摘要:

AbstractExperiments on spindles in normal and chronically denervated lateral costocutaneous muscles of snakes are described. The discharge patterns in response to stretch of tonic and phasic spindles are compared between normal spindles and those denervated for various periods of time. The main findings are that spindle function is lost after denervation periods of about 150 hours (the animal being kept at 30°C during the denervation period), and that prior to this (130–140 hours) both tonic and phasic spindles lose their ability to discharges; i.e., they become totally adapting.Electronmicrographs, prepared mainly from material used in the physiological experiments, reveal certain structural changes occurring in parallel with the physiological changes. These consist of increase of neurofilaments, swelling and increasing electron density of mitochondria and appearance of electron‐dense bodies in the sensory ending; these changes occur at times when the spindles are still functioning, though in a modified way. Later the gap between nerve ending and underlying intrafusal fiber is invaded by satellite cell processes. Eventually the nerve endings totally disap

ISSN:0092-7317    

DOI:10.1002/cne.901430202

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe opossum midbrain was sectioned in frontal, sagittal and horizontal planes and subsequently stained with cresyl violet to determine the cytoarchitecture of the red nucleus. The neurons were visualized in more detail in Golgi preparations, one micron plastic sections and by employing electron microscopy.Distinct parvicellular and magnocellular subdivisions are not apparent in this species. The characteristic neurons can be divided into three types by utilizing the following criteria: size, distribution of Nissl bodies and dendritic patterns. The cytoplasm of the giant neurons (45–70 μ) is filled with Nissl granules and the dendrites are long and tapered, and display an occasional spine. The large‐medium neurons (40–25 μ) can be differentiated from the giant neurons on the basis of size and their less extensive pattern of dendritic branching. Small neurons (10–20 μ) are achromatic or have a uniformly basophilic cytoplasm and may be classified as Golgi type II neurons.The large‐medium size neurons are the most numerous of the three types described and they are distributed throughout the entire extent of the nucleus. The small neurons, although found less frequently than the large‐medium size cells, also are scattered throughout the nucleus. The giant neurons are limited to the caudal medial 0.5 mm of the nucleus.A morphological classification of synaptic terminals is described: (1) small (1–2 μ), (2) elongate (up to 10 μ), (3)boutons en passageand (4) large (2–4 × 5–9 μ). Differences in the population of synaptic vesicles in the four types of synaptic endings are described. In addition, differences in the distribution of the four types of synaptic terminals with respect to the soma, proximal dendrites and dendrites in the

ISSN:0092-7317    

DOI:10.1002/cne.901430203

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe distribution of the axonal and terminal degeneration in the posterior group and principal nuclei of the thalamus of the cat has been studied with the Nauta technique following lesions of the major ascending sensory pathways and of most areas of the cerebral cortex. The cellular changes occurring in the same parts of the thalamus after damage of the cortex of the somatic, auditory and visual sensory areas have also been investigated.It has been found that the posterior group receives fibers from all parts of the cortex on the lateral surface of the hemisphere caudal to area 4, with the exception of areas 17, 18 and 19 of the visual cortex, and that cellular degeneration occurs in the posterior group after damage of the same areas of cortex. Both fiber and cellular degeneration can be found in the posterior group after a lesion confined to either the somatic sensory or auditory cortex.Experiments with smaller lesions have shown that all areas of the cortex which have been studied send fibers to parts of three distinct types of thalamic nuclei — to the relevant principal nucleus, to a part of the intralaminar group of nuclei or the posterior group, and to a part of the reticular nucleus. After larger lesions of the cortex cellular degeneration is always found in parts of these three types of nuclei. Ascending fibers in the somatic and auditory sensory pathways also terminate in the principal nuclei and in one or other part of the intralaminar nuclei‐posterior group systembut notin the reticular nucleus.There is a definite interrelationship in the somatic and auditory sensory systems between the site of termination of the ascending fibers of these pathways, the principal nuclei and parts of the posterior group in which these two pathways end, and the area of cortex to which these principal nuclei project and which, in turn, sends fibers back to them and to the posterior group. It is suggested that there is a similar relationship between the site of termination in the intralaminar nuclei of afferent fibers from subcortical structures, the principal nuclei in which the same afferent pathways end, and the area of cortex with which these principal nuclei are related. This appears to be true at least for the pathways from the cerebellum and globus pallidus to the ventrolateral nucleus and the relevant components of the intralaminar nuclei.On the basis of the experimental findings it is suggested that the posterior group should be included with the intralaminar group of nuclei, and that the region equivalent to the intralaminar nuclei‐posterior group system for the visual cortex is the pretectum (either the whole or a part) or the nucleus of the optic tract. If this hypothesis is correct there is a continuous, well‐organized projection of the neocortex upon the entire extent of the intralaminar nuclei‐posterior group‐pretectal area complex: prefrontal and limbic cortex being related to rostral intralaminar nuclei, areas 6 and 4 to the parafascicular, centre median and central lateral nuclei, the somatic sensory cortex to the medial division of the posterior group, the auditory cortex to the lateral division of the posterior group, the supra‐sylvian cortex to the suprageniculate nucleus and intermediate division of the posterior group and the visual cortex to the pretectum and adjo

ISSN:0092-7317    

DOI:10.1002/cne.901430204

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

年代:1971

数据来源: WILEY

摘要:

AbstractIn a series of seventeen rhesus monkeys attempts were made to produce discrete stereotaxic lesions in the anteroventral cochlear nucleus (Av). Anterograde degeneration was described in detail in four cases with lesions confined within the cochlear complex to Av. Fibers decussating at pontine levels coursed exclusively in the trapezoid body. Degenerated fibers projected: ipsi‐laterally to the lateral superior olivary nucleus; bilaterally to the preolivary nuclei; to the lateral side of the ipsilateral medial superior olive and the medial side of the contralateral medial superior olive; and to the contralateral medial trapezoid nucleus. A topographic projection upon the medial superior olive was demonstrated. Projections were bilateral but mainly crossed to the nuclei of the lateral lemniscus and central nucleus of the inferior colliculus; the posterior end of the ipsilateral ventral nucleus of the lateral lemniscus contained an island of profuse degeneration. A few fibers crossed in the commissure of the inferior colliculus. Few if any fibers from Av projected to the contralateral magnocellular medial geniculat

ISSN:0092-7317    

DOI:10.1002/cne.901430205

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

年代:1971

数据来源: WILEY

摘要:

AbstractThese studies were carried out to show the manner of projection of the dorsal lateral geniculate nucleus and other thalamic nuclei to striate cortex in the Virginia opossum. In order to demonstrate these projections, lesions were made in the dorsal lateral geniculate nucleus, in the ventral lateral geniculate nucleus, in most of the thalamus on one side except for the dorsal lateral geniculate nucleus, and in the entire unilateral thalamus. Following various survival times, usually seven days, the brains were appropriately prepared and stained with procedure I of the Fink‐Heimer technique. Dorsal lateral geniculate neurons project in a topographical manner only to certain layers of striate cortex. These projections from the lateral geniculate are compared with the same system in other mammals, and it is concluded that it is similar in all mammals studied, except for the cat. In the cat the lateral geniculate projects beyond the border of striate cortex, but even in the cat the layers of termination within striate cortex are apparently similar. The ventral lateral geniculate nucleus does not project to visual cortex. Dorsal thalamic nuclei other dian the lateral geniculate project to peristriate cortex and to layers VI and I of striate cortex. The finding that thalamic nuclei, other than the lateral geniculate nucleus, project to striate cortex has never been described as part of the visual pathways in other mammals. It is suggested that these additional projections arise mainly from the lateral nuclear group of the thalamus in the opossum, and must be considered in relation to any response characteristics and organization of striate cells determined from physiological studies. These multiple thalamic projections can provide the substrate for more than one representation or “map” of sensory information in striate c

ISSN:0092-7317    

DOI:10.1002/cne.901430206

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

年代:1971

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901430207

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

年代:1971

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901430201

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

年代:1971

数据来源: WILEY