Reductions in CI amplitude after repetitive transcranial magnetic stimulation (rTMS) over the striate cortex

Slow repetitive transcranial magnetic stimulation (rTMS) is a method capable of transiently inhibiting cortical excitability and disrupting information processing in the visual system. This method can be used to topographically map the functional contribution of different cortical brain areas in visual processing. An early electrophysiological component, the CI is argued to reflect early visual processing. In addition, source-localization studies have provided evidence for the assumption that the striate cortex is the underlying neural generator of CI. In the present placebo-controlled, crossover study, slow rTMS was applied in order to further investigate the relationship between the striate cortex and the CI component. Based on the inhibitory effects of slow rTMS, a reduction in CI amplitude and an increase in latency were expected. Compared to placebo stimulation, slow rTMS over the striate cortex resulted in significant decreases of the CI amplitude, but did not affect latency. The present study provides causal evidence for the involvement of the striate cortex in generating the CI component.