摘要:

AbstractThe distribution of motoneurones to the cat dorsal neck muscles biventer cervicis, splenius and complexus has been examined using the technique of retrograde horseradish peroxidase transport. A comparison was initially made of HRP uptake into motoneurones produced either by injecting HRP solution directly into a singly neck muscle or by exposing the cut ends of motor nerves to an HRP solution. The injection of HRP into single neck muscles was found to produce widespread labelling of motoneurones presumably due to diffusion of HRP into adjacent muscles. For the examination of individual motoneurone pools the technique of cut nerve exposure was therefore used.Labelled neck muscle motoneurones ranged from 10–70 μ in diameter, but the majority of cells had diameters which were less than 40 μ. Most cells were located in the ventromedial nucleus and along the medial border of the ventral horn. In these regions there was considerable overlap between the motoneurones pools of the three neck muscles examined. In addition, some splenius motoneurones were located in the nucleus of the spinal accessory nerve. Labelled neck muscle motoneurones were also located in areas not usually considered to contain motoneurones such as the commissural and centrodorsal nuclei and in the ventral commiss

ISSN:0092-7317    

DOI:10.1002/cne.901810302

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe efferent and afferent pathways of the carp torus longitudinalis were studied by means of degeneration and retrograde HRP methods. Efferent projections were only seen in the most superficial layer of the ipsilateral optic tectum (stratum fibrosum marginale).Afferent pathways to the torus longitudinalis were found to originate mainly in the valvula cerebelli. Degenerating fibers course in the tractus mesencephalocerebellaris posterior within the valvula, and join the tractus mesencephalocerebellaris anterior in the tegmentum. The fibers which ascend in the tract gradually invade the optic tectum through which they are distributed to the torus longitudinalis. The remaining fibers pass through the posterior commissure and terminate in the torus longitudinalis at the rostral end of the tract.Degenerating terminals were also seen in the torus longitudinalis when lesions were made in the optic tectum, tectal commissure, torus semicircularis, and in the area between the valvula and the corpus cerebelli. The possibility of projection from these areas is discussed depending upon the results of the retrograde HRP method.

ISSN:0092-7317    

DOI:10.1002/cne.901810303

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

年代:1978

数据来源: WILEY

摘要:

AbstractEfferent and afferent connections of primary visual cortex, Area 17, were determined in a prosimian,Galago senegalensis, by autoradiographic methods after injections of3H‐proline or3H‐HRP. The cortical connections of Area 17 with Areas 18 and MT were homotopic and reciprocal. Projections from Area 17 terminated largely in layer IV and somewhat in layer III of both Areas 18 and MT. Most of the cells projecting to Area 17 were located in layer V of Area 18 and layer VI of MT. Subcortical projections included the reticular nucleus of the thalamus, where columns of label corresponding to injection sites were found in the caudal forth of the nucleus. Projections to the lateral geniculate nucleus were along lines of isorepresentation and were in register with the cells projecting back to the injection site. The parvocellular layers were less densely labeled than other layers by the transport of3H‐proline, while concentrations of label were noted on the dorsal and ventral margins of the nucleus and in interlaminar regions between the internal parvocellular and magnocellular layers and between the two magnocellular layers. The pattern of terminations in the pulvinar complex suggested functional subdivisions. We have divided the inferior pulvinar into a large central nucleus, IPc, with topologically organized input from Area 17; a smaller medial nucleus, IPm, with a second pattern of input from Area 17; and a dorso‐posterior nucleus, IPp, without input from striate cortex. The superior pulvinar likewise appears to have several subdivisions. One of these, a “central” nucleus of the superior pulvinar, SPc, receives topologically organized projections from Area 17. SPc is about the same size as IPc and is organized as a mirror image of IPc. Thus, both IPc and SPc represent the lower visual quadrant medially and the upper visual quadrant laterally; central vision is represented along the common border for both nuclei, while peripheral vision is represented dorsorostrally in SPc and ventrocaudally in IPc. Finally, the superficial grey of the superior colliculus receives topologically organized input f

ISSN:0092-7317    

DOI:10.1002/cne.901810304

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

年代:1978

数据来源: WILEY

摘要:

AbstractAn analysis based on Nissl, anterograde degeneration, and sucinic dehydrogenase histochemical techniques reveals that there are two distinct regions of parietal cortex which are characterized by different cytoarchitectonic features and anatomical connections. The “granular” cortical zone possesses a well‐defined fourth layer composed of small, densely‐packed cells, receives dense projections from the ventral posterior nucleus of the thalamus, and is essentially free of callosal inputs. “Agranular” cortical areas which surround or lie embedded within the granular zone lack a well‐defined fourth layer, receive sparse projection from the ventral posterior nucleus, but send and receive extensive callosal projections. These findings suggest that thalamic and callosal projections to the parietal cortex maintain a pattern of areal segregation. The granular cortical zone, which apparently corresponds to SmI, projects ipsilaterally to motor cortex, SmII, and adjacent agranular areas. The superficial layers of the granular cortex also project heavily upon the underlying layer V. This intracortical projection is not organized in discrete clusters within the “barrel field” cortex. This suggests that the specialized organization of thalamic afferents and granule cells within the “barrel field” is not maintained in the intracortical cir

ISSN:0092-7317    

DOI:10.1002/cne.901810305

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe hypothalamic magnocellular system of the adult female rhesus monkey is studied here, using immunoperoxidase technique and antisera to estrogen stimulated neurophysin (ESN), nicotine stimulated neurophysin (NSN), oxytocin (OT) and vasopressin (VP). These observations confirm and enlarge previous descriptions by others using Gomori techniques.It is apparent from this study that the magnocellular system spreads through a broader area than is generally accepted. A group of cells ventral to the head of the caudate nucleus and medial to the internal capsule is described.The general orientation of the nuclei and their tracts can only be appreciated when coronal, horizontal and sagittal sections are compared. Our observations suggest that the supraoptic nucleus is made up of a single group of cells that straddles the optic pathways, and is not divided in three segments, as it is generally described. It is also shown that the rostral extensions of the paraventricular and supraoptic nuclei merge above the optic chiasm.Cells containing ESN/OT and NSN/VP are evenly dispersed in the paraventricular nucleus but a topographical arrangement is present in the supraoptic nucleus.The magnocellular nuclei project to the organum vasculosum of the lamina terminalis, zona externa of the median eminence and pars nervosa of the pituitary gland. Reactive fibers were also seen within islets of cells from the pars in termedia located inside the pars nervosa.A globular structure containing small blood vessels surrounded by positive fibers was noticed protruding into the floor of the third ventricle, at the level of the median eminence.

ISSN:0092-7317    

DOI:10.1002/cne.901810306

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

年代:1978

数据来源: WILEY

摘要:

AbstractPreparation of a stereotaxic atlas of the brain of the 3‐day‐old domestic chick was prompted by the widespread use of chicks in behavioral and pharmacological research.The atlas is comprised of 26 frontal plates extending from the frontal pole to the level of the hypoglossal nucleus, and one sagittal plate at lateral 0.4 mm. Marking lesions were used to ascertain coordinates, the brains were embedded in albumin and sections cut at 36 mμ. The brain sections were stained with cresyl violet for nuclei and with hematoxylin for fibers. Unstained brain sections were used as a guide in drawing the plates to correct for shrinkage and distortion.The use of the atlas for research purposes for one year, plus test lesions targeted for specific brain structures, indicates the atlas is accurate to within 0.

ISSN:0092-7317    

DOI:10.1002/cne.901810307

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe medial interlaminar nucleus (MIN) of the cat lies medial to the laminated region of the dorsal lateral geniculate (lamLGN). This latter region includes the A and C laminae. As does lamLGN, MIN receives direct retinal input and projects to various visual cortical areas. We examined the MIN of 15 normal adult cats with electrophysiological and anatomical techniques.Autoradiographs processed from cats that had one eye injected with tritiated fucose and proline indicate that MIN is composed of at least two laminae, one for each eye. The area which receives input from the ipsilateral eye is a small central region surrounded dorsally, medially, and ventrally by a larger crescent shaped region that receives input from the contralateral eye. This pattern was also evident from electrophysiological recording experiments.Extracellular recordings from 102 single‐units in MIN indicate that these cells have properties essentially identical to lamLGN Y‐cells. That is, they had short latencies to orthodromic stimulation of the optic chiasm and antidromic stimulation of the visual cortices, responded in a phasic manner to the presentation of a standing contrast within the receptive field center, responded to rapidly moving visual stimuli, and showed non‐linear spatial summation properties typical of lamLGN Y‐cells. We discovered two difference between MIN cells and lamLGN Y‐cells. First the mean receptive field center size of MIN cells is considerably larger than that of lamLGN Y‐cells, and second, MIN cells do not have the non‐dominant eye inhibitory receptive fields found for many lamLGN Y‐cells.Cell size measurements indicate that while the mean cell size in MIN is approximately 30% greater than in the A laminae of lamLGN, the distribution of MIN cell sizes extends over the full range of cell sizes in the A laminae. Since the A laminae are comprised mostly of X‐ and Y‐cells, this suggests that, although Y‐cells on average are larger than X‐cells, considerable overlap exists in their size distribution. No differences between the ipsilateral and contra lateral terminal zones were found on any measure.Since MIN cells share most or all the fundamental features of lamLGN Y‐cells, we suggest that these cell groups should be considered subpopulations of a more general group of geniculate Y‐cells. Accordingly, we refer to these two subpopulations as lam

ISSN:0092-7317    

DOI:10.1002/cne.901810308

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

年代:1978

数据来源: WILEY

摘要:

AbstractSingle unit extracellular recordings, cell size measurements, and cell packing density measurements were made in the medial interlaminar nucleus (MIN) of nine adult cats that had been monocularly deprived by lid suture prior to natural eye opening. The electrophysiological properties of neurons in the nondeprived regions of MIN (areas receiving input from the nondeprived eye) remained unaffected by monocular lid suture. The latencies to optic chiasm stimulation and receptive field properties, including receptive field center size, were essentially the same as those found for MIN neurons of normal adult cats. In contrast, cells in the deprived regions were severely affected by monocular deprivation. We encountered in the deprived regions of MIN only about one half as many active neurons per mm of electrode penetration as we did in the nondeprived regions. Of the physiologically active cells remaining, about one half had abnormal receptive field and/or response properties. This resulted in a sampling density of 5.1 normal Y‐cells per mm of penetration in nondeprived regions of MIN compared to 1.0 normal Y‐cell per mm in deprived regions of MIN.Histological effects of deprivation were also seen. Deprived regions of MIN were distinguished from nondeprived regions in four cats by autoradiography following intravitreal injection of tritiated proline into the deprived or nondeprived eye (2 cats each). The man cell size of deprived regions of MIN was 34% smaller than that of nondeprived regions. We did not find a difference in cell packing density between these two regions.It appears that the effects of monocular lid suture upon MIN are in most respects similar to the effects of monocular lid suture previously reported for the A laminae. Since MIN is composed solely of Y‐cells, these data support the idea that the Y‐pathways are more severely affected by visual deprivation than are the X‐pathways. Further, since MIN projects largely outside the striate cortex, these data give the first clear demonstration of a primary effect of early lid suture upon extrastriate visual

ISSN:0092-7317    

DOI:10.1002/cne.901810309

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

年代:1978

数据来源: WILEY

摘要:

AbstractA recently developed Golgi‐electron microscopic technique (Fairén et al., '77) has been used to identify neurons in mouse SmI cortex which that thalamic axon terminals synapsed with dendrites of several distinct neuronal types whose cell bodies occurred either in layer III, IV or V. The procedures employed were as follows: electrolytic lesions were used to destroy the cortical projections of the nucleus ventralis posterior pars lateralis thalami (homologous to medial portion of ventrobasal complex) and the nucleus posterior thalami. These two thalamic nuclei project to the posteromedial barrel subfield (PMBSF) in mouse somatosensory cortex. Blocks of cortex containing the PMBSF were processed by the Golgi method, sectioned at 150 μm and examined with the light microscope. Neurons of interest were then selected for Golgi deimpregnation (Fairén et al., '77). Portions of these cells were serial thin sectioned and subsequently examined with the electron microscope to determine if they synapsed with degenerating axon terminals.Degenerating thalamocortical axon terminals synapsed at asymmetrical synaptic junctions with dendritic spines of pyramidal cells whose somata occurred in layers III and V, and with dendritic spines of spiny stellate cells with somata in layer IV. Only normal, symmetrical synapses occurred on the cell bodies of these neurons, and no degenerating axon terminals synapsed with the shafts of their dendrites. Two, unimpregnated, non‐spiny stellate cells whose somata occurred in layers IV and IV/V were partially reconstructed from serial thin sections. Many degenerating thalamocortical axon terminals synapsed with the dendrites and somata of these non‐spiny cells. In fact, for similar lengths of dendrite, the non‐spiny stellate cells made the most synapses with thalamocortical axon terminals, followed in order of decreasing frequency by the layer IV spiny stellate cells, the layer III pyramids and finally the layer V pyramids which received only few synapses from thalamocortical axon terminals.Direct evidence has been provided that at least six different types of neurons whose somata occur in several layers of the neocortex receive synapses from thalamocortically projecting neurons. It has been proposed that the cortex is organized such that thalamic input is processed sequentially by neurons of increasingly complex response properties beginning with cells in layer IV and proceeding to cells in other layers (Hubel and Wiesel, '62, '68). The results of this study now suggest that any such hierarchical processing of thalamic input must occur in conjunction with theparallel, and perhaps simultaneous, processing of thalamic input by neurons at several hierarchical levels. The evidence for, and some implications of, a newly proposed model of cortical organization which combines hierarchical and parallel processing are

ISSN:0092-7317    

DOI:10.1002/cne.901810310

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn the neocortex of 6‐day‐old rat, abundant axon terminals which exhibit specific catecholamine fluorescence are found in all regions and throughout all cortical layers. The overall density of axons in 6‐day‐old cortex in similar to the density in the adult cortex. In immature cortex, there are two distinct fluorescent plexuses, both presumably noradrenergic, one in the molecular layer and another in the lower half of the cortex. The superficial plexus is composed primarily of horizontal fibers, and the deep plexus of a dense feltwork of obliquely oriented fibers suggestive of a terminal field. The cortical plate itself is traversed by a few vertical processes. Following lesions of the midbrain tegmentum no fluorescent axons are seen in cortex, providing evidence that the fluorescent axons in cortex arise from brain stem neurons. The deep and superficial plexuses can be differentially visualized depending on the histochemical techniques employed and on pharmacological treatment, such as loading with a monoamine congener. Both deep and superficial axons are shown to contain endogenous catecholamines but those fibers in the deep plexus are filled to far less than their maximum capacity. The pharmaco‐histochemical differences between axons in the two plexuses suggest that there may exist two distinct catecholaminergic projections to lateral neocortex. The demonstration of an extensive cortical monoamine innervation early in ontogeny supports the possibility that monoamine neurons play an important role in information processing and/or developmental interactions in the immat

ISSN:0092-7317    

DOI:10.1002/cne.901810311

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

年代:1978

数据来源: WILEY