摘要:

AbstractThe calcium‐binding protein, parvalbumin, was localized immunohistochemically in the human amygdaloid complex. Neuronal cell bodies and fibers that are immunoreactive to parvalbumin were observed in most of the amygdaloid nuclei and cortical areas. Three types of immunoreactive aspiny neurons, ranging from small spherical cells (type 1) to large multipolar cells (type 2) and fusiform cells (type 3), were observed. The densities of the types of neurons that were parvalbumin‐immunoreactive varied in the different regions of the amygdala. The highest densities of parvalbumin‐immunoreactive neurons were observed in the lateral nucleus, in the magnocellular and intermediate divisions of the basal nucleus, in the magnocellular division of the accessory basal nucleus and in the amygdalohippocampal area. The regions containing the lowest density of parvalbumin‐immunoreactive cells were the paralaminar nucleus, the parvicellular division of the basal nucleus, the central nucleus, the medial nucleus and the anterior cortical nucleus. In general, the distribution of immunoreactive fibers and terminals paralleled that of immunoreactive cells. Parvalbumin‐immunoreactive varicose fibers formed basket‐like plexi and cartridges around the unstained neurons, which suggests that parvalbumin is located in GABAergic basket cells and chandelier cells, respectively. The distribution of parvalbumin‐immunoreactive profiles in the human amygdaloid complex was similar to, rather than different from that previously reported in the monkey amygdala (Pitkänen and Amaral [1993] J. Comp. Neurol.331:14–36). This study provides baseline information about the organization of GABAergic inhibitory circuitries in the human amygdaloid complex. © 199

ISSN:0092-7317    

DOI:10.1002/cne.903600202

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe organization of axonal projections from the four recognized parts of the medial amygdalar nucleus (MEA) were characterized with thePhaesolus vulgarisleucoagglutinin (PHAL) method in male rats. The results indicate that the MEA consists of two major divisions, ventral and dorsal, and that the former may also consist of rostral and caudal regions. As a whole, the MEA generates centrifugal projections to several parts of the accessory and main olfactory sensory pathways, and projections to (a) several parts of the intrahippocampal circuit (ventrally); (b) the ventral striatum, ventral pallidum, and bed nuclei of the stria terminalis (BST) in the basal telencephaon; (c) many parts of the hypothalamus; (d) midline and medial parts of the thalamus; and (e) the periaqueductal gray, ventral tegmental area, and midbrain raphé. The dorsal division of the MEA (the posterodorsal part) is characterized by projections to the principal nucleus of the BST, and to the anteroventral periventricular, medial, and central parts of the medial preoptic, and ventral premammillary hypothalamic nuclei. These hypothalamic nuclei project heavily to neuroendocrine and autonomic‐related parts of the hypothalamic periventricular zone. The ventral division of the MEA (the anterodorsal, anteroventral, and posteroventral parts) is characterized by dense projections to the transverse and interfascicular nuclei of the BST, and to the lateral part of the medial preoptic, anterior hypothalamic, and ventromedial hypothalamic nuclei. However, dorsal regions of the ventral division provide rather dense inputs to the medial preoptic region and capsule of the ventromedial nucleus, whereas ventral regions of the ventral division preferentially innervate the anterior hypotha lamic, dorsomeclial, and ventral parts of the ventromedial nuclei. Functional evidence suggests that circuits associated with dorsal regions of the ventral division may deal with reproductive behavior, whereas circuits associated with ventral regions of the ventral division may deal preferentially with agonistic behavior. © 1995 Wiley‐Liss

ISSN:0092-7317    

DOI:10.1002/cne.903600203

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractStimulation of gastric vagal afferents by systemic administration of cholecystokinin octapeptide (CCK) inhibits gastric motility, reduces food intake, and stimulates pituitary secretion of oxytocin and adrenocorticotropic hormone in rats. To characterize further the central neurol circuits responsible for these effects, the present study used triple‐labeling immunocytochemical methods to determine whether or not exogenous CCK activates cFos expression in catecholaminergic neurons in the caudal medulla that project to the paraventricular nucleus of the hypothalamus (PVN). To identify these neurons, the retrograde tracer fluorogold (FG) was iontophoresed into the PVN of anesthetized rats under stereotaxic guidance. After 2 weeks, rats were injected with CCK (100 μg/kg, i. p.) and then anesthetized and killed 1 hour later by perfusion fixation. Medullary sections were processed for triple immunocytochemical localization of cFos, retrogradely transported FG, and tyrosine hydroxylase (TH). In rats with FG injections centered in the PVN (n = 10), approximately 70% of the FG‐labeled neurons in the caudal nucleus of the solitary tract (NST) and ventrolateral medulla (VLM) expressed cFos. Of these activated PVN‐projecting neurons, approximately 78% in the NST and 89% in the VLM were catecholaminergic (TH positive). These results indicate that PVN‐projecting catecholaminergic neurons within the caudal medulla are activated by periph eral administration of CCK, further implicating these ascending catecholaminergic path ways in the neuroendocrine, physiological, and behavioral effects produced by gastric vagal stimulation. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903600204

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe tree shrew is one of the few mammalian species whose retinae are strongly cone dominated, which is usually the case in reptilian and avian retinae. Müller cells of the tree shrew (Tupaia belangeri) retina were studied by transmission electron microscopy of tissue sections and freeze‐fracture replicas, by immunolabeling of the intermediate filament protein vimentin in radial paraffin sections and in whole retinae, as well as by intracellular dye injection in slices of retinae. In addition, enzymatically isolated cells were stained by Pappenheim's panoptic staining method. The cells showed an ultrastructure that is similar to other mammalian Müller cells with two exceptions: Due to the extensive lateral fins of cone inner segments, the apical microvilli of Müller cells are arranged in peculiar palisades, and the basket‐like Müller cell sheaths around neuronal somata in both nuclear layers consist of unusual multilayered membrane lamellae. Unlike Müller cells in other mammalian species studied thus far, but similar to reptilian and avian Müller cells, those of tree shrews commonly have two or more vitread processes rather than one main trunk. Müller cell densities range between some 13,000 mm−2in the periphery and about 20,000 mm−2in the retinal center. Neuron:(Müller) glial cell ratios were estimated to be 7.9:1 in the center and 6.2:1 in the periphery. For each Müller cell, about 1.5 (cone) photoreceptor cells, four or five interneurons of the inner nuclear layer, and about one cell of the ganglion cell layer were counted. This is a much lower number of neurons per Müller cell than in most other mammals studied. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903600205

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe efferent projections of the nucleus of the optic tract (NOT) and dorsal terminal nucleus of the accessory optic system (DTN) to the contralateral NOT‐DTN, ipsilateral inferior olive (IO), ipsilateral nucleus prepositus hypoglossi (NPH), and ipsilateral dorsal lateral geniculate. nucleus (LGNd) were examined in pigmented rats and in cats by using anterograde and retrograde tract tracing, as well as extracellular recording and electrical stimulation.Anterograde tracing in the rat revealed a dense termination field of NOT‐DTN efferents throughout the homologous contralateral territory.In both species three different cell populations, projecting to the contralateral NOT‐DTN, ipsilateral IO, and ipsilateral LGNd, respectively, were distinguished by means of multiple retrograde tracing. No clear topographical segregation of the different NOT‐DTN relay cell populations was observed. On the other hand, a large proportion (at least 60%) of NOT‐DTN neurons projecting to the ipsilateral NPH were found to bifurcate upon the IO in the rat.Electrophysiologically, NOT‐DTN neurons projecting to the IO were identified by their directionally selective responses. Such neurons were never activated by electrical stimulation of either the contralateral NOT‐DTN or the ipsilateral LGNd. Neurons antidromically activated from the contralateral NOT‐DTN could not be activated from the ipsilateral LGNd.Thus, in both cat and rat the NOT‐DTN includes at least three independent relay cell populations. As a consequence, the NOT‐DTN must serve functions additional to the generation of eye movements during optokinetic nystagnus, a function subserved by the directionally selective NOT‐DTN cells.

ISSN:0092-7317    

DOI:10.1002/cne.903600206

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe distribution of neurons expressing Fos within the periaqueductal gray (FAG) following pharmacologically induced high or low blood pressure was examined to determine (1) if PAG neurons are responsive to changes in arterial pressure (AP) and (2) the relationship of these cells to the functionally defined hypertensive and hypotensive columns in PAG. Changes in AP differentially induced robust Fos expression in neurons confined to discrete, longitudinally organized columns within PAG. Increased AP produced extensive Fos‐like immunoreactivity within the lateral PAG, beginning at the level of the oculomotor nucleus. At the level of the dorsal raphe, Fos expression induced by increased AP shifted dorsally, into the dorsolateral division of PAG; this pattern of Fos labeling was maintained throughout the caudal one‐third of PAG. Double‐labeling for Fos and nicotinamide adenine dinucleotide phosphate diaphorase confirmed that Fos‐positive cells induced by increased AP were located in the dorsolateral division of PAG at these caudal levels. Fos positive cells were codistributed, but not colocalized, with nicotinamide adenine dinucleotide phosphate diaphorase‐positive cells. Decreased AP evoked a completely different pattern of Fos expression. Fos‐positive cells were predominantly located within the ventrolateral PAG region, extending from the level of the trochlear nucleus through the level of the caudal dorsal raphe. Double‐labeling studies for Fos and serotonin indicated that only 1–2 double‐labeled cells per section were present. Saline infusion resulted in very few Foslike immunoreactive cells, indicating that volume receptor activation does not account for Fos expression in PAG evoked by changes in AP. These results indicate that (1) substantial numbers of PAG neurons are excited by pharmacologically induced changes in AP and (2) excitatory barosensitive PAG neurons are anatomically segregated based on their responsiveness to a specific directional change in AP. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903600207

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study employed orthogradely transported axonal tracers to demonstrate, in the rat, projections that reach the basilar pontine nuclei from the zona incerta or pretectal nuclei. Except for the most rostral levels, all subdivisions of the zona incerta give rise to substantive basilar pontine projections. Although some topographic differences exist among the temination patterns of various subdivisions, no clear somatotopically organized scheme is apparent. Most incertopontine axons descend to the basilar pons in association with fibers of the medial lemniscus or crus cerebri and reach ipsilateral ventral and medial pontine gray regions. A sparse number of terminals are evident in the contralateral medial pontine gray. The anterior pretectal axons also descend with the medial lemniscus and crus cerebri to enter exclusively the ipsilateral basilar pons where they terminate most densely in ventral and medial regions. Dual orthograde labeling experiments indicate that some pretectal terminal fields in the pontine gray are shared with incertopontine projections and with afferents from the dorsal column nuclei. This potential convergence of basilar pontine afferent projections is significant in light of (1) the known somatosensory input to the zona incerta and pretectum and (2), the fractured somatotopy of peripheral cutaneous inputs that arrive in the cerebellar cortex via mossy fibers. The present studies also employed electron microscopy to identify synaptic boutons formed by incerto‐ and pretectopontine axons, and they proved to be remarkably similar. Each is a medium to small‐sized bouton that contains spheroidal synaptic vesicles and forms asymmetric membrane specializations. Most incerto‐ and pretectopontine boutons participate in glomerular synaptic complexes that include a single, centrally located bouton contacted on its perimeter by several types of dendritic profiles including shafts and spine‐like appendages. A relatively small number of labeled boutons of either type contacts single, isolated dendritic elements in the neuropil. Taken together, these findings suggest that some basilar pontine neurons might receive convergent inputs from the zona incerta and pretectum as well as other somatosensory related systems such as the dorsal column nuclei and sensorimotor cortex. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903600208

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe present light and electron microscopic experiments were carried out on the first somatic sensory area (SI) of cats to determine the laminar distribution of axon terminals from the ipsilateral second somatic sensory area (SII) and to identify the types of synapses between these terminals and the neuronal elements of SI.Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was iontophoretically injected into multiple sites and at different cortical depths of the forepaw representation zone of SII. Fixed brain blocks containing the injected SII and ipsilateral SI were cut into slices and processed immunocytochemically to stain PHA‐L‐filled fibers and terminals. Light microscopic examination of SI revealed patches of anterograde labeling in the forepaw representation zone, concentrated mainly in supragranular layers. In these layers, thin immunolabeled fibers branched extensively and formed a dense plexus that was more prominent in layers II and I. Conversely, the infragranular layers contained fragments of vertically oriented thick fibers that rarely emitted axon collaterals. PHA‐L‐labeled axons had numerous swellings along their course, interpreted as boutons en passant, and stalked boutons. Of 19,661 labeled terminals (17,833 beads and 1,828 stalked boutons), 84.74% were obse in supragranular layers, with the highest concentration in layer II(33.15%) and lower in layers I (26.27%) and III (25.30%). The proportion of terminals was lower in layers IV (6.49%) and V (5.45%) and lowest in layer VI (3.32%). These counts also showed that boutons en passant were the majority (90.70%) and stalked boutons, the minority (9.30%). The ratio of these two types of presynaptic specializations was similar (9:1) in all six layers.Electron microscopic examination of the labeled regions of SI showed that both axon swellings and stalked boutons formed synapses of the asymmetric type with SI neuronal elements. The majority (85.37%) of a sample of 130 labeled terminals synapsed on SI neurons in layers I‐Ill. The identified postsynaptic profiles were dendritic spines (61.11%) or mediumsized and small dendrites (38.89%). These results are discussed in relation to those of a companion study on the laminar pattern of the projection from SI to SII of cats (P. Barbaresi, A. Minelli, and T. Manzoni, 1994, J. Comp. Neurol. 343:582–596). Based on the anatomical organization of these reciprocal connections, there seems to be no clear hierarchicalal relationship between SI and SII in cats. © 1995

ISSN:0092-7317    

DOI:10.1002/cne.903600209

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA light microscopic immunocytochemical study, using antisera against noradrenaline (NA) and dopamine‐β‐hydroxylase (DBH), revealed the noradrenergic system in the brain of the chicken (Gallus domesticus). NA‐ and DBH‐immunoreactive (ir) elements showed a similar distribution throughout the whole brain. The neurons immunoreactive for the monoamine were confined to the lower brainstem, the pons, and the medulla. In the pons, a rather dense group of cells was found in the dorsal, most posterior part of the locus coeruleus and in the caudal nucleus subcoeruleus ventralis. A few labeled cells appeared in and around the nucleus olivaris superior in the most caudal part of the metencephalic tegmentum. In the medulla oblongata, noradrenergic cells could be visualized at the level of the nucleus of the solitary tract and in a ventrolateral complex. Virtually all regions of the brain contained a rather dense innervation by NA‐ and DBH‐immunopositive varicose fibers. Noradrenergic fibers and terminals were especially abundant in the ventral forebrain and in the periventricular hypothalamic regions. DBH‐ir and NA‐ir fibers, varicosities, and punctate structures could be observed in close association with immunonegative perikarya in several brain regions, more specifically in the ventral telencephalon, in the mid‐ and tuberal hypothalamic region, and in the dorsal rostral pons. Some perikarya in these brain areas were completely surrounded by noradrenergic structures that formed pericellular arrangements around the cells. The present study on the distribution of the noradrenergic system in the brain of the chicken combined with the results of a previous report on the distribution of L‐Dopa and dopamine in the same species (L. Moons, J. van Gils, E. Ghijsels, and F. Vandesande, 1994, J. Comp. Neurol.346:97–118) offers the opportunity to differentiate between the various catecholamines in the brain of this vertebrate. The results are discussed in relation to catecholaminergic systems previously reported in avian species and in the mammalian brain.

ISSN:0092-7317    

DOI:10.1002/cne.903600210

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSynaptogenesis has been tracked by using quantitative electron microscopic methods in the inner plexiform layer (IPL) of the developingMacaca monkeyfovea from fetal day (Fd) 55 to Fd132. Vesicle‐containing profiles were classified according to whether (1) they contained a ribbon indicating that they originated from a bipolar cell, or (2) the profile formed a junction. Group 2 was further subdivided by morphological characteristics into (2a) amacrine, (2b) bipolar, or (2c) unknown profiles. Ribbon‐containing bipolar profiles are clearly identifiable at Fd55 when they occur at a density of 0.9/100 μm2. Bipolar synapses increase rapidly to 4.7/100 μm2by Fd88, similar to their density at Fd132. Identifiable amacrine profiles forming a junction are rare at Fd55–68. By Fd88, amacrine synaptic density has jumped to 6.7/100 μm2and continues to increase to 9.5/100 μm2at Fd132. These quantitative data strongly suggest that, at theMacacafovea, bipolar synaptogenesis both begins and ends before amacrine synaptogenesis. The large number of immature amacrine synaptic profiles and densities at Fd132 suggests that amacrine synapses continue to form after Fd132. This study confirms that cone‐dominated monkey fovea has a different sequence of synaptogenesis than the rod‐ dominated peripheral retina (Nishimura and Rakic, [1985] J. Comp. Neurol 241:420–434). The data support the concept that synaptic developmental sequence is determined by the type of photoreceptor which dominates a particular retinal region or species.Bipolar ribbon synapses are observed in the outer half of the IPL at Fd55, are present in the inner IPL at Fd60, and then, with increasing age, are found throughout the IPL. This pattern strongly suggests that vertical OFF bipolar pathways form earlier than ON pathways in the IPL. In contrast, amacrine profiles are found throughout the IPL at the youngest ages, with an adult‐like banding pattern present by Fd132. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903600211

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY