Exploring the time course of N170 repetition suppression: a preliminary study

Several studies employed the repetition suppression paradigm to investigate the face-specific N170 component of the event-related potential (ERP), but yielded highly inconsistent results. Varying inter-stimulus intervals (ISIs) may account for inconsistencies between studies. This study aimed at exploring the time course of repetition suppression by systematically investigating the association between ISI and ERP adaptation. Fourteen healthy subjects were investigated with a passive face recognition paradigm using paired stimuli. Stimuli were presented for 500ms and ISIs parametrically varied between 400 and 2000ms. N170 was constructed to investigate adaptation effects on the level of perceptual face processing. We found an evidence for an asymptotic decay of repetition suppression over time with significant N170 adaptation effects only after the shortest ISI. Our results robustly demonstrate that N170 adaptation in a paired stimulus protocol critically depends on short ISIs, thereby explaining the inconsistencies observed in the previous studies. For future social cognition studies using neuronal adaptation to face stimuli, the current results provide a well defined ISI associated with a large N170 adaptation effect.