摘要:

AbstractThe projections of the main and the accessory olfactory bulb in the tree shrew (Tupaia glis) have been analyzed with anterograde degeneration and autoradiographic methods for identifying axonal projections, and with the horseradish peroxidase method for identifying the distributions of neurons from which these projections originate. The cytoarchitectonic features of the paleocortical areas which receive projections from the main and the accessory olfactory bulb have also been described.The efferent projections of theaccessory olfactory bulbare distributed to the bed nucleus of the accessory olfactory tract, the medial amygdaloid area, the posteromedial cortical amygdaloid area, and to the caudal portion of the bed nucleus of the stria terminalis. In contrast, the efferent projections of themain olfactory bulbare distributed to the anterior olfactory nucleus, the tenia tecta, the olfactory tubercle, the pyriform cortex, the anterior cortical amygdaloid area, the posterolateral cortical amygdaloid area, and to the lateral entorhinal cortex. These observations are consistent with the notion that the olfactory system can be divided into at least two major subsystems: one related to the vomeronasal organ and accessory olfactory bulb, and another related to the main olfactory organ and main olfactory bulb.The paleocortical areas receiving olfactory projections have three basic layers: a superficially positioned plexiform layer (layer I), a pyramidal cell layer (layer II), and a polymorphic cell layer (layer III). The projections of both the main and the accessory olfactory bulb terminate in the outer portion of the plexiform layer (sublamina la). Sublamina Ia contains the distal segments of dendrites which originate from a heterogeneous population of neurons located in layer II and, to a lesser extent, layer III.Although the efferent projections of the main and the accessory olfactory bulb are segregated, evidence for a more refined topographical organization within these projections was not obtained. However, the distribution of retrogradely labeled neurons in the main olfactory bulb, following injections of horseradish peroxidase into its various paleocortical targets, indicates that the olfactory projections to these areas may not all originate from the same population of cells.

ISSN:0092-7317    

DOI:10.1002/cne.901720102

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

年代:1977

数据来源: WILEY

摘要:

AbstractABSTRACT This study shows that approximately 30% of the axons in the Tll and T12 ventral roots of the cat are unmyelinated. The unmyelinated axons fall into two categories. Slightly less than half are efferents from the spinal cord and slightly more than half arise from dorsal root ganglion cells. The efferent fibers are regarded as unmyelinated preganglionic sympathetics, the fibers of dorsal root ganglion origin are regarded as sensory. This organization of the T11‐T12 ventral roots, which are part of the sympathetic outflow, is similar to that of cat ventral roots S3 and Cal, which are part of the parasympathetic outflow, but different from cat ventral roots L7 and Sl, which are between the visceral outflow

ISSN:0092-7317    

DOI:10.1002/cne.901720103

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe efferent connections of the hippocampal formation of the rat have been re‐examined autoradiographically following the injection of small quantities of3H‐amino acids (usually3H‐proline) into different parts of Ammon's horn and the adjoining structures. The findings indicate quite clearly that each component of the hippocampal formation has a distinctive pattern of efferent connections and that each component of the fornix system arises from a specific subdivision of the hippocampus or the adjoining cortical fields. Thus, the precommissural fornix has been found to originate solely in fields CA1‐3of the hippocampus proper and from the subiculum; the projection to the anterior nuclear complex of the thalamus arises more posteriorly in the pre‐ and/or parasubiculum and the postsubicular area; the projection to the mammillary complex which comprises a major part of the descending columns of the fornix has its origin in the dorsal subiculum and the pre‐ and/or parasubiculum; and finally, the medial cortico‐hypothalamic tract arises from the ventral subiculum. The lateral septal nuclei (and the adjoining parts of the posterior septal complex) constitute the only subcortical projection field of the pyramidal cells in fields CA1‐3of Ammon's horn. There is a rostral extension of the pre‐commissural fornix to the bed nucleus of the stria terminalis, the nucleus accumbens, the medial and posterior parts of the anterior olfactory nucleus, the taenia tecta, and the infralimbic area, which appears to arise from the temporal part of field CA, or the adjacent part of the ventral subiculum. The projection of Ammon's horn upon the lateral septal complex shows a high degree of topographic organization (such that different parts of fields CA1and CA3project in an ordered manner to different zones within the lateral septal nucleus). The septal projection of “CA2” and field CA3is bilateral, while that of field CA1is strictly unilateral. In addition to its subcortical projections, the hippocampus has been found to give rise to a surprisingly extensive series of intracortical association connections. For example, all parts of fields CA1, CA2and CA3project to the subiculum, and at least some parts of these fields send fibers to the pre‐ and parasubiculum, and to the entorhinal, perirhinal, retrosplenial and cingulate areas. From the region of the preand parasubiculum there is a projection to the entorhinal cortex and the parasubiculum of both sides. That part of the postsubiculum (= dorsal part of the presubiculum) which we have examined has been found to project to the cingulate and retrosplenial areas ipsilaterally, and to the entorhinal cortex and pa

ISSN:0092-7317    

DOI:10.1002/cne.901720104

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

年代:1977

数据来源: WILEY

摘要:

AbstractFollowing injections of horseradish peroxidase (HRP) in the cerebellar cortex of the anterior lobe of the cat, the distribution of labeled cells in the inferior olive was mapped. The findings largely confirm those made previously in studies of olivary retrograde cell loss following cerebellar ablations (Brodal, 1940b). In addition, they reveal further olivary areas projecting onto the anterior lobe, and permit a more detailed analysis of the pattern in this projection. Concerning major points the results are in agreement with physiological studies by Armstrong et al. (1974). They bring supporting evidence for a longitudinal zonal pattern in the anterior lobe (fig. 6C).The middle zone of thevermisreceives its fibers from a large central area in the caudal half of the medial accessory olive, a lateral zone of the vermis from the lateral half of the dorsal accessory olive. Both olivary areas project to the corresponding cerebellar zone throughout lobules V‐I.Thelateralmostpart of the anterior lobe (lobules IV‐V) receives afferents from an area in the dorsal lamella of the principal olive. Theintermediate partof lobules IV‐V receives afferents from the medial half of the dorsal accessory olive and from an area in the rostral half of the medial accessory olive. There is suggestive evidence that the latter projects lo a middle zone, the former to a medial and a lateral zone within the intermediate part as found physiologically. Conclusions concerning projections to the intermediate part of lobules III‐II could not be made.The findings in this and preceding studies with the HRP‐method show that the concept of a longitudinal pattern in the cerebellum is scarcely generally valid of the entire olivocerebellar projection.Within the projections of the lateral half of the dorsal accessory olive and the area in the rostral part of the medial accessory olive there appears to be a topical relation with the folial pattern in the anterior lobe.An analysis of the findings with reference to the afferents traced anatomically to the various olivary areas permits some conclusions as to the functional role of the olivary areas. Comparison with Oscarsson's (1973) diagram of the sites of termination of two of the spinal‐olivary pathways (his DF‐SOCP and VF‐SOCP) permits an anatomical explanation as concerns the projections to the vermis, while correlations as concerns the intermediate part are le

ISSN:0092-7317    

DOI:10.1002/cne.901720105

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe responses of horizontal cell bodies and cones in the retina of the cat have been studied by means of intracellular recording and Procion dye injection In an isolated, arterially perfused eyecup preparation. Comparison of the hyperpolarizing responses of these units to red and blue stimuli of different intensities indicated that all morphological varieties of horizontal cells and, additionally, cones themselves, had mixed rod and cone input. The rod input into horizontal cell bodies is thus explained on the basis of cone physiology. The half‐saturating intensity of 441 nm stimuli for the rod input into cones and horizontal cells was about 400 quanta/μm2/sec and about 160,000 quanta/μm2/sec for the cone input. Little of this difference can be related to the different quantum catching abilities of rods and cones. The spatial properties of horizontal cell bodies and cones have been characterized using stimuli consisting of long slits in conjunction with a continuous cable model. Space constants for horizontal cells ranged from 210 μm to 410pm, whereas those for cones ranged from 50μm, or possibly less, to 180 μm. It is argued that horizontal cell bodies of the cat retina form electrical networks, and that the sizes of the receptive fields generated in these networks may be limited by the diameters of the primary and secondary dendrites of horizontal cells. The rod and cone fields of horizontal cell bodies were found to be nearly coextensive in space, arguing against the notion that substantial rod input came from distant, rod‐dominated terminal arbor

ISSN:0092-7317    

DOI:10.1002/cne.901720106

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

年代:1977

数据来源: WILEY

摘要:

AbstractDenervation of specialized cutaneous mechanoreceptors (Haarscheiben or domes) in cats was followed after 20 and 25 days by the following alterations in receptor structure: (1) reduced numbers of Merkel cells, (2) Merkel cells degenerating in situ, (3) fewer dense‐core granules in the cytoplasm of Merkel cells, (4) an increased number of agranular dendritic cells and Langerhans cells in the dome, (5) the apparent phagocytosis of Merkel cells by Schwann and Langerhans cells, (6) fewer epithelial cell layers over the dome, and (7) a decrease in the number of transitional cells.Skin excised between the domes in the denervated nerve field appeared normal when compared to innervated skin, and it was considered unlikely that the alterations in dome structure were due to generalized nutritional changes in the skin caused by transection of sympathetic axons or to some other side effect of denervation. Since domes are formed in new locations on the skin after nerves have regenerated (Burgess et al.,1974), changes in dome structure following nerve transection are probably due to loss of the “trophic” influence of the nerves supplying the

ISSN:0092-7317    

DOI:10.1002/cne.901720107

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe application of microelectrode recording and anatomical tracing methods to the subcortical optic projections of the normal rat shows that the uncrossed pathway from the retina of this mammal is substantially composed of branches of crossed axons. In the recording experiments, paired stimuli to the optic tracts produces an attenuated antidromic response in the optic nerve which is best explained by the collision of impulses which travel in branches of the same parent axon. Cobalt injection of one optic tract results in retrograde filling of axons in the entire contralateral optic nerve and filling of axons in restricted regions of the ipsilateral optic nerve. This procedure also results in the filling of axons in the opposite optic tract. The locations of the filled axons in the opposite tract correspond to the positions of crossed and uncrossed projections from the temporal retinae: ventrolateral and dorsomedial, respectively. The position of the temporal retinal projections in both optic tracts was determined by applying silver degeneration methods after small lesions of the retina.

ISSN:0092-7317    

DOI:10.1002/cne.901720108

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe facial nucleus of the brush‐tailed possum has been studied using Nissl staining and the horseradish peroxidase (HRP) retrograde tracing technique. In Nissl stained sections the nucleus is seen to comprise five distinct subnuclei. Injections of HRP into individual facial muscle groups have shown that these subnuclei reflect the peripheral innervation pattern of efferents from this nucleusAlthough in most cases, injection of HRP into a single facial muscle group resulted in the labelling of neurons in more than one facial subnucleus, the following subnuclei were most completely labelled subsequent to intramuscular injection of HRP: the dorsal intermediate subnucleus was labelled with HRP reaction product following injection of m. auricularis anterior; the middle intermediate subnucleus was labelled following injection of the muscle underlying the malar vibrissae; the ventral intermediate subnucleus was labelled following injection of the m. mentalis; the medial subnucleus was labelled following injection of the m. auricularis posterior; the lateral subnuleus was labelled following injection of the m. nasolabialis with HRPIn general there is a mediolateral representation in the facial nucleus of neurons innervating facial muscle groups which are found in anteroposterior succession along the head of the animal. Muscle groups found in dorsoventral succession on the animal are represented dorsoventrally in the facial nucleu

ISSN:0092-7317    

DOI:10.1002/cne.901720109

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

年代:1977

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901720101

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

年代:1977

数据来源: WILEY