HEMISPHERIC-ASYMMETRY FOR EMOTIONAL STIMULI DETECTED WITH FMRI

CURRENT brain models of emotion processing hypothesize that positive ( or approach-related) emotions are lateralized towards the left hemisph ere, whereas negative (or withdrawal-related) emotions are lateralized towards the right hemisphere. Brain imaging studies, however, have so far failed to document such hemispheric lateralization. In a function al magnetic resonance imaging (fMRI) study, 14 female subjects viewed alternating blocks of emotionally valenced positive and negative pictu res. When the experience of valence was equated for arousal, overall b rain reactivity was lateralized towards the left hemisphere for positi ve pictures and towards the right hemisphere for negative pictures. Th is study provides direct support for the valence hypothesis, under con ditions of equivalent arousal, by means of functional brain imaging. ( C) 1998 Lippincott Williams & Wilkins.