摘要:

AbstractThis study examined the morphology of thalamocortical neurons projecting to the primary somatosensory cortex (SI; hand region of areas 3a, 3b, 1, and 2) and their relationship to the spinothalamic (STT) terminals in the squirrel monkey. Retrogradely labeled thalamocortical neurons were intracellularly filled with Lucifer yellow (LY), and the STT terminals were anterogradely labeled with biotinylated dextran. Both filled neurons and labeled terminals were differentially visualized in the same field by a dual immunocytochemical staining method. SI‐projecting neurons appeared at the light level to be in contact with STT terminal boutons in the ventroposterior lateral (VPL), ventroposterior inferior (VPI), and centrolateral (CL) nuclei and the posterior complex (PO). The analyses of the neuronal morphology revealed that somatic and dendritic morphologies of SI‐projecting neurons in these thalamic nuclei, as well as in the anterior pulvinlar (Pub), centromedial (CM), and ventrolateral (VL) nuclei, were generally comparable with some exceptions: VPL neurons had the largest soma sizes, the most primary dendrites, and the longest total dendritic length among all neurons studied; VPI neurons had the smallest soma sizes; VPL SI‐projecting neurons were different from those in VPI in their soma sizes, shape factors, and orientations; in VPL the cells projecting to the superficial layers of SI were smaller than those projecting to the deeper layers, but in VPI the two groups of neurons were similar in soma sizes. In general, the SI‐projecting neurons in VPL, VPI, and CL were similar in their dendritic morphologies and branching patterns, and varied from those in Pub, PO, CM, and VL. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903610102

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have analyzed thecis‐regulatory regions in the 5′ flanking DNA of theDrosophila melanogastercholine acetyltransferase (ChAT; E.C. 2.3.1.6) gene by using germline transformants. These transformants are carrying wild‐type ChAT cDNA fused to different lengths of 5′ flanking sequence of the ChAT gene. Appropriate genetic crosses were used to introduce the transgene into animals with a presumptive null genetic background for endogenous ChAT. Expression of ChAT protein could thus be attributed exclusively to the transgene. Using a monoclonal antibody againstDrosophilaChAT, we have investigated the spatial distribution of transgenic ChAT and compared it to the normal distribution of ChAT protein in wild‐type animals. The brains of 7.4 kb cDNA transformants showed a ChAT expression pattern similar to that of wild‐type anin in the first‐ and second‐order sensory neuropil but reduced expression in other highly ordered neuropil. Several lines that were transformed with 1.2 kb or 0.8 kb of 5′ flanking DNA demonstrated relatively normal expression in sensory neuropil. In addition, these lines also showed ectopic expression in higher order neuropil. In the optic lobe, the expression pattern directed by 7.4 kb of 5′ flanking DNA was very similar to that of wild‐type ChAT expression. In contrast, 1.2 kb or 0.8 kb transformants showed reduced levels of expression and a more limited pattern of distribution in the optic lobe. Our results suggest that the 5′ flanking DNA of the ChAT gene can be divided into several separable positive and negative regulatory regions, which define various subsets of cholinergic neurons in the nervous system.

ISSN:0092-7317    

DOI:10.1002/cne.903610103

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractImmunocytochemical techniques for double staining were employed to investigate the morphological basis for interactions between enkephalins and other neuroactive compounds in the behavior of the gastropod molluscCepaea nemoralis. Coexistence of each of the two enkephalins with FMRFamide, serotonin or GABA‐like immunoreactivity was found in certain neurons in cerebral, parietal, and pedal ganglia. Tyrosine hydroxylase‐immunoreactive neurons were occasionally seen in close apposition to, but never colocalized with, the enkephalins. A comparison between these anatomical observations and previous behavioral studies suggests that in gastropod molluscs cotransmission of enkephalins with classical transmitters may, at least partly, reflect synergism of these substances in the control of definite behavioral programs. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903610104

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractVasopressin (VP) neurons have been identified in several brain regions where VP has been hypothesized to act as a neurotransmitter or neuromodulator. In many sites, VP is colocalized with the neuropeptide galanin (GAL). Here, using single in situ hybridization histochemistry, we have identified a novel group of neurons within the nucleus of the horizontal diagonal band of Broca (HDB) that express the VP gene and have assessed the distribution of these cells in adult male and female rats (90 days old, n = 7/group). VP mRNA‐expressing neurons were scattered throughout the rostrocaudal extent of the HDB, and the number of VP neurons detected unilaterally ranged from 1 to 17 cells per 20 μm section. Using double in situ hybridization histochemistry on alternate sections, we have assessed the number of cells expressing VP and/or GAL mRNAin the diagonal band and have determined the extent of their colocalization. Approximately 50% of all VP‐expressing neurons in the HDB coexpressed GAL mRNA, and 33% of GAL‐expressing neurons in this region coexpressed VP mRNA. No sex differences were detected in the number of neurons expressing either VP or GAL mRNA or in the incidence of coexpression of VP and GAL mRNAs in this region. VP neurons in the HDB exhibited a low level of expression, and cellular VP mRNA content did not differ between male and female rats. However, sex differences were present in the bed nucleus of the stria terminalis (BNST) of these same rats. Consistent with our previous findings, both the number of VP‐expressing neurons (P≤ 0.0004) and the cellular VP mRNA content (P≤ 0.02) in the BNST were greater in male than in female rats. These results suggest that VP gene expression is differentially regulated by gonadal hormones in the HDB compared to the BNST. Because GAL was previously reported to colocalize with acetyicholine (ACh) and gonadotropin‐releasing hormone (GnRH) in the diagonal band of Broca, our findings suggest that VP may also colocalize with these transmitters in this brain region. Our observations may provide an anatomical basis for the postulated actions of VP in functions involving ACh or GnRH pathways. © 1995

ISSN:0092-7317    

DOI:10.1002/cne.903610105

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractColocalization of proenkephalin and prodynorphin mRNAs with each other as well as with D1, D2, and D3 dopamine receptor mRNAs was analyzed in the nucleus accumbens of the rat. Distinct combinations were detected in the rostral pole, core, and shell subdivisions of the nucleus accumbens. Proenkephalin and prodynorphin mRNAs were principally localized in separate cells in the core. All detectable prodynor cells in the core expressed D1 mRNA but not D2 mRNA. Conversely, approximately 95% of the proenkephalin‐positive cells in this region expressed D2 mRNA but not D1 mRNA. This pattern was identical to that observed in the caudate putamen. In the rostral pole and the shell, embedded in a background of this “typical” colocalization pattern, clusters of cells expressing a distinct configuration were found. In these clusters, proenkephalin‐positive cells expressed both prodynorphin and D1 mRNAs, but they did not express D2 mRNA.D3 and prodynorphin mRNAs were colocalized in “limbic” striatal areas, including the ventromedial caudate putamen, the rostral pole, and the medial shell. In contrast, D3 mRNA was not detected in any proenkephalin‐positive cells. Together with the prodynorphin/D1 data, this suggests that a subset of prodynorphin cells expresses both D1 and D3 mRNAs.It is concluded that (1) clusters of cells that coexpress proenkephalin, prodynorphin, and D1 mRNAs overlap extensively with previously defined cytoarchitectural cell clusters in the nucleus accumbens and (2) a subset of the prodynorphin cells in the ventromedial caudate putamen and the nucleus accumbens contains both D1 and D3 mRNAs. © 1995 W

ISSN:0092-7317    

DOI:10.1002/cne.903610106

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have explored basic rules guiding the early development of topographically organized projections, employing the rat corticopontine projection as a model system. Using anterograde in vivo tracing with 1,1′, dioctadecyl‐3,3,3′,3′ ‐tetramethylindocarbocyanine perchiorate (DiI), we studied the distribution of labelled fibers in the pontine nuclei in relation to cortical site of origin during the first postnatal week.Labelled corticopontine fibers enter the pontine nuclei in distinct, sharply defined zones. The putative terminal fibers typically occupy lamella‐like subspaces. Related to changes in cortical site of origin, we describe mediolateral, internal to external, and caudorostral distribution gradients in the pontine nuclei. Fibers originating in the anterolateral cortex occupy an internal central core, while implantations at increasing distance from the anterolateral cortex produce (1) more externally located lamellae, and (2) a caudal to rostral shift in fiber location. Previous investigations have shown that pontocerebellar neurons migrate into the ventral pons in a temporal sequence (Altman and Bayer [1987] J. Comp. Neurol. 257:529). The earliest arriving neurons occupy the central core and later arriving neurons settle in more externally and rostrally located subspaces. We hypothesize that the earliest arriving corticopon tine fibers grow into the then only available zone of pontocerebellar neurons (central core), attracted by a diffusible chemotropic cue. Later arriving fibers grow into correspondingly later and more externally and rostrally located contingents of pontocerebellar neurons. Thus, we propose that the topographical organization in the early postnatal corticopontine projections determined by simple temporal and spatial gradients operative within source cerebra cortex and target region (pontine nuclei). © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903610107

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have examined the subependymal region of the diencephalic third ventricle in notothenioid perciforms and report a pattern of neuropil expansions that appears to be phyletically derived for notothenioids and their outgroups but that is otherwise unique among vertebrates. We recognize five types of expansions based on their composition (from less dense neuropil to sacs) and width or protrusion into the third ventricle. In the species with the most elaborate morphology,Trematomus bernacchii, bilateral subependymal expansions fuse along the midline to form a single sac within the ventricular cavity. The extent of these expansions loosely corresponds with phyletic position but also (and perhaps more importantly) is correlated with the habitation of cold water (r2= 0.48;P= 0.012). Furthermore, subependymal expansion type is positively correlated with the maximum size of the soma of neurons in two hypothalamic nuclei, the preopticus magnocellularis (r2= 0. 54;P= 0. 006) and the lateralis tuberis (r2= 0.40;P= 0.038). These nuclei project to the pituitary and contain cerebrospinal fluid‐contacting neurons. In considering the functional consequences of this morphology, we cannot dismiss the possibility that these structures form a specialized enteroceptive system tied to the monitoring of cerebrospinal and extracellular fluid components, including antifreeze glycopeptides and inorganic ions. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903610108

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAlthough the cat visual system has been the subject of intensive investigation, little attention has been given to the morphological features of ganglion cell projections to the suprachiasmatic nucleus. The present study has utilized anterograde transport of horseradish peroxidase and wheat germ agglutinin–conjugated horseradish peroxidase to label ganglion cell terminals in the cat suprachiasmatic nucleus. Visualization of the reaction product was facilitated through the use of gold‐substituted silver intensification. Ganglion cell terminals were found to be morphologically diverse, making both asymmetric and symmetric contacts with postsynaptic processes. Synaptic vesicles were either scattered or densely packed, sometimes forming paracrystalline arrays. In contrast to other retinorecipient areas in which ganglion cell terminals have, been characterized by the presence of lightly staining mitochondria, many of the retinal terminals in the suprachiasmatic nucleus were seen to contain darkly stained mitochondria. Postembedding antiglutamate immunocytochemistry was used to evaluate the level of endogenous glutamate in these ganglion cell terminals. Although morphologically diverse, all of the retinal terminals in the suprachiasmatic nucleus were glutamate positive, consistent with the postulated role of glutamate as the neurotransmitter of retinal ganglion cells. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903610109

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the rat, callosal cells occupy lateral as well as medial portions of striate cortex. In the region of the border between areas 17 and 18, which contains a representation of the vertical meridian of the visual field, cells projecting through the corpus callosum are concentrated throughout the depth of the cortex. In contrast, in medial portion of striate cortex, where peripheral portions of the visual field are represented, callosal cells are preferentially found in infragranular layers. These differences in topography and laminar distribution suggest that these callosal regions, referred to as medial and lateral callosal regions in the present study, subserve different functions. We explored this possibility by analyzing the patterns of callosal linkages in these two cailosai regions. We charted the location of retrogradely labeled cells within striate cortex of one hemisphere after placing restricted injections of one or more fluorescent tracers into selected sites in the contralateral striate cortex.We found the medial and lateral callosal regions have distinctly different topographic organizations. Injections into medial striate cortex of one hemisphere produced labeled cells predominantly in mirror‐symmetric loci in medial portions of contralateral striate cortex. The arrangement of these connections suggests that they mediate direct interactions between cortical regions representir visual fields located symmetrically on opposite sides of the vertical meridian of the visual field. In contrast, the mapping in the lateral callosal region is reversed: injections into the 17/18a border produced labeled fields locatedmedialto the contralateral 17/18a border, while injections slightly medial to the 17/18a border produced labeled fields located at the contralateral 17/18a border. Assuming that lateral striate cortex represents aportion of the ipsilateral visual field, this reversal in the callosal mapping suggests that callosal fibers in the lateral callosal region interlink cortical loci representing similar portions of the visual field. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903610110

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractLewis and Olavarria ([1995] J. Comp. Neurol. 361:119–137) showed that the mediolateral organization of callosal linkages differs markedly between medial and lateral regions of striate cortex in the rat. Thus, callosal fibers originating from medial regions of striate cortex interconnect loci that are mirror‐symmetric with respect to the midsagittal plane. In contrast, fibers from lateral regions of striate cortex show a reversed pattern of connections: tracer injections into the 17/18a border produce retrograde cell labeling in regionsmedialto the contralateral 17/18a border, whereas injections placed somewhat medial to the 17/18a border label cells locatedatthe contralateral 17/18a border.Based on the interpretation that callosal fibers from lateral striate cortex connect retinotopically corresponding loci (Lewis and Olavarria [1995] J. Comp. Neurol. 361:119–137) we propose here that the development of the reversed pattern of connections in lateral portions of striate cortex is guided by activity‐dependert cues originating from spontaneously active ganglion cells in temporal retina. In the present study we have attempted to falsify this hypothesis by investigating the effects of neonatal bilateral enucleation on the organization of callosal linkages in striate cortex of the rat.Once enucleated rats reached adulthood, we studied the mediolateral organization of callosal connections by placing small injections of different fluorescent tracers into different loci within medial and lateral striate cortex. The analysis of the distribution of retrogradely labeledcallosal cells indicated that connections from lateral portions of striate cortex were no longer organized in a reversed fashion, rather, they resembled the mirror image pattern normally found in the medial callosal region, i. e., injections at the 17/18a border produced labeled cells at the opposite 17/18a border, whereas injections into slightly more medial regions produced labeled cells in the opposite, mirror‐symmetric location. In addition, we found that enucleation does not alter the organization of callosal linkages in medial portions of striate cortex.Thus, by showing that enucleation significantly changes the pattern of connections from lateral portions of striate cortex, the present study does not falsify, but rather strengthens the hypothesis that interhemispheric correlated activity driven from the temporal retinal crescent guides the normal development of reversed callosal linkages in lateral portions of rat striate cortex. Furthermore, the present study shows that, in the absence of the eyes, the pattern of callosal linkages in lateral portions of striate cortex resembles the mirror image pattern normally found only in medial striate cortex. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903610111

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY