摘要:

AbstractWe have undertaken a determination of the vertical horopter in two species by simultaneously mapping the receptive field positions of binocular cortical neurons at various elevations along the zero azimuthal meridians.In the paralyzed cat our recordings show that the zero meridians of the two eyes are parallel and vertical under paralysis. Slit‐pupil photographs demonstrate that paralysis induces an average net intorsion of 9° between the two eyes. Correction back to the unparalyzed state results in the zero meridians themselves being out‐torted with respect to each other. Since the two eyes' zero meridians define physiologically the positions of corresponding retinal points, this out‐torsion results in a vertical horopter in the mid‐sagittal plane which is tilted away from the alert, unparalyzed cat.The limited eye movements of the owl permit the use of an unparalyzed preparation; it is therefore possible to avoid the problem of the cyclotorsion under paralysis which occurs in the cat. The results of our physiological analysis in the burrowing owl (Speotyto cunicularia) also reveal a tilted horopter in this terrestrial avian

ISSN:0092-7317    

DOI:10.1002/cne.901840102

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe topography of the cerebellar nucleo‐cortical projection was investigated in the cat by experiments employing the horseradish peroxidase (HRP) technique or by combined HRP‐autoradiographic methods. The results of the HRP studies extend previous findings showing that neurons in the deep nuclei project to the cerebellar cortex in an orderly way. Thus, it appears that the cortex of the vermis‐proper receives projections fron neurons located predominately in the fastigial nucleus. Intermediate and lateral zones of mid‐vermal cerebellar cortex are projected on by neurons located in the interposed and dentate nuclei. Crus II receives input from neurons located predominately in the dentate nucleus, while the paramedian lobule is projected on by neurons located in a large postero‐dorsal sector of the interposed nucleus and in a smaller medial strip of the dentate nucleus. Neurons in the ventral part of the dentate nucleus and the lateral part of the interposed nucleus send fibers to the paraflocculus. The nucleo‐cortical pathway to the flocculus and nodulus arises largely from a population of neurons located in a ventral region stretching from the medial border of the dentate nucleus to the lateral border of the fastigial nucleus.The results of experiments using the combined HRP‐autoradiographic method show that clusters of neurons in the deep cerebellar nuclei project back to the cerebellar cortical areas from which they receive input, establishing a fairly precise feedback loop between the cerebellar cortex an

ISSN:0092-7317    

DOI:10.1002/cne.901840103

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe efferent connections of the cortex projected upon by the mediodorsal thalamic nucleus (MD‐projection cortex) have been re‐examined autoradiographically in the rat following the microelectrophoretic injection of3H‐proline‐leucine into different parts of the medial and sulcal MD‐projection cortex. Contrary to previous negative findings, the present experiments revealed a system of extensive corticocortical projections and indicated that different areas of the MD‐projection cortex have distinctive patterns in both their corticocortical and subcortical projections. Thus, cell of Brodmann's area 32 send axons to the retrosplenial cortex, area 29d, the peri‐ and entorhinal cortices, and the presubiculum. Both supragenual and more posterior regions of area 24 project to the retrosplenial cortex and area 29d, but only the posterior portion projects additionally to the entorhinal area and presubiculum. The cortical targets of axons from the sulcal MD‐projection cortex are mainly the anterior part of the piriform cortex and, for the posterolateral part of the sulcal cortex (insular area), the retrosplenial area, lateral entorhinal area, and presubiculum. While the medial and sulcal divisions of the MD‐projection cortex project upon one another, the medial‐to‐sulcal projection is in general denser than its reciprocal.Earlier findings of projections to subcortical structures affiliated with the limbic system such as midline thalamic nuclei, hypothalamus, and paramedian mesencephalic tegmentum are confirmed, and appear to originate primarily in area 32 and the insular part of the sulcal cortex. The corticothalamic projection to MD in general terms reciprocates the organization seen in the thalamocortical projection from the various subnuclei within MD. Previously undocumented projections are demonstrated mainly from area 32 of the medial cortex and the insular part of the sulcal cortex to the lateral and basal amygdaloid nuclei, the medial part of the lateral septal nucleus, the nucleus accumbens, and the deep layers of the olfactory tubercle; the medial part of the lateral habenular nucleus receives a projection from areas 32 and 24. Projections to the pretectal area and superior colliculus appear to originate from all parts of the medial MD‐projection cortex, but are markedly denser when the posterior part of area 24 is injected. The distribution of this corticotectal projection shows a highly characteristic configuration in which areas of high grain concentration surround areas of lo

ISSN:0092-7317    

DOI:10.1002/cne.901840104

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe distribution of spinal neurons with long descending axons was studied in the cat by means of retrograde transport of horseradish peroxidase. Labeled neurons appeared bilaterally in the cervical and the thoracic cord following injections in the lumbosacral cord. In some cases hemisections were made rostrally and contralaterally to the injections in an attempt to determine whether or not the axons crossed.Neurons with uncorssed descending axons were located in laminae I, V, VII and VIII. Lamina I neurons were present in all the spinal segments. In lamina V labeled neurons were distributed mainly laterally in the cervical cord but medially and laterally in the thoracic cord. In the upper cervical and the thoracic cord laminae VII and VIII neurons were distributed very densely along the lateral cord, accounting for 30% and 40% of the total labeled neurons, respectively. In the cervical enlargement they were located in the middle part of lamina VII and in lamina VIII, accounting for about 25% of the total labeled neurons. Neurons with crossed descending axons were found in laminae VI, VII and VIII, in the medial part of lamina VII including the intermediomedial nucleus of the thoracic levels and close to the central canal. Lamina V neurons were very small in number. The largest collections of labeled neurons were present in the medial part of laminae VII and VIII. They accounted for about 45% to 55% and 37percnt; of the total in the cervical and the thoracic cord.These neurons may function as the long spinal reflex paths for forelimb‐hindlimb synergies and the intercalated paths between the supraspinal descending tracts and the spinal motor center

ISSN:0092-7317    

DOI:10.1002/cne.901840105

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe distribution of spinocerebellar tract (SCT) neurons has been studied in the entire length of the spinal cord of the cat following injections of horseradish peroxidase into the cerebellum, and whether or not the axons of the labeled neurons crossed within the spinal cord was determined in cases with injections preceded by hemisections at the cervical levels.The SCTs were classified into the following corssed and uncrossed tracts according to the cell origin and the fiber course; The crossed SCTs originate from (1) the central cervical nucleus (the CCN‐SCT), (2) lamina VIII neurons of the cervical to the lumbar cord (the lamina VIII‐SCT), (3) spinal border cells (the border cell‐SCT), (4) neurons in the medial lamina VII of the lumbar to the caudal spinal segments (the medial lamina VII‐SCT), (5) ventral horn neurons (laminae VII and VIII) of the sacral and caudal segments (the ventral horn‐SCT) and (6) dorsal horn neurons (lamina V) of the sacral and the caudal segments (the dorsal horn‐SCT). The uncorssed tracts originate from (1) neurons of the medial lamina VI of C2 to T1 (the medial lamina VI‐SCT of the cervical cord), (2) neurons in the central part of lamina VII of C6 to T1 (the central lamina VII‐SCT of the cervical enlargement), (3) lamina V neurons of the lower cervical to the lumbar cord (the lamina V‐SCT), (4) Clarke's column (the Clarke's column‐SCT) and (5) neurons in the medial lamina VI of L5 and L6 (the medial lamina VI‐SCT of the lumbar cord).The present study suggests that the spinocerebellar system originates from more diverse laminae than has previously been known, and further refined studies on the topographic projections of each tract will yield more important and valuable info

ISSN:0092-7317    

DOI:10.1002/cne.901840106

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

年代:1979

数据来源: WILEY

摘要:

AbstractIn an earlier study (Giesler et al., 1976), antidromically identified cells of origin of the rat spinothalamic tract (STT) were found to be widely distributed throughout the lumbar dorsal horn and intermediate gray zone (IGZ). Interestingly, it appeared that STT neurons located within the ventral dorsal horn and IGZ, which appeared to respond to stimuli delivered to subcutaneous tissue, tended to be activated only from midline thalamic structures. In contrast, STT neurons withinnucleus propriusand the marginal zone, which responded to noxious and innocuous cutaneous stimuli, were activated from lateral thalamic structures. The present study has investigated this apparent dichotomy in thalamic afferents using the technique of retrograde transport of horseradish peroxidase (HRP).Single and multiple small injections of HRP were made in various thalamic regions. Tissue was reacted with diaminobenzidine (DAB) or o‐dianisidine (OD). Our data provide evidence that DAB histochemistry yields a more accurate reflection of the HRP concentrations surrounding an injection site which are necessary for visible retrograde transport. On the other hand, OD was found to be the more useful technique for examining labeled spinal cord neurons. With this method, 3 to 5.3 times more STT neurons were seen and far greater morphological detail was evident.Multiple HRP infusions which filled an entire hemi‐thalamus labeled large numbers of cells within the spinal extensions of the dorsal column nuclei, the lateral cervical nucleus, the ventral horns and IGZ bilaterally within C1 and C2, and thenucleus propriusand IGZ at all levels. STT neurons were also seen, but in lesser numbers within the marginal zone. Labeling in spinal segments below C3 was, with a single exception, exclusively contralateral. The lumbar enlargement was seen to contribute a greater number of STT neurons than the cervical enlargement. Injections into posterior medial thalamic structures produced bilateral labeling in the ventral horns and IGZ in upper cervical segments. Within the cervical and lumbar enlargements, labeled neurons were restricted to ventral dorsal horn and to IGZ contralaterally. With the exception of the ventral horn cells of C1 and C2 where a marked reduction in labeling occurred, more anterior medial thalamic injections produced labeling within the identical areas of the gray matter and in numbers comparable to those produced by more posterior medial thalamic injections. In contrast, injections into lateral thalamic areas yielded dense labeling within the caudal extensions of the dorsal column nuclei and lateral cervical nucleus. Labeled cells were seen in the marginal zone andnucleus propriusat all levels.Together with our earlier findings, these data suggest that the rat STT is composed of two components which vary in their cells of origin, their terminations and, very likely, their functi

ISSN:0092-7317    

DOI:10.1002/cne.901840107

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

年代:1979

数据来源: WILEY

摘要:

AbstractA population of catecholamine‐containing cells that borders the interventricular foramen of the toad brain has been studied by both fluorescence histochemical and electron microscopic methods. The perikaryon of these cells, which lies immediately subjacent to the ependyma, sends a fluorescent apical process between the ependymal cells to border on the ventricular surface and a basal process displaying fluorescent varicosities into the underlying neuropil. A few cells possess a broad lateral extension which runs parallel to the ventricular surface. Histochemical and pharmacological specificity tests indicate that the cells contain catecholamines, including epinephrine. The most distinctive ultrastructural feature of the subependymal cells' cytoplasm is large numbers of dense cored vesicles that vary in diameter from 500 A to 2,400 A; these are found in the perikarya, apical and basal processes, and lateral extensions. In addition, bundles of filaments ($100 A in diameter) are seen lying adjacent to the nucleus, and numerous axosomatic synapses are found along the surface of the cell bodies. The luminal surface of the apical processes is covered by microvilli and extends a short distance into the ventricular lumen. The basal processes are narrow in diameter, measuring 0.5‐1.1 $m, and contain some filaments, microtubules and dense cored vesicles, but no clusters of ribosomes and no granular endoplasmic reticulum. The characteristics of these subependymal cells, i.e., apical processes which contact the cerebrospinal fluid and basal processes which resemble axons, suggest that the cells may be sensory neurons, and as such, they may respond to the changing composition or pressure of the cerebrospinal fluid and relay this information via their axons to other neurons. The results of this study contribute further evidence that the cerebrospinal fluid provides a means of chemical communication within the br

ISSN:0092-7317    

DOI:10.1002/cne.901840108

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

年代:1979

数据来源: WILEY

摘要:

AbstractNumerous reports have described variability in the morphology of identified neurons; none, however, has previously reported variability in the pattern of synaptic connection. In this report we describe variability in the synaptic connections of an identified interneuron in two species of locust (Locusta migratoriaandSchistocerca gregaria) and show that this variability is associated with a large variation in the structure of the interneuron.The morphology of the descending contralateral movement detector (DCMD) interneuron was determined in the thoracic ganglia by intracellularly staining with cobalt sulphide followed by Timm's silver‐intensification of whole‐mount preparations. The striking characteristic of the structure of this interneuron was the variability from animal to animal. This was so large we were unable to describe a “normal” structure. However, five distinct branches of the interneuron were identified in the metathoracic ganglion. In each animal the structure of DCMD could be described by specifying which of these branches were present. One or more of these branches were usually absent, and there were differences in the probability of any particular branch being absent.Corresponding to the variation in the structure of DCMD there was a large variation in the synaptic connections made by this interneuron. DCMD can make monosynaptic connections to the fast extensor tibiae (FETi) motoneuron, fast and intermediate flexor tibiae motoneurons, and depressor and elevator flight motoneurons. These functional connections were not found in all animals. The absence of an EPSP from DCMD in FETi was associated with either the complete absence of a ventral branch or with the absence of an identifiable process of a ventral branch, and the absence of an EPSP from DCMD in flight motoneurons was associated with the absence of the dorsal branch. The connection of each of these specific branches of DCMD to FETi and flight motoneurons respectively was confirmed by double staining the motoneurons and DCMD in cases which had the functional connection. The implication of our findings is that the connections of interneurons in invertebrates may, in some cases, be far more variable than is generally believed at the prese

ISSN:0092-7317    

DOI:10.1002/cne.901840109

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe horizontal cell system in the retina of the fishCallionymus IyraL. was investigated light microscopically and electron microscopically. One type of rod horizontal cells, which are only found in the mixed ventral part, exclusively contacts spherules with lateral endknobs in the triads. Three types of cone horizontal cells occur. The first type, c‐H1, contacts pedicles of pale and dark double cones and single cones. The processes always have a lateral position in the triads. This type has a constant contact pattern with the photoreceptor cells. The second type, c‐H2, selectively contacts pedicles of pale double cones and the endbuds occupy a central position in the triads. In the single cone pedicles in the dendritic field of the c‐H2 horizontal cell, the endbuds never seem to reach the triads. The third type, c‐H3, only sends processes to pedicles of single cones where the endbuds occupy a central position in the triads. The synaptic connections of the horizontal cells ofCallionymusdiffer from those observed inNannacara anomalaandCarassius auratus. The difference from the results obtained fromCarassiusis such that the information transfer model proposed forCarassiuscannot apply toCall

ISSN:0092-7317    

DOI:10.1002/cne.901840110

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe present study demonstrates that there are more dorsal root axons than dorsal root ganglion cells in the L6‐S1dorsal roots of the rat. The excess fibers do not come from aberrant dorsal root ganglion cells and our control procedures indicate that there are no extraneous fibers in these dorsal roots. Accordingly many dorsal root axons must branch in the dorsal roo

ISSN:0092-7317    

DOI:10.1002/cne.901840111

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

年代:1979

数据来源: WILEY