Search PubMed⌕ Search

Biomedical subjects

S Kawaguchi

Publications and source records attributed to S Kawaguchi.

At least 271 records · Page 15Linked to original sources
PubMed1982

Postnatal development of evoked responses in the auditory cortex of the cat.

Postnatal development of the auditory evoked cortical response was investigated in the cat by laminar field potential analysis. Responses were induced by electrical stimulation of the cochlear nuclear complex and by sonic stimulation under sodium pentobarbital anesthesia. As is well known, the auditory evoked cortical response in adult cats is a diphasic positive-negative wave in the superficial cortical layers and a negative-positive wave in the deeper cortical layers. By contrast, the cortical response in neonatal kittens was a monophasic negative wave in the superficial cortical layers and a positive wave in the deeper cortical layers (sN-dP wave). After 1 week, the sN-dP wave was preceded by a small wave which was positive in the superficial cortical layers and negative in the deeper cortical layers (sP-dN wave). As animals grew older, the sP-dN wave became dominant over the sN-dP wave to take an adult-like configuration of responses at 3 to 4 weeks of age. The sN-dP wave was separable from the preceding sP-dN wave by double shock stimulation at a certain time interval. Therefore, these two wave components are presumably mediated by two different types of thalamocortical projections. The level of potential reversal in each wave component shifted from the deeper cortical layers to the more superficial cortical layers during maturation. The latency of the response decreased sharply from 44 msec at birth to 11 msec by 3 weeks, and thereafter gradually to 5 msec in adulthood.

Acoustic Stimulation↗
PubMed1981

Morphological and electrophysiological evidence for axonal regeneration of axotomized cerebellothalamic neurons in kittens.

Against the current concept of abortive regeneration of axotomized neurons in the mammalian central nervous system, the occurrence of remarkable axonal regeneration of cerebellothalamic projection neurons following transection of the decussation of the superior cerebellar peduncle was proved in kittens morphologically by utilizing anterograde axonal transport of horseradish peroxidase and electrophysiologically by recording the cerebellar-induced cerebral cortical potential. Following axotomy, not only axonal regeneration occurred but also retrograde degeneration of somata which was apparently noticeable as cell loss. The extent of cerebellar nuclear cell loss was inversely related to the extent of regeneration of cerebellofugal axons.

Animals↗
PubMed1981

Electrophysiological studies on plasticity of cerebellothalamic neurons in rats following neonatal hemicerebellectomy.

Changes in the cerebello-thalamo-cerebral projection following hemicerebellectomy were investigated in 16 rats by laminar field potential analysis of cerebello-cerebral responses in the cerebral cortex and by unitary recording of antidromic responses of cerebellar nuclear neurons to stimulation of the thalamus. In contrast to the occurrence of an exclusively contralateral cerebello-cerebral response in intact rats, a significant bilateral cerebello-cerebral response could be evoked in all 8 rats hemicerebellectomized before 6 days of age (early hemicerebellectomy). On the other hand, in all 5 rats operated on at 8 to 15 days of age (late hemicerebellectomy) and in the 3 rats operated on in adulthood, the cerebello-cerebral response was evoked only contralaterally just as in intact rats. Unitary recordings of antidromic responses of cerebellar nuclear neurons revealed that bilateral or ipsilateral cerebellothalamic projection neurons were remarkably more numerous in early hemicerebellectomized rats than in controls (P less than 0.001). Such neurons were less frequently found in late hemicerebellectomized rats, but they were still more numerous than in controls (P less than 0.005). Absence of the ipsilateral cerebello-cerebral response in late hemicerebellectomized rats indicates that even though bilateral or ipsilateral cerebellothalamic projection neurons may exist in these rats more numerously than in intact rats, they may not be sufficient in number or in efficiency to mediate a detectably response.

Animals↗