Stimulus-specific plasticity in human visual gamma-band activity and functional connectivity

Abstract

Stimulus repetition reduces neuronal responses in sensory areas, while leaving perceptual fidelity and behavioral performance intact. Visual gamma-band activity decreases for few stimulus repetitions in humans, yet increases for many repetitions in macaques. Using magnetoencephalography, we confirmed that gamma decreases for the first few stimulus repetitions, and, as in macaques, increases for further repetitions. Crucially, this increase did not transfer to other stimuli, suggesting that the circuit changes were specific to the inducing stimulus. The increase partially persisted when the inducing stimulus was repeated after 25 minutes of intervening stimuli. The increase was most pronounced in early visual areas, and entailed an increased feedforward influence onto higher areas. Our results suggest that early visual cortex gamma synchronization subserves adaptative neuronal processing of recurring stimuli. We propose that drive-dependent gamma phase shifting combines with spike timing-dependent synaptic plasticity to reduce overall responses, while maintaining the impact on higher areas and behavior.