摘要:

AbstractThe longer associational connections of the hippocampal formation have been studied autoradiographically in a series of adult rats after small injections of3H‐amino acids into each of its various cytoarchitectonic fields. The major findings can be summarized as follows. The dentate gyrus projects in a topographically ordered manner upon the pyramidal cells of theregio inferiorby way of the supra‐ and infrapyramidal bundles of mossy fibers. Certain cells in the hilar region of the dentate gyrus (which operationally may be defined as constituting field CA4of Ammon's horn) give rise to a hippocampodentate projection to the inner one‐quarter of the molecular layer of the dentate gyrus. Either the same or closely related cells give rise to fibers which join the Schaffer collateral system from field CA3to thestratum radiatumandstratum oriensof theregio superior. Theregio inferioris also characterized by a longitudinally directed associational bundle which runs throughout the septo‐temporal extent of the hippocampus and is centered in the region of subfield CA3a. Theregio superiorhas no reciprocal projection to theregio inferiorbut sends a substantial projection back to the subiculum and to the entorhinal area. There is also a projection to the subiculum from theregio inferior, and the subiculum itself probably contributes significantly to the projection to the entorhinal and perirhinal cortices.There is a striking parallelism between certain of these associational connections and the commissural projections to the hippocampus and dentate gyrus. Each cytoarchitectonic field that contributes a commissural projection also gives rise to an ipsilateral associational pathway which in its intrahippocampal course and its mode of termination exactly matches that of the commissural projection, although in general, the associational connections are more extensive in their distribution along the septo‐temporal extent of the hippocampus than the corresponding commissural connections. The reverse is not true; there are a number of associational projections which are not paralleled by commissural projection. All of the associational projections are topographically arranged, but those which extend across the transverse axis of the hippocampus usually show considerable divergence so that afferents from different levels overlap fairly considerably within their respective projecti

ISSN:0092-7317    

DOI:10.1002/cne.901810402

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe pattern of projections of peripheral receptors to the neocortex in the second somesthetic receiving area (SII) was mapped in raccoons. The purpose was to determine if the projection area of peripheral receptors to the forepaw area in the SII region is disproportionally enlarged as it is in SI.Tungsten microelectrode recording procedures were used to map thoroughly the inferior wall of the suprasylvian sulcus for regions responsive to mechanical stimulation of peripheral receptors.The results show that:1The forepaw area in SII shows an enlargement commensurate with that found in the SI. This suggests that those factors that are selective for tactile acuity of the raccoon forepaw were operating in the evolution of SII as they were in SI.2The somatotopic organization of mechanoreceptive projections to SII is reversed mediolaterally compared to previous descriptions of this arrangement in other mammals: projections form axial structures lie medially and those from apical structures lie laterally along the inferior bank of the suprasylvian sulcus in the raccoon.

ISSN:0092-7317    

DOI:10.1002/cne.901810403

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe distributions of spinal and medullary cells projecting to the lateral cervical nucleus (LCN) have been investigated in young cats and dogs using the retrograde horseradish peroxidase (HRP) technique. Labeled spinal cells, whose axons contribute to the spinocervical tract (SCT), were found at all levels of the spinal cord ipsilateral to the injection sites. No significant differences were found between cat and dog, nor between cases with single injections at different levels of the LCN. SCT cells were found predominantly, in not exclusively, within lamina IV, with some extension into medial lamina V. No apparent mediolateral or dorsoventral density gradient was observed within lamina IV; cells of all sizes were labeled. Cells in cervical laminae I and V‐VII were occasionally labeled; these, however, were considered to be propriospinal, supplying afferent fibers to the C1–2dorsal horn. Cells of origin of spinocerebellar fibers consistently remained unlabeled in cases with restricted HRP injections and minimal fiber damage in the dorsolateral funiculus (DLF) around the injection sites. These results, therefore, corroborate and refine the findings of electrophysiological studies of the SCT and the LCN.Labeled medullary cells were located in the caudoventral and rostral portions of the dorsal column nuclei (DCN; stellate and fusiform cells), the underlyingn. medullae oblongatae centralis, subnucleus dorsalis(parvicellular medullary reticular formation), the marginal and magnocellular layers (both large and small cells) of then. trigeminalis spinalis pars caudalisand also inpars interpolaris; a cluster of cells was also consistently labeled in the lateral reticular formation just ventral topars caudalis. The projection from the DCN to the LCN was confirmed with the anterograde Nauta technique. Fiber degeneration was observed in the entire ipsilateral LCN, although it was less abundant than that observed in the adjacent C1–2dorsal horn. These results indicate that neurons in the rostral portions of the DCN not only may affect the input to the LCN (at the level of the dorsal horn), but also the output of the LCN itself. These data also suggest the possibility of both noxious and non‐noxious facial input to

ISSN:0092-7317    

DOI:10.1002/cne.901810404

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe localization of the motor neurons innervating the extraocular muscles in the oculomotor nuclei of adult cats and rabbits was investigated by means of retrograde labelling with horseradish peroxidase (HRP).The groups consisting of the motor neurons innervating an individual muscle lay in the nucleus as elongated columns extending in a longitudinal direction. The position of each group in the transverse section varied according to the rostro‐caudal level of the nucleus. In the cat and rabbit, entire contralateral innervation of the superior rectus and entire ipsilateral innervation of three muscles of the inferior rectus, medial rectus and inferior oblique were similarly observed. However, the arrangement of individual motor groups differed considerably in both animals except for the group innervating the inferior rectus which was generally found in the ventral position running through the rostral two‐thirds of the oculomotor nucleus.In the case of cats, the central caudal nucleus bilaterally innervated the levator palpebrae superioris. The motor neurons innervating this muscle in the rabbit (which lacks the central caudal nucleus) formed a rostro‐caudal club‐shaped column close to the group innervating the superior rectus.The aberrant cellular mass in the adjoining medial longitudinal fasciculus which belongs to the medial rectus appears to play an important role in the eye movement, because it commonly appears in various

ISSN:0092-7317    

DOI:10.1002/cne.901810405

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

年代:1978

数据来源: WILEY

摘要:

AbstractAnatomical studies have demonstrated that the output of the striopallidal system is distributed to two areas of the thalamus: the ventrolateral‐vertroanterior and the centromedian nuclei. The two areas are involved in different ways in the control of somatic motor activity. Pallidal efferents are also distributed to a still obscure tegmental area in the midbrain, the pedunculopontine nucleus, and to the lateral habenular nucleus, a structure of the limbic system. The present study compares the projections of entopeduncular neurons to the four sites in cats. The comparison is based on an estimation of the number of entopeduncular neurons sending fibers to each site and branching to more than one site. The four projection sites were stimulated electrically in anesthetized cats and the number of entopeduncular neurons excited antidromically were counted.At least 68% of entopeduncular neurons were excited antidromically by stimulation of the ventrolateral nucleus, an equal number were excited antidromically by stimulation of the nucleus centromedian and slightly fewer but still more than 50% by stimulation of the pedunculopontine nucleus. The three sites gave rise to antidromic responses of the same entopeduncular neuron in at least 33% of the cases. Only 25% of entopeduncular neurons responded antidromically to stimulation of the lateral habenular nucleus exclusively (one‐third) or not (two‐thirds). Some neurons recorded incidentally in the globus pallidus responded antidromically to the stimulation sites. Neurons were also recorded in the preoptico‐hypothalamic area and 67% responded antidromically exclusively to the stimulation of the lateral habenular

ISSN:0092-7317    

DOI:10.1002/cne.901810406

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe structure and connections of areas within the olfactory peduncle (anterior olfactory nucleus and tenia tecta) have been examined. The anterior olfactory nucleus has been divided into external, lateral, dorsal, medial, and ventro‐posterior parts. In spite of the term nucleus which is applied to these areas, all of them contain pyramidal‐type cells with apical and basal dendrites oriented normal to the surface, and are essentially cortical in organization. Experiments utilizing retrograde and anterograde axonal transport of horseradish peroxidase (HRP) have demonstrated that each of these parts of the anterior olfactory nucleus possesses a unique pattern of afferent and efferent connections with other olfactory areas. All subdivisions have projections to both the ipsilateral and contralateral sides, although the ipsilateral projection of the pars externa (to the olfactory bulb) is extremely light. Interestingly, crossed projections are in each case directed predominantly to areas adjacent to the homotopic areas.Two primary subdivisions may also be distinguished in the tenia tecta: a dorsal part composed largely of tightly packed neurons which closely resemble the granule cells of the dentate gyrus (bushy apical but no basal dendrites) and a ventral part which contains predominantly pyramidal‐type cells. The connections of these two parts are also very different. The ventral tenia tecta receives substantial projections from the olfactory bulb, pars lateralis of the anterior olfactory nucleus, piriform cortex and lateral entorhinal area. It gives off a heavy return projection to the pars lateralis and lighter projections to the olfactory bulb, piriform cortex and olfactory tubercle. The dorsal tenia tecta receives a heavy projection from the piriform cortex, but none from the olfactory bulb. A few cells in the dorsal tenia tecta are retrogradely labeled from HRP injections into the medial aspect of the olfactory peduncle (involving the ventral tenia tecta and adjacent areas), but none are labeled from the other olfactory areas that have been injected.An area on the dorsal aspect of the olfactory peduncle that differs significantly from the anterior olfactory nucleus, tenia tecta and piriform cortex in terms of its connections and cytoarchitecture has been termed the dorsal peduncular cortex. The most striking feature of this area is its very heavy reciprocal connection with the entorhinal cortex, although it is also reciprocally connected with the olfactory bulb and piriform cortex and projects to the olfactory tubercle.Cells in layer I of the medial and ventral aspects of the olfactory peduncle have been retrogradely labeled from HRP injections into the olfactory tubercle and lateral hypothalamic area. These cells overlie the ventral tenia tecta, medial part of the anterior piriform cortex and pars ventro‐posterior and pars lateralis of the anterior olfactory nucleus, but do not appear to be distributed in relation to the cytoarchitectonic boundaries.Possible functional roles of the areas within the olfactory peduncle have been di

ISSN:0092-7317    

DOI:10.1002/cne.901810407

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

年代:1978

数据来源: WILEY

摘要:

AbstractHorseradish peroxidase (HRP) was injected into visual cortex of four normal cats and five cats raised with monocular lid suture, and retrograde labelling was assessed in cells of the lateral geniculate nucleus. In all but one of the sutured cats (noted below) focal injections were carefully limited to area 17 or 18 and analysis of labelling focused on laminae A and A1. The effects of deprivation were indistinguishable whether lamina A or A1 was deprived, and in all cases, the nondeprived laminae had labelling essentially identical to that seen in normal cats.After area 17 injections (bilateral in one normal cat and unilateral in 3 deprived cats), roughly 77% of the cells in nondeprived laminae were labelled and they were mostly small to medium in size. Deprived laminae, when compared to nondeprived laminae, had two abnormalities: (1) cells, both labelled and unlabelled, were smaller; and (2) roughly 11% fewer cells (i.e., 66%) were labelled, and this represents a small but statistically significant difference for each cat. After area 18 injections (bilateral in one normal cat plus unilateral in 3 other normal and 3 deprived cats), roughly 15% of the cells in nondeprived laminae were labelled, and they tended to be large in size. Deprived laminae, when compared to nondeprived laminae, had three abnormalities: (1) only 5–6% of the cells were labelled, and these tended to be quite faintly labelled; (2) the volume occupied by labelled cells was small; and (3) both labelled and unlabelled cells were reduced in size. Finally, large bilateral injections were made throughout occipitotemporal cortex in one lid sutured cat in an effort to label completely the terminal zones of cells in the medial interlaminar nucleus (MIN), a division of the lateral geniculate nucleus; this cat also had a prior intraocular injection of tritiated proline to provide through subsequent autoradiography a delineation of deprived and nondeprived portions of MIN. Roughly 78% of the cells in nondeprived portions of MIN were labelled in this cat. In the deprived portions, only about 51% of the cells were labelled, and these tended to be faintly labelled. Also, labelled cells were smaller, and unlabelled cells were larger in deprived than they were in nondeprived portions.Since prior studies have shown that, within the A laminae, X‐cells project exclusively to area 17 whereas the Y‐cell population projects to areas 17 and 18, these data are taken as further support of the conclusion that geniculate Y‐cells are more seriously affected by the early deprivation than are geniculate X‐cell. That is, these data are consistent with the suggestion that a similar population of Y‐cells in deprived laminae (roughly 10% of the overall cell total) fail to transport HRP from area 17 or area 18 injections. This can be extended to the MIN, which seems to be comprised nearly exclusively of Y‐cells. However, these conclusions must be considered tentative, since interpretation of HRP data can be difficult as evidenced by discrepancies in t

ISSN:0092-7317    

DOI:10.1002/cne.901810408

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe cell bodies of the neurons of the spinocerebellar pathways were examined using large injections of horseradish peroxidose into the cerebellum. Sections of each spinal segment were examined with both the DAB and the de Olmos O‐dianisidine techniques. Results common to all three species were found. In Clarke's nucleus, the central cervical nucleus, and the spinal border cells there were many heavily labeled cells. Clarke's nucleus was found to project primarily ipsilaterally; the spinal border cells primarily contralaterally; and the central cervical nucleus bilaterally. In addition to these aggregates of spinocerebellar neurons there were numerous labeled neurons scattered throughout the spinal grey. Labeled neurons were found in all portions of the spinal grey except the substantia gelatinosa and lateral cervical nucleus and occurred in all spinal segments. They varied in morphology from large multipolar neurons, found predominantly in the ventral horn to small globular and fusiform neurons that were most abundant in the dorsal horn. These cells were found to project both ipsilaterally and contralaterally. Results common to only two of the species examined were also found. In the squirrel monkey and the cat, but not the rat, the marginal layer of the dorsal horn in all segments of the spinal contained numerous labeled neurons. These marginal neurons were especially numerous in the squirrel monkey, where as many as 13 to 16 labeled neurons per section of the dorsal horn were found. In the rat and the squirrel monkey but not the cat, some intensely labeled large multipolar neurons were found in the sacral and caudal segments. These are the cells of Stilling's nucleus, a column of cells similar in position and orientation to that of Clarke's column but different in its projections and details of cytoarchitecture. Thus we have not only confirmed that Clarke's nucleus, the central cervical nucleus, and the spinal border cells project to the cerebellum but we have also found several new sources of spinocerebellar afferent

ISSN:0092-7317    

DOI:10.1002/cne.901810409

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

年代:1978

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901810401

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

年代:1978

数据来源: WILEY