摘要:

AbstractThe aim of this investigation was to characterize auditory areas of the primate cerebral cortex on the basis of chemoarchitecture. Cortical areas of the supratemporal plane were delineated inMacaca fuscata(M. fuscata) by immunocytochemical staining for parvalbumin, staining for cytochrome oxidase, examination of cyto‐ and myeloarchitecture, and retrograde tracing of corticocortical connections. Comparative observations were made onMacaca fascicularis(M. fascicularis).Differential staining of fiber plexuses, probably of thalamic origin, identifies a central core zone of dense iznmunostaining and a surrounding zone of moderate‐to‐dense immunostaining composed of anteromedial, lateral, and posteromedial fields. Outside the second zone, there is a third anterolateral zone of weaker immunoreactivity, and, outside that zone, there is a fourth zone in which immunoreactivity is virtually absent. Differences in parvalbumin immunostaining in the auditory fields may reflect differences in relative contributions of thalamic inputs from parvalbumin‐immunoreactive cells in the medial geniculate complex.The central core zone and the surrounding three fields can be correlated with major auditory fields previously defined by multiunit mapping and thalamocortical connectivity. The core zone contains a large principal field and an anterior extension. The pattern of corticocortical connections between thse and adjoining fields suggests that the anteromedial, lateral, and posteromedial fields represent first steps in three streams of connections passing outward from auditory into association cortex.M. fuscatahas an unusually large auditory cortex that is more deeply placed in the lateral sulcus in comparison to that ofM. fascicularis. A small annectant gyrus provides a guide to the position of the primary auditory area. © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903620202

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study investigated differentiation ofMacaca fuscataauditory thalamus into chemically defined nuclei forming relays to auditory cortical areas. The thalamus was stained immunocytochemically for parvalbumin and 28 kDa calbindin in normals and in brains in which retrogradely transported tracers were injected into middle layers of auditory cortical areas or applied to the cortical surface.Parvalbumin‐ and calbindin‐immunoreactive cells show a complementary distribution in ventral, anterodorsal, post and magriocellular medial geniculate nuclei. The ventral nucleus has a high density of parvalbumin cells and few calbindin cells, and the anterodorsal nucleus has a high density of parvalbumin cells and moderate numbers of calbindin cells. Both nuclei have a dense parvalbumin‐immunoreactive neuropil formed by terminations of fibers ascending in the brachium of the inferior colliculus. The posterodorsal nucleus has approxi mately equal proportions of parvalbumin and calbindin cells; neuropil staining is weak but contains terminations of calbindin‐immunoreactive fibers ascending in the midbrain tegmenturn. The magnocellular nucleus contains domains of parvalbumin and calbindin cells.Parvalbumin cells in the ventral nucleus project to a central core of auditory cortex with densest parvalbumin immunoreactivity. Those in anterodorsal and posterodorsal nuclei project to surrounding auditory fields with less dense parvalbumin immunoreactivity; those in the magnocellular nucleus project widely to auditory and other fields.Injections of middle cortical layers label a large majority of parvalbumin cells in the ventral, anterodorsal, or posterodorsal nuclei and in the magnocellular nucleus. Superficial deposits label calbindin cells only, usually in more than one nucleus, implying a widespread projection system. © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903620203

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe object of this study was to identify the terminal distributions of thalamocortical axons arising in chemically characterized subdivisions of the medial geriiculate complex. Large injections of wheat germ agglutinin‐conjugated horseradish peroxidase or small injections ofPhaseolus vulgarisleucoagglutinin were made in the medial geniculate complex ofMacaca fuscata. The terminal distributions of labeled axons in the cortex were correlated with auditory cortical fields demonstrable by different intensities of immunoreactivity for parvalbumin.Fibers from theventral nucleusterminated mainly in layer IV and deep portion of layer III (IIIB), with additional terminations in layers I‐IIIA and in layer VI. In layers IIIB‐IV, a major terminal plexus was formed by a small number of dense patches, 300–500 μm in diameter, surrounded by smaller satellite patches. The patches conformed to a similarly lobulated pattern of parvalbumin fiber immunoreactivity. Terminations of some individually labeled thalamocortical fibers were restricted to a single patch, whereas others innervated more than one patch by collateral branches. Fibers from thedorsal nucleiending in areas of less dense parvalbumin immunoreactivity surrounding the primary auditory cortex formed much larger terminal patches centered largely in layer IIIB. Fibers from themagnocellular nucleushad relatively few terminal branches but innervated extremely wide areas by collaterals of single axons. Two types of axons arose from the magnocellular nucleus, one terminating preferentially in middle cortical layers and the other exclusively in layer I. These may arise respectively from parvalbumin‐ and calbindin‐immunoreactive cell populations in the magrnocellular nucleus. © Wi

ISSN:0092-7317    

DOI:10.1002/cne.903620204

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCollateral sprouting of dentate granule cell axons, the mossy fibers, occurs in response to denervation, kindling, or excitotoxic damage to the hippocampus. Organotypic slice culture of rodent hippocampal tissue is a model system for the controlled study of collateral sprouting in vitro. Organotypic roller‐tube cultures were prepared from hippocampal slices derived from postnatal day 7 mice. The Timm heavy metal stain and densitometry were used to assay the degree of mossy fiber collateral sprouting in the molecular layer of the hippocampal dentate gyrus. Factors influencing mossy fiber collateral sprouting were time in culture, positional origin of the slice culture along the septotemporal axis of the hippocampus, and presence of attached subicular‐entorhinal cortical tissues. Collateral sprouting in the molecular layer was first detected after 6 days in culture and increased steadily thereafter. By 2 weeks considerable sprouting was apparent, and at 3 weeks intense sprouting was observed within the molecular layer. An intrinsic septal‐to‐temporal gradient of collateral sprouting was apparent at 14 days in culture. To determine whether differential damage to the mossy fibers was the basis for the differences in collateral sprouting along the septotemporal axis, we made complete transections of the mossy fiber projection as it exited the dentate hilus at various levels along the septotemporal axis; no differences were found on subsequent collateral sprouting in the dentate molecular layer. Timm‐stained hippocampal cultures with an attached entorhinal cortex, a major source of afferent innervation to the dentate granule cells, displayed significantly less collateral sprouting at 10 days in culture compared to that in cultures from adjacent sections without attached subicular‐entorhinal tissues present. Thus, time in culture, position along the septotemporal axis, and presence of afferent cortical tissues influence aberrant neurite collateral sprouting in organotypic slice cultures of neonatal mouse hippocampus. © Wil

ISSN:0092-7317    

DOI:10.1002/cne.903620205

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn Mongolian gerbils, the content of vasopressin in the cerebral cortex, the striatum, and the hypothalamus is increased after induction of acute cerebral ischemia. We used an iodinated vasopressin analogue and light microscopic autoradiography to study the distribution of vasopressin V1receptors in the brain of adult male gerbils and to evaluate the effects of a transient bilateral cerebral ischemia (6 minutes) on the density of this receptor population. The animals were killed immediately or 10, 30, or 100 hours after transient bilateral occlusion of the common carotid arteries.In control animals, specific [125I]‐VPA binding sites were present in various structures of the brain (olfactory bulb, anterior olfactory nucleus, lateral septum, bed nucleus of the stria terminalis, median preoptic area, ventral pallidum, substantia innominata, amygdala, thalamus, hypothalamic mammillary nuclei, superior colliculus, subiculum, central gray, nucleus of the solitary tract, hypoglossal nucleus). The strongest labeling was detected in the cerebral cortex, layers 5–6. After 30–100 hours of survival time following ischemia there was a marked decrease in [125I]‐VPA binding site density in these cerebral cortex layers. To a lesser degree, a decrease was also detected in the lateral septal nucleus. In contrast, labeling in other noncortical structures remained unchanged. All animals with 100 hours recovery showed a loss of cells in hippocampus (CA1 layer) and striatum. In addition, ischemia induced concomitant and proliferative changes in cortical and hippocampal astrocytes assessed by glial fibrillary acid protein immunoreactivity. These observations indicate a role for vasopressin in the cerebral cortex either on neurons or on glial cells and the modulation of vasopressin receptor expression by transient cerebral isehemia. © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903620206

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractNeurons of area 17, the primary visual cortex, project to various anatomically and physiologically different extrastriate areas and subcortical regions. In the present investigation, we addressed the question of whether the efferent neurons in area 17 can contribute to functional diversity between these regions. We approached this question by analyzing the dendritic morphology of neurons in area 17 projecting to area MT, area 19DM, and the superior colliculus in the new world simian primateCallithrix jacchus, because dendritic morphology is an important factor in determinng physiological properties of nerve cells. Retrograde transport of fluorochromes injected into the target regions, and intracellular injections of Lucifer yellow in the prelabelled neurons, revealed the following. (1) Morphologically identical large pyramidal cells in layer VI of area 17 project to all three targets. Some of them possess axon collaterals to two or all three targets, suggesting that they provide common infcrmation to all three areas. (2) Pyramidal cells in layer IIIc projecting to area MT form a morphologically homogeneous population. (3) Three small to medium‐sized pyramidal cell types in layers IIIa‐c, spiny stellate cells in layer IIIc, and another large pyramidal cell type in layer VI project to area 19DM. (4) Pyramidal cells in the lower two‐thirds of layer V in area 17 project to the superior colliculus. In conclusion, we have shown that inCallithrixone efferent pathway may originate from several cell types. However, with the exception of the large cells in layer VI, efferent cells projecting to area MT, area 19DM, and the superior colliculus were morphologically distinct. This suggests that functional differences between brain regions could arise in part from morphological heterogeneity between and within the efferent cell populations. © Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903620207

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractImmunocytochemistry and in situ hybridization were used to test the hypothesis that gonadotropin‐releasing hormone (GnRH) neurons are formed in the olfactory placode during embryonic development in a salmonid,Oncorhynchus nerka. The development of GnRH neurons and the pituitary cell types was examined from 19 through 910 days after fertilization. Immunoreactive GnRH was first detected at 19 days in the cells of the olfactory placode. GnRH immunoreactivity was not detected in any other structure of the central nervous system at this age. By day 24, GnRH‐immunoreactive neurons were seen in the apical, intermediate, and basal layers of the olfactory placode. From days 30 through 51, GnRH neurons were seen emerging from the epithelium, along the olfactory nerve, and at the rostral olfactory bulb. By day 41, GnRH immunoreactivity was lost in the nasal epithelium. In the 72–day‐old fish, most of the GnRH neuronal population was found in ganglia of the nervus terminalis, at the cribriform bone (gCB), and at the rostral olfactory bulb (gROB).On day 293, a decrease in GnRH‐immunoreactive neurons in the gCB and gROB was concomitant with an initial appearance of GnRH‐immunoreactive neurons and fibers along the caudoventral olfactory bulb. By day 462, the distribution of GnRH neurons and fibers was almost similar to adults. In maturing adults (910 days), GnRH‐immunoreactive neurons were rarely seen in the nasal regions, but were primarily found in the basal forebrain. GnRH fibers were widespread in the brain, proximal pars distalis, and in the pars intermedia of the pituitary.Our study supports the notion that neurons expressing salmon‐GnRH mRNA and peptide originate in the medial olfactory placode and migrate into the basal forebrain during development. The midbrain neurons did not express salmon‐GnRH mRNA or peptide in the larval and juvenile fish.

ISSN:0092-7317    

DOI:10.1002/cne.903620208

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAt least five subtypes of muscarinic acetyicholine receptors are expressed in various mammalian tissue preparations. The following experiment, through the use of direct binding assays (using tritiated quinuclidinyl benzilate), competitive binding assays (using tritiated quinuclidinyl benzilate and unlabeled pirenzepine or AF‐DX 116), and autoradiographic techniques, examined whether two of these five putative muscarinic acetylcholine receptor subtypes can be found in avian brain. Accordingly, autoradiographic mapping of pirenzepine sensitive (M1‐like) and AF‐DX 116‐sensitive (M2‐like) muscarinic acetylcholine receptor subtypes in the pigeon telencephalon was condu Although both ligands bound throughout the brain, most telencephalic regions, including the archistriatum, the neostriatum, and basal ganglia structures like lobus paraolfactorius, nucleus accumbens, and paleostriatum, showed a higher density of M1‐like sites. The exception to this finding was the nucleus basalis which appeared as a region where M2‐like sites predominated. Moreover, the telencephalic region with the largest ratio of M1‐like to M2‐like sites was the lateral portion of the parahippocampus; a characteristic shared with the mammalian dentate gyrus. The findings reported here are generally consistent with previous reports of mammalian M1/M2 receptor distributions.

ISSN:0092-7317    

DOI:10.1002/cne.903620209

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study demonstrates that exposure to an alcohol regimen that resulted in low, uniform blood alcohol concentrations during a period of rapid brain growth can lead to a permanent deficit in the number of Purkinje cells and granule cells in the floccular‐parafloccular region of the cerebellum. Sprague‐Dawley rat pups were artificially reared and were administered alcohol over postnatal days 4 through 9, a period of brain development similar to that of the human third trimester. Two groups received a daily alcohol dose of 4.5 g/kg, administered either as a 10.2% solution in two of the 12 daily feedings (10.2% group) or as a 5.1% solution in four of the 12 feedings (5.1% group). A third group received a daily dose of 6.6 g/kg administered as a 2.5% solution in every feeding (2.5% group). The condensed patterns of alcohol administration resulted in high peak blood alcohol concentrations with near total clearance while the higher daily dose (6.6 g/kg), administered continuously, resulted in low but continuous blood alcohol concentrations. Pups were allowed to grow to adulthood and killed on postnatal day 115. The total number of Purkinje cells and granule cells in the floccular‐parafioccular region of the cerebellum was estimated using unbiased stereological methods. Exposure to alcohol resulted in significant deficits in the number of both Purkinje cells and granule cells at 115 days of age in all three treatment groups. Most importantly a significant deficit of Purkinje cells and granule cells was found following continuous exposure to low blood alcohol concentrations, i.e., in the 2.5% group. The total number of Purkinje cells in the 2.5% group was 2.33 ± 0.31 x 104compared with 3.18 ± 0.30 x 104in the artificially reared controls. The total number of granule cells in the 2.5% group and the controls was 1.24 ± 0.10 x 107and 1.64 ± 0.19 x 107respectively.These results support the hypothesis that exposure to a continuous, low blood alcohol concentration can result in the death of developing neurons and lead to permanent neuronal deficits. The degree of neuronal loss does not correlate with the magnitude of the peaks of blood alcohol concentration © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903620210

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractMost species of insects have two or three ocelli, in addition to a pair of compound eyes. In the cockroach ocellus, a large number of photoreceptors converge upon four second‐order neurons, which exit the ocellus and project into the ocellar tract neuropil of the brain, where they form synapses with at least 15 third‐order neurons. Third‐order neurons project into a variety of neuropils in the brain, including the posterior slope, a premotor center from which descending neurons originate. I examined the morphology and ocellar response of neurons in the posterior slope of the cockroach, using intracellular recording and stainings. Most ocellar neurons of the posterior slope exhibited transient depolarizations at the cessation of ocellar illumination, which seem to reflect sign‐conserving synaptic input from third‐order neurons. Ocellar neurons of the posterior slope project into various areas of the brain, including (1) the central complex, a higher center implicated in higher locomotory control, (2) the pedunculus of the mushroom body, an associative center, (3) the lamina (the first neuropil of the optic lobe), (4) the antennal lobe (olfactory center), (5) the tritocerebrum (mechanosensory center), and (6) the subesophageal and thoracic motor centers. These results suggest that the posterior slope is a high‐order ocellar center from which ocellar signals are transmitted to various target neuropils of the brain, as well as a premotor center to form descending motor commands. © 1995 Wi

ISSN:0092-7317    

DOI:10.1002/cne.903620211

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY