Biomedical subjects

T Hiyoshi

Publications and source records attributed to T Hiyoshi.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Lasting nature of both transfer and interference in amygdaloid kindling in cats: observation upon stimulation with 11-month rest following primary site kindling.

Eleven months after the completion of primary site amygdaloid (AM) kindling, three cats experienced kindling of the secondary site AM. At the secondary site, animals developed kindled seizure with a mean of eight stimulations, which was significantly fewer than the 29 required at the primary site, indicating a presence of a positive transfer effect. However, the ictal architecture of the secondary site-kindled seizure was significantly different from that of the primary site: in the former, there was a marked delay in secondary generalization, with individual kindled seizure having a significantly prolonged seizure duration. Both the transhemispheric positive and negative transfer effects observed with the secondary site AM kindling reflect the lasting nature of the neural remodeling induced by the primary site AM kindling. This finding may have clinical relevance.

Amygdala↗

PubMedDate not supplied

Evidence of secondary epileptogenesis in amygdaloid overkindled cats: electroclinical documentation of spontaneous seizures.

Twenty-four spontaneously occurring convulsive seizures were documented by closed-circuit TV (CCTV)-EEG monitoring in 3 cats subjected to unilateral amygdaloid overkindling for < or = 2 years. Electroclinical manifestations suggested that the seizures originated in the kindled amygdala (AM) (10 seizures in 3 cats), contralateral AM (7 seizures in 3 cats), or ipsilateral frontal cortex (7 seizures in 1 cat). All seizures of AM origin except one occurred during sleep 23 h to 20 days after the last stimulation-induced kindled seizure and culminated in secondarily generalized seizures. The seizures of frontal cortical origin occurred during waking within 1 h of a kindled seizure and remained partial in nature. In seizures of AM origin, ictal patterns at the primary and secondary sites were mirror images of each other, but latency of onset of each seizure stage in seizures of secondary site AM origin was longer than that in seizures of primary site AM origin in 2 of the 3 animals. We conclude that the secondary epileptogenic functional alterations capable of producing clinical seizures do occur in AM-overkindled cats, but the seizures are not entirely independent of the primary kindled site.

Amygdala↗

PubMedDate not supplied

Feline amygdaloid kindling and the sleep-waking pattern: observations on daily 22-hour polygraphic recording.

For 22 h daily, polygraphic examination was made of sleep organization in four cats, both before and after amygdaloid (AM) kindling. After the completion of AM kindling and repetitive induction of kindled convulsion, the percentage of time spent in rapid eye movement sleep (REMS) significantly decreased, while the total sleep time (TST) remained unchanged. REMS suppression was most profound during the immediate postictal hours and continued through the 22-h period without a rebound increase. Slow wave sleep (SWS) was also suppressed during the postictal hours; however, this suppression was exceeded by that of REMS and was followed by a rebound increase. These changes in sleep organization were transient. During a rest interval of 2 months without kindled convulsions, they gradually disappeared and there was a complete recovery to the prekindling baseline. However, when the AM-kindled convulsion was reintroduced, there was an abrupt REMS suppression without TST change. We conclude that changes in sleep organization after AM kindling are (a) characterized by suppression of REMS and a compensatory increase in SWS, and (b) a direct but transient correlate of convulsion rather than of an acquired seizure susceptibility.

Amygdala↗