Effect of EDA-driven sympathetic responses on the central processing of faces cued by hedonic odors: a preliminary ERP study

Olfactory stimuli are powerful cues capable of modulating behavioral and physiological responses to other stimuli, such as visual stimuli. In this study, we investigated the integration of autonomic-driven information into the central nervous system dynamics during a contextual presentation of neutral faces and hedonic odors. To this aim, we simultaneously acquired the electrodermal activity (EDA) and EEG signals from a group of 20 healthy volunteers. We applied a novel methodological approach to identify event-related potentials (ERPs) with and without a concomitant EDA-related sympathetic response. Then, we investigated the effect of both sympathetic responses and contextual odors on ERP components involved in the processing of faces. Preliminary results showed a significant increase of the N170 amplitude in the left parieto-temporal region when a sympathetic response was present, compared to ERPs associated with no sympathetic responses, irrespective of odors' valence. This may suggest that sympathetic responses identified from EDA have an effect on the early central processing of faces with background odors, possibly reflecting enhanced arousal triggered by salient features of the stimuli.