucleus (AD) was devoid of CR-ir neurons in all studied stages. In conclusion, our results demonstrate that calretinin appears for the first time in neurons of various anterior thalamic nuclei of the guinea pig between 40th and 60th day of prenatal development.     

Observations on the projection from the perihypoglossal nuclei to the cerebellar cortex and nuclei in the cat

Summary The origin and distribution of cerebellar cortical and nuclear afferents from the perihypoglossal nuclei have been studied by means of retrograde transport after implants and injections of the wheat germ agglutinin-horse-radish peroxidase complex in the cat. The projection reaches all the cerebellar nuclei as well as vermal, intermediate and lateral parts of the cerebellar cortex. It is bilateral with an ipsilateral predominance and originates from all the perihypoglossal nuclei. The majority of the projecting neurons are situated caudally in the nucleus prepositus, while smaller numbers of projecting neurons are located in the rostral part of this nucleus, in the rostral nucleus intercalatus and in the nucleus of Roller. Small and medium-sized spindle-shaped to round cells located throughout the nucleus prepositus and in the rostral nucleus intercalatus have widespread projections, reaching all parts of the cerebellar cortex and nuclei, whereas large multipolar cells located in the caudal ventromedial part of the nucleus prepositus and in the nucleus of Roller have projections only to the flocculus and nodulus and the lateral and intermediate cortices.Retrograde fluorescent double-labelling experiments were made to investigate possible axonal branching of the perihypoglosso-cerebellar fibres. In experiments with injections of rhodamine-B-isothiocyanate (RITC) in the left cerebellar hemisphere and implants of crystalline Fluoro-Gold in the right hemisphere, single- and double-labelled cells were found intermingled throughout the perihypoglossal nuclei. Experiments with cerebellar cortical injections of RITC and implants of crystalline Fluoro-Gold in the underlying nucleus, demonstrated single- and double-labelled cells in the nucleus prepositus and the rostral nucleus intercalatus, while only single-labelled RITC neurons were seen in the group of large neurons in the ventromedial part of the nucleus prepositus and the nucleus of Roller. After injections of RITC in the cerebellar cortex and implants of crystalline Fluoro-Gold in the abducent nucleus on the same side, double-labelled neurons were found only in the rostral nucleus prepositus.     

Subcortical projections to the prefrontal cortex in the rat as revealed by the horseradish peroxidase technique

The sources and distribution of subcortical afferents to the anterior neocortex were investigated in the rat using the horseradish peroxidase technique. Injections into the prefrontal cortex labelled, in addition to the mediodorsal thalamic nucleus, neurons in a total of fifteen subcortical nuclei, distributed in the basal telencephalon, claustrum, amygdala, thalamus, subthalamus, hypothalamus, mesencephalon and pons. Of these, the projections from the zona incerta, the lateroposterior thalamic nucleus, and the parabrachial region of the caudal mesencephalon to the prefrontal cortex have not previously been described.Different parts of the mediodorsal thalamic nucleus project to different areas of the frontal cortex. Thus, horseradish peroxidase injections in the most ventral pregenual part of the medial cortex labelled predominantly neurons in the medial anterior and dorsomedial posterior parts of the mediodorsal nucleus; injections into the more dorsal pregenual area labelled only neurons in the lateral and ventral parts of the nucleus; injections placed supragenually labelled neurons in the dorsolateral posterior part of the nucleus; and injections into the dorsal bank of the anterior rhinal sulcus labelled neurons in the centromedial part of the nucleus.Several other subcortical nuclei had projections overlapping with that of the mediodorsal thalamic nucleus. Five different types of such overlap were distinguished: (1) cell groups labelled after horseradish peroxidase injections into one of the subfields of the projection area of the mediodorsal nucleus (defined as the prefrontal cortex), but not outside this area (parataenial nucleus of the thalamus); (2) cell groups labelled both after injection into a subfield of the projection area of the mediodorsal nucleus and after injections in a restricted area outside this area (anteromedial, ventral and laterposterior thalamic nuclei); (3) cell groups labelled after injections into all subfields of the mediodorsal nucleus projection area, but not outside this area (ventral tegmental area, basolateral nucleus of amygdala); (4) cell groups labelled after injections into any area of the anterior neocortex, including the mediodorsal nucleus projection area (parabrachial neurons of the posterior mesencephalon); (5) cell groups labelled after all neocortical injections investigated (claustrum, magnocellular nuclei of the basal forebrain, lateral hypothalamus, zona incerta, intralaminar thalamic nuclei, nuclei raphe dorsalis and centralis superior, and locus coeruleus).We can draw the following conclusions from these and related findings. First, because of the apparent overlap of projections of the mediodorsal, the anteromedial and ventral thalamic nuclei in the rat, parts of the prefrontal cortex can also be called ‘cingulate’ and ‘premotor’. Second, on the basis of projections from parts of the mediodorsal nucleus, the prefrontal cortex of the rat can be subdivided into areas corresponding to those in other species. Third, the neocortex receives afferents from a large number of subcortical cell groups outside the thalamus, distributed from the telencephalon to the pons; however, the prefrontal cortex seems to be the only neocortical area innervated by the ventral tegmental area and amygdala. Finally, neither the prefrontal cortex nor the mediodorsal thalamic nucleus receives afferents from regions directly involved in sensory and motor functions.     

Projections from the raphe nuclei to the suprachiasmatic nucleus of the rat

The presence of serotonergic afferents in the hypothalamic suprachiasmatic nucleus (SCN) is well documented and several functional roles of serotonin (5-HT) in circadian function are well established. However, there is some controversy about the precise location of the serotonergic neurones from where this input arises. Discrete injection of the tracer Cholera toxin, subunit B, (ChB) was centred in the rat SCN, and a few retrograde labelled neurones were distributed in the dorsal and median raphe nuclei (MnR) and in the rostral part of the raphe magnus (RMg), but no neurones were found in the raphe pallidus or raphe obscurus. In addition, a group of neurones was consistently found in the medial part of the pontine supra lemniscal nucleus but not including the serotonergic B₉ region. A combination of retrograde tracing with Fluoro-Gold together with 5-HT-immunolabelling, showed few double-labelled neurones in the dorsal, MnR and B₉. However, the majority of projecting neurones were not co-storing 5-HT immunoreactivity. Phaseolus vulgaris-leucoagglutinin (PHA-L) injections in the dorsal raphe resulted in faint labelling, whereas the MnR gave rise to several labelled fibres in the SCN. Individual delicate PHA-L nerve fibres were found in all compartments of the SCN both in terms of rostrocaudal, ventromedial and dorsomedial extent, without any sign of a topographical organisation of the MnR input to the SCN. PHA-L injections into RMg gave rise to labelling of a few processes within the SCN. In conclusion, the main serotonergic input to the rat SCN originates from a few neurones in the MnR.     

The topographical organization of neurons in the dorsal hypothalamic area that project to the spinal cord or to the nucleus raphé pallidus in the rat

Summary The present study was undertaken using retrograde labeling techniques to clarify whether the neurons in the dorsal hypothalamic area (DHA) that project to the spinal cord are the same as those that project to the nucleus raphé pallidus (NRP). Following an injection of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) in the NRP many labeled small neurons (6–13×9–22 m) with an oval shape were found in the ventromedial part of the DHA. At the level of the dorsomedial hypothalamic nucleus, they formed a distinct and compact cell cluster. Labeled neurons, which were large in size (9–22×11–36 m) with oval and triangular shapes, were found mainly in the dorsolateral part of the DHA after injections of horseradish peroxidase (HRP) in the spinal cord. In a double-labeling experiment, Fast Blue or True Blue, and Nuclear Yellow were injected in the NRP and in the spinal cord, respectively. A large number of blue-fluorescent neurons were located mostly in the ventromedial part of the DHA, while yellow-fluorescent ones were found in the dorsolateral part of the DHA. However, no double-labeled neurons were found in the DHA. These results show that the neurons of the DHA projecting to the NRP are essentially different from those which project to the spinal cord.     

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

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

大鼠眶皮质的间脑和脑干的传入投射

目的：研究间脑和脑干对眶皮质的传入投射。方法：ＨＲＰ逆行示踪法。结果：将ＨＲＰ分别导入１８只大鼠的内侧及腹侧眶区、腹外侧内和外侧区后，在同侧丘脑背内侧核中可见密集的标记细胞，并有一定的局部定位，其次在内丘脑的胶状核、前内侧核、菱形核、腹我侧和腹内侧核中可见大量标记细胞。在同侧下丘脑餐侧区、背侧区、未定带和背内侧核中可见少量标记细胞。在脑干的黑质致密部、腹侧被盖区、中缝背核、导水管周灰质中也可见标记     

Projections of cholinergic and non-cholinergic neurons of the brainstem core to relay and associational thalamic nuclei in the cat and macaque monkey

The projections of brainstem core neurons to relay and associational thalamic nuclei were studied in the cat and macaque monkey by combining the retrograde transport of wheat germ agglutinin conjugated with horseradish peroxidase with choline acetyltransferase immunohistochemistry. All major sensory (medial geniculate, lateral geniculate, ventrobasal), motor (ventroanterior, ventrolateral, ventromedial), associational (mediodorsal, pulvinar, lateral posterior) and limbic (anteromedial, anteroventral) thalamic nuclei of the cat were found to receive projections from cholinergic neurons located in the peribrachial area of the pedunculopontine nucleus and in the laterodorsal tegmental nucleus as well as from non-cholinergic neurons in the rostral (perirubral) part of the central tegmental mesencephalic field. Specific relay nuclei receive less than 10% of their brainstem afferents from non-cholinergic neurons located at rostral midbrain levels and receive 85-96% of their brainstem innervation from a region at midbrain-pontine junction where the cholinergic peribrachial area and laterodorsal tegmental nucleus are maximally developed. Of the total number of horseradish peroxidase-positive brainstem neurons seen after injections in various specific relay nuclei, the double-labeled (horseradish peroxidase + choline acetyltransferase) neurons represent approximately 70-85%. Three to eight times more numerous horseradish peroxidase-labeled brainstem cells were found after injections in associational (mediodorsal and pulvinar-lateral posterior complex) and diffusely cortically-projecting (ventromedial) thalamic nuclei of cat than after injections in specific relay nuclei. The striking retrograde cell labeling observed after injections in nuclei with associative functions and widespread cortical projections was due to massive afferentation from non-cholinergic parts of the midbrain and pontine reticular formation, on both ipsi- and contralateral sides. After wheat germ agglutinin-horseradish peroxidase injections in the associative pulvinar-lateral posterior complex and mediodorsal nucleus of Macaca sylvana, 45-50% of horseradish peroxidase-positive brainstem peribrachial neurons were also choline acetyltransferase-positive. While cells in the medial part of the cholinergic peribrachial area were found to project especially towards the pulvinar-lateral posterior nuclear complex in monkey, the retrograde cell labeling seen after the mediodorsal injection was mostly confined to the lateral part of both dorsal and ventral aspects of the peribrachial area.(ABSTRACT TRUNCATED AT 400 WORDS)     

Topographical arrangement of hypoglossal motoneurons: an HRP study in the cat

Myotopical localization of hypoglossal motoneurons and representation of the main branches of the hypoglossal nerve within the hypoglossal nucleus were examined in the cat by the HRP method. The hypoglossal nucleus is divided cytoarchitectonically into the ventromedial and dorsolateral divisions; the medial and lateral branches of the hypoglossal nerve are represented respectively in the ventromedial and dorsolateral divisions. The genioglossus motoneurons are located in the ventrolateral part of the ventromedial division, and the geniohyoid motoneurons are in the most ventral part of the ventromedial division. The hypoglossus and styloglossus motoneurons are located in the lateral and dorsolateral parts of the dorsolateral division.