Modulating emotional responses: effects of a neocortical network on the limbic system

Humans share with animals a primitive neural system for processing emotions such as fear and anger. Unlike other animals, humans have the unique abili ty to control and modulate instinctive emotional reactions through intellec tual processes such as reasoning, rationalizing, and labeling our experienc es. This study used functional MRI to identify the neural networks underlyi ng this ability. Subjects either matched the affect of one of two faces to that of a simultaneously presented target face (a perceptual task) or ident ified the affect of a target face by choosing one of two simultaneously pre sented linguistic labels (an intellectual task). Matching angry or frighten ed expressions was associated with increased regional cerebral blood flow ( rCBF) in the left and right amygdala, the brain's primary fear centers. Lab eling these same expressions was associated with a diminished rCBF response in the amygdalae. This decrease correlated with a simultaneous increase in rCBF in the right prefrontal cortex, a neocortical region implicated in re gulating emotional responses. These results provide evidence for a network in which higher regions attenuate emotional responses at the most fundament al levels in the brain and suggest a neural basis for modulating emotional experience through interpretation and labeling. NeuroReport 11:43-48 (C) 20 00 Lippincott Williams & Williams.