Visual evoked potentials (VEP) without Visual Input: EEG Correlates of Phosphene Perception after single pulse TMS

Objective: To measure the electrophysiological correlates of TMS evoked phosphene perception with EEG and comparison with results of an fMRI study using the same paradigm. Methods: EEG was recorded continuously with a TMS compatible device (slew-rate-limiting preamplifier, 200Hz, 45 electrodes) online to single pulse TMS over the occipital pole in 5 healthy volunteers (3 male, mean age 24–39 years). TMS was applied at individual phosphene threshold (PT) intensity such that subjects perceived phosphenes in 50% of the trials. Offline analysis included averaging over artefact-free epochs (-400ms pre to +400ms post…