The Korean Journal of Physiology and Pharmacology  2004;8(3):129-132

Interhemispheric Modulation on Afferent Sensory Transmission to the Ventral Posterior Medial Thalamus by Contralateral Primary Somatosensory Cortex.

Sung Cherl JUNG 1 ; In Sun CHOI ; Jin Hwa CHO ; Ji Hyun KIM ; Yong Chul BAE ; Maan Gee LEE ; Hyung Cheul SHIN ; Byung Ju CHOI

Affiliations

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Keywords

Somatosensory; VPM thalamus; SI cortex; Interhemispheric modulation; GABA; Bicuculline; Callosal projection

Country

Republic of Korea

Language

English

Abstract

Single unit responses of the ventral posterior medial (VPM) thalamic neurons to stimulation were monitored in anesthetized rats during activation of contralateral primary somatosensory (SI) cortex by GABA antagonist. The temporal changes of afferent sensory transmission were quantitatively analyzed by poststimulus time histogram (PSTH). Mainly, afferent sensory transmission to VPM thalamus was facilitated (15 neurons of total 23) by GABA antagonist (bicuculline) applied to contralateral cortex, while 7 neurons were suppressed. However, when ipsilateral cortex was inactivated by GABA agonist, musimol, there was significant suppression of afferent sensory transmission of VPM thalamus. This suppressed responsiveness by ipsilateral musimol was not affected by bicuculline applied to contralateral cortex. These results suggest that afferent transmission to VPM thalamus may be subjected to the interhemispheric modulation via ipsilateral cortex during inactivation of GABAergic neurons in contralateral SI cortex.