摘要:

AbstractIt has been proposed that the neurotoxic action of kainic acid is a result of the seizure activity which it induces. In this study intraventricular injection of kainic acid, and three other putative neurotoxins, was used in an attempt to investigate the role of electrical seizure activity and neurotoxicity in the rat hippocampus, Two separate groups of experiments were performed. First,&histological study of the neurotoxic potency of the compounds under investigation was carried out, and second, an electrophysiological study of those compounds which displayed neurotoxicity. In these experiments, extracellular recordings were made in the hippocampus ipsilateral to infusion during and after administration of the neurotoxin.Kainic acid (5.0 μg) produced unilateral lesions of the CAB and C A4/ hilus cells of the hippocampus, but CA1 and granule cells remained intact. Electrical seizure activity could be recorded from both CS3 and CA1 regions after kainic acid infusion. Dihydrokainic acid displayed no neurotoxicity. α‐ketokainic acid (5.0 μg) only produced minor toxic effects such as small areas of pyknosis, but electrical seizure activity was produced in both CA3 and CA1 cell regions. Cis 1‐amino 1,3‐dicarboxycyclopentane (cis‐ADCP), (5.0 μg) produced unilateral lesions of the CA3 area without any extension into the CA4/hilus cell layer. There was no electrical seizure activity associated with the action of this compound.These results show that the presence of seizure activity in the hippocampus is not invariably followed by loss of pyramidal cells. As cis‐ADCP produces a discrete lesion in the absence of any seizure activity, this compound may prove to be a more useful neurotoxin for producing experimental models of disease states in the central n

ISSN:0092-7317    

DOI:10.1002/cne.902110202

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe cytoarchitecture of the dorsal cochlear nucleus (DCN) was compared in 3‐ and 26‐month‐old C57BL/6 mice. The effects of genetically controlled progressive hearing loss present in the CNS in this mouse strain were analyzed with Nissl‐stained and Golgi‐impregnated material. The DCN was divided into the superficial molecular, an intermediate fusiform‐granule, and the deep polymorphic layers. The molecular layer (ML) consisted of many fibers and a few small ovoid to spherical, fusiform, and granule cells. The fusiform‐granule layer (FL) contained large fusiform and many granule cells. Most FL fusiform cells were oriented with their long axes perpendicular to the DCN surface and were present as small aggregations or individually. Cartwheel cells were adjacent to the FL fusiform cells. The deep polymorphic layer (PL) contained spherical, fusiform, granule, and multipolar neurons. The granule cells formed a dorsal cap of the DCN. From this cap, sheets of granule cells separated the DCN from the posterior ventral cochlear nucleus (PVCN) and from the brainstem.The internal organization, neuronal location, orientation, and morphology were similar in both age groups. The granule cells had four to five primary dendrites, varicosities, and few to no dendritic appendages. The FL fusiform cells displayed different dendritic morphology in the two ages. One or two elaborate primary ML apical dendrites in the 3‐month‐old mice were covered with spikelike dendritic spines. The basal one or two PL dendrites were less elaborate and had few dendrite spines. In contrast, FL fusiform neurons in 26‐month‐old mice had regular dendritic varicosities and fewer spines which were short and stumpy. Basal dendrites had varicosities and interruptions. Cartwheel neurons in 3‐month‐old mice had elaborate ML dendritic trees covered with dendritic spines. In 26‐month‐old mice the dendrites had many varicosities and fewer short blunted dendritic spines. Large multipolar neurons in older mice had thinner dendrities with more varicosities than were in the 3‐mcnth group. In both age groups multipolar cells had few dendritic spines limited distally. Small and large spherical cells had two to five primary dendrites with varicosities, little higher‐order branching, and spines. Fusiform cells had one or two primary dendrites, little secondary branching, and few to no spines. Minor degenerative changes were noted in spherical and fusiform cells in the two age groups. These included dendritic varicosities, interruptions, and some irregularities of somata surface. Degenerative changes present in the cochlea had significant effects on a limited population of DCN neurons. Finally, the neusronal morphology and architecture of the DCN in C57BL/6 mouse is s

ISSN:0092-7317    

DOI:10.1002/cne.902110203

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe electrosensory system of weakly electric gymnotiform fish is described from the receptor distribution on the body surface to the termination of the primary afferentsin the posterior lateral line lobe (PLLL). There are two types of electroreceptor(ampullary and tuberous) and a single type of lateral line mechanoreceptor (neuromast). Receptor counts in Apteronotus albifronsshow that (1) neuromasts are distributed as in other teleosts; (2) ampullary receptors number 151 on one side of the head and 208 on one side of the body; (3) tuberous receptors were estimated to number 3,000‐3,500 on one side of the head and 3,500‐5,000 on one side of the body. The distribution of each receptor type is described.Each receptor is innervated by a single primary afferent. Electro‐sensory afferents have myelinated cell bodies in the ganglion of the anterior lateral line nerve (ALLN). The distribution of these ganglion cell diameters is strongly bimodal inApteronotus and Eigenmannia: The smaller‐diameter cells may be those which innervate ampullary electroreceptors, the larger‐diameter tuberous electroreceptors.Transganglionic HRP transport techniques were used to determine the first‐order connections of the anterior lateral line nerve in six species of gymnotiform fish. Small branches of the ALLN were labeled so as to determine the somatotopic organization in the PLLL. The PLLL is divided into four segments from medial to lateral, termed medial, centromedial, centrolateral, and lateral segments (Heiligenberg and Dye, '81). Representations of the head are found rostrally in each zone, and the trunk is mapped caudally in each zone. Thus there are four body maps in the PLLL. The medial segment receives ampullary input (Heiligenberg and Dye, '82) and maps the dorsoventral body axis mediolaterally, as does the tuberous centrolateral segment. The tuberous centromedial and lateral segments map the dorsoventral axis lateromedially. Thus the medial and centromedial segments meet belly to belly, the centromedial and centrolateral segments meet back to back, and the centrolateral and lateral segments meet belly to belly. Adjacent electrosensory maps within the PLLL are therefore always mi

ISSN:0092-7317    

DOI:10.1002/cne.902110204

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe posterior lateral line lobe (PLLL) of gymnotoid fish has efferent projections to two midbrain regions: the nucleus praeeminentialis dorsalis (n.P.d.) and the torus semicircularis dorsalis (T.Sd.). Both ipsilateral and contralateral connections are present; the n.P.d. receives nearly equal input from both sides while the T.Sd. receives a stronger contralateral input. The PLLL projection to n.P.d. merely maps medial PLLL to ventral n.P.d. and lateral PLLL to dorsal n.P.d., thus preserving the separate topography and relative orientation of the four electrosensory maps found in the PLLL. Only PLLL pyramidal cells (basilar and nonbasilar pyramids) contribute to this projection. The four PLLL electrosensory maps converge onto T.Sd. so that they map the dorsal body surface onto medial T.Sd. and the ventral body surface onto lateral T.Sd. Pyramidal cells, spherical cells, and multipolar cells contribute to this projection.A small commiusural connection links homologous segments of the PLLL; these fibers arise from polymorphic cells of the PLLL.

ISSN:0092-7317    

DOI:10.1002/cne.902110205

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractInjections of trkiated proline and horseradish peroxidase were used to study cortical connections of striate cortex in owl monkeys. All cases resulted in label in area 18 (V‐II) and the middle temporal visual area (MT). In most, but not all cases, label was also present in the dorsomedial visual area (DM). The connections between striate cortex and each of these three visual areas were retinotopic and reciprocal. Projections to V‐II, MT, and DM were concentrated in layers IV and III, while pyramidal cells in layers III, V, and VI of these areas projected back to striate cor

ISSN:0092-7317    

DOI:10.1002/cne.902110206

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractMicroelectrode multiunit mapping techniques were used to determine the somatotopic organization of postceritral parietal cortex in the squirrel monkeySaimiri sciurus.Recordings were largely confined to architectonic areas 3b and 1. Results were compared to those from similar studies of owl (Merzenich et al., '78) and macaque (Nelson et al., '80) monkeys. As in these previous investigations, separate representations of the body surface were found in areas 3b and 1 of squirrel monkeys. These representations were organized in parallel, so that both proceeded from the tail on the medial wall of the cerebral hemisphere, to the lips and oral cavity on the lateral margin of these areas along the sylvian fissure. The representations were also roughly mirror images of each other so that whatever skin surface was represented rostrally in area 3b was represented caudally in area 1, and similar skin surfaces were represented along the common border. However, the representations were not identical. For example, the split representations of the leg differed so that the distal leg was represented in cortex lateral to that devoted to the foot in area 1 and medial to the foot in area 3b. Remarkably, the representations of some body parts were reversed in orientation in both area 3b and area 1 in squirrel monkeys as compared to owl and macaque monkeys. The face, arm, trunk, and leg representations were all reversed in squirrel monkeys, while the orientations of the hand and foot representations were the same. For example, the dorsal trunk is represented rostrally in area 3b and caudally in area 1 and the ventral trunk is represented at the 3b/l border in owl and macaque monkeys, while the ventral trunk is represented rostrally in area 3b and caudally in area 1 and the dorsal trunk is represented at the 3b/1 border in squirrel monkeys. These reversals of somatotopic organization in part but not all of the representations in areas 3b and 1 suggest that both fields are divided into sectors where the basic somatotopic orientation is independently determined, that the orientation of some of these sectors is subject to reversal in evolution, and that matching sectors in areas 3b and 1 are not independent in somatotopic organization.

ISSN:0092-7317    

DOI:10.1002/cne.902110207

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractProjections of the middle temporal visual area, MT, and of visual cortex adjoining MT were investigated with autoradiographic methods in the prosimian primate,Galago senegalensis.Ipsilateral cortical targets of MT included area 17, area 18, cortex caudal to MT, cortex ventral to MT, and parietal‐occipital cortex dorsal to MT. This pattern of projections suggests that extrastriate cortex contains a number of visual subdivisions in addition to MT. Contralateral projections were to MT and parietal‐occipital cortex. Projections from MT to areas 17 and 18 connected regions representing similar parts of the visual hemifield while the location of callosal projections in MT matched the location of the injection site in the other hemisphere. Label in area 17 wac concentrated in layers I, III, and VI whereas other cortical areas were most densely labeled in the granular and supragranular layers. Subcortical projections of MT included the reticular nucleus of the thalamus, the lateral posterior nucleus, the superior pulvinar, the inferior pulvinar, the superior colliculus, and the pontine nuclei. The projection pattern to the superior and inferior pulvinar nuclei suggests that MT projects in a topographic manner to two subdivisions within each of these structures.Injections in cortex just outside of MT labeled area 18, inferotemporal cortex, parietal‐occipital cortex, and, to a lesser extent, MT. The projections to inferotemporal cortex clearly distinguish the bordering cortex from MT. Contralateral cortical terminations were in locations corresponding to the injection site. Subcortical targets were generally similar to those seen after MT injections, although additional projections were observed depending on the location of the injection.Comparison of these results from the prosimian galago with studies in New and Old World monkeys indicates there are substantial similarities in projections. Thus, some of the cortical and thalamic subdivisions described for monkeys appear to exist in prosi

ISSN:0092-7317    

DOI:10.1002/cne.902110208

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902110209

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902110201

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY