摘要:

AbstractRecent studies have shown that the presence of immunoreactivity for parvalbumin (PV‐IR) and calbindin‐D 28k (Cal‐IR) can be used as markers for certain types of gamma‐aminobutyric acid (GABA) immunoreactive interneurons in monkey cerebral cortex. Little quantitative information is available regarding the features that distinguish these two subpopulations, however. Therefore, in this study we localized PV‐IR and Cal‐IR neurons inMacacamonkey striate cortex and analyzed quantitatively their laminar distribution, cell morphology, and co‐localization with GABA by double‐labeling immunocytochemistry. PV‐IR was found in nonpyramidal cells in all layers of the cortex, although PV‐IR cells in layer 1 were rare. In contrast, Cal‐IR was found mainly in nonpyramidal cells in two bands corresponding to layers 2–3 and 5–6. We found very few double‐labeled PV‐IR/Cal‐IR cells but confirmed that almost all PV‐IR and Cal‐IR cells are GABAergic. Overall, 74% of GABA neurons in striate cortex displayed PV‐IR compared to only 12% that displayed Cal‐IR and 14% that were GABA‐IR only. Quantitative analysis indicated that the relative proportion of GABA cells that displayed PV‐IR or Cal‐IR showed conspicuous laminar differences, which were often complementary. Cell size measurements indicated that PV‐IR/GABA cells in layers 2–3 and 5–6 were significantly larger than Cal‐IR/GABA cells. Analysis of the size, shape, and orientation of stained cell bodies and proximal dendrites further demonstrated that each subpopulation contained several different types of smooth stellate cells, suggesting that Cal‐IR and PV‐IR are found in functionally and morphologically heterogeneous subpopulations of GABA neurons.There was a thick bundle of PV‐IR axons in the white matter underlying the striate but not prestriate cortex. PV‐IR punctate labeling matched the cytochrome oxidase staining pattern in layers 4A and 4C, suggesting that PV‐IR is present in geniculocortical afferents as well as intrinsic neurons. Cal‐IR neuropil staining was high in layers 1, 2, 4B, and 5, where cytochrome oxidase staining is relatively low. We did not find a preferential localization of either PV‐IR or Cal‐IR cell bodies in any cytochrome oxidase compartments in layers 2–3 of the cortex. These findings in

ISSN:0092-7317    

DOI:10.1002/cne.902980102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractStimulus‐evoked metabolic activity in the anterior parietal cortex (areas 3a, 3b, 1, and 2) occurs in the form of column‐like patches. Similar patches characterize the connections to, within, and from these fields. The relation of the patches elicited metabolically to those formed by retrograde or anterograde transport, however, is not clear. If a type of projection connecting areas 3a, 3b, 1, and 2 transmits sensory information among these cortical fields, the resultant projection pattern may directly contribute to the definition of somatosensory metabolic “columns.” To test this possibility, electrophysiological recordings in areas 3b and 1 ofMacaca fascicularismonkeys characterized stimuli that elicited the best neuronal response at a specific cortical site. Iontophoretic injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) were subsequently made into the identified cortical sites. Two days later, the animals were injected with 2‐deoxyglucose (2DG) and received the somatic stimulus previously determined to best activate the neurons isolated at the injected cortical site. After injections of WGA‐HRP into physiologically defined loci in area 3b, the patches of transported label within areas 3b and 1 were colocalized with evoked metabolic activity. Injections of WGA‐HRP into area 1 produced anterogradely labeled terminals in areas 1 and 2 that also overlapped with patches of evoked metabolic activity, as did patches of retrogradely labeled cells located in area 3b. Patches of anterograde label found in area 3b after area 1 injections, however, were not coincident with the metabolically activated patches. These findings suggest that excitatory information is transmitted from area 3b to area 1 in a way that connects clusters of cells with similar re

ISSN:0092-7317    

DOI:10.1002/cne.902980103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractProjections from the basolateral nucleus of the amygdala (BLA) to the frontal cortex and the striatum were studied by usingPhaseolus vulgaris‐leucoagglutinin (PHA‐L) anterograde tracing technique in the rat.PHA‐L injections into the rostral part of the BLA resulted in a dense labeling of fibers with boutons in the dorsal bank of the rhinal fissure and in the lateral and the medial agranular cortex. PHA‐L injections into the caudal part of the BLA produced a dense labeling of fibers in the medial surface of the frontal cortex. In most of the cortical regions, labeled fibers were predominantly distributed in two bands: one in the deep part of layers I and II and the other, heavier band, in layers V and VI.PHA‐L injections into the rostral BLA resulted in a dense labeling of fibers with boutons in the olfactory tubercle, the rostral and caudolateral portion of the nucleus accumbens, and a large region of the caudate–putamen. The labeled area of the caudate–putamen included the rostroventral area, the central area, and the area caudal to the anterior commissure and dorsal and lateral to the globus pallidus. PHA‐L injections into the caudal BLA produced fiber labeling in the most rostromedial area of the caudate–putamen facing the lateral ventricle, the medial portion of the nucleus accumbens, and the lateral septum. In the rostroventral striatum, PHA‐L‐labeled fibers selectively innervated the matrix compartment that contains abundant somatostatin‐immunoreactive fibers. Compartmental segregation was less clear in the caudo‐dorsolateral caudate–putamen and in the nucleus accumbens. Electron microscopy revealed that PHA‐L‐labeled boutons in the striatum contained abundant, small, round vesicles. These boutons formed asymmetrical synapses with dendr

ISSN:0092-7317    

DOI:10.1002/cne.902980104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe organization of cortical circuitry responsible for processing sensory information is a subject of intense examination. However, it is not known whether cortical cells in different sensory cortices process information in a way that is specific to the modality of their input, or whether there are commonalities in processing circuitry across different cortices. In our laboratory, this question has been investigated at the level of the geniculocortical pathway by routing information of one sensory modality into the processing circuitry of another modality. Appropriate early lesions cause growth of retinal axons into the auditory thalamus (MGN) (Sur et al., Science242: 1437, '88). Previously, we have established that the MGN carries the resulting visual information on to primary auditory cortex (AI), which thus contains visually responsive neurons and a topographic representation of the retina (Roe et al., Soc. Neurosci. Abstr.14:460, '88; Sur et al., Science242:1437, '88), In this paper, we describe anomalous projections from the dorsal part of the thalamus, specifically the lateral posterior/pulvinar complex, into AI. This result demonstrates that thalamic neurons belonging to one modality can be induced to project to cortex that is normally of a different modality. In addition, we have studied in detail the nature of the MGN to AI projection in these animals as compared to the normal projection. The MGN to AI projection appears to be unaltered by the lesions; the location and topography of labelled cells are similar to that in normal animals. Because the MGN to AI projection is still highly divergent along the “isofrequency” dimension when compared to the tonotopic dimension, our data suggest that visual topography in the cortical map is created within the auditory cortex, perhaps by activity‐dependent sharpening of the retinal representation during develo

ISSN:0092-7317    

DOI:10.1002/cne.902980105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe role of antennal sensory axons in the induction and stabilization of olfactory glomeruli has been explored in the mothManduca sexta.First, we asked the question: how many axons are necessary to induce glomerulus formation within the first‐order olfactory neuropil of the brain? Axons from as few as 10 of the normal 70–80 repeating antennal segments were sufficient to induce glomeruli. However, there was a dose dependence in the number of glomeruli that developed in partially innervated lobes. When only 11 segments of the antenna were allowed to provide innervation to the lobe, only 37 of the normal 59 ± 2 glomeruli developed; over 20 segments were necessary to induce the normal number of glomeruli. In a second set of experiments, we asked: for how long must antennal axons be present to stabilize newly formed glomeruli? We found that antennal axons must be intact for at least 2 to 4 stages (roughly equivalent to 2 to 4 days) for glomeruli to be stable even if the axons are subsequently severed. This finding, taken in the light of other recent findings in our laboratory, suggests that the formation of synapses may be a crucial element in the stabilization of glomerular structure. All together, the results of the present study indicate that induction and stabilization of glomeruli are separable events with different underlying cellular b

ISSN:0092-7317    

DOI:10.1002/cne.902980106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe distribution of histamine in the nervous system of the marine molluscsAplysia californicaandPleurobranchaea californicawas studied by using a newly available immunohistochemical localization technique and specific antiserum against histamine‐protein conjugate. We examined several sets of complete histological sections through the major ganglia of both animals, as well as all nerve roots of the buccal and cerebral ganglia and the corresponding target tissues. The results indicate that histamine is present in several neurons and/or nerve fibers of all major ganglia. An especially dense histamine fiber network in the buccal ganglion of both species suggests a major role for histamine in regulation of buccal‐oral behaviors. Histamine was also observed in several identified nerve roots of the buccal and cerebral ganglia, as well as in the corresponding target tissues. Its localization in theAplysiaradular sac and in the statocyst neurons of both species suggest a role for histamine in sensory functions. Our study revealed many previously unknown histamine cells or cell clusters, some of which may be identifiable by electrophysiological methods. The findings also point to possible reinterpretation of previous findings, indicating that histamine may be a cotransmitter in identified cells, whereas the methodology itself suggests that special precautions must be taken to avoid spurious interpretations of specificity. As has now been observed in studies of serotonergic immunohistochemistry and in our own findings on VIP, histamine terminals were observed to lie in close contact with somata and axon hillocks, all of which suggest that axo‐somatic connections in molluscs may be more prevalent than previously consi

ISSN:0092-7317    

DOI:10.1002/cne.902980107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe SI forelimb area of cats was examined with receptive field (RF) mapping techniques. Arrays of closely spaced, near‐radial microelectrode penetrations were inserted into the crown of postsigmoid gyrus of ketamine anesthetized subjects and minimal RFs were obtained at several depths. The minimal RF was defined as the skin site providing the strongest input to each recorded cluster of neurons. Data analysis showed that all studied cortical territories contained groups of discrete cortical columns, 300–400 μm in diameter. The columns were regarded as topographic entities because no change in minimal RF location could be observed within their boundaries. The boundaries of columns were sharp and could be unequivocally distinguished because the minimal RFs sampled on opposite sides of a boundary occupied displaced, nonoverlapping positions.Pair‐wise comparison of single neuron maximal RFs (defined as the entire skin area providing input to the recorded neuron) further clarified the nature of the SI place‐defined columns: (1) nosystematicdifferences in maximal RF position could be demonstrated for different parts of the same column (even though the maximal RFs in most columns varied extensively in size and skin areas covered), and (2) at the boundary between neighboring columns maximal RFs shifted en masse to center on a new skin locus. These minimal and maximal RF observations strongly support our recent proposal that body surface is represented in SI by a honeycomblike mosaic of discrete place‐defined cortical columns,

ISSN:0092-7317    

DOI:10.1002/cne.902980108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have studied the relationship of retinal afferents, glial cell processes, and neuronal cytoarchitectonics in the lateral geniculate nucleus (LGN) of two species: tree shrews (Tupaia belangeri) and ferrets (Mustela putoris). Both species are relatively immature at birth, allowing the development of these features to be studied in the perinatal period.Retinal afferents, visualized by intraocular injection of a wheat germ agglutinin/horseradish peroxidase conjugate (WGA‐HRP), are apparently the first elements of the developing LGN to exhibit a characteristic layered pattern in tree shrews and ferrets. Some radial glia still remain in the LGN of both species as the retinal afferents are in the process of segregating.Glial cell processes were visualized immunohistochemically with antibodies to glial fibrillary acidic protein (GFAP) or vimentin. In both the ferret and tree shrew, layering of glial cell processes is first seen as the overlap of retinal terminal fields diminishes. In the tree shrew LGN, these bands of dense glial cell staining are seen in apparent future cellular layers, whereas in the ferret, glial cell banding appears in interlaminar zones. If one or both eyes are removed at birth in tree shrews (before LGN cell layers are formed), the glial cell pattern seen 1 week later is in accord with the distribution of surviving nerve cells. The glial processes do not appear to invade regions left by degenerating retinal terminals or dying LGN cells.Several days after the appearance of layered glial cell processes (in the tree shrew) or at about the same time as glial layering (in the ferret), the first interlaminar spaces develop between neuronal cells, marking the beginning of cytoarchitectonic lamination, with its distinctive alternating cell‐rich and cell‐poor zones. Over the next several weeks, LGN neurons in both species continue to segregate into characteristic layers until the final, adult pattern of neuronal lamination is evident; as this process is completed, glial cell lamination disappears.These observations suggest that glial cells may be involved in establishing the neuronal layers that characterize the mature LGN of many sp

ISSN:0092-7317    

DOI:10.1002/cne.902980109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902980101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY