Riboflavin-like inmunoreactive fibers in the monkey brain

Using an antiserum directed against the vitamin riboflavin, we studied the distribution of riboflavin-like immunoreactive structures in the monkey brain. In the mesencephalon, at the level of the mesencephalic-diencephalic junction, single riboflavin-like immunoreactive fibers were observed in its dorsal part, whereas a low density of immunoreactive fibers was found below the surface of the section and close to substantia nigra, and a high density was observed above the substantia nigra and close to the medial geniculate nucleus. In the thalamus, single riboflavin-like immunoreactive fibers were found in the ventral regions of the lateral posterior and the medial geniculate nuclei; a low density in the region located above the medial and lateral geniculate nuclei and a high density in the ventral part of the pulvinar nucleus and in the region extending from this latter to the caudate nucleus. Immunoreactive fibers were not observed in the medulla oblongata, pons, cerebellum, hypothalamus, basal ganglia and cerebral cortex. Moreover, no riboflavin-like immunoreactive cell bodies were observed in the monkey brain. The distribution of riboflavin-like immunoreactive fibers in the monkey suggests that this vitamin could be involved in several physiological mechanisms.     

The cingulate bridge between allocortex,isocortex and thalamus

The Fink-Heimer silver impregnation and the autoradiographic methods were used to study the fiber projections of the cingulate cortex in the squirrel monkey. It was found that this cortex provides inputs to the striatum, thalamus and several areas of isocortex. Evidence was found for a number of fiber projections (1) Fibers from the anterior limbic area were traced to the central part of the head of the caudate nucleus, putamen, septum, dorsomedial nucleus of the thalamus, anterior hypothalamus and lateral basal nucleus of the amygdala. (2) Projections from the cingulate area were traced to the lateral part of the head of the caudate nucleus, putamen, and to the centromedian, anterior, lateral dorsal, and lateral ventral thalamic nuclei and to medial nuclei of the base of the pons. (3) There were projections from the retrosplenial area of the anterior, lateral dorsal, dorsomedial, and posterior thalamic nuclei and lateral nuclei of the pons. These results indicate that most of the cingulate gyrus is an intermediate structure between the thalamus and overlying cortex. The anterior limbic area forms a bridge between the thalamus and other areas of the cingulate gyrus and the frontal cortex. (4) The retrosplenial area and the posterior part of the cingulate area bridge the adjacent visual sensory association cortex and pelvic areas of the sensory motor cortex, respectively. These areas of the cingulate gyrus project directly to the striatum as well as to the thalamus, structurally providing limbic system input to subcortical motor structures.     

The cingulate bridge between allocortex, isocortex and thalamus.

The Fink-Heimer silver impregnation and the autoradiographic methods were used to study the fiber projections of the cingulate cortex in the squirrel monkey. It was found that this cortex provides inputs to the straitum, thalamus and several areas of isocortex. Evidence was found for a number of fiber projections (1) Fibers from the anterior limbic area were traced to the central part of the head of the caudate nucleus, putamen, septum, dorsomedial nucleus of the thalamus, anterior hypothalamus and lateral basal nucleus of the amygdala. (2) Projections from the cingulate area were traced to the lateral part of the head of the caudate nucleus, putamen, and to the centromedian, anterior, lateral dorsal, and lateral ventral thalamic nuclei and to medial nuclei of the base of the pons. (3) There were porjections from the retrosplenial area of the anterior, lateral dorsal, dorsomedial, and posterior thalamic nuclei and lateral nuclei of the pons. These results indicate that most of the cingulate gyrus is an intermediate structure between the thalamus and overlying cortex. The anterior limbic area forms a bridge between the thalamus and other areas of the cingulate gyrus and the frontal cortex. (4) the retrosplenial area and the posterior part of the cingulate area bridge the adjacent visual snesory association cortex and pelvic areas of the snesory motor cortex, respectively. These areas of the cingulate gyrus project directly to the striatum as well as to the thalamus, structurally providing limbic system input to subcortical motor structures.     

大鼠视前内侧区的传入性神经纤维联系,HRP,EB,NY法研究

本文应用轴突逆行运输HRP、EB、NY研究大鼠视前内侧区的传入性神经纤维联系。所用三种示踪剂结果基本一致。结果为:在外侧隔核、外侧嗅束核、杏仁内侧核、下丘脑外侧区、下丘脑腹内侧核和乳头体前腹核内观察到密集的标记细胞。在杏仁皮质核、杏仁中央核、下丘脑室旁核、下丘脑后核、弓状核、乳头体上核、丘脑腹核尾侧部、未定带、腹侧被盖区、脚间核、中缝正中核和背核内观察到较多标记细胞。在中脑中央灰质腹侧部、兰斑核、外侧臂旁核及海马腹下角内观察到少数标记细胞。     

The topographic order of inputs to nucleus accumbens in the rat

Afferents to the nucleus accumbens have been studied with the retrograde transport of unconjugated wheatgerm agglutinin as detected by immunohistochemistry using the peroxidase-antiperoxidase method, in order to define precisely afferent topography from the cortex, thalamus, midbrain and amygdala. Cortical afferent topography was extremely precise. The largest number of cells was found following injections to the anterior accumbens. Anteromedial injections labelled a very large extent of the subiculum and part of the entorhinal cortex. Anterolateral injections produced less subicular and entorhinal label but also labelled the posterior perirhinal cortex. Posteromedial injections labelled only the ventral subiculum and a few cells in the adjacent medial entorhinal cortex. Posterolateral injections labelled few lateral entorhinal neurones but did label a long anteroposterior strip of perirhinal cortex. Prefrontal cortex label was found only after anterior accumbens injections. In the amygdala labelled neurones were found in cortical, central, lateral posterior, anteromedial and basolateral nuclei. Basolateral amygdala projected chiefly to the anteromedial accumbens and central nucleus to anterolateral accumbens. Only a weak amygdala label was found after posterior accumbens injections. In the ventral tegmental area, the midline interfascicular nucleus projected only to medial accumbens. The paranigral ventral tegmentum projected chiefly to the medial accumbens and the parabrachial area chiefly to the lateral accumbens. In the thalamus, heaviest label was found after anterior accumbens injections. Most cells were found in the paraventricular, reuniens and rhomboid nuclei and at posterior thalamic levels lying medial to the fasciculus retroflexus. There was only restricted topography found from thalamic sites. Retrograde label was also found in the ventral pallidum and lateral hypothalamus. Single small injection sites within accumbens received input from the whole anteroposterior extent of the thalamus and ventral tegmentum. The medial accumbens was found to have a close relationship to habenula, globus pallidus and interfascicular nucleus. It appeared that the heaviest volume of inputs projected to anteromedial accumbens, where output from hippocampus (CAI), subiculum, entorhinal and prefrontal cortices converged with output from amygdala, midline thalamus and ventral tegmentum.     

Acetylcholinesterase histochemistry in the macaque thalamus reveals territories selectively connected to frontal, parietal and temporal association cortices

The patterns of histochemical staining for acetylcholinesterase (AChE) activity in the macaque thalamus were analyzed and compared with the distribution of cells and terminals labeled from injections of axonal tracers in the dorsolateral and orbital prefrontal cortex, in area 7a of the posterior parietal cortex and in the polysensory cortex of the superior temporal sulcus. AChE histochemistry is very useful in delineating the thalamic nuclei connected with the association cortex and in uncovering thalamic subdivisions that are barely evident on cytoarchitectonic grounds. Moreover, AChE activity reveals previously unrecognized heterogeneities within several thalamic nuclei, like the ventral anterior (VA), where a new ventromedial subdivision (VAvm) is described, the medial pulvinar (PuIM) or the mediodorsal nucleus (MD). In this nucleus three distinct chemical domains are present: the medial, ventral and lateral sectors characterized by low, moderate and high AChE activities, respectively. The staining pattern of the lateral sector is markedly heterogeneous with patches of intense AChE activity surrounded by a moderately stained matrix. The MD medial sector is connected with the orbitofrontal cortex, whereas the AChE-rich patches in the lateral sector are selectively connected with the dorsolateral prefrontal, parietal and temporal association cortices. In the PulM, a dorsomedial AChE-rich patch is selectively connected with the orbitofrontal cortex, whereas the surrounding territory, which shows moderate AChE activity, is preferentially connected with the parietal and temporal cortices. Chemically specific domains in the anterior, ventral anterior, midline, and intralaminar thalamic nuclei are also connected with the examined association cortices. These findings indicate that the topographic patterns of the thalamo-cortical connections of primate association areas conform to the chemical architecture of the thalamus. This implies that because each cortical area is connected to a particular set of thalamic regions, the influence of the thalamus on cortical function is exclusive for each area, highly diverse among the various association areas, and subject to a wide range of modulation at the thalamic level.     

Mapping Pavlovian conditioning effects on the brain: blocking, contiguity, and excitatory effects

Pavlovian conditioning effects on the brain were investigated by mapping rat brain activity with fluorodeoxyglucose (FDG) autoradiography. The goal was to map the effects of the same tone after blocking or eliciting a conditioned emotional response (CER). In the tone-blocked group, previous learning about a light blocked a CER to the tone. In the tone-excitor group, the same pairings of tone with shock US resulted in a CER to the tone in the absence of previous learning about the light. A third group showed no CER after pseudorandom presentations of these stimuli. Brain systems involved in the various associative effects of Pavlovian conditioning were identified, and their functional significance was interpreted in light of previous FDG studies. Three conditioning effects were mapped: 1) blocking effects: FDG uptake was lower in medial prefrontal cortex and higher in spinal trigeminal and cuneate nuclei in the tone-blocked group relative to the tone-excitor group. 2) Contiguity effects: relative to pseudorandom controls, similar FDG uptake increases in the tone-blocked and -excitor groups were found in auditory regions (inferior colliculus and cortex), hippocampus (CA1), cerebellum, caudate putamen, and solitary nucleus. Contiguity effects may be due to tone-shock pairings common to the tone-blocked and -excitor groups rather than their different CER. And 3) excitatory effects: FDG uptake increases limited to the tone-excitor group occurred in a circuit linked to the CER, including insular and anterior cingulate cortex, vertical diagonal band nucleus, anterior hypothalamus, and caudoventral caudate putamen. This study provided the first large-scale map of brain regions underlying the Kamin blocking effect on conditioning. In particular, the results suggest that suppression of prefrontal activity and activation of unconditioned stimulus pathways are important neural substrates of the Kamin blocking effect.     

The regional distribution of the nerve-stimulating phosphopeptide (nerveside, substance B) in the central nervous system

1. The nerve-stimulating phosphopeptide, nerveside, is present mainly in the cerebrum and brain stem, while the cerebellum contains only a trace amount of it.2. Nerveside is uniformly distributed over all parts of the cerebral cortex.3. The cerebral cortex contains the greatest concentration of nerveside. If the nerveside activity of 1 g cerebral cortex is expressed as 100 then the relative activities of the other parts of the C.N.S. are hippocampus 41, caudate nucleus 21, diencephalon (without hypothalamus) 24, midbrain 19, pons 7, medulla 12 and cerebellum 6.4. The nerveside activity of the hypothalamus is the same as that of the cerebral cortex.5. The pattern of distribution of nerveside in the C.N.S. suggests that it may be part of a corticipetal or corticifugal system.     

Changes of acetylcholinesterase activity in the brain following septal lesions in the rat

Acetylcholinesterase activity in different parts of the limbic system (hippocampus, hypothalamus and amygdala) was decreased following medial septal lesions. On the other hand, this activity in the thalamus, frontal cortex, bulbus olfactorius, nucleus ruber, substantia nigra and basal ganglia was unaffected.These results raise the possibility that there is a functional relationship of the medial septum and those parts of the limbic system that we have studied.     

Noggin在大鼠中枢神经系统发育过程中的表达

目的 研究Noggin基因在大鼠中枢神经系统(CNS)发育过程中的表达。方法 地高辛标记的cRNA探针原位杂交组织化学技术。结果 ISHH结果显示，在胚胎期(E16)大鼠，noggin mRNA阳性细胞主要位于大脑皮质、海马、丘脑与下丘脑的部分核团。新生期(P1-P2)大鼠，noggin在大脑皮质与海马的表达均降低，而在丘脑与延脑的表达增强；生后1周(P1W)noggin在脑内的表达明显降低，生后2周noggin在脑内的表达开始升高，在大脑皮质与海马升高尤为明显。生后1个月，noggin表达继续升高，在额叶皮质、顶叶皮质、扣带皮质、梨状皮质及海马的齿状回可检测到强阳性信号；而在丘脑的侧核、网状核、腹内侧核与腹外侧核可见中等强度的阳性信号。此外，在下丘脑的室旁核和视上核亦可见密集深染的阳性神经元。生后3个月，noggin阳性细胞在脑内的表达开始降低；生后18个月，noggin表达降至最低，仅见散在的阳性神经元。此外，在不同发育期大鼠的脊髓亦未观察到noggin mRNA阳性细胞。结论 提示noggin基因参与大鼠生后CNS的发育。     

Fronto-striatal connections in the human brain: a probabilistic diffusion tractography study

Anatomical studies in animals have described multiple striatal circuits and suggested that sub-components of the striatum, although functionally related, project to distinct cortical areas. To date, anatomical investigations in humans have been limited by methodological constraints such that most of our knowledge of fronto-striatal networks relies on nonhuman primate studies. To better identify the fronto-striatal pathways in the human brain, we used Diffusion Tensor Imaging (DTI) tractography to reconstruct neural connections between the frontal cortex and the caudate nucleus and putamen in vivo. We demonstrate that the human caudate nucleus is interconnected with the prefrontal cortex, inferior and middle temporal gyrus, frontal eye fields, cerebellum and thalamus; the putamen is interconnected with the prefrontal cortex, primary motor area, primary somatosensory cortex, supplementary motor area, premotor area, cerebellum and thalamus. A connectivity-based seed classification analysis identified connections between the dorsolateral prefrontal areas (DLPFC) and the dorsal-posterior caudate nucleus and between the ventrolateral prefrontal areas (VLPFC) and the ventral-anterior caudate nucleus. For the putamen, connections exist between the supplementary motor area (SMA) and dorsal-posterior putamen while the premotor area projects to medial putamen, and the primary motor area to the lateral putamen. Identifying the anatomical organization of the fronto-striatal network has important implications for understanding basal ganglia function and associated disease processes.     

Increase in taurine content before onset of seizures induced by a glutamate decarboxylase inhibitor

Summary The concentration of taurine was measured in 15 brain regions of the rabbit before the onset of convulsions induced by the potent glutamate decarboxylase inhibitor methoxypyridoxine. A significant rise in taurine content was observed in the hippocampus, putamen, caudate nucleus, frontal cortex, thalamus and hypothalamus. GABA levels determined from the same tissue samples were all significantly reduced. An unaffected taurine synthesis coupled with blocked transport to the blood is considered as a possible explanation for this taurine increase.     

Comparison of neuronal inositol 1,4,5-trisphosphate 3-kinase and receptor mRNA distributions in the adult rat brain using in situ hybridization histochemistry.

As a result of its interaction with a specific receptor, inositol 1,4,5-trisphosphate mobilizes intracellular calcium. The metabolism of inositol 1,4,5-trisphosphate is rather complex: inositol 1,4,5-trisphosphate 3-kinase produces inositol 1,3,4,5-tetrakisphosphate, a putative second messenger. In order to elucidate inositol 1,3,4,5-tetrakisphosphate function, a comparative in situ hybridization study of the distributions of inositol 1,4,5-trisphosphate 3-kinase and receptor mRNAs was performed in the adult rat brain using oligonucleotides derived from their cDNA sequences. The neuronal distributions of the mRNA for the receptor were larger than for the kinase. Highest levels of both mRNAs were found in the cerebellar Purkinje cells, where they were enriched in their neuronal perikarya and to a lesser extent in their dendrites. In addition to the cerebellum, mRNAs were mainly detected in the hippocampal pyramidal cells of the CA1 sector of the Ammon's horn and in the granule cells of the dentate gyrus, and also in a majority of the neurons in the cortical layers II-III and V, especially in the frontal cortex and cingulate cortex; caudate-putamen, accumbens, olfactory tubercle and Calleja islets; claustrum; anterior olfactory nucleus; taenia tecta; piriform cortex; dorsolateral septum; bed nucleus stria terminalis; amygdala; hippocampal CA2-4 sectors and subiculum. The inositol 1,4,5-trisphosphate receptor mRNA but not kinase mRNA was found in a majority of the neurons in the thalamus, especially in the parafascicular nucleus; hypothalamus, especially the medial hypothalamus; substantia nigra pars compacta and ventral tegmental area; superior colliculus; lateral interpeduncular nucleus and central gray. Taking into account the limitation in sensitivity of the technique, both mRNAs were not detected in glial cells and in the olfactory bulb; basal nucleus of Meynert, diagonal band nuclei; medial septal nucleus; substantia innominata; globus pallidus; entopeduncular nucleus; substantia nigra pars reticulata; ventral pallidum; subthalamic nucleus; spinal cord and dorsal root ganglia. In conclusion, cerebellum and hippocampus appear to contain almost similar levels of kinase mRNA. This is in contrast to receptor mRNA levels which were at much higher levels in the cerebellum when compared with the hippocampus. For this reason, we have chosen hippocampal CA1 pyramidal cells and dentate gyrus granule cells for studying inositol 1,4,5-trisphosphate 3-kinase function.     

Changes in [14C]deoxyglucose incorporation into rat brain regions during heat-seeking behavior in the cold environment

The central nervous structures involved in behavioral thermoregulatory responses during cold exposure were investigated in conscious rats by means of the 2-deoxy-D-[14C]glucose ([14C]-DG) autoradiographic technique. According to autoradiographs, many brain regions with significant increases or decreases in [14C]-DG incorporation were observed during thermoregulatory behavior. When animals were only exposed to cold, significant increases in [14C]-DG incorporation were observed in the caudate putamen, lateral preoptic area, medial forebrain bundle, ventromedial hypothalamus (VMH), posterior hypothalamus, ventroposteromedial thalamus (VPM), dorsomedial thalamus (MD), substantia nigra (SN) and red nucleus (RN). Lower activities were observed in the hippocampus and the medial habenula. However, when animals performed the behavioral thermoregulation (heat seeking behavior) significant increases were noted in the sulcal prefrontal cortex, sensory-motor cortex, and MD, while decreases were noted in the piriform cortex, VMH, VPM, medial habenula, SN and RN, compared with those in the group without the thermoregulatory behavior.     

Changes in the content of GFAP in the rat brain during pregnancy and the beginning of lactation

Several changes in brain function, including learning and memory, have been reported during pregnancy but the molecular mechanisms involved in these changes are unknown. Due to the fundamental role of glial cells in brain activity, we analyzed the content of glial fibrillary acidic protein (GFAP) in the hippocampus, frontal cortex, preoptic area, hypothalamus and cerebellum of the rat on days 2, 14, 18, and 21 of pregnancy and on day 2 of lactation by Western blot. A differential expression pattern of GFAP was found in the brain during pregnancy and the beginning of lactation. GFAP content was increased in the hippocampus throughout pregnancy, whereas a decrease was observed in cerebellum. GFAP content was increased in the frontal cortex and hypothalamus on days 14 and 18, respectively, with a decrease in the following days of pregnancy in both regions. In preoptic area a decrease in GFAP content was observed on day 14 with an increase on days 18 and 21. In the frontal cortex and cerebellum, GFAP content was increased on day 2 of lactation, while it was maintained as on day 21 of pregnancy in the other regions. Our data suggest a differential expression pattern of GFAP in the rat brain during pregnancy and the beginning of lactation that should be associated with changes in brain function during these reproductive stages.     

Evidence of direct nociceptive projections from the spinal cord to the hypothalamus and telencephalon

Many nociceptive neurons in the spinal cord of rats project directly to the hypothalamus. The axons of these neurons cross into the contralateral spinal cord and ascend through the posterior thalamus before entering the contralateral hypothalamus. The majority of these axons decussate again in the posterior optic chiasm, enter the ipsilateral hypothalamus, turn posteriorly and descend into the ipsilateral thalamus, midbrain, and in some cases, pons and even medulla before terminating. A smaller number of spinal neurons project directly to several telencephalic areas including the amygdala, nucleus accumbens, septal nuclei and the frontal cortex. Each of these direct projections to the hypothalamus and telencephalon may contribute to nociception.     

Afferent connections of dorsal and ventral agranular insular cortex in the hamsterMesocricetus auratus

The agranular insular cortex is transitional in location and structure between the ventrally adjacent olfactory allocortex primutivus and dorsally adjacent sensory-motor isocortex. Its ventral anterior division receives major afferent projections from olfactory areas of the limbic system (posterior primary olfactory cortex, posterolateral cortical amygdaloid nucleus and lateral entorhinal cortex) while its dorsal anterior division does so from non-olfactory limbic areas (lateral and basolateral amygdaloid nuclei).The medial segment of the mediodorsal thalamic nucleus projects to both the ventral and dorsal divisions of the agranular insular cortex, to the former from its anterior portion and to the latter from its posterior portion. Other thalamic inputs to the two divisions arise from the gelatinosus, central medial, rhomboid and parafascicular nuclei. The dorsal division, but not the ventral division, receives input from neurons in the lateral hypothalamus and posterior hypothalamus.The medial frontal cortex projects topographically and bilaterally upon both ventral and dorsal anterior insular cortex, to the former from the ventrally located medial orbital and infralimbic areas, to the latter from the dorsally-located anterior cingulate and medial precentral areas, and to both from the intermediately located prelimbic area. Similarly, the ipsilateral posterior agranular insular cortex and perirhinal cortex project in a topographic manner upon the two divisions of the agranular insular cortex.Commissural input to both divisions originates from pyramidal neurons in the respective contralateral homotopical cortical area. In each case, pyramidal neurons in layer V contribute 90% of this projection and 10% arises from layer III pyramidals.In the brainstem, the dorsal raphe nucleus projects to the ventral and dorsal divisions of the agranular insular cortex and the parabrachial nucleus projects to the dorsal division.Based on their cytoarchitecture, pattern of afferent connections and known functional properties, we consider the ventral and dorsal divisions of the agranular insular cortex to be, respectively, periallocortical and proisocortical portions of the limbic cortex.     

Mu and kappa1 opioid-stimulated [35S]guanylyl-5'-O-(gamma-thio)-triphosphate binding in cynomolgus monkey brain

Agonist-stimulated [35S]GTPgammaS binding allows the visualization of receptor-activated G-proteins, thus revealing the anatomical localization of functional receptor activity. In the present study, agonist-stimulated [35S]GTPgammaS binding was used to demonstrate mu and kappa1 opioid-stimulated [35S]GTPgammaS binding in tissue sections and membranes from cynomolgus monkey brain using DAMGO and U50,488H, respectively. Concentrations of agonists required to produce maximal stimulation of [35S]GTPgammaS binding were determined in membranes from the frontal poles of the brain. Receptor specificity was verified in both membranes and sections by inhibiting agonist-stimulated [35S]GTPgammaS binding with the appropriate antagonist. Mu opioid-stimulated [35S]GTPgammaS binding was high in areas including the amygdala, ventral striatum, caudate, putamen, medial thalamus and hypothalamus. Dense mu-stimulated [35S]GTPgammaS binding was also found in brainstem nuclei including the interpeduncular nucleus, parabrachial nucleus and nucleus of the solitary tract. Kappa1 opioid-stimulated [35S]GTPgammaS binding was high in limbic and association cortex, ventral striatum, caudate, putamen, globus pallidus, claustrum, amygdala, hypothalamus and substantia nigra. These results demonstrate the applicability of [35S]GTPgammaS autoradiography to examine receptor-activated G-proteins in the primate brain and reveal functional mu and kappa1 opioid receptor activity that may contribute to the reported central nervous system effects of opiates.     

The thalamic connections of motor, premotor, and prefrontal areas of cortex in a prosimian primate (Otolemur garnetti)

Connections of motor areas in the frontal cortex of prosimian galagos (Otolemur garnetti) were determined by injecting tracers into sites identified by microstimulation in the primary motor area (M1), dorsal premotor area (PMD), ventral premotor area (PMV), supplementary motor area (SMA), frontal eye field (FEF), and granular frontal cortex. Retrogradely labeled neurons for each injection were related to architectonically defined thalamic nuclei. Nissl, acetylcholinesterase, cytochrome oxidase, myelin, parvalbumin, calbindin, and Cat 301 preparations allowed the ventral anterior and ventral lateral thalamic regions, parvocellular and magnocellular subdivisions of ventral anterior nucleus, and anterior and posterior subdivisions of ventral lateral nucleus of monkeys to be identified. The results indicate that each cortical area receives inputs from several thalamic nuclei, but the proportions differ. M1 receives major inputs from the posterior subdivision of ventral lateral nucleus while premotor areas receive major inputs from anterior parts of ventral lateral nucleus (the anterior subdivision of ventral lateral nucleus and the anterior portion of posterior subdivision of ventral lateral nucleus). PMD and SMA have connections with more dorsal parts of the ventral lateral nucleus than PMV. The results suggest that galagos share many subdivisions of the motor thalamus and thalamocortical connection patterns with simian primates, while having less clearly differentiated subdivisions of the motor thalamus.     

Multiple connections of medial hypothalamic neurons in the rat

Summary The responses of 700 single neurons in the hypothalamus to electrical stimulation of the preoptic area, limbic structures, and midbrain were studied to determine the location of neurons with multiple inputs and to identify by antidromic activation the projection areas of those neurons.Converging excitatory inputs, observed in 134 responsive hypothalamic neurons, were principally derived from the preoptic, limbic, and midbrain areas. Inputs from separate nuclei of the amygdala were noted in the response of individual hypothalamic neurons. Two classes of short latency transsynaptic responses to amygdala stimulation were defined, indicating either separate pathways from the amygdala to the medial hypothalamus or two types of fibers conducting at different velocities. Stimulation of single or multiple sites in the preoptic and limbic areas, as well as in the arcuate nucleus and medial forebrain bundle produced inhibition of hypothalamic neuronal activity.Most antidromically identified medial hypothalamic neurons projected to the preoptic area, median eminence (tuberoinfundibular neurons), or midbrain. Evidence is presented for collateral projections of tuberoinfundibular neurons to the preoptic area and reticular formation. Medial hypothalamic neurons received inputs from the preoptic area, lateral septal nucleus, amygdala, ventral hippocampus (subiculum), and fornix. These findings illustrate a pattern of reciprocal connections between the medial hypothalamus and limbic and midbrain structures.It was concluded that the hypothalamus contains a type of neuron that is equipped to perform complex integrations and to coordinate directly the behavior of neurons in a diversity of anatomical regions.Abbreviations ABL basolateral nucleus of the amygdala - ACO cotical nucleus of the amygdala - AHA anterior area of the hypothalamus - ARH arcuate nucleus of the hypothalamus - DMH dorsomedial nucleus of the hypothalamus - FX fornix - HPC ventral hippocampus (subiculum) - LS lateral septal nucleus - ME median eminence - MH medial hypothalamus - MFB medial forebrain bundle - MP posterior mamillary nucleus - PH posterior nucleus of the hypothalamus - PMD dorsal premamillary nucleus - PMV ventral premamillary nucleus - POA preoptic area - PVG periventricular gray - PVH paraventricular nucleus of the hypothalamus - RF reticular formation of the mesencephalon - RT reticular nucleus of the thalamus - SUM supramamillary nucleus - VMH ventromedial nucleus of the hypothalamus Performed with financial support from the National Institutes of Health (Grants NS 09688 and RR 00165)