摘要:

AbstractTo determine the organizational principles underlying the peripheral electrosensory nervous system of weakly electric gymnotiform teleosts we labelled each of the four anterior lateral line nerve branches with HRP. We determined the position of labelled cell bodies within the ganglion and followed anterogradely filled fibers to their termination sites in one of the four somatotopic maps in the electroreceptive lateral line lobe (ELL). Within the ganglion, cell bodies exhibit a loose somatotopy based on nerve branch position: trunk electroreceptors have their cell bodies located in the caudal ganglion; cell bodies to the head receptors are rostral. Cell bodies to the head exhibit a rough dorsoventral polarity, supraorbital cells tend to be located dorsally, infraorbital cells centrally, and mandibular cells ventrally. Despite this general somatotopy there is substantial overlap (up to 30%) of cell bodies among regions. There appears to be no rostrocaudal topography within nerve branch regions. Iontophoretic WGA‐HRP injected into the medial segment of the ELL retrogradely labelled cell bodies that innervate ampullary organs. These cell bodies were dispersed throughout the ganglion, indicating that cell bodies do not cluster by receptor type. Peripherally directed axons from the ganglion appear to undergo an active reorganization in order to form the nerve branches. Within nerve branches, axons to a particular area of skin do not cluster together.Centrally from the ganglion, axons retain the position of their cell body until they reach the ELL border. Once in the ELL, fibers become sorted in the deep fiber layer according to receptor type and the map they terminate in. This reorganization involves rearrangement of fascicles and axons within fascicles. In toto, proceeding from peripheral to central, the electrosensory periphery loses at least a portion of its receptor topography in the distal nerve and ganglion and then acquires both a functional and somatotopic organization after reaching the ELL; conceptually it is torn down and rebuilt again. From an ontogenetic perspective, axonal growth occurs from the ganglion outward; the fact that ganglion cell bodies are not highly organized while the receptors they innervate and their central processes are suggests that active axonal guidance mechanisms are involve

ISSN:0092-7317    

DOI:10.1002/cne.902800302

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe efferent projection from the rostral cortices of the temporal lobe to the magnocellular division of the medial dorsal nucleus (MDmc) was studied in the rhesus monkey (Macaca mulatta). The temporal pole region contains four architectonically defined cortical divisions. Medially, the allocortex of the temporal limb of the pyriform cortex is annexed to the temporal lobe neocortices at the limen insulae. Two transitional neocortices, the periallocortical and proisocortical divisions, are situated subjacent to the pyriform area. They make up the largest part of the temporal tip and separate the pyriform cortex from the architecturally more progressive isocortical divisions of the pole found laterally at the rostral ends of the superior and inferior temporal gyri. Neuroanatomical tracers were injected into each of the major divisions of the temporal pole cortex, and the injection site locations were characterized cytoarchitectonically as well as geographically. Injections of tritiated amino acids into pyriform allocortex or into the transitional neocortical fields revealed an efferent projection to the magnocellular medial dorsal nucleus. The terminal field was characterized by a mosaic type of organization and contained discrete zones of axonal termination in which bursts of coarse label surrounded neuronal perikarya and their proximal dendrites. A similar projection was also observed when horseradish peroxidase was injected into the transitional cortices. However, perikarya participating in the terminal clusters were not retrogradely labeled. Intracortical injections restricted to lateral polar isocortex did not result in either anterograde or retrograde transport of label to MDmc. These findings demonstrate a nonreciprocal, corticofugal pathway to MDmc that originates in the phylogenetically older districts of the temporal pole. The conduction of limbic sensory information directly from temporal neocortex to the medial thalamus may play a fundamental role in human and primate memory.

ISSN:0092-7317    

DOI:10.1002/cne.902800303

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractLigands that are highly specific for the mu, delta, and kappa opiate receptor binding sites in mammalian brains have been identified and used to map the distribution of these receptor types in the brains of various mammalian species. In the present study, the selectivity and binding characteristics in the pigeon brain of three such ligands were examined by in vitro receptor binding techniques and found to be similar to those reported in previous studies on mammalian species. These ligands were then used in conjunction with autoradiographic receptor binding techniques to study the distribution of mu, delta, and kappa opiate receptor binding sites in the forebrain and midbrain of pigeons. The autoradiographic results indicated that the three opiate receptor types showed similar but not identical distributions. For example, mu, delta, and kappa receptors were all abundant within several parts of the cortical‐equivalent region of the telencephalon, particularly the hyperstriatum ventrale and the medial neostriatum. In contrast, in other parts of the cortical‐equivalent region of the avian telencephalon, such as the dorsal archistriatum and caudal neostriatum, only kappa receptors appeared to be abundant. Within the basal ganglia, all three types of opiate receptos were abundant in the striatum and low in the pallidum. Within the diencephalon, kappa and delta binding was high in the dorsal and dorsomedial thalamic nuclei, but the levels of all three receptor types were generally low in the specific sensory relay nuclei of the thalamus. Kappa binding and delta binding were high, but mu was low in the hypothalamus. Within the midbrain, all three receptor types were abundant in both the superficial and deep tectal layers, in periventricular areas, and in the tegmental dopaminergic cell groups.In many cases, the distribution of opiate receptors in the pigeon forebrain generally showed considerable overlap with the distribution of opioid peptide‐containing fiber systems (for example, in the striatal portion of the basal ganglia), but there were some clear examples of receptor‐ligand mismatch. For example, although all three receptor types are very abundant in the hyperstriatum ventrale, opioid peptide‐containing fibers are sparse in this region. Conversely, within the pallidal portion of the basal ganglia, opioid peptide‐containing fibers are abundant, but the levels of opiate receptors appear to be considerably lower than would be expected. Thus, receptorligand mismatches are not restricted to the mammalian brain, since they are a prominent feature of the organization of the brain opiate systems in pigeons. Although the precise functional significance of such mismatches will require further elucidation, it nonetheless appears likely that the endogenous opioid peptides of the avian brain act through the opiate receptors whose distribution is described in the pr

ISSN:0092-7317    

DOI:10.1002/cne.902800304

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe laminar and areal distribution of neuropeptide Y (NPY)‐containing perikarya and their processes was analyzed immunocytochemically in Brodmann's neocortical areas 17, 18, 7, 22, 3, 4, 24, and 9 (Walker's area 46) in seven macaque monkeys. Most NPY‐containing cells are distributed in two broad bands in layers II–III and V–VI in all areas; relatively few cells can be found in layer I and virtually none in layer IV. Numerous NPY‐containing cells are situated in the white matter immediately subjacent to the cortical gray. Severalfold regional and individual differences in the density of NPY‐positive somata were found in supra‐ and infragranular layers. However, the interareal variations in the density of NPY‐containing somata do not conform to a universal pattern, because of either individual variability or inherent difficulties in standardizing immunocytochemical labeling. In contrast, the laminar differences in the distribution of NPY‐containing axons among cortical areas are consistent in all animals. In general, primary sensory and motor areas have a lesser density of NPY‐containing axons than association and limbic areas. Within this general pattern, area‐specific laminar segregation of NPY‐containing axons occurs. The regional differences in the distribution of NPY‐like immunoreactivity in the neocortex may reflect innate characteristics of local neuronal circuits serv

ISSN:0092-7317    

DOI:10.1002/cne.902800305

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe avidin‐biotin‐peroxidase method was used at the light and electron microscopic levels to analyze neuropeptide Y (NPY)‐containing neurons in the neocortex of six adult macaque monkeys. Regions studied included various sensory, motor, limbic, and association areas, designated as 17, 18, 7, 22, 3, 4, 6, 24, and 9 by Brodmann (Beiträge zur Histologischen Lokalisation der Grosshirnrinde. Leipzig: Barth, '06). Several types of NPY‐containing neurons can be distinguished by their laminar location, by the size of their perikarya, and by the size, shape, and pattern of ramification of their processes: (1) layer I small local circuit neurons; (2) layer II granule cells; (3) aspiny stellate cells located in layers II–III and V–VI, with long, slender dendrites; (4) sparsely spiny stellate cells; (5) aspiny stellate cells with long, horizontally oriented dendrites, whose cell body is situated in layer VI; (6) Martinotti cells in areas 9, 7, and 24; and (7) multipolar neurons situated in the white matter subjacent to the cortical gray. The possibility of additional neuronal types containing NPY is suggested by labeled densely spinous dendrites in area 6 and recurving axons and axonal loops in the supragranular layers in areas 7 and 9. No NPY‐containing neurons were found in layer IV of any area, except layers IVA and B of the visual cortex. Likewise, nonneuronal elements were not labeled. The regional differences in the distribution of some NPY‐containing neuron types may reflect adaptations of local neuronal circuits for speci

ISSN:0092-7317    

DOI:10.1002/cne.902800306

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution and morphology of adenosine deaminase, substance P, leucine‐enkephalin, corticotropin‐releasing factor, and calcitonin gene‐related peptidelike immunoreactive cells and fibers throughout the superior colliculus of the rat were examined by means of the unlabelled‐antibody peroxidase‐antiperoxidase method. Adenosine deaminase immunoreactive cells were found in the stratum opticum and lower stratum griseum superficiale; substance P immunoreactive cells were localized to the upper stratum griseum superficiale, and calcitonin gene‐related peptide immunolabelled neurons were situated in deeper strata. Substance P, leucine‐enkephalin, and calcitonin gene‐related peptide immunoreactive fibers were distributed similarly in their lamination and in their patchlike organization. Corticotropin‐releasing factor immunoreactive fibers were observed evenly throughout all the strata and were fewer in the stratum griseum superficiale.These findings suggest that, as in afferent modules and segregated efferents of the mammalian superior colliculus, the cells and fibers containing neuroactive substances and neuroactive substance‐related enzymes also show a segregated and l

ISSN:0092-7317    

DOI:10.1002/cne.902800307

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis study, which uses immunocytochemical methods at the light microscopical level, examines the cell types in the turtle retina that contain corticotropin‐releasing factor (CRF)‐like immunoreactivity. Two anatomically distinct amacrine cell types are labeled when antiserum directed against ovine CRF is used to label the turtle retina. These cell types each have a different dendritic arborization pattern and regional distribution. Type A cells are found only in the visual streak and have elongated dendritic arborizations that run parallel to the visual streak. These cells arborize primarily in stratum 1 and near the border of strata 2 and 3, with some processes extending into stratum 5. Type B amacrine cells are found only ventral to the visual streak and arborize primarily in a wide band in strata 4 and 5 with sparse dendritic arborizations in stratum 1. No labeled amacrine cells of any type were found dorsal to the visual streak. The asymmetric dendritic arborizations of the type A amacrine cells and the different regional distributions of the A and B cell types suggest that these two amacrine cell types perform distinct physiological functions.In addition to these labeled amacrine cells, there are also some immunoreactive cell bodies in the ganglion cell layer. Rhodamine crystals were applied to the optic tectum to retrogradely label the ganglion cell bodies. Double label studies indicate that some of the rhodamine‐labeled ganglion cells also contain CRF‐like immunoreactivity. The localization of CRF‐like immunoreactivity in two distinct amacrine cell types and in ganglion cells suggests that it may play multiple roles in visual processing in the turt

ISSN:0092-7317    

DOI:10.1002/cne.902800308

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe localization of neutral endopeptidase‐24.11 (E.C. 3.4.24.11; enkephalinase) in rat spinal cord was investigated by a novel fluorescent histochemical method. Enkephalinase was localized by using a coupled enzyme assay based upon the sequential cleavage of the synthetic peptide substrate glutaryl‐ala‐ala‐phe‐4‐methoxy‐2‐naphthylamide by enkephalinase and exogenous aminopeptidase M. Enzyme distribution was examined in segments from cervical, thoracic, lumbar, and sacral cord.At all spinal cord levels, enkephalinase was localized to discrete regions of the gray matter. The substantia gelatinosa displayed rich enkephalinase staining which overlapped the inner and outer zones of lamina II. A staining pattern similar to that observed in lamina II was observed in the spinal trigeminal nucleus in the medulla. In lamina III the enzyme was associated with small and medium‐sized cells. Lamina IV showed staining associated with medium‐sized and large cell bodies. The medial boundary of the dorsal gray of laminae IV and V had medium‐sized fusiform cells which stained for enkephalinase. In the lateral reticulated areas of lamina V, enkephalinase reaction product was localized to scattered medium‐sized and large cells compressed against the white matter of axon bundles. Staining in lamina VI was similar in appearance to lamina V. Enkephalinase reaction product was widely distributed in the ventral horn. Numerous ventral horn motor neurons of varied size and morphology in laminae VIII and XI stained richly for the enzyme. The enzyme was also localized to medium‐sized and large cells in lamina X and to cells of the central cervical nucleus.The size and morphology of the cell types associated with the enzyme supported a neuronal association for enkephalinase. The regional distribution of the enzyme overlapped that of enkephalin‐ and substance‐P rich regions of the spinal cord. These findings support a role for enkephalinase in the metabolic regulation of c

ISSN:0092-7317    

DOI:10.1002/cne.902800309

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe biochemical characterization and anatomical distribution of somatostatin binding sites were examined in the brain of the frogRana ridibunda, and the distribution of the receptors was compared with the location of somatostatin immunoreactive neurons. The pharmacological profile of somatostatin receptors was determined in the frog brain by means of an iodinated superagonist of somatostatin, [125I‐Tyr0,DTrp8]S‐14. Membrane‐enriched preparations from frog brain homogenates were shown to contain high‐affinity receptors (KD= 0.78 ± 0.34 nM; Bmax = 103 + 12.7 fmoles /mg protein) with pharmacological specificity for [DTrp] substituted S14 and S28 analogs. The distribution of somatostatin‐binding sites was studied by autoradiography on coronal sections of frog brain. Various densities of somatostatin receptors were detected in discrete areas of the brain. The highest concentration of binding sites was observed in the olfactory bulb, in the pallium, and in the superficial tectum. Moderate binding was observed in the striatum, amygdaloid complex, preoptic area, and cerebellum.Immunocytochemical studies of the distribution of somatostatin‐28 (S28) related peptides were also conducted in the frog brain. Two antisera that recognize distinct epitopes of the somatostatin molecule have been used for immunohistochemical mapping of the peptide. Antiserum SS9 recognizes both S28 and somatostatin‐14 (S14) and allowed the labelling of perikarya. Antiserum S320 recognizes the N‐terminal fragment (1–12) resulting from enzymatic cleavage of S28. This latter antiserum, which does not cross‐react with S28, stained mainly neuronal processes. At the infundibular level, however, both antisera stained cell bodies and fibers. Immunoreactive somatostatin‐related peptides were detected in many areas of the frog brain. In the diencephalon, a heavy accumulation of perikarya and fibers was seen in the preoptic nucleus, the dorsal and ventral infundibular nuclei, and the median eminence. Immunoreactive perikarya were also observed in the telencephalon, especially in the pallium and in thalamic nuclei. Immunostained processes were detected in many telencephalic areas and in the tectum.There was good correlation between the distribution of somatostatin‐immunoreactive elements and the location of somatostatin‐binding sites in several areas of the brain, in particular in the median pallium, the tectum, and the interpeduncular nucleus. In contrast, mismatching was observed in the olfactory bulb, lateral pallium, and the cerebellum (which contained moderate to high levels of binding sites but virtually no somatostatin‐immunoreactive fibers) and the hypothalamic areas (preoptic area and infundibular nuclei), in which a low concentration of binding sites but a high density of immunoreactive perikarya and fibers were detected.The present data provide the first pharmacological characterization and anatomical distribution of somatostatin‐binding sites in the brain of a non‐mammalian vertebrate species. The present results suggest that many of the major features of somatostatinergic systems described in mammals (e.g., the wide distribution of somatostatinergic neurons and somatostatin‐binding sites; pharmacological characteristics of somatostatin receptors) had already arisen in tetrapod ancestors. Such findings suggest that both neuroendocrine and extrahypothalamic somatostatinergic systems have important function

ISSN:0092-7317    

DOI:10.1002/cne.902800310

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractRecent cytoarchitectonic, histochemical, and hodological studies in primates have shown that area 6 is formed by three main sectors: the supplementary motor area, superior area 6, which lies medial to the spur of the arcuate sulcus, and inferior area 6, which is located lateral to it. Inferior area 6 has been further subdivided into two histochemical areas: area F5, located along the inferior limb of the arcuate sulcus, and area F4, located between area F5 and area 4 (area F1).The present study traced the thalamocortical projections of inferior area 6 and the adjacent part of area 4 by injecting small amounts of WGA‐HRP in specific sectors of the agranular frontal cortex.Our data showed that each histochemical area receives a large projection from one nucleus of the ventrolateral thalamus (motor thalamus) and additional projections from other nuclei of this thalamic sector. Area F5 receives a large projection from area X of Olszewski ('52) and additional projections from the caudal part of the nucleus ventralis posterior lateralis, pars oralis (VPLo), and the nucleus ventralis lateralis, pars caudalis (VLc) (VPLo‐VLc complex). Area F4 receives a large projection from the nucleus ventralis lateralis, pars oralis (VLo), and additional projections from area X and the VPLo‐VLc complex. The rostral part of area F1 is innervated chiefly by VLo, plus smaller contributions from rostral VPLo and the VPLo‐VLc complex. The caudal part of F1 receives its greatest input from VPLo, with a small contribution from VLo. In addition, each histochemical area receives projections originating from the intralaminar thalamic nuclei, the posterior thalamus, and–for area F4 and area F5–also from the nucleus medialis dorsalis (MD).Analysis of the physiological properties of the various histochemical areas in relation to their main thalamic input showed that those cortical fields in which distal movements are predominant (area F5, caudal part of area F1) are innervated chiefly by area X and VPLo, wheras those cortical fields in which proximal movements are predominant receive their main input from VLo. Because VPLo and area X are targets of cerebellothalamic pathways, whereas VLo receives a pallidal input, we propose that the cortical fields in which distal movements are most heavily represented are mainly under the influence of the cerebellum, whereas the cortical fields in which proximal movements are most heavily represented are mainly under the influence of the ba

ISSN:0092-7317    

DOI:10.1002/cne.902800311

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY