摘要:

AbstractThe red nucleus and its spinal projections in the pigeon(Columba livia)have been studied using both normal and experimental material. The cytoarchitecture of the nucleus is described on the basis of Nissl‐stained sections and reveals an organization generally similar to that of mammals. The large neurons (40‐50μm) tend to be located dorsomedially and ventrolaterally at more caudal nuclear levels, while the small‐and medium‐sized neurons (15‐35μm) predominate at rostral levels. However, neurons of all sizes are present throughout the nucleus.Following lesions of the nucleus, the course of degenerating axons stained with the Fink‐Heimer method has been traced throughout the brainstem and spinal cord. The rubrospinal tract crosses the midline, courses past the ventrocaudal aspect of the contralateral nucleus ruber, and then descends rostroventral and lateral to the nucleus tegmenti pontinus. In its caudal continuation the tract lies ventral to the brachium conjunctivum and the entering radix of the trigeminal nerve. It then assumes a ventrolateral position in the caudal brainstem before shifting to a dorsolateral position in the lateral funiculus of the spinal cord. Within the spinal grey the rubrospinal tract terminates in laminae V, VI and to a lesser extent VII.The possibility of a topographical organization of the nucleus was investigated with injections of horseradish peroxidase into brachial, thracic and lumbar spinal cord. Regardless of the level of injection, labelled neurons of all sizes were present throughout the contralateral nucleus ruber, indicating the absence of an obvio

ISSN:0092-7317    

DOI:10.1002/cne.901870402

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractPatterns of connections with other visual structures and architectonic characteristics were used to subdivide the inferior pulvinar complex of owl monkeys into three distinct nuclei termed the central inferior pulvinar, IPc, the medial inferior pulvinar, IPm, and the posterior inferior pulvinar, IPp. IPc occupies about 70%; IPm about 20%, and IPp about 10% of the inferior pulvinar complex. Encapsulating fiber bands distinguish the boundaries of the three nuceli. IPm is also identified by a much greater packing density of neurons than IPc and IPp. Both IPp and IPc receive input from the superior colliculus, but the terminations in IPp are denser. Visual cortical Areas 17, 18, MT, DM, M and PP (Allman and Kaas, '76) project to IPc and IPm in patterns that indicate that central vision is represented dorsorostrally and peripheral vision ventrocaudally in both nuclei. Terminations in IPm from Area MT are particularly dense. None of these visual areas projects to IPp. Rather, input to IPp appears to originate in cortex rostral to Area MT in the temporal lobe.

ISSN:0092-7317    

DOI:10.1002/cne.901870403

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractUsing a two‐choice visual discrimination paradigm, thresholds for size (gratings), parallelness (parallel vs. non‐parallel lines), contour alignment (vernier offset), and angularity (polygon figures) were behaviorally determined in cats before and after ablations of portions of the geniculo‐cortical system.Animals with a total loss of cortical area 17, and with a loss, in some cases, of up to 90% of area 18 (with and without infringement into area 19), showed about a 30% reduction in grating acuity, a three‐fold increase in parallelness and angularity thresholds, and a total loss of contour alignment ability. Control animals with ablations sparing area 17 showed no significant threshold changes. All animals were able to learn classic form discriminations postoperatively, but those with area 17‐18 lesions at a somewhat slower than normal rate. Control procedures indicated that all tested discrimination capabilities did not depend on luminance differences between targets, local flux cues within the targets, or on the animals' use of residual portions of area 17 representing the peripheral visual field.Since the cat has multiple thalamo‐cortical visual pathways, the results of the present study are consistent with the hypothesis that pathways parallel to the geniculo‐striate system are capable of processing spatial information of considerable detail. The results also suggest, however, that the geniculo‐striate system is uniquely necessary for the processing of the finest attributes of s

ISSN:0092-7317    

DOI:10.1002/cne.901870404

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractA hitherto unsuspected degree of regional topographic organization in the noradrenergic nucleus, locus coeruleus, was revealed by the use of retrograde transport of horseradish peroxidase (HRP) from terminal areas receiving noradrenergic innervation. HRP was injected into hippocampus, hypothalamus, thalamus, caudate‐putamen, septum, amygdala‐piriform cortex, cerebellum and cortex. Successful transport was obtained from all areas, including the caudate‐putamen and cerebral cortex. The pattern of HRP positive cells in the ipsilateral locus coeruleus was markedly different depending on the location of the HRP injection. Thus, hippocampal injections labeled cells i the dorsal locus coeruleus but not at all in the ventral tip. Injections of HRP into caudate‐putamen or cerebellum labeled the ventral tip along with the rest of the dorsal portion. HRP injections into the septum labeled cells only in the dorsal half of the dorsal locus coeruleus. There thus exists a three tier division of locus coeruleus into the ventral one third, dorsal one third and intermediate one third. A further division was seen in the anterior‐posterior plane with HRP injections into the thalamus labeling the posterior pole of locus very intensely but with little transport to more anterior levels; conversely HRP injection into the hypothalamus resulted in intense labeling only in the anterior pole of locus coeruleus. Amygdala‐piriform cortex HRP injections revealed a further pattern with very intensely reactive cells scattered sparsely throughout the nucleus. Cortical HRP injections yielded weaker lebeling also in occasional, scattered cells. All HRP transport to locus coeruleus was shown to be noradrenergic by degeneration with 6‐hydroxydopamine and due to terminal, rather than fiber of passage, uptake by control injection into the dorsal NA bundle. It is concluded that the locus coeruleus is not an homogenous nucleus with respect to the origin of the noradrenergic projections to sundry forebrain, spinal and cerebellar areas, but is comprised of distinct subdivisions of noradren

ISSN:0092-7317    

DOI:10.1002/cne.901870405

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractA laminar distribution of different functional cell types in the striate cortex of the cat is drawn up from the visual responses of single cells recorded in 64 electrode penetrations in 38 cats. In summary, S cells were found to be concentrated in laminae 4 and 6; SHcells in laminae 2, 3 and 4; C cells in laminae 5 and lower 3; B cells in laminae 3 and upper 5 and cells with non‐oriented receptive fields in lamina 4.In addition, the nature of afferent innervation to striate neurons was derived from the latency of the orthodromic response to electrical stimulation in the optic chiasm and optic radiations in 19 cats. An analysis of latency values allowed the afferent innervation to a cell to be classed as belonging either to fast or slow conducting streams in the population of dLGN axons and also permitted a decision to be made on whether or not the afferent path passed directly to the cell. Direct afferent innervation from the dLGN was not found to be confined to a single class of striate neuron. Instead, examples of cells with S, SH, C, B and non‐oriented receptive fields all had orthodromic latencies that met the requirement for direct innervation. Instances of cells with orthodromic latencies suggestive of indirect innervation were also found for most receptive field classes but these cells were encontered less frequently than those with a direct afferent input. It is argud that a variety of different cell types may act as first order neurons in the striate cortex and that cells occurring at later stages in the sequence of cortical processing may have been incompletely studied because they are more difficult to stimulate either visually or electrica

ISSN:0092-7317    

DOI:10.1002/cne.901870406

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractFollowing injections of horseradish peroxidase (HRP) into parafloccular cortex, the location of nucleocortical cells in the cerebellar nuclei was determined and compared to the distribution of corticonuclear fibers arising from the same cortical region. Parafloccular corticonuclear fibers, visualized utilizing the Fink and Heimer (1967) method, project to caudal and lateral NIP and caudal and ventral NL. No degeneration is seen in either the NIA or NM. HRP‐positive nucleocortical cells (DAB‐technique) are found in caudal and lateral NIP and caudal NL with the former containing greater numbers of reactive somata. Rostral regions of the NL, medial NIP as well as the NIA and NM are divoid of cells containing HRP reaction product.At least two identifiable populations of HRP‐positive nucleocortical cells are seen. Numerous reactive cells are found in the NIP and NLipsilateralto the injection site and sparse numbers of HRP‐containing somata are present in homologous areas of thecontralateralNL and NIP. Contralateral nucleocortical cells are not only sparse in number but do not receive direct input from the opposite cortex to which they project. Consequently, these particular cells represent non‐reciprocal neurons in corticonuclear –; nucleocortical feedback loops. Ipsilateral nucleocortical cells are numerous and found almost exclusively within the distribution of parafloccular corticonuclear fibers. Also seen on the ipsilateral side interspersed among the HRP‐positive somata are numerous fibers which contain non‐granular homogeneous reaction product. These fibers represent diffusely filled axons of Purkinje cells which were damaged during the injection process. The location of ipsilateral nucleocortical cells within the borders of corticonuclear terminal fields coupled with their intimate opposition to some orthogradely filled terminal branchlets of Purkinje axons, indicates the probability of a precise interaction between these two fiber systems. Although a few HRP‐positive ipsilateral cells are found outside the boundaries of corticonuclear terminal fields they represent only a small fraction of the total number of reactive cells and, indeed, may function as part of the reciproca

ISSN:0092-7317    

DOI:10.1002/cne.901870407

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractDescending paths from the inferior colliculus (IC) and dorsal (DNLL) and ventral (VNLL) nuclei of the lateral lemniscus and their terminations in the caudal cochlear nucleus in cats were studied both in silver degeneration material following central lesions and in autoradiographs following central injections of tritiated leucine (3H‐leu). Eight adult cats received electrolytic lesions of the IC, the IC and DNLL, or the IC, DNLL and VNLL. Control cats were subjected either to surgery alone or to a lesion in a non‐auditory nucleus. After survival periods of 1 to 16 days, all cats were killed and their brain stems prepared by modified Nauta methods. Twenty‐two other cats received injections of3H‐leu into the dorsal IC, the ventral IC and DNLL, or the DNLL and VNLL. Their brains were prepared for LM autoradiography. After lesions of the IC, Nauta material contained moderate degeneration of fine fibers that coursed predominantly in the lateral lemniscus, and partially decussated in the caudal trapezoid body to enter the cochlear nuclei of both sides. Sparse, mainly peridendritic degeneration of fine fibers occurred in the PVCN, while moderate, peridendritic and perisomatic degeneration occurred in the deep and innermost fusiform cell layers of the dorsal cochlear nucleus (DCN). Lesions of both the ventral IC and the DNLL showed additional bilateral degeneration of medium‐caliber axons in the descending tracts as well as preterminal degeneration of these larger axons sparsely distributed in the deep layers of the DCN. The density of medium‐caliber axonal degeneration (particularly in the deep DCN) increased when lesions also included the VNLL. After3H‐leu injections into the tectum and/or upper pons, autoradiographs confirmed the presence of sparse bilateral inputs from both the IC and from the DNLL and VNLL to ventral cochlear nucleus neurons, including some octopus cell dendrites. The autoradiographic studies also clearly revealed a predominant input to the outer layer of the DCN from the dorsal IC, a predominant input to the middle layer from the ventral IC, and a predominant input to the deeper DCN from the lateral lemniscal nuclei. Limited evidence of a topographic, perhaps tonotopic, order within the descending connections was best seen in Nauta material. The differences shown here in fiber types, trajectories, and target sites from the IC, the DNLL, and the VNLL are discussed in terms of possible functional differences among the descending influences on neurons of the caudal coc

ISSN:0092-7317    

DOI:10.1002/cne.901870408

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901870401

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY