摘要:

The method of retrograde axonal transport of horseradish peroxidase was employed to demonstrate certain organizational features of the pontocerebellar system in adult opossums. The spinal cerebellum (anterior lobe, pyramis and paramedian lobule) receives input from neurons situated in ventral and lateral regions throughout the rostro-caudal extent of the pons. The projection to the anterior lobe and pyramis was primarily contralateral, whereas the projection to the paramedian lobule included a substantial ipsilateral contribution. The pontine projection to the vermal visual-auditory area was also found to include significant bilateral components which were observed to be organized in mirror image locations in medial, ventral and lateral regions. The paraflocculus was found to receive input from a relatively large number of pontine neurons, the medial injection producing a more bilateral distribution of labeled neurons while the lateral injection resulted in primarily contralateral labeling. Crus I and crus II of the cerebellar hemispheres received a bilateral projection which also included neurons distributed in mirror image locations in both halves of the pontine gray. Taken together such observations indicate that the pontocerebellar system includes a more substantial ipsilateral contribution than has heretofore been recognized. In addition, comparison of the locations of various groups of labeled neurons resulting from spatially separate injection sites suggests the possibility that some pontocerebellar neurons might diverge to reach more than one cerebellar zone, i.e. cells in a similar ventrolateral pontine region were labeled following injections in the anterior lobe, pyramis and crus I. Evidence for convergence of multiple pontine areas to single cerebellar foci was not as compelling.

ISSN:0006-8977    

DOI:10.1159/000121798

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The method of retrograde axonal transport of horseradish peroxidase was employed to demonstrate certain organizational features of the pontocerebellar system in adult opossums. The spinal cerebellum (anterior lobe, pyramis and paramedian lobule) receives input from neurons situated in ventral and lateral regions throughout the rostro-caudal extent of the pons. The projection to the anterior lobe and pyramis was primarily contralateral, whereas the projection to the paramedian lobule included a substantial ipsilateral contribution. The pontine projection to the vermal visual-auditory area was also found to include significant bilateral components which were observed to be organized in mirror image locations in medial, ventral and lateral regions. The paraflocculus was found to receive input from a relatively large number of pontine neurons, the medial injection producing a more bilateral distribution of labeled neurons while the lateral injection resulted in primarily contralateral labeling. Crus I and crus II of the cerebellar hemispheres received a bilateral projection which also included neurons distributed in mirror image locations in both halves of the pontine gray. Taken together such observations indicate that the pontocerebellar system includes a more substantial ipsilateral contribution than has heretofore been recognized. In addition, comparison of the locations of various groups of labeled neurons resulting from spatially separate injection sites suggests the possibility that some pontocerebellar neurons might diverge to reach more than one cerebellar zone, i.e. cells in a similar ventrolateral pontine region were labeled following injections in the anterior lobe, pyramis and crus I. Evidence for convergence of multiple pontine areas to single cerebellar foci was not as compelling.

ISSN:0006-8977    

DOI:10.1159/000121799

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Monkeys were observed for hand preference during simple reaching for food. The position of the animal relative to the food had only a slight influence upon the strength of hand preference. With repeated reaching, the strength of preference for the preferred hand tended to increase. The hand preferred on the first reach was predictive of that preferred over the entire series of 600 reaches in a significant proportion of individuals. This was not true of the animals presumed to be youngest and suggests that past experiential or developmental factors influence the hand preference displayed in later circumstances.

ISSN:0006-8977    

DOI:10.1159/000121800

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The localization and organization of primary (SmI) and secondary (SmII) somatic sensory cortical regions in agoutis, have been studied with micro- and macroelectrode-evoked potential techniques. For SmI, the mean surface area determined using microelectrodes was 13% smaller than that obtained using macro-electrodes. The location and organization of SmI are similar to those of other rodents: the largest representations were those of the vibrissae, the perioral regions and the first digit of the hand. As in some other animals, SmII is related both sides of the body. It shows excellent somatotopic differentiation and was located lateral and posterior to SmI, in relation to which it is arranged as a reduced mirror image. The area of SmII represents 31% of that of SmI in agoutis. The large size of the forepaw representation in SmI is reflected in SmII, that of the face representation is not; this agrees with similar findings from several other species. SmI was completely mapped using light touch stimuli, and contains many projections from vibrissae and hairs along with some proprioceptive projections. SmI overlaps with visual projections. SmII receives less light touch, vibrissae and hair projections than SmI, and it receives numerous deep mechanical and auditory projections. In SmII latencies were 10.96 msec for somesthetic and 13.39 msec for auditory stimuli; in SmI latencies were 13.25 msec for somesthetic and 39.80 msec for visual stimuli. One sulcus separates the SmI projections of the forelimb from those of the hind-limb, and another is often found marking the posterolateral boundary of SmII.

ISSN:0006-8977    

DOI:10.1159/000121801

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The Purkinje cells of the premetamorphic frog tadpole cerebellum were studied with the transmission electron microscope. At this stage of histogenesis, when the external granular layer is yet to be formed, their maturational state varied greatly from randomly oriented cells with a thin rim of cytoplasm to well-formed cells with an abundance of organelle-rich cytoplasm and well-developed dendrites. The well-developed cells were seen in the apical (marginal) region of the cerebellar plate and the poorly developed cells in the basal region. Climbing fibers and other unidentified processes formed synapses on the well-developed Purkinje cell somata and somatic dendrites and on the spines and smooth surfaces of the primary dendrites.

ISSN:0006-8977    

DOI:10.1159/000121802

出版商:S. Karger AG    

年代:1980

数据来源: Karger