Functional and structural modifications in cells of theVA-VL thalamic nuclei under the influence of the neurotoxin MPTP

We analyzed the peculiarities of interaction between the cerebellar and pallidal effects on the same thalamic neuron observed in intact cats and in cats injected with N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), as well as ultrastructural changes, which develop in the motor thalamic neurons affected by this toxin. Responses of 225 neurons of the ventral anterior (VA) and ventral lateral (VL) thalamic nuclei were studied in intact animals, and 218 neurons of these nuclei were recorded in MPTP-treated cats. Nerve cells responding to stimulation of both cerebellar and pallidal inputs constituted 7–8% of all neurons under study; they were mostly localized in the medialVA-VL regions. In the norm, conditioning stimulation of the pallidum was accompanied in 68% of the cases by complete inhibition of neuronal responses to test stimulation of cerebellar fibers (at 1- to 6-msec-long interstimulus intervals). After a 5-day-long course of MPTP injections, conditioning pallidal stimulation-induced inhibition of test responses was observed in a much smaller share of the cases (27%). Such a drop in the efficacy of pallidal inhibitory influences may be related to MPTP-induced structural modifications of the pallido-thalamic synapses. Electron microscopic examination showed that MPTP treatment resulted in the development of ultrastructural manifestations of hydropic dystrophy and clearly expressed depletion of synaptic vesicles in the F1-type synapses distributed on the dendrites of thalamo-corticalVA-VL neurons (these synapses, according to their structural features, were identified as pallido-thalamic contacts). A decrease in the dimension of axon terminals and intensified osmium staining of the synaptoplasm were also observed.     

Morphology of neurons and axon terminals associated with descending and ascending pathways of the lateral forebrain bundle in Rana esculenta

Summary The cells of origin of afferent and efferent pathways of the lateral forebrain bundle were studied with the aid of the cobalt-filling technique. Ascending afferents originated from the lateral thalamic nucleus, central thalamic nucleus, posterior tuberculum and the cerebellar nucleus. They terminated in the anterior entopeduncular nucleus, amygdala and the striatum. Telencephalic projection neurons, which are related to the lateral forebrain bundle, were located mainly in the ventral striatum and the anterior entopeduncular nucleus, but were not so numerous in the dorsal striatum. Irrespective of their location, most of the neurons projecting axons into the lateral forebrain bundle had piriform or pyramidal perikarya. Long apical dendrites usually arborized in a narrow space, whereas widely arborizing secondary dendrites originated from short dendritic trunks. The other neurons that contributed to the lateral forebrain bundle were fusiform or multipolar cells. Striatal efferents terminated in the pretectal area and in the anterodorsal, anteroventral and posteroventral tegmental nuclei.     

Neural mechanisms in disorders of movement

1. Experimental models of ballism, chorea and Parkinson's disease have been developed in the primate, and the underlying neural mechanisms which mediate these disorders of movement have been investigated using the 2-deoxyglucose uptake technique. 2. In ballism, the subthalamic nucleus is either lesioned or underactive. Because of the excitatory nature of subthalamic efferent fibres, this leads to abnormal underactivity of neurons in the medical segment of the globus pallidus which project to the ventral anterior and ventral lateral nuclei of the thalamus, and to the pedunculopontine nucleus of the caudal midbrain. 3. In chorea, there is underactivity of GABAergic striatal (putaminal) neurons which project to the lateral segment of the globus pallidus. This leads to overacting of lateral pallidal neurons and, thus, physiological inhibition of the subthalamic nucleus. Common neural mechanisms, therefore, underlie the appearance of dyskinesia in ballism and chorea. 4. In parkinsonism, there is overactivity of putaminal neurons projecting to the lateral pallidal segment. This results in excessive inhibition of lateral pallidal neurons and, as a consequence, disinhibition of the subthalamic nucleus. Overactivity of the subthalamic nucleus provides excessive drive upon medial pallidal neurons projecting to thalamic and pedunculopontine nuclei.     

The neurons of origin of non-cortical afferent connections to the oculomotor nucleus. A retrograde labeling study in the rabbit.

The cellular origin of the brainstem projections to the oculomotor nucleus in the rabbit has been investigated by using free (HRP) and lectin-conjugated horseradish peroxidase (WGA-HRP). Following injections of these tracers into the somatic oculomotor nucleus (OMC), retrogradely labeled cells have been observed in numerous brainstem structures. In particular, bilateral labeling has been found in the four main subdivisions of the vestibular complex, predominantly in the superior and medial vestibular nuclei and the interstitial nucleus of Cajal, while ipsilateral labeling was found in the rostral interstitial nucleus of the medial longitudinal fascicle (Ri-MLF), the Darkschewitsch and the praepositus nuclei. Neurons labeled only contralaterally have been identified in the following structures: mesencephalic reticular formation dorsolateral to the red nucleus, abducens internuclear neurons, group Y, several areas of the lateral and medial regions of the pontine and medullary reticular formation, ventral region of the lateral cerebellar nucleus and caudal anterior interpositus nucleus. This study provides also information regarding differential projections of some centers to rostral and caudal portions of the OMC. Thus, the rostral one-third appears to receive predominant afferents from the superior and medial vestibular nuclei, while the caudal two-thirds receive afferents from all the four vestibular nuclei. Finally, the group Y sends afferents to the middle and caudal, but not to the rostral OMC.     

Telencephalic sources of the afferents of the main olfactory bulb in the frog Rana temporaria

Following horseradish peroxidase iontophoretic application into the main olfactory bulb (MOB) retrograde neuronal labeling was examined in the telencephalon in the frog. Labeled neurons, the sources of the MOB afferents are found in the mitral cell layer of the contralateral MOB, pallial and some subpallial areas. Very heavy labeling is observed in the pars ventralis of the lateral pallium, and to a lesser extent in the medial pallium, pars dorsalis of the lateral pallium and in the dorsal pallium. In subpallium labeled neurons are found in the eminentia postolfactoria, the rostral part of the medial septal nucleus, and in the nucleus of the ventro-medial telencephalic wall, which is probably homologous to the nucleus of the diagonal band (Broca) of mammals. No labelled neurons were found in the caudal portion of the MOB granular layer, usually referred to as the anterior olfactory nucleus. The arrangement of the MOB centrifugal innervation in amphibians is discussed in comparison with that in mammals.     

Intersubnuclear connections within the rat trigeminal brainstem complex

Prior intracellular recording and labeling experiments have documented local-circuit and projection neurons in the spinal trigeminal (V) nucleus with axons that arborize in more rostral and caudal spinal trigeminal subnuclei and nucleus principalis. Anterograde tracing studies were therefore carried out to assess the origin, extent, distribution, and morphology of such intersubnuclear axons in the rat trigeminal brainstem nuclear complex (TBNC). Phaseolus vulgaris leucoagglutinin (PHA-L) was used as the anterograde marker because of its high sensitivity and the morphological detail provided. Injections restricted to TBNC subnucleus caudalis resulted in dense terminal labeling in each of the more rostral ipsilateral subnuclei. Subnucleus interpolaris projected ipsilaterally and heavily to magnocellular portions of subnucleus caudalis, as well as subnucleus oralis and nucleus principalis. Nucleus principalis, on the other hand, had only a sparse projection to each of the caudal ipsilateral subnuclei. Intersubnuclear axons most frequently traveled in the deep bundles within the TBNC, the V spinal tract, and the reticular formation. They gave rise to a number of circumscribed, highly branched arbors with many boutons of the terminal and en passant types. Retrograde single- or multiple-labeling experiments assessed the cells giving rise to TBNC intersubnuclear collaterals. Horseradish peroxidase (HRP) and/or fluorescent tracer injections into the thalamus, colliculus, cerebellum, nucleus principalis, and/or subnucleus caudalis revealed large numbers of neurons in subnuclei caudalis, interpolaris, and oralis projecting to the region of nucleus principalis. Cells projecting to more caudal spinal trigeminal regions were most numerous in subnuclei interpolaris and oralis. Some cells in lamina V of subnucleus caudalis and in subnuclei interpolaris and oralis projected to thalamus and/or colliculus, as well as other TBNC subnuclei. Such collateral projections were rare in nucleus principalis and more superficial laminae of subnucleus caudalis. TBNC cells labeled by cerebellar injections were not double-labeled by tracer injections into the thalamus, colliculus, or TBNC. These findings lend generality to currently available data obtained with intracellular recording and HRP labeling methods, and suggest that most intersubnuclear axons originate in TBNC local-circuit neurons, though some originate in cells that project to midbrain and/or diencephalon.     

Internuclear connections between the pretectum and the accessory optic system in Salamandra salamandra

Summary Application of horseradish peroxidase into the posterior thalamic and basal optic neuropils of Salamandra salamandra (L.) revealed strong reciprocal connections between the pretectum and the accessory optic system. Pretectal neurons located within the periventricular gray matter project to the basal optic neuropil distributing their terminals over the whole extent of this neuropil. A well developed nucleus of the basal optic neuropil, with its neurons within and medial to this neuropil, projects to the posterior thalamic neuropil. Its terminals appear to be located selectively within the core of the posterior thalamic neuropil which receives no ipsilateral retinal afferents.The pretectum and the accessory optic system are reciprocally connected to a ventral tegmental nucleus, which has not previously been described in urodeles. This nucleus is located immediately dorsal to the oculomotor and trochlear nuclei and extends from the oculomotor root to the middle of the trochlear nucleus.Dendrites of the nucleus of Darkschewitsch reach the posterior thalamic neuropil but mainly enter the rostral tegmental neuropil, while the dendrites of the nucleus of the medial longitudinal fasciculus ramify within the basal optic neuropil and the anterior tegmental neuropil with minor branches in the caudal posterior thalamic neuropil.     

A thalamo-cerebral connection in vocal center of canary

Canary song is controlled by two groups of thalamo-cerebral nuclei. One, the hyperstriatum ventrale pars caudale (HVc) and the robust nucleus of the archistriatum (RA), is a motor driving system for vocalization. The other group, which includes the HVc, the nucleus magnocellularis of neostriatum (MAN), Area X and the nucleus dorsointermedius posterior thalami (DIP), modulates the driving system. The HVc receives synaptic projections from the MAN and sends fibers to Area X. Axons of Area X monosynaptically innervate the thalamic nucleus, the DIP, from which neurons extend axons back to the cerebral nucleus, the MAN. DIP neurons relay incoming impulses by way of Area X to the MAN. Double labeling of DIP neurons with HRP and Fast Blue shows that axonal terminals from Area X connect directly with DIP neurons which send fibers to the MAN. The axon formed a bulge from which multiple branches extended to the postsynaptic cell bodies covering most of the surface. The structure of the DIP synapse may be related to a characteristic pattern of discharge of the DIP neuron, which is transmitted over thalamic projection to cerebral vocal nuclei.     

Intersubnuclear Connections within the Rat Trigeminal Brainstem Complex

Prior intracellular recording and labeling experiments have documented local-circuit and projection neurons in the spinal trigeminal (V) nucleus with axons that arborize in more rostral and caudal spinal trigeminal subnuclei and nucleus principalis. Anterograde tracing studies were therefore carried out to assess the origin, extent, distribution, and morphology of such intersubnuclear axons in the rat trigeminal brainstem nuclear complex (TBNC). Phaseolus vulgaris leucoagglutinin (PHA-L) was used as the anterograde marker because of its high sensitivity and the morphological detail provided. Injections restricted to TBNC subnucleus caudalis resulted in dense terminal labeling in each of the more rostral ipsilateral subnuclei. Subnucleus interpolaris projected ipsilaterally and heavily to magnocellular portions of subnucleus caudalis, as well as subnucleus oralis and nucleus principalis. Nucleus principalis, on the other hand, had only a sparse projection to each of the caudal ipsilateral subnuclei. Intersubnuclear axons most frequently traveled in the deep bundles within the TBNC, the V spinal tract, and the reticular formation. They gave rise to a number of circumscribed, highly branched arbors with many boutons of the terminal and en passant types.

Retrograde single- or multiple-labeling experiments assessed the cells giving rise to TBNC intersubnuclear collaterals. Horseradish peroxidase (HRP) and/or fluorescent tracer injections into the thalamus, colliculus, cerebellum, nucleus principalis, and/or subnucleus caudalis revealed large numbers of neurons in subnuclei caudalis, interpolaris, and oralis projecting to the region of nucleus principalis. Cells projecting to more caudal spinal trigeminal regions were most numerous in subnuclei interpolaris and oralis. Some cells in lamina V of subnucleus caudalis and in subnuclei interpolaris and oralis projected to thalamus and/or colliculus, as well as other TBNC subnuclei. Such collateral projections were rare in nucleus principalis and more superficial laminae of subnucleus caudalis. TBNC cells labeled by cerebellar injections were not double-labeled by tracer injections into the thalamus, colliculus, or TBNC.

These findings lend generality to currently available data obtained with intracellular recording and HRP labeling methods, and suggest that most intersubnuclear axons originate in TBNC local-circuit neurons, though some originate in cells that project to midbrain and/or diencephalon.     

Distribution of reticulospinal neurons in the chicken by retrograde transport of WGA-HRP

To determine the distribution of reticulospinal (RS) neurons in the chicken, WGA-HRP was injected into the cervical or lumbosacral enlargement either unilaterally or bilaterally. The brainstem reticular nuclei sent largely descending fibers to both the spinal enlargements. The mesencephalon (medial and lateral mesencephalic reticular formation) and the rostral pons (nucleus reticularis [n.r.] pontis oralis) project mainly to the cervical enlargement. RS neurons were mainly distributed from the pontomedullary junction to the rostral medulla including n. r. pontis caudalis and pars gigantocellularis, n. r. gigantocellularis, n. r. parvocellularis, n. r. paragigantocellularis, and n. r. subtrigeminalis. It is suggested that the majority of these neurons send axons at least as far as the lumbosacral enlargement. In the lower medulla, RS neurons were distributed in the dorsal and ventral parts of the central nucleus of the medulla.     

Characterization of the Circadian System in a Brazilian Species of Monkey (Callithrix jacchus): Immunohistochemical Analysis and Retinal Projections

The hypothalamic suprachiasmatic nucleus (SCN) and the thalamic pregeniculate nucleus (PGN), which appears to include the intergeniculate leaflet (IGL), comprise circadian related centers in the primate brain. In this study, these centers were analysed in respect to their cytoarchitecture, retinal afferents and chemical of major cells and axon terminals with tract tracers and immunohistochemical techniques to define cytoarchitecture and connections, in the common marmoset. The SCN was shown to be a triangularly shaped cluster of compact cells just dorsal to the optic chiasm and lateral to the third ventricle. It is innervated in its ventral portion by terminals from the retina, and NPY-ergic fibers. Serotonergic and SP-staining processes are distributed throughout. VIP-neurons form a dorsolateral group of cells and CB-immunoreactive neurons fill much of the nucleus. The PGN was shown to be a wedge-shaped cluster of cells located dorsomedially to the dorsal lateral geniculate nucleus. It appears to comprise a ventral portion which receives a bilateral retinal projection and contains NPY-neurons, suggesting that this portion may correspond to IGL. The PGN also contains CB-neurons, PV-neurons and fibers, and SP- and 5-HT-fibers. These results in marmoset show that, beside a common plan revealed for most mammals, there are significant interspecific variations in the circadian timing system. Future studies are needed in order to elucidate the circadian organization in this primate species.     

Characterization of the Circadian System in a Brazilian Species of Monkey (Callithrix jacchus): Immunohistochemical Analysis and Retinal Projections

The hypothalamic suprachiasmatic nucleus (SCN) and the thalamic pregeniculate nucleus (PGN), which appears to include the intergeniculate leaflet (IGL), comprise circadian related centers in the primate brain. In this study, these centers were analysed in respect to their cytoarchitecture, retinal afferents and chemical of major cells and axon terminals with tract tracers and immunohistochemical techniques to define cytoarchitecture and connections, in the common marmoset. The SCN was shown to be a triangularly shaped cluster of compact cells just dorsal to the optic chiasm and lateral to the third ventricle. It is innervated in its ventral portion by terminals from the retina, and NPY-ergic fibers. Serotonergic and SP-staining processes are distributed throughout. VIP-neurons form a dorsolateral group of cells and CB-immunoreactive neurons fill much of the nucleus. The PGN was shown to be a wedge-shaped cluster of cells located dorsomedially to the dorsal lateral geniculate nucleus. It appears to comprise a ventral portion which receives a bilateral retinal projection and contains NPY-neurons, suggesting that this portion may correspond to IGL. The PGN also contains CB-neurons, PV-neurons and fibers, and SP- and 5-HT-fibers. These results in marmoset show that, beside a common plan revealed for most mammals, there are significant interspecific variations in the circadian timing system. Future studies are needed in order to elucidate the circadian organization in this primate species.     

The thalamus in the motor system.

The ventrolateral (VL) and anterior (VA) are the main thalamic relay for cerebellar and pallidal efferents going to the motor cortex. Four aspects of the function of these nuclei are briefly considered. (1) It is well known that these thalamic structures are not a simple relay on the way to the motor cortex, but that they have a gating function for the cerebellar afferents. The gating mechanism is active during slow-wave sleep, with deafferentation and with the use of various anesthetics. Possibly, it might play a role in the central organization of movement. (2) The organization at the unitary level of the projections between VL and motor cortex is examined and their role in the command of motor synergies through the motor cortex is strongly suggested. (3). It appears that unitary activity of VL neurons is not only related to movement but also to postural changes associated with movement. (4) The sensory input to VL nucleus is briefly analyzed. The inefficacy of exteroceptive stimulation in awake animals, in contrast with the effect of the same stimulation in anesthetized preparations, is discussed.     

Branching-pattern analysis of the dendritic arborization in the thalamic nuclei of the rat brain

We investigated the dendritic patterns of rapid Golgi-impregnated, highly similar multipolar neurons from two functionally different thalamic regions of the rat brain: two dorsal nuclei (the nucleus laterodorsalis thalami, pars dorsomedialis and the nucleus laterodorsalis thalami, pars ventrolateralis), and two ventral nuclei (the nucleus ventrolateralis thalami and the nucleus ventromedialis thalami). The analysis involved conventional morphometric parameters (height and size) and a new parameter derived from graph theory, the relative imbalance (RI), derived from the branching patterns of the dendrites, which permits quantitative characterization of the dendritic arborization of a neuron. On this basis, neurons can be grouped into three fundamentally different types: type A, or highly-polarized (imbalanced) neurons (RI values close to 1); type B, or medium-polarized neurons (RI values around 0.5); and type C, or balanced neurons with low polarization (RI values close to 0). The orientations of the dendritic arbor, and thus the receptive fields, of the dorsal and ventral thalamic neurons, were mutually perpendicular. The H and S values indicated that the neurons in the dorsal and ventral thalamic nuclei differed significantly. However, their RI values demonstrated that they were similar neurons of type B. Our data reveal that 1 ) the dendritic arbor cannot be reliably characterized purely on the basis of height and size, and 2) RI is a valuable morphometric parameter that identifies the true nature of the dendritic arborization.     

Distribution of trigeminothalamic and spinothalamic lamina I terminations in the cat

The distribution in the thalamus of terminal projections from lamina I neurons of the trigeminal, cervical, and lumbosacral dorsal horn was investigated with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) in the cat. Iontophoretic injections were guided by single- and multi-unit physiological recordings. The injections in particular cases were essentially restricted to lamina I, whereas in others they spread across laminae I-III or laminae I-V. The trigemino- and spinothalamic (TSTT) terminations were identified immunohistochemically. In all cases, regardless of the level of the injections, terminal fibers were consistently distributed in three main locations: the submedial nucleus; the ventral aspect of the basal ventral medial nucleus and ventral posterior nuclei; and, the dorsomedial aspect of the ventral posterior medial nucleus. The terminal fields in the submedial nucleus and the ventral aspect of the ventral posterior group were topographically organized. Terminations along the ventral aspect of the ventral posterior group extended posterolaterally into the caudal part of the posterior nucleus and anteromedially into the ventromedial part of the ventral lateral nucleus. In several cases with trigeminal lamina I injections, a terminal labeling patch was observed within the core of the ventral posterior medial nucleus. In cases with spinal lamina I injections, terminations were also consistently found in the lateral habenula, the parafascicular nucleus, and the nucleus reuniens. Isolated terminal fibers were occasionally seen in the zona incerta, the dorsomedial hypothalamus, and other locations. These anatomical observations extend prior studies of TSTT projections and identify lamina I projection targets that are important for nociceptive, thermoreceptive, and homeostatic processing in the cat. The findings are consistent with evidence from physiological (single-unit and antidromic mapping) and behavioral studies. The novel identification of spinal lamina I input to the lateral habenula could be significant for homeostatic behaviors.     

Distribution of trigeminothalamic and spinothalamic lamina I terminations in the cat

The distribution in the thalamus of terminal projections from lamina I neurons of the trigeminal, cervical, and lumbosacral dorsal horn was investigated with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) in the cat. Iontophoretic injections were guided by single- and multi-unit physiological recordings. The injections in particular cases were essentially restricted to lamina I, whereas in others they spread across laminae I–III or laminae I–V. The trigemino- and spinothalamic (TSTT) terminations were identified immunohistochemically. In all cases, regardless of the level of the injections, terminal fibers were consistently distributed in three main locations: the submedial nucleus; the ventral aspect of the basal ventral medial nucleus and ventral posterior nuclei; and, the dorsomedial aspect of the ventral posterior medial nucleus. The terminal fields in the submedial nucleus and the ventral aspect of the ventral posterior group were topographically organized. Terminations along the ventral aspect of the ventral posterior group extended posterolaterally into the caudal part of the posterior nucleus and anteromedially into the ventromedial part of the ventral lateral nucleus. In several cases with trigeminal lamina I injections, a terminal labeling patch was observed within the core of the ventral posterior medial nucleus. In cases with spinal lamina I injections, terminations were also consistently found in the lateral habenula, the parafascicular nucleus, and the nucleus reuniens. Isolated terminal fibers were occasionally seen in the zona incerta, the dorsomedial hypothalamus, and other locations. These anatomical observations extend prior studies of TSTT projections and identify lamina I projection targets that are important for nociceptive, thermoreceptive, and homeostatic processing in the cat. The findings are consistent with evidence from physiological (single-unit and antidromic mapping) and behavioral studies. The novel identification of spinal lamina I input to the lateral habenula could be significant for homeostatic behaviors.     

Tectal and Related Target Areas of Spinal and Dorsal Column Nuclear Projections in Hedgehog Tenrecs

The terminal distributions of spinal and dorsal column nuclear projections to tectum, pretectum, and central gray of hedgehog tenrecs (Echinops telfairi and Setifer setosus) were investigated using anterograde axonal flow and various tracer substances. In the inferior colliculus, the densest and most extensive mesencephalic projections were found within the pericentral regions. One target area, referred to as the external portion of the inferior colliculus, was represented as a semicircle of grain patches lateral and caudal to the central nucleus. This region received somesthetic afferents from the dorsal column nuclei and from spinal segments at various levels. In contrast, after high cervical injections, the pericentral portion dorsomedial to the rostral half of the central nucleus was labeled almost exclusively. This area of labeling was distinct from the labeling in the central gray and might be best compared with the intercollicular zone in other species. The superior colliculus received projections predominantly from the high cervical cord; minor projections also arose from lumbar spinal segments and the dorsal column nuclei. The terminal field covered roughly the caudal half of the colliculus and involved the stratum griseum intermediale in a patch-like fashion. Some labeling was also found in the stratum griseum profundum and in the stratum griseum superficiale. Other than in the colliculi, weak pretectal projections were observed following dorsal column nuclear injections, while the nucleus of Darkschewitsch was labeled best following lumbosacral injections. All mesencephalic target areas were labeled consistently on the contralateral side, while their ipsilateral side was involved to a varying degree: The relatively most prominent ipsilateral labeling was seen in the central gray, being roughly similar on both sides; scarcely any labeling was noted in the ipsilateral superior colliculus. Tectal injections of retrograde tracer, in addition, revealed a considerable number of labeled neurons in a relatively cell-poor region immediately ventral to the high cervial dorsal horn. This region might correspond to the lateral cervical nucleus, an aggregation of neurons that so far has only been demonstrated in higher mammals.     

Pattern of afferents to the lateral septum in the guinea pig

Summary The septal region represents an important telencephalic center integrating neuronal activity of cortical areas with autonomous processes. To support the functional analysis of this brain area in the guinea pig, the afferent connections to the lateral septal nucleus were investigated by the use of iontophoretically applied horseradish peroxidase (HRP). Retrogradely labeled perikarya were located in telencephalic, diencephalic, mesencephalic and metencephalic sites. The subnuclei of the lateral septum (pars dorsalis, intermedia, ventralis, posterior) receive afferents from the (i) medial septal nucleus, diagonal band of Broca (pars horizontalis and pars ventralis), and the principal nucleus of the stria terminalis, the hippocampus, and amygdala (nucleus medialis); (ii) the medial habenular nucleus, and the para- (peri-) ventricular, parataenial and reuniens nuclei of the thalamus; the anterior, lateral and posterior hypothalamic areas in particular, the medial and lateral preoptic, suprachiasmatic, periventricular, paraventricular, arcuate, premammillary, and supramammillary nuclei; (iii) the periaquaeductal grey, ventral tegmental area, nucleus interfascicularis, nucleus reticularis linearis, central linear nucleus, interpeduncular nucleus; (iv) dorsal and medial raphe complex, and locus coeruleus. Each subnucleus of the lateral septum displays an individual, differing pattern of afferents from the above-described regions. Based on a double-labeling method, the vasopressinergic and serotonergic afferents to the lateral septum were found to originate in the nucleus paraventricularis hypothalami and the raphe nuclei, respectively.Abbreviations ARC arcuate nucleus - BNST bed nucleus of the stria terminalis - CL central linear nucleus - DBBh diagonal band of Broca (pars horizontalis) - DBBv diagonal band of Broca (pars ventralis) - DR dorsal raphe nucleus - HC hippocampus - IF interfascicular nucleus - IP interpeduncular nucleus - LC locus coeruleus - LDT laterodorsal tegmental nucleus - LHA lateral hypothalamic area - LPO lateral preoptic area - LSN lateral septal nucleus - MA medial amygdaloid nucleus - MH medial habenular nucleus - MPO medial preoptic region - MR medial raphe nucleus - MSN medial septal nucleus - PAG periaquaeductal grey - PEN periventricular nucleus - PHA posterior hypothalamic area - PMd premammillary region (pars dorsalis) - PMv premammillary region (pars ventralis) - PT parataenial nucleus - PVN paraventricular hypothalamic nucleus - PVT paraventricular thalamic nucleus - RE nucl. reuniens - RL nucl. reticularis linearis - SCN suprachiasmatic nucleus - SMl supramammillary region (pars lateralis) - SMm supramammillary region (pars medialis) - SUB subiculum - TS triangular septal nucleus - VTA ventral tegmental area - ac anterior commissure - bc brachium conjunctivum - bp brachium pontis - cc corpus callosum - fr fasciculus retroflexus - fx fornix - ml medial lemniscus - mlf fasciculus longitudinalis medialis - mp mammillary peduncle - mt mammillary tract - oc optic chiasm - on optic nerve - pc posterior commissure - pt pyramidal tract - sm stria medullaris - st stria terminalis - vhc ventral hippocampal commissure Supported by the Deutsche Forschungsgemeinschaft (Nu 36/2-1)     

Reorganization of the vestibular-thalamic projections following injury of the cerebellar interpositus and deiters vestibuar nuclei

Plastic reorganization of the vestibular-thalamic system was studied in adult cats. It was shown, that preliminary (3 months before) injury of the cerebellar contralateral nucleus interpositus or lateral vestibular nucleus of Deiters leads to reorganization of vestibular-thalamic projections. Ipsilateral projections to the ventrolateral nucleus of thalamus arised from vestibular nuclear complex since the pattern of normal representations to mentioned thalamic nucleus were changed. The peculiarities of distribution and morphological structure of vestibular neurons forming new projections to the ventrolateral thalamic nucleus were studied as well.     

Opiocortin and catecholamine projections to raphe nuclei

Afferent projections to the nucleus raphe magnus (NRM) and dorsal raphe nucleus (DRN) were identified using retrograde transport of horseradish peroxidase conjugated wheat germ agglutinin (HRP-WGA). Neurons were labeled in important nociceptive regions including periaqueductal gray (PAG), arcuate nucleus, lateral hypothalamus and medial thalamic nuclei following both injections. We have immunocytochemically identified opiocortin/WGA neurons in the arcuate nucleus following NRM and DRN injections. Dual stained catecholamine/WGA perikarya were found in zona incerta, locus coeruleus, substantia nigra, nucleus tractus solitarius and adjacent A2, C2 and C3, lateral paragigantocellular reticular nucleus/C1 and lateral reticular nucleus/A1 following DRN injections and in zona incerta, substantia nigra, nucleus tractus solitarius/A2 and lateral reticular nucleus/A1 after NRM injections. These results provide further evidence for opiocortin and catecholamine modulation of analgesia.