摘要:

AbstractParvalbumin (PV) is a calcium‐binding protein present in GABAergic cells in the cerebral cortex and in thalamic relay neurons. In the present study, parvalbumin immunocytochemistry (PVi) and stereological methods were used to obtain estimates of cortical volume, total neuron number, laminar density, and the percentage of PV‐immunoreactive neurons in auditory neocortex. PVi clearly delineated the primary auditory cortex (AI), which was characterized by two PV+ bands: dense terminal‐like labeling within lamina III/IV and PV+ somata in lamina VIa. Stereological analysis of Nissl‐stained sections revealed that the total number of neurons in rabbit AI was 1.48 × 106with a mean neuronal density of 55 × 103/mm3. Based on a mean cortical thickness of 1.92 mm, there are approximately 106,000 neurons in a 1 mm2column of auditory cortex.PVi yields an extraordinary Golgi‐like staining of nonpyramidal cells in all cortical layers. PV+ nonpyramidal cells constitute approximately 7.0% of the neurons in AI. There were significant differences in the morphology and density of PV+ neurons across layers. Although only 5% of cells in lamina I were PV+, three nonpyramidal cell types were present. Lamina II had the highest numerical density within AI but the lowest percentage of PV+ neurons (3.3%). Lamina II, however, contained the greatest diversity of PV+ nonpyramidal cell types, which included small multipolar cells, bipolar cells, and, less frequently, large cells of the bitufted, bipolar, and stellate varieties. Lamina IV had one of the highest numerical densities (67.6 × 103neurons/mm3) and contributed nearly 27% of the total neuron number in AI. The numerical density of PV+ nonpyramidal cells was also greatest within lamina IV (7.1 × 103/mm3) where they formed 10.4% of the neuronal population. PV+ nonpyramidal cells in lamina IV and lamina III were predominantly large basket‐type cells with bitufted dendritic domains and tangentially oriented local axonal plexuses. The terminal‐like label within lamina III/IV derived in part from the basket‐cell axons, which formed pericellular arrays around unstained somata. Cell‐sparse lamina V contained the largest PV+ nonpyramidal cells in AI. These cells, which formed 11% of the neuron population in lamina V, were notable for their tangentially oriented dendritic fields and local axonal arbors. PVi partitioned lamina VI into VIa and VIb. Large multipolar nonpyramidal cells were distributed throughout lamina VI and made up approximately 6% of the total population. Lamina VIa contained a band of lightly labeled PV+pyramidalneurons that formed 15% of the neuronal population. Double‐labeling experiments revealed that some PV+ pyramidal neurons within VIa also project to the ventral subdivision of the medial geniculate body (MGB).PVi demarcated the three major subdivisions of the MGB: the ventral (vMGB), dorsal (dMGB), and internal (iMGB) nuclei. The vMGB was strongly PV immunoreactive due to dense labeling of the neuropil and moderately labeled somata. The dMGB was characterized by scattered large PV+ cells and coarse PV+ axons. Relative to the vMGB, the neuropil of the dMGB contained only light terminal‐like labeling. The internal MGB contained few, if any, PV+ somata and had the least terminal‐like labeling of all MGB subdivisions. Because calcium‐binding proteins delineate functionally distinct, parallel pathways to sensory neocortex, they will be useful chemoarchitectonic tools for guiding future connectional studies of the MGB with the auditory neocortex and brai

ISSN:0092-7317    

DOI:10.1002/cne.903490402

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

年代:1994

数据来源: WILEY

摘要:

AbstractNucleus uvaeformis (Uva), previously identified as a component of song control circuitry in songbirds, and nucleus dorsolateralis posterior thalami, pars caudalis (DLPc) in pigeon, were compared with respect to their relative positions in the dorsolateral part of the posterior thalamus, their cell types, and their afferent and efferent projections. Both nuclei are closely related to the habenulointerpeduncular tract, have similar cell types, and receive a dense projection from deep layers of the optic tectum, predominantly ipsilaterally, and a distinct projection from the dorsal column and external cuneate nuclei, predominantly contralaterally. Recordings of multiple unit activity evoked by visual and somatosensory stimuli were used to guide injections of tracer into either DLPc or Uva, and the projections to the telencephalon were charted. Both nuclei were found to have a major terminal field in the medial part of the ipsilateral neostriatum intermedium (NI), known as nucleus interfacialis (NIf) in songbirds, and a minor terminal field in the roof of the neostriatum caudale (NC). In pigeon, the DLPc terminations in NC were within a region known as neostriatum dorsale (Nd), and, in male songbirds, the Uva terminations were in the high vocal center (HVC). Recordings of visual and somatosensory evoked activity were then used to guide injections of tracer into NI, and the afferent and efferent projections were again compared in pigeon and songbirds. The projections from either DLPc or Uva were confirmed, and terminal fields were observed either in Nd in pigeon, the dorsolateral part of NC in female songbirds, or HVC in male songbirds. Injections of tracer into either Nd or HVC confirmed their sources of afferents in DLPc or Uva, respectively, and in NI, but there was incomplete overlap of the distribution of retrogradely labelled cells in NI and the terminal fields of DLPc or Uva.It is concluded that DLPc and Uva are comparable nuclei having similar afferent and efferent projections relaying visual and somatosensory information to the telencephalon. The possible role of this information in vocal control is discussed. © 1994 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903490403

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

年代:1994

数据来源: WILEY

摘要:

AbstractAs the first part of an investigation of the motor thalamus and its cortical connections in the owl monkey, a New World anthropoid primate, we studied thalamic architecture by using stains for Nissl, acetylcholinesterase (AChE), and cytochrome oxidase (CO), in order to identify subdivisions of the ventrolateral thalamic region as well as other nuclei with motor connections. Material was obtained from brains cut in the frontal, horizontal, and parasagittal planes. Our results indicate that the ventrolateral thalamic region (VL) of owl monkeys is a heterogeneous structure composed of several architectonic subdivisions that resemble divisions that have been described in macaques and other Old World anthropoids. All of these subdivisions are more readily distinguished in AChE than in Nissl or CO preparations.The anterior part of VL, VLa (VLo of Olszewski), is characterized by clusters of medium‐sized, darkly stained neurons. VLa is also distinguished by AChE‐positive cells embedded in a matrix of neurites as well as by a characteristic dark, irregular net of blood vessels. The posterior part of VL is rather uniform cytoarchitectonically and contains large, darkly stained, and sparsely distributed neurons. However, we were able to distinguish three subdivisions of posterior VL that closely correspond to structures described by Olszewski in macaques: a principal segment, VLp (VPLo of Olszewski), a medial segment, VLx (“area X” of Olszewski), and a dorsal segment, VLd (VLc and VLps of Olszewski). In AChE, VLd is much darker than the other divisions. The distinction between VLp and VLx, which together make up the largest part of VL, is less marked, although VLp is somewhat darker and more irregular in appearance in AChE than is VLx. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903490404

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

年代:1994

数据来源: WILEY

摘要:

AbstractTo determine the relative contributions of transthalamic cerebellar and pallidal projections to the primary motor cortex (M1) of owl monkeys, we examined the thalamic labeling resulting from injections of fluorescent tracers and wheatgerm agglutinin/horseradish peroxidase conjugate (WGA‐HRP) into regions of M1 identified by intracortical microstimulation. Injections were placed in the major somatotopic divisions of M1 (the hindlimb, trunk, forelimb, and face representations) and in the caudal and rostral M1 subareas. In most cases, we injected several differentiable tracers into different parts of M1. Our results indicate that the strongest connections of M1 are with subdivisions of the ventral lateral thalamus (VL); other connections are mainly with intralaminar nuclei (the central lateral, paracentral, and center median nuclei) and the reticular nucleus. Most projections are reciprocal and topographically organized. M1 is strongly connected with the principal (VLp), medial (VLx), and anterior (VLa) subdivisions of the VL complex but has at most weak connections with the dorsal division (VLd). Each of the major somatotopic divisions of M1 is connected with an anteroposteriorly elongated territory within the VL complex. The connections are somatotopically organized such that the M1 hindlimb representation is connected with a band of cells in the lateral and anterior portions of the VL complex (spanning VLa and VLp), whereas the trunk, forelimb, and face representations are connected with successively more medially and posteriorly situated cell bands (spanning VLa, VLp, and VLx). There is some degree of overlap between the somatotopic territories within VL, although the absence of double‐labeled cells in cases with injections of adjacent somatotopic divisions of M1 suggests that individual thalamic neurons project to single somatotopic regions.In addition to somatotopic differences, the connections of the caudal and rostral subdivisions of M1 differ to some extent. Caudal M1 is connected most strongly with VLp, a target of cerebellar projections, but it is also connected with VLa, which receives pallidal inputs. In complementary fashion, rostral M1 is most strongly connected with VLa, but it is also connected with VLp. VLx, a target of cerebellar projections, has significant connections with both caudal and rostral M1. These results indicate that all parts of M1 are influenced by both the cerebellum and globus pallidus in owl monkeys, as has been suggested in some recent studies of macaque monkeys. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903490405

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn the striatum of rat, somatostatin 14, somatostatin 28, and somatostatin 28 (1–12) have previously been localized within a small population of medium aspiny local circuit neurons. Because all three peptide fragments are generated through the cleavage of prosomatostatin by different converting enzymes, the possibility for differential expression of these peptides exists. In order to investigate this possibility, frozen sections were collected from the brains of adult female Wistar rats fixed with 4% paraformaldehyde and double labelled using immunocytochemistry and in situ hybridization. Sections were first processed for somatostatin 14, somatostatin 28, or somatostatin 28(1–12) by using the avidin‐biotin complex immunocytochemical technique followed by in situ hybridization using35S‐labelled antisense riboprobes to somatostatin mRNA. The results of such analysis revealed that somatostatin 28 and somatostatin mRNA are 100% colocalized. Somatostatin 14 and somatostatin 28(1–12), in contrast, are only present within 66% of the neurons that express somatostatin mRNA. Examination of the anatomical distribution of neurons that express both somatostatin mRNA and somatostatin 14 or somatostatin 28(1–12) protein reveals that these neurons are present throughout the caudate‐putamen of rat but are more prevalent in the ventromedial regions. Neurons that express somatostatin mRNA but not somatostatin 14 or somatostatin 28(1–12) are also present throughout the caudate‐putamen but are most numerous within a dorsolateral strip just beneath the corpus callosum. These results suggest that the somatostatin neuron population within the rat caudate‐putamen is actually composed of two smaller subpopulations based on neuropeptide content. The first subpopulation contains somatostatin 28 and constitutes one‐third of the total somatostatin population, whereas the other contains somatostatin 28, somatostatin 14, and somatostatin 28(1–12) and represents the remaining two‐thirds of the cells that express somatostatin mRN

ISSN:0092-7317    

DOI:10.1002/cne.903490406

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

年代:1994

数据来源: WILEY

摘要:

AbstractTo understand the possible role of retinoic acid during inner ear development and cellular regeneration, we have examined the expression pattern of two intracellular retinoid‐binding proteins, the cellular retinol‐ and retinoic acid‐binding proteins of type I in the developing and mature rat inner ear. Expression of cellular retinol‐binding protein type I was seen in the supporting cells of the organ of Corti and vestibular organs as soon as the first signs of differentiation of the adjacent hair cells were seen. In the developing organ of Corti, the expression pattern followed the basal‐to‐apical coil differentiation gradient. After the 1st postnatal week, detectable expression of cellular retinol‐binding protein type I disappeared from the organ of Corti, but persisted in the supporting cells of vestibular organs throughout life. Expression of cellular retinoic acid‐binding protein type I was not found in the inner ear sensory epithelia. Cellular retinol‐binding protein type I has previously been shown to act as a substrate carrier in the synthesis of retinoic acid from its precursor, retinol. Our data suggest that retinoic acid is synthesized in the developing sensory epithelium of the cochlear and vestibular organs and that a concentration gradient formed by retinoic acid may have a role in differentiation of the cochlear sensory epithelium. Furthermore, retinoic acid may have a role in damage‐induced hair cell regeneration in the developing and mature vestibular organs as well as in the developing auditory organ. The absence of cellular retinol‐binding protein type I from the supporting cells of the mature organ of Corti may be associated with the inability of this organ to regenerate hair cells after damage.

ISSN:0092-7317    

DOI:10.1002/cne.903490407

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

年代:1994

数据来源: WILEY

摘要:

AbstractPresence and distribution of glutamate, glycine, GABA and β‐alanine in VIIIth nerves of frogs and rats were investigated with postembedding immunocytochemical methods on serial semithin sections.In Scarpa's ganglion of the frog, all cell bodies were glutamate immunoreactive. About 17% of the cells per section were also glycine immunoreactive, but none were GABA or β‐alanine immunoreactive. The mean diameter of glycine‐positive cell bodies (26.7 ± 6.9 μm; N = 130) was significantly (P<0.0001) larger than that of glycine‐negative cell bodies (15.7 ± 5.4 μm; N = 272). The intensity of glutamate immunostaining decreased with cell diameter, whereas the intensity of glycine immunostaining increased with cell diameter. As a result, the staining intensities for glutamate and glycine in a given cell were negatively correlated. Glycine immunoreactivity was also present in a size‐related manner in distal and proximal afferent fibers. The majority of thin fibers (10 μm) were glycine positive. Glycine‐positive fibers were observed in the sensory epithelia of all end organs in the inner ear. The saccular macula and its nerve, however, contained only few glycine immunoreactive structures.In Scarpa's ganglion of the rat, all cells were immunoreactive for glutamate, about 12% for colocalized glycine, and none for GABA or β‐alanine. Glycine‐positive cell bodies were significantly (P<0.0001) larger (32.2 ± 5.2 μm; N = 82) than glycine‐negative cell bodies (25.1 ± 5.3 μm; N = 274). Cell bodies in the spiral ganglion were only glutamate immunoreactive, whereas staining for glutamate, glycine, and GABA was dense in the ventral cochlear nucleus.These results demonstrate that thicker vestibular afferent fibers represent a particular subpopulation that differs from the majority of thinner afferents due to their glycine immunoreac

ISSN:0092-7317    

DOI:10.1002/cne.903490408

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe metabotropic glutamate receptor mGluR1 is a G‐protein‐coupled glutamate receptor whose activation induces phosphotidylinositol hydrolysis and increases diacylglycerol and cytoplasmic calcium. By using affinity‐purified antisera against a partial amino acid sequence of mGluR1α, deduced from the nucleotide sequence of the cloned gene, the heterogeneous expression of this glutamate receptor was studied immunocytochemically with light and electron microscopy in the rat hypothalamus. Immunoreactivity was restricted to cell bodies and dendrites throughout many regions of the adult hypothalamus, including the preoptic area, anterior hypothalamus, suprachiasmatic nucleus, dorsomedial hypothalamus, and periventricular region. Strong immunolabeling was found in the lateral hypothalamus where immunoreactivity could be detected as early as embryonic day 18. Intense immunoreactivity was also found in the medial mammillary nuclei. In contrast to the strong labeling in many other regions, the neuroendocrine neurons of the arcuate, supraoptic, and paraventricular nuclei showed relatively little staining in adults.With light microscopy, immunoperoxidase labeling was found distributed in patches on the cytoplasmic side of the plasma membrane of immunoreactive neurons. When the same tissue was examined ultrastructurally, the patches were not restricted to synaptic specializations but were also found distributed on perikaryal and dendritic membranes sometimes associated with synapses and sometimes not. Some immunoreactive membranes showed no immunolabeling at the synaptic junction. When the tissue was strongly stained, labeling could be found in the cytoplasm of immunoreactive cells. No immunostaining was found on axons or presynaptic boutons.Together with other evidence showing a widespread expression of many different subtypes of both ionotropic and metabotropic receptors, these data support the hypothesis that glutamate may regulate hypothalamic cellular activity with a number of physiologycally different mechanisms, and these mechanisms include second‐messenger systems activated by G proteins. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903490409

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe organisation of the tritocerebrum ofDrosophila melanogasterwas studied by Bodian‐Protargol reduced silver staining, Golgi‐silver impregnation, horseradish peroxidase (HRP), and cobalt‐chloride labelling of neurones and transmission electron microscopy. Nerve fibres of six categories were found to project to the tritocerebrum. (1 and 2) The sensory fibres from the internal mouthpart sensilla known to course along pharyngeal and accessory pharyngeal nerves were found to project in mainly two tiers, in the tritocerebrum. (3) Stomodaeal nerve fibres also project along the pharyngeal nerve, to the tritocerebrum. (4) Cells of the pars intercerebralis (PI) project along the median bundle and arborise in the tritocerebrum. HRP labelling and subsequent examination by transmission electron microscopy indicated their neurosecretory nature. (5 and 6) Two tracts of ascending fibres, designated as dorsal and ventral ascending tracts, were found to project to the tritocerebrum.Some of the sensory fibres from the labial nerve extend close to the sensory projections of the tritocerebrum, suggesting a possible convergence of the two sensory inputs. In the tritocerebrum, the sensory input, the stomodaeal input, the neurosecretory fibres of PI, and the ascending fibres were found to have overlapping fields, suggesting mutual interaction. The medial subesophageal ganglion and the tritocerebrum may interact through the ventral ascending tract. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903490410

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

年代:1994

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903490401

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

年代:1994

数据来源: WILEY