S1). We chose three time intervals for our TMS–EEG experiment: an “early” time window (96–119 msec) and a “late” time window (236–259 msec) with a behavioral effect and as a control one “intermediate” interval (156–179 msec) without a behavioral effect. We also presented stimuli without applying TMS (the no TMS condition),

Inhibitors,research,lifescience,medical creating a total of four TMS conditions (see Fig. 2A). To rule out any TMS effects unrelated to the disruption of neural activity in V1/V2 (i.e., noisy clicks), we added an extra session in which we applied sham TMS. Seven participants (also participating in the TMS–EEG experiment) performed the discrimination task while sham TMS was applied over V1/V2. We used the same time windows and stimulator output as during actual stimulation. We recorded 48 sham trials per condition (576 trials in total), while an EEG cap was placed on the heads of the participants (although no actual EEG signals were recorded Inhibitors,research,lifescience,medical during sham TMS, we wanted to keep the circumstances identical to that of effective stimulation). During sham stimulation, the coil was tilted ventrally, 90° from the plane tangential Inhibitors,research,lifescience,medical to the scalp (Lisanby et al. 2001). Behavioral analysis Almost all participants were able to reach a moderate overall performance Inhibitors,research,lifescience,medical level. However,

two participants failed to reach a level above 67% correct (stack detection remained around chance level). These two participants were selleckchem excluded so that all further analyses were performed on the remaining 11 participants.

To examine the effect of TMS on behavioral scores, we performed a 3 Inhibitors,research,lifescience,medical × 4 repeated measures analysis of variance (ANOVA) on mean percentage correct with factors: stimulus type (homogenous, frame, and stack) and TMS time window (none, early, intermediate, and late). A 3 × 4 repeated measures ANOVA was also performed on mean reaction times (RTs) with factors: stimulus type and TMS time window. RTs of less than 100 and greater than 1500 msec were excluded from all analyses. EEG measurements and analyses EEG was recorded and sampled at 1048 Hz using an ANT 64-channel system with eight bipolar inputs allowing the recording of EOG (ANT – ASA-Lab system Carfilzomib of ASA, Enschede, The Netherlands). Sixty-four scalp electrodes were measured, as well as four electrodes for horizontal and vertical eye movements (each referenced to their counterpart). After acquisition, EEG data were KPT-185 filtered using a special filtering algorithm designed to eliminate ringing effects that occur when filtering signals that have high-frequency components. To overcome ringing effects, both the original signal and its mirrored version (transposed in time) are filtered.