摘要:

AbstractIt is generally assumed that (i) all neurones of the inferior olive send their axons to the cerebellum; (ii) the fibers from the olive end as climbing fibers; (iii) one climbing fiber establishes extensive synaptic contact with one Purkinje cell. From this it has been inferred that there is one inferior olivary neurone per Purkinje cell. The number of neurones in both inferior olives from four cats have been counted in histologic sections. The totals obtained are 145380, 127270, 126920 and 121360, respectively. In two of the cats the Purkinje cells were counted. The ratios of inferior olivary neurones to Purkinje cells were found to be 1 : 10 and 1 : 11, respectively.

ISSN:0092-7317    

DOI:10.1002/cne.901470102

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe intrinsic organization of the central nucleus of the inferior colliculus has been studied in the adult cat by means of the Golgi and Nauta techniques. On the basis of cytoarchitecture and fiber connections, the central nucleus can be divided into: (i) a smaller,dorsomedial divisionconsisting mainly of large cells and receiving fibers from the auditory cortex, lateral lemniscus and probably the central nucleus of the other side; (ii) a larger,ventrolateral divisionconsisting mainly of medium and small cells but with some intermingled larger types. This part receives fibers from the lateral lemniscus only.The ventrolateral division has a pronounced laminar arrangement of cells, dendrites and axons. The laminae, although overlapping extensively, form an onion‐like series of concentric, curved shells, most of which are incomplete except for those closest to the center of curvature in the dorsolateral part of the nucleus. It is probable that these laminae provide a basis for the pronounced tonotopic organization of neurons in the nucleus. The thickness of the laminae is determined by the dendritic ramifications of two principal cell types which are fusiform or bi‐tufted. Other, multipolar and large cells have dendrites which lie across one or several laminae and may form a basis for interaction between laminae.Four axon types can be distinguished:Type I(lateral lemniscal) andtype II(corticofugal) axons run parallel to the laminae but in opposite directions, though type II axons are confined to the parts of the laminae projecting into the large‐celled, dorsomedial division.Type IIIaxons are widely ramifying and may arise within the central nucleus or be another form of afferent fiber. Type I and III axons end in dense clusters of terminals on principal cells but as singleen passantterminals on multipolar cells.Type IVaxons are the efferents of the inferior colliculus and run a recurrent course through the central nucleus giving off collaterals which sometimes end on the parent

ISSN:0092-7317    

DOI:10.1002/cne.901470103

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe central nucleus of the inferior colliculus has been examined electron microscopically in the adult cat, particular attention being paid to its ventrolateral division in which the majority of lateral lemniscal afferents end.Two cell types can be recognized: one, which is the equivalent of the spiny principal cell of light microscopy, is distinguished by having its soma and large proximal dendrites covered by axon terminals. More distally situated dendrites have fewer terminals ending mainly on dendritic spines. These spines resemble those of the cerebral cortex and have a modified spine apparatus. The second type of cell is the equivalent of the small multipolar cell of light microscopy. It has spineless dendrites and these and the soma receive relatively fewer axon terminals. It has a very thin axon.Several types of axon terminal can be recognized. Type I terminals are large, contain spherical synaptic vesicles and end by means of asymmetrical synaptic contacts, on the somata and proximal dendrites of principal cells and on the smaller dendrites of multipolar cells. The extracellular space on one or both sides of the synaptic complex is often characteristically widened. Correlative experimental degeneration studies show that these are the terminals of lateral lemniscal fibers. Various forms of smaller terminal also make asymmetrical contacts and have spherical vesicles. One type has a high concentration of large, densecored vesicles as well.Two types of axon terminal end in symmetrical synaptic contacts. One contains large, homogeneously flattened synaptic vesicles; the other, which is more common, contains smaller, irregularly flattened or pleomorphic synaptic vesicles.In the dorsomedial division of the central nucleus, the terminals of corticofugal fiber have spherical synaptic vesicles and end in asymmetrical synaptic contacts upon large dendritic spines.

ISSN:0092-7317    

DOI:10.1002/cne.901470104

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe central nucleus of the inferior colliculus has been examined electron microscopically two, four and five days after section of the lateral lemniscus and four and five days after ablation of the auditory cortex. The findings confirm the differential distribution of lateral lemniscal and corticofugal fibers to the two divisions of the central nucleus and, in the case of the lateral lemniscal fibers, to the two cell types of the ventro‐lateral division.The material from brains in which the lateral lemniscus was divided contains examples of every type of terminal degeneration which has been described: swelling and glycogen deposition, swelling (often with flattening) of synaptic vesicles, neurofilamentous hyperplasia, greatly increased electron density. At two days, only the first three of these are seen; at four days, all occur together; at five days, only the electron dense type is present. In addition, at two days, a proportion of the early degenerating terminals show almost complete loss of synaptic vesicles and their replacement by the empty “shells” of complex vesicles (of Gray). Aggregations of shell fragments can be discerned at this and later survival periods clustered about presynaptic membranes left devoid of synaptic vesicles.These observations are considered in terms of recent concepts of the mode of formation and release of synaptic vesicles. It is postulated that terminals showing replacement of synaptic vesicles by shell fragments may have been excessively stimulated during or after the operation and have, thus, had a higher turn‐over of synaptic vesicles. It is suggested that, in this and other sites, accumulation of large numbers of shell fragments may be a necessary pre‐requisite for neurofilamentous hyperplasia, the protein of the shells being reorganized into neuro

ISSN:0092-7317    

DOI:10.1002/cne.901470105

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

年代:1973

数据来源: WILEY

摘要:

AbstractSingle unit responses were recorded from neurons in the nucleus basalis of the pigeon. Two hundred and twelve basalis cells, from 23 birds, were characterized in terms of modality, receptive area and adaptive properties. Most basalis units (97%) fired spontaneously in bursts of a few spikes separated by one to two seconds of silence. All units were activated by light mechanical stimulation of the beak or buccal cavity. The units adapted rapidly to a maintained stimulus, but fired vigorously when the stimulating probe moved back and forth across the surface of the receptive area. Receptive fields fell into two clearly separable groups with respect to size: small fields, less than 15 mm2, generally clustered near the beak tips, and large fields occupying from one‐third to the entire beak surface. Both unilateral (ipsilateral or contralateral) and bilateral receptive areas were encountered. Nucleus basalis units could be driven electrically by stimulation of the beak surface or the main sensory trigeminal nucleus (PrV). The data suggest that n. basalis cells are particularly responsive to movement of food (grains) within the mouth and that this information is relayed by trigeminal afferents to the PrV, thence to the n. basalis via a partially decussating quinto‐rontal tract. The results are discussed in relation to the role of the n. basalis in the control of feeding behavior in the pig

ISSN:0092-7317    

DOI:10.1002/cne.901470106

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

年代:1973

数据来源: WILEY

摘要:

AbstractSections prepared by the Nauta method were used to study the fiber degeneration in the dorsal lateral geniculate nucleus and the pulvinar of the rabbit after lesions in the visual cortex, and sections processed by the Golgi and the Cajal methods provided the material needed to study the normal fiber architecture of these nuclei.Two distinct systems of fibers are recognizable in the dorsal lateral geniculate nucleus and in the pulvinar. One is a transverse system formed by the fiber bundles which run within these nuclei oriented in parallel with the optic tract; some of these bundles mingle with the fibers of the optic tract. The other is a longitudinal system whose fibers course perpendicularly to those of the transverse system. Lesions in the visual cortex produce degeneration within both of these fiber systems, in the geniculate nucleus as well as in the pulvinar. The degenerating transverse fibers are corticopretectal and corticotectal axons, and these send collateral branches into the longitudinal systems of these nuclei.The degenerating longitudinal fibers are of two types. One type consists of fibers which are fine in caliber, give rise to numerous short terminal branches, and degenerate early (undegenerated fibers showing this same morphology are identified in the Golgi preparations). These longitudinal fibers are the collateral branches of the degenerating transverse fibers and at the same time they represent the terminal portions of the fibers which provide the visual cortical input to the geniculate nucleus and the pulvinar. It is noteworthy that within the geniculate nucleus these terminal fibers run along the lines of projection for individual points on the visual field.The second type of degenerating longitudinal fibers is found in the dorsal lateral geniculate nucleus but not in the pulvinar. Its fibers are coarser and degenerate later than the longitudinal fibers described above, and they are probably geniculocortical axons undergoing retrograde degeneration.

ISSN:0092-7317    

DOI:10.1002/cne.901470107

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

年代:1973

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901470101

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

年代:1973

数据来源: WILEY