Temporal dynamics revealed by paired stimulation in the sensory cortex

We report here that temporally paired stimulation to the peripheral body of rat results in synchronized time locked gating of sensory transmission to the central nervous system (CNS). Gating of sensory inflow at the cerebral 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 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 stimulation 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 mechanisms of time-locked synchronized gating, but at present, we can not fully disregard synaptic modulation.