Examining cortical dynamics and connectivity with simultaneous single-pulse transcranial magnetic stimulation and fast optical imaging

► The event-related optical signal (EROS) was recorded concurrently with TMS. ► The time course of TMS-evoked activity was imaged in primary motor cortex (M1). ► Activity was measured with high spatial (< 1 cm3) and temporal resolution (8 ms). ► M1 activity peaked at 16 ms post-pulse followed by contralateral activity at 40 ms. ► This method provides a new tool to study dynamics and connectivity of human cortex.