INTERHEMISPHERIC MODULATION OF SENSORY TRANSMISSION IN THE PRIMARY SOMATOSENSORY CORTEX OF RATS

Single unit responses of the primary somatosensory (SI) cortical neuro ns to the stimulation of the forepaw single digit were monitored in an esthetized rats before and after subcutaneous injection of lidocaine t o an ipsilateral homologous receptive field (IHRF). Quantitative deter mination of the temporal changes of afferent sensory transmission was done by analyzing poststimulus time histograms of unit responses. Temp orary deafferentation to the IHRF induced immediate, but reversible su ppression of afferent sensory transmission in the SI cortex and this s uppression lasts up to 35 min post-deafferentation period (during 10-1 5 min, -21.81 +/- 5.9%, P < 0.01). This result suggests that temporary absence of afferent inflow from the digit to the SI cortex may exert interhemispheric modulation of afferent sensory transmission in the op posite somatosensory cortex of anesthetized rats. (C) 1997 Elsevier Sc ience Ireland Ltd.