fMRI identifies a network of structures correlated with retention of positive and negative emotional memory

It is likely that the encoding of emotional experiences involves a complex network of interacting brain regions. The present study used fMRI to identify brain structures involved in the encoding of negative and positive emotional stimuli. Ten subjects viewed alternating blocks of emotionally negative and positive pictures and were tested for long-term recognition memory several months later. Recognition memory for negative and positive pictures was highly correlated. Brain reactivity to negative pictures was positively correlated with better recognition memory for both negative and positive pictures in the amygdala, the insula, and the right middle frontal gyrus. Brain reactivity to positive pictures was positively correlated with better recognition memory for both negative and positive pictures in the left anterior cingulate gyrus. Activation among these brain regions was highly correlated and suggests a network of structures that interact to encode either negative or positive emotional stimuli for long-term recognition memory. Two mechanisms by which this encoding may take place are discussed.