摘要:

AbstractNeuropsychological studies have recently demonstrated that the macaque monkey perirhinal (areas 35 and 36) and parahippocampal (areas TH and TF) cortices contribute importantly to normal memory function. Unfortunately, neuroanatomical information concerning the cytoarchitectonic organization and extrinsic connectivity of these cortical regions is meager. We investigated the organization of cortical inputs to the macaque monkey perirhinal and parahippocampal cortices by placing discrete injections of the retrograde tracers fast blue, diamidino yellow, and wheat germ agglutinin conjugated to horseradish peroxidase throughout these areas. We found that the macaque monkey perirhinal and parahippocampal cortices receive different complements of cortical inputs. The major cortical inputs to the perirhinal cortex arise from the unimodal visual areas TE and rostral TEO and from area TF of the parahippocampal cortex. The perirhinal cortex also receives projections from the dysgranular and granular subdivisions of the insular cortex and from area 13 of the orbitofrontal cortex. In contrast, area TF of the parahippocampal cortex receives its strongest input from more caudal visual areas V4, TEO, and caudal TE, as well as prominent inputs from polymodal association cortices, including the retrosplenial cortex and the dorsal bank of the superior temporal sulcus. Area TF also receives projections from areas 7a and LIP of the posterior parietal lobe, insular cortex, and areas 46, 13, 45, and 9 of the frontal lobe. As with area TF, area TH receives substantial projections from the retrosplenial cortex as well as moderate projections from the dorsal bank of the superior temporal sulcus; unlike area TF, area TH receives almost no innervation from areas TE and TEO. It does, however, receive relatively strong inputs from auditory association areas TE and TEO. It does, however, receive relatively strong inputs from auditory association areas on the convexity of the superior temporal gyrus. © 1994 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903500402

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractCorticotropin‐releasing factor (CRF) and CRF binding sites have been described in the cerebellum of several species, including the North American opossum (Didelphis marsupialis virginiana), the species used in the present study. Iontophoretic application of this peptide in the adult cerebellum enhances the spontaneous and amino acid‐induced firing rate of Purkinje cells and overcomes the GABA‐induced suppression of Purkinje cell activity. The present account provides immunohistochemical evidence for the localization of CRF in the North American opossum within developing axons and their growth cones prior to the formation of the Purkinje cell and granule cell layers. CRF mRNA is present on postnatal day (PD) 1 within the internal migratory stream of the ventral lateral medulla, which contains migrating olivary neurons, and within the ventral medulla in the region, where inferior olivary neurons first aggregate to form the inferior olivary complex. The olivary complex can first be identified on PD2 and is well defined by PD3. CRF‐immunoreactive axons are evident within the cerebellar primordium on PD4 and penetrate the nascent Purkinje cell layer between PD14 and PD26. By PD26, CRF‐immunoreactive puncta are organized within the Purkinje cell layer as parasagittal bands. Thus, olivary neurons express CRF mRNA prior to the time that the first CRF‐labeled axons are present in the cerebellar anlage (PD4), suggesting that olivary axons are among the first to reach the developing cerebellum. Coincident (PD1–3) with the early transcription of CRF mRNA in the inferior olive, cells in the medullary reticular formation (PD1) and locus coeruleus (PD2) also transcribe CRF mRNA. These brainstem sites also could provide CRF‐immunoreactive axons to the developing cerebellum; however, based on the results of this study and correlative data reported in the literature, we propose that the primary source of early‐arriving CRF fibers is the inferior olivary complex. The early arrival of CRF‐containing axons in the cerebellum prior to synaptogenesis and migration of both granule cells and Purkinje cells suggests a role for this peptide in target recognition and synaptic organization. ©

ISSN:0092-7317    

DOI:10.1002/cne.903500403

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractNADPH‐diaphorase‐positive neurons have been demonstrated in the inner nuclear layer and ganglion cell layer of the retina of different mammalian species, but so far no experiments have been conducted to identify whether these cells are amacrine cells and/or retinal ganglion cells. We attempted to solve this problem by studying the NADPH‐diaphorase‐positive neurons in the hamster retina.From the NADPH‐diaphorase histochemical reaction, two distinct types of neurons in the hamster retina were identified. They were named ND(g) and ND(i) cells. The ND(g) cells were cells with larger somata, ranging from 10 to 21 μm in diameter with a mean of 15.58 μm (S.D.= 2.59). They were found in the ganglion cell layer only. The ND(i) cells were smaller, with the somata ranging from 7 to 11 μm and having the mean diameter of 8.77 μm (S.D. = 1.24). Most of the ND(i) cells were found in the inner nuclear layer, and only very few could be observed in the inner plexiform layer. On average, there were 8,033 ND(g) and 5,051 ND(i) cells in the ganglion cell layer and inner nuclear layer, respectively.Two experiments were performed to clarify whether any of the NADPH‐diaphorase neurons were retinal ganglion cells. Following unilateral optic nerve section, which leads to the retrograde degeneration of retinal ganglion cells, the numbers of both ND(g) and ND(i) cells did not change significantly for up to 4 months. In addition, when retinal ganglion cells were prelabeled retrogradely (horseradish peroxidase of flurescent microspheres) and retinas were then stained for NADPH diaphorase, no double‐labeled neurons were detected. These results indicated that the NADPH‐diaphorase neurons in the hamster retina were the amacrine cells in the inner nuclear layer and displaced amacrine cells in the ganglion cell layer.Dendrites of the ND(g) and ND(i) cells were found to stratify in sublaminae 1, 3, and 5 of the inner plexiform layer, with a prominent staining in the sublamina 5. The possible importance of this arrangement in the rod pathway is also discussed. ©

ISSN:0092-7317    

DOI:10.1002/cne.903500404

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractAn antiserum against the cockroach cardioactive peptide corazonin was used to investigate the distribution of immunoreactive neurons and neurosecretory cells in the nervous system of the blowfly,Phormia terraenovae, during postembryonic development. A small number of corazonin‐immunoreactive neurons was found at larval, pupal, and adult stages. At all postembryonic stages two cell groups were found in the protocerebrum of the brain: (1) two lateral cell clusters and (2) two median cells. In the larva eight bilateral cell pairs were found in thoracic and abdominal neuromeres of the fused ventral ganglion. The lateral brain neurons are located in the lateral neurosecretory cell group and extend axons with branches in several components of the retrocerebral neuroendocrine complex, in the stomatogastric nervous system of larvae and adults, and additionally in muscles of the alimentary canal in the adult. The most prominent element of these peripheral processes is a large plexus of varicose fibers located in the wall of the aorta, the main site for the release of neurohormones produced in the brain of blowflies. The presence of corazonin‐immunoreactive material in the aortic plexus suggests that this peptide functions as a neurohormone, During metamorphosis, the immunoreactive neurons found in the thoracic‐abdominal ganglion of the larva disappear, and in the brain new immunoreactive neurons are added to those that persist from larval stages. The bulk of the corazonin‐immunoreactive material extracted from adult brains and corpora cardiaca‐aorta complexes was found to co‐elute with synthetic corazonin in reversed‐phase high‐performance liquid chromatography as monitored with enzyme‐linked immunosorbent assay. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903500405

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe serial homology of arthropods, together with our ability to identify individual neurons from segment to segment, and from animal to animal, provides opportunities for studying the changes wrought by natural selection on specific neural elements when functional requirements change in different parts of the trunk. Using this concept as a guide, we studied the morphology and physiology of the thoracic N‐cells and muscle receptor organs (MROs) of the crayfishCherax destructorfor evidence of serial homology and functional plasticity. Methylene blue staining, together with anterograde and retrograde filling with cobalt through cut axons, revealed the morphology of the receptors, disposition of their endings, and the pathways of their axons from receptor to ganglion. The seventh thoracic segment has tonic and phasic MROs with receptor muscles in parallel with different heads of the deep thoraco‐abdominal extensor muscle. The sixth segment has a tonic MRO with a receptor muscle in parallel with one head of the abdominal abductor. These three receptors are typical MROs complete with accessory nerves. Thoracic segments 1–5 each give rise to one mechanosensory N‐cell with a small cell body and long processes ramifying in a target muscle. N‐cell 5 is associated with the abdominal‐thoracic abductor muscle, and the other four are associated with parts of the epimeral attractor. The responses of N‐cells 1–4 range from tonic to phasico‐tonic and show a range of thresholds to passive muscle stretch and active contraction. Cobalt introduced into bundles of nerve fibers known to include N‐cell axons reveals projections with branching patterns and morphology similar to abdominal MROs. The present findings, together with information on thoracic MROs and N‐cells from other species, were tabulated according to neurotome. The clear pattern revealed leads us to propose that N‐cells are derivatives of segmentally repeating MROs modified to monitor postural and locomotory movements in

ISSN:0092-7317    

DOI:10.1002/cne.903500406

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe present investigation used an antibody directed against the extracellular domain of the signal transducing nerve growth factor recepto, trkA, to reveal immunoreactive perikarya or fibers within the olfactory bulb and tubercle, cingulate cortex, nucleus accumbens, striatum, endopiriform nucleus, septal/diagonal band complex, nucleus basalis, hippocampal complex, thalamic paraventricular and reuniens nuclei, periventricular hypothalamus, interpeduncular nucleus, mesencephalic nucleus of the fifth nerve, dorsal nucleus of the lateral lemniscus, prepositus hypoglossal nucleus, ventral cochlear nucleus, ventral lateral tegmentum, medial vestibular nucleus, spinal trigeminal nucleus oralis, nucleus of the solitary tract, raphe nuclei, and spinal cord. Colocalization experiments revealed that virtually all striatal trk‐Aimmunoreactive neurons (>99%) coexpressed choline acetyltransferase (ChAT) but not p75 nerve growth factor receptor (NGFR). Within the septal/diagonal band complex virtually all trkA neurons (>95%) coexpressed both ChAT and p75 NGFR. More caudally, dual stained sections revealed numerous trkA/ChAT (>80%) and trkA/p75 NGFR (>95%) immunoreactive neurons within the nucleus basalis. In the brainstem, raphe serotonergic neurons (45%) coexpressed trkA. Sections stained with a pan‐trk antibody that recognizes primarily trkA, as well as trkB and trkC, labeled neurons within all of these regions as well as within the hypothalamic arcuate, supramammilary, and supraoptic nuclei, hippocampus, inferior and superior colliculus, substantia nigra, ventral tegmental area of T'sai, and cerebellar Purkinje cells. Virtually all of these other regions with the exception of the cerebellum also expressed pan‐trk immunoreactivity in the monkey. The widespread expression of trkA throughout the central neural axis suggests that this receptor may play a role in signal transduction mechanisms linked to NGF‐related substances in cholinergic basal forebrain and noncholinergic systems. These findings suggest that pharmacological use of ligands for trkA could have beneficial effects on the multiple neuronal systems that are affected in such disorders as Alzheimer's disease. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903500407

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractNonpyramidal neurons containing the calcium‐binding protein parvalbumin (PV) are one of the inhibitory elements of the hippocampal network. Previous studies have indicated that they are involved in septohippocampal disinhibitory circuits. This study analyzes the commissural and ipsilateral associational afferents of parvalbumin neurons. Injections of the anterograde tracerPhaseolus vulgaris‐leucoagglutinin (PHA‐L) into the hilus of the fascia dentata labeled numerous axons in the molecular layer that established synaptic contacts with parvalbumin‐immunoreactive neurons on both the injection and the contralateral side. Mossy fibers, labeled by injections into the granule cell layer, terminated on parvalbumin neurons in the hilus and in CA3. Injections of PHA‐L into CA3 resulted in a dense labeling of fibers in the hilus and in CA3, CA2, and CA1 on both the injection and the contralateral side. In all these hippocampal fields, PHA‐L‐labeled fibers established asymmetric contacts with PV‐immunoreactive, presumably GABAergic, inhibitory neurons. These observations indicate that parvalbumin‐immunoreactive inhibitory neurons in the hippocampus are targets of presumably excitatory associational and commissural projections and suggest that they are involved in feed‐forward and feed‐back circuits.

ISSN:0092-7317    

DOI:10.1002/cne.903500408

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractRetinal ganglion cells in the turtle,Pseudemys scripta elegans, were examined by intracellular recording with a protocol of stationary and moving lights. Responses were apportioned among OFF, and ON, and ON‐OFF categories, and directional selectivity. Cells were injected with Neurobiotin, then later conjugated with avidin‐horseradish peroxidase in standard procedure. Morphological analysis of the stained cells included measurements of soma and dendritic field sizes, dendritic stratification, number of cell processes, dendritic branchings, and dendritic symmetry ratios.ON and ON‐OFF cells are at least bistratified, sometimes tristratified, in both sublaminae A and B whether directionally selective or not. OFF cells, in contrast, are monostratified, or at least confined to sublamina A.Morphological parameters of somal and dendritic field areas, branch point densities, and dendritic field asymmetries do not predict directional selectivity. Membrane polarization accompanying moving stimulation is discussed in terms of shunting inhibition and recording site. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903500409

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractBoth the nucleus of the optic tract (NOT) and the superior colliculus (SC) are thought to play important roles in the regulation of eye movements. The superior colliculus contributes to visual orientation and saccades, and the nucleus of the optic tract contributes to the detection of slow movements of the visual surround. Recently, a GABAergic projection has been described between these two nuclei in the cat, a species with frontal vision. The present study aimed at determining whether a similar GABAergic pathway exists in the rabbit, a species with lateral vision. To study this pathway we used the retrograde tracer cholera‐toxin (CTB) to identify NOT neurons projecting to the SC and GABA‐antibody immunostaining to identify GABA‐containing neurons and processes.CTB injections into the superficial laminae of the SC showed that GABAergic and non‐GABAergic neurons in the NOT project to the SC. Both types of neurons have structural characteristics similar to other projection neurons in the NOT. In contrast to the NOT neurons projecting to the inferior olive (IO) which are mainly located in the rostral NOT, the GABAergic and non‐GABAergic NOT‐SC neurons are situated throughout the nucleus. The somata and principal dendrites of both neuron types receive numerous synaptic contacts from GABAergic terminals and only a few from retinal terminals. The NOT projection neurons to the SC thus establish prominent excitatory and inhibitory links between the two structures, suggesting the existence of separate circuits that could interact through a GABAergic and non‐GABAergic NOT‐SC projection. It is further suggested that these circuits may be involved in the regulation of saccades in the SC during optokinetic nystagmus. © 1994

ISSN:0092-7317    

DOI:10.1002/cne.903500410

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe macaque red nucleus receives afferents from two major sources, the cerebral cortex and the deep cerebellar nuclei. Approximately 90% of the corticorubral afferent axons project to pars parvicellularis of the red nucleus, the neurons of which transmit information to the cerebellum by way of the inferior olivary nucleus. The remaining 10% project to pars magnocellularis of the red nucleus, the major projection of which is to the spinal cord. In this study, corticorubral terminations labeled following lesions or injections of wheatgerm agglutinin conjugated to horseradish‐peroxidase into the topographically defined hand area of the primary motor cortex were quantitatively studied via electron microscopy. Cortical afferent terminals within pars parvicellularis and pars magnocellularis synapse upon all regions of the dendritic arbors of rubral projection neurons. However, the majority of these labeled afferents synapse upon thin‐diameter shafts or presumed spinous processes of rubral distal dendrites as well as upon vesicle‐containing profiles of presynaptic dendrites of local circuit interneurons that are γ‐aminobutyric acid‐immunoreactive, as identified by postembedding immunohistochemistry. Synaptic contacts formed by the labeled cortical terminal were large in width and extended through several serial sections. Synaptic contacts formed by the presynaptic dendritic profiles, on the other hand, were more punctate and could be seen in only one or two serial sections. These latter synaptic interactions probably provide a modification of the effects of cortical input to rubral projection neurons as suggested by previous physiological studies that indicated the dominance of cortical input onto distal dendrites as well as involvement with inhibitory circuits. An example of the complexities of these synaptic interactions is further demonstrated by a three‐dimensional computer reconstruction. This quantitative study of corticorubral afferents in the macaque monkey provides insight into the interactions of cerebral cortical afferents with rubral projection neurons and their relationship with local circuit inhibitory interneurons to elucidate the role played by the cortex in the activation of rubral neurons. © 1994 Wi

ISSN:0092-7317    

DOI:10.1002/cne.903500411

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY