Emotions and BIS/BAS components affect brain activity (ERPs and fNIRS) in observing intra-species and inter-species interactions.

Affective response to observation of intra-species and inter-species interactions was considered in the present research. The brain activity (optical imaging: functional Near-Infrared Spectroscopy, fNIRS; and event-related potentials, ERPs, N200) was monitored when subjects observed interactive situations (human-human, HH; human-animal, HA) with a positive (cooperative), negative (uncooperative) or neutral (no emotional) content. In addition, cortical lateralization (more left or right prefrontal activity) and personality component (Behavioral Activation System, BAS; Behavioral Inhibition System, BIS) effects were explored. Both ERP and fNIRS showed significant brain activity increasing in response to positive and negative compared with neutral interactions for HH and HA. However, some differences were found between HH (more "negative valence" effect) and HA (more "positive valence" effect). Finally BAS and BIS were related respectively to more left (positive conditions) or right (negative conditions) hemispheric activity. These results supported the significance of affective behavior differentiating the species-specific and species-aspecific relationships.