摘要:

AbstractAn epileptic focus was formed in the anteromedial part of the prefrontal cortex in rats by means of intracortical injection of penicillin, and radioactively labeled deoxyglucose was immediately injected intravenously. Autoradiograms revealed that, in addition to the injected cortical area, a number of formations increased their consumption of deoxyglucose.The labeled formations were the posterior medial and perirhinal cortical areas, the anteromedial part of the neostriatum, the anterior and intermediodorsal part of globus pallidus, the entopeduncular nucleus, the reticular portion of the substantia nigra, the claustrum, and the basolateral nucleus of amygdala. In addition, several thalamic nuclei were activated, including the entire parataenial, paraventricular, anteromedial, and axial nuclei, as well as distinct parts of the mediodorsal and lateral nuclei and, in the instances of spread of cortical activity to the dorsal surface, of the ventral nucleus. In some animals, activation of the ventral tegmental area of Tsai was also found.All these formations have previously been shown by neuroanatomcial techniques to be directly connected with the anteromedial cortex of the neostriatum. Some of them were included in the “prefrontal system.” The present findings, in agreement with earlier neurobehavioral studies, indicate that, in the rat, the anteromedial part of the neostriatum, but not other neostriatal regions, is functionally related to the anteromedial part of the prefrontal cortex.The present and earlier similar studies suggest that the mammalian forebrain contains a number of “systems”, each of which consists of a neocortical area and a set of associated subcortica

ISSN:0092-7317    

DOI:10.1002/cne.901900102

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

年代:1980

数据来源: WILEY

摘要:

AbstractSerotonergic neurons have previously been identified in the enteric nervous systems of humans, subhuman primates, rodents, and rabbits. The distribution of enteric serotonergic neurons in lower vertebrates was examined in order to determine if these neurons are restricted to mammals and, if they are found more generally amongst vertebrates, when they first appear in vertebrate phylogeny. Since mammalian enteric serotonergic neurons take up3H‐serotonin by a highly specific mechanism, the radioautographic demonstration of axonal uptake of3H‐serotonin was used as the primary tool in looking for these neurons. As controls, conditions known to interfere with3H‐serotonin uptake by mammalian enteric neurons were also examined. These controls included incubation with 10 μ fluoxetine, a specific antagonist, incubation in Na+‐free medium, and incubation in the presence of a 100‐fold excess of nonradioactive serotonin. Radioautographic labeling had to be absent or greatly reduced under all three control conditions for labeling by3H‐serotonin to be considered specific. Labeled enteric axons were found in cyclostomes (hagfish), teleosts (goldfish), and amphibia (bullfrog) but not in tunicates (sea squirt; sea vase) or echinoderms (sea cucumber). In addition, the serotonin concentration was measured in the intestine of two vertebrates, hagfish and goldfish, that do not have serotonin‐containing enterochromaffin cells. Serotonin was found in both; in hagfish, the amine concentration was highest in preparations of muscularis externa containing the myenteric plexus. It is concluded that enteric serotonergic neurons arose early in vertebrate evolution, possibly in an ancestral chordate resembling amphioxus, although probably not in more primitive prevertebrates, and that they are a general feature of the ve

ISSN:0092-7317    

DOI:10.1002/cne.901900103

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

年代:1980

数据来源: WILEY

摘要:

AbstractGolgi and electron microscopic observations were made on the neurons in the deep layers (below the stratum opticum) of the cat superior colliculus. Large neurons, 35–60 μ in somal diameter, occur mainly in the lateral two‐thirds of the colliculus. They have numerous somatic and dendritic spines and receive a large number of axon terminals (bouton covering ratio: more than 70%). The medium‐sized neurons (20–30 μ), with a moderate number of dendritic spines, show a lower bouton covering ratio (25–30%). The ratio for small neurons (8–15 μ), with very few dendritic spines, is less than 10%. The medium‐sized and small neurons are distributed throughout the colliculus and show marked variability in the dendritic arrangement.Seven different types of axon terminals were distinguished: types I, II, V, and VII form asymmetrical and types III, IV, and VI symmetrical synapses. Type I terminals represent small boutons containing predominantly spherical vesicles, and are in contact mainly with small dendritic profiles. Type II terminals are medium‐sized and slender, contain a mixture of spherical and slightly oval vesicles, and make synaptic contacts with small to medium‐sized dendrites and somatic spines. This type of terminal is occasionally presynaptic to vesicle‐containing dendrites (type VIII). Type III terminals are small, contain flattened vesicles predominantly, and are presynaptic to a wide variety of neuronal elements in the deep layers of the superior colliculus. Type IV terminals are represented by medium to large‐sized boutons that contain pleomorphic vesicles and make synaptic contacts chiefly with the large neurons. Type V and VI terminals exhibit a quite dense axoplasmic matrix and mainly contact the large neurons. Type VII terminals are often in the form ofboutons en passantand contain numerous large granular vesicles. Pleomorphic vesicle‐containing dendrites (type VIII terminals) are also observed to participate in the axodendr

ISSN:0092-7317    

DOI:10.1002/cne.901900104

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

年代:1980

数据来源: WILEY

摘要:

AbstractRecent evidence from extracellular recording studies indicates that the medial terminal nucleus (MTN) of the rabbit accessory optic system receives inputs from a particular functional class of retinal ganglion cells—specifically, the on‐type direction‐selective cells. These ganglion cells have been selectively labeled by the retrograde transport of horseradish peroxidase (HRP) injected into the MTN. The number of labeled cells, their distribution over the retina, and their soma areas were determined. In one animal in which the HRP injection completely filled the nucleus, two thousand ganglion cells were labeled. This number agrees with previous estimates of the number of retinal axons terminating in the MTN. Unlike results in avians, none of the ganglion cells was displaced—i.e., they were not Dogiel cells. The density of labeled cells was highest in the visual streak and, overall, the distribution of labeled cells corresponded to the physiologically determined distribution of on‐type direction‐selective cells. Cells labeled by the HRP injection were among the 20% largest cells in the retina. This result, in conjunction with conclusions from other studies, leads to the prediction that on‐type direction‐selective cells can be characterized morphologically as cells with large cell bodies and a very extensive dendritic spread in which the dendrites ramify in the vitreal sublamina of the inner

ISSN:0092-7317    

DOI:10.1002/cne.901900105

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

年代:1980

数据来源: WILEY

摘要:

AbstractResponses of striate cortical cells in Midwestern Siamese cats to moving slits and stationary flashed spots were recorded and compared to similar data in common cat controls obtained under identical experimental conditions. Over 90% of the neurons sampled had receptive fields within 10° of the area centralis.The proportion of binocularly excited cells in Siamese striate cortex was less than that found in the control cats, but more than has previously been reported, and was inversely related to the extent of convergent misalignment exhibited by each animal. Those striate neurons which could be driven by either eye had normal binocular receptive fields and demonstrated normal binocular interaction effects except facilitation.Receptive field dimensions (length, width, area) were significantly larger in Siamese than in common cats. For the simple cells, strabismic Siamese cats had larger receptive fields than orthophoric Siamese cats. Average spontaneous activity in Siamese cats was significantly higher than in the controls. However, similar encounter rates of simple, complex, and hypercomplex units were observed in both Siamese and common cats, and peak responses were not different. Velocity preference in complex Siamese units was shifted to slower velocities compared to common cat complex cells. A loss of direction selectivity was also revealed in the Siamese simple and complex neurons. Finally, sharpness of orientation tuning was dramatically reduced in Siamese complex cells, and this reduction was directly related to the extent of convergent squint exhibited by each animal. The results are discussed in terms of developmental anomalies and neurophysiological retinal abnormalities in Siamese cats

ISSN:0092-7317    

DOI:10.1002/cne.901900106

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

年代:1980

数据来源: WILEY

摘要:

AbstractNeurogenesis in the rat hippocampal region was examined with3H‐thymidine autoradiography. The rats in the prenatal groups were the offspring of pregnant females given two injections of3H‐thymidine on consecutive days in an overlapping series: embryonic (E) day E13+E14, E14+E15,…, E21+E22. The rats in the postnatal (P) groups were injected in two nonoverlapping series: first, the day of birth (PO) and P1, P2+P3,…, P18+P19; second, P0–P3, P4–P7,…, P16–P19. On 60 days of age, the percentage of labelled cells and the proportion of cells added during each day of formation were determined at several anatomical levels within each structure of the hippocampal region (entorhinal cortex, parasubiculum, presubiculum, subiculum, Ammon's horn, and the dentate gyrus) and the hippocampal rudiment (tenia tecta, indusium griseum). The neurons in each structure arise in overlapping, but still significantly different, waves: the hippocampal rudiment between E16–E17; the entorhinal cortex between E15–E17; the para‐ and presubiculum between E16–E19; the subiculum between E16–E18; large cells in strata oriens, radiatum, lacunosum‐moleculare of Ammon's horn between E15–E17; Ammon's horn pyramidal cells between E17–E19; large cells in the dentate hilus and molecular layer between E15–E19. Dentate granule cells begin to originate on E17, and 10% of the population forms after P18.There are three characteristic gradients of formation within structures. First, deep cells are generated before superficial cells. Second, cells closer to the rhinal fissure are formed before those lying farther away (“rhinal to dentate” gradient). Third, later forming cells are flanked by earlier forming superficial and deep cells (“sandwich gradient”) in the entorhinal cortex (layer III cells originate after layers II and IV), Ammon's horn (pyramidal cells originate after large cells in strata oriens, radiatum, and lacunosum‐moleculare), and the dentate gyrus (granule cells originate after large cells in the hilus and molecular layer). There is a “rhinal to dentate” gradient between structures. The entorhinal cortex starts first, next is the subiculum, then field CA3 of Ammon's horn, and finally, the dentate gyrus. Two structures are exceptions to this gradient. The para‐ and presubiculum form significantly later than the subiculum, and CA1 forms significantly later than adjacent CA3 cells; this late neurogenesis may be related to prominent thalamic input to both structures.Neurogenetic gradients between the cells providing laminated afferent input to the Ammonic pyramidal and dentate granule cells correlate with their order of termination: afferents from progressively later‐originating cells terminate progressively closer to the cell body. Topographic hippocampal projections along the dorsoventral axis correlate with formation patterns in target structures: dorsal hippocampal fibers project to zones occupied by earlier‐forming cells in the lateral septal nucleus and pars posterior of the mammillary body; ventral hippocampal fibers project to zone

ISSN:0092-7317    

DOI:10.1002/cne.901900107

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

年代:1980

数据来源: WILEY

摘要:

AbstractMorphogenesis of the entire hippocampal region was examined in normal rats from embryonic (E) day E10 to E22 and on postnatal (P) days P1, P7, and P21, and was correlated with autoradiographic datings (Bayer, '79c). This region is postulated to form from two connected primordia in the telencephalon, easily recognizable on E16. One lies in the dorsomedial wall and generates a portion of the subiculum, Ammon's horn and the dentate gyrus. The other lies in the dorsoposterior wall and generates the entorhinal cortex and part of the parasubiculum and presubiculum. A cortical plate appears in the presumptive entorhinal region on E17; a cell‐sparse fibrous zone appears in the middle of the cortical plate on E19. Lamination in the entorhinal cortex proceeds from lateral to medial and from deep to superficial, with the thickening of layer III being the last to appear on E22. Lamination in the subiculum starts on E18, but the distinction between superficial laminae in the para‐ and presubiculum cannot be made until E22. The stratum pyramidale is small on E20 in presumptive Ammon's horn, then greatly lengthens between E21‐P1. In early dentate gyrus development, cells migrate from the neuroepithelium near the outgrowth of the fimbria and adjacent to the choroid plexus toward a subpial location. The ectal limb of the granular layer appears at the two extremes of the dentate gyrus on E20; the endal limb apears perinatally and develops rapidly to become morphologically similar to the ectal limb by P7.A volumetric analysis of growth in Ammon's horn (including a portion of the subiculum), dentate gyrus, fimbria, and fornix was made from E15 to P21. The neuroepithelium increases to a peak volume on E18 and disappears by P1. The subependymal zone becomes distinct on E18, reaches a peak volume on E20 and disappears by P7. Rapid rates of growth in the stratum oriens and strata radiatum, lacunosum‐moleculare occur between E16‐E17 and between E22‐P1. The pyramidal layer grows rapidly between E18‐E19 (presumptive subicular pyramids) and between E22‐P1 (presumptive Ammon's horn pyramids). Growth rates of the dentate hilus are rapid prenatally and decline postnatally, while dentate granular and molecular layers maintain high postnatal growth rates. The fimbria and fornix have early (E18‐E19) and late (E21‐E22) spurts of growth.To accurately locate regions of primitive migratory and mitotic cells within each lamina of Ammon's horn and the dentate gyrus, the number of cells surviving a single exposure to 200 R X‐rays in embryonic brains (E15‐E22) were compared with controls. The neuroepithelium increases its radioresistance from E15‐E21 and reaches control levels by E22; the subependymal zone is highly radiosensitive throughout development. In contrast, radioresistance in the stratum oriens and dentate hilus declines and reaches a low point on E20. Over 70% of the cells in the strata pyramidale, radiatum, lacunosum‐moleculare, and dentate granular layer are radioresis

ISSN:0092-7317    

DOI:10.1002/cne.901900108

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

年代:1980

数据来源: WILEY

摘要:

AbstractLocalization of enkephalins and opiate binding sites in the central nervous system of rats has been reported by several authors. These studies did not reveal an extensive enkephalinergic system in the hypothalamo‐hypophyseal axis of rats. The present paper reports on an extensive enkephalinergic system in the cat hypothalamo‐hypophyseal system. Sections of paraformaldehyde fixed cat hypothalami were incubated with anti‐methionine enkephalin serum, anti‐vasopressin serum, and anti‐oxytocin serum. Immunohistochemical localization of methionine enkephalin fibers and terminals in the median eminence, hypophyseal stalk, and pars nervosa was similar, but not identical to the distribution of vasopressin and oxytocin in these structures. Neuronal perikarya localized with the three antisera in the nucleus supraopticus and nucleus paraventricularis were of a similar size and morphology. In cats treated with colchicine prior to sacrifice, the anti‐methionine enkephalin serum revealed a group of periventricular cell bodies. Cell bodies were not localized in this area with anti‐vasopressin or anti‐oxytocin sera. The functional significance of such an extensive enkephalinergic system in the cat hypothalamo‐hypophyseal

ISSN:0092-7317    

DOI:10.1002/cne.901900109

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

年代:1980

数据来源: WILEY

摘要:

AbstractElectron microscopic studies were conducted on cat sympathetic preganglionic neurons which were labeled using retrograde transport of horseradish peroxidase from the injection site in the stellate ganglion to somas in the thoracic spinal cord. Based on size, the identified somas were divided into two groups: large multipolar somas (25–35 μm), usually having three dendrites with a mean diameter of 8 μm, and small fusiform somas (12–24 μm), with two primary dendrites with a mean diameter of about 4 μm. The ultrastructures of the perikarya and dendrites were similar to other spinal neurons. Three types of terminals were identified: 1) round asymmetric terminals, 2) pleomorphic symmetric terminals, and 3) round symmetric terminals. On the soma, pleomorphic terminals were more numerous than round asymmetric terminals. On the dendrites, the density of round asymmetric terminals was similar to plemorphic symmetric terminals. Round symmetric terminals represent only a small percent on either the soma or dendrites. Because of the greater total density of terminals on the dendrites than soma, pleomorphic symmetric and round asymmetric terminals are primarily located on the dendrites. Very few dense‐core vesicles characteristic of monoamine terminals were observed, perhaps due to the fixa

ISSN:0092-7317    

DOI:10.1002/cne.901900110

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe effects of 3‐acetylpyridine (3‐AP) intoxication on the inferior olivary complex and cerebellar cortex of the rat were examined at both the light and electron microscopic level. Following intraperitoneal injection of 65 mg of 3‐AP per kg body weight, the inferior olivary neurons were observed to undergo a rapid form of electron dense degeneration. A complete bilateral involvement of the nuclear complex was well advanced as early as 12 hours following injection. Marked astrocytic proliferation also occurred by 12 hours and appeared essential for neuronal fragmentation and disintegration. Microglial activity was prominent in the later stages, from 60 hours onwards, and participated in the phagocytic removal of degenerating neuronal fragments. By the end of the second week, all cytoplasmic and nuclear debri was removed. Concurrently, degenerative changes in the cerebellar cortex were evident from 12 hours onwards. All climbing fiber varicosities were observed to be degenerative as early as 24 hours following treatment. Electron microscopic observations revealed that these electron dense fragments were largely phagocytized and cleared by Bergmann glial cells around 7 days. The sensitivity of the olivocerebellar system to 3‐AP thus provides a convenient and selective means of eliminating all of the inferior olivary neurons and their axons, the climbing fibers of the cerebellar cortex. In contrast to the more conventionally used electrolytic methods, 3‐AP causes a complete bilateral ablation of all olivary neurons while avoiding the problems inherent to electrolytic procedures, such as incomplete destruction of the nucleus and involvement of fibers o

ISSN:0092-7317    

DOI:10.1002/cne.901900111

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

年代:1980

数据来源: WILEY