Exp Neurobiol 2004; 13(1): 15-19

Published online July 1, 2004

© The Korean Society for Brain and Neural Sciences

Temporal Dynamics Revealed by Paired Stimulation in the Primary SomatosensoryCortex of Anesthetized Rats

Sang-Eok Kim, Young-Sil Kim and Hyung Cheul Shin*

Department of Physiology, College of Medicine, Hallym University,Chuncheon 200-702, Korea

Correspondence to: *To whom correspondence should be addressed.
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We report here that temporally paired stimulation to the peripheral body of rat results in synchronized time locked gating of sensory transmission to the primary (SI) somatosensory cortex. Gating of sensory inflow at the SI cortex was related to inter- spike interval of paired stimulus, suggesting that previous sensory experience may strictly dictate subsequent sensory input. Blocking the inhibitory synapses in the SI cortex showed similar result, suggesting that lateral inhibition in cortex can not explain the cause of this sensory gating. The curve-fitted characteristic function of paired stim-ulation shows early near gating-off and long lasting but shallow suppression of sensory transmission. This characteristic is similar to the activity dependent sensory modulation in nerve fibers. In conclusion, we here propose active modulation in axon fiber as possible mechanism of time-locked synchronized gating, but at present, we can't fully disregard synaptic modulation.

Keywords: Somatosensory, paired stimulation, temporal dynamics, sensory proc-essing