NEURAL EFFECTS OF VISUALIZING AND PERCEIVING AVERSIVE STIMULI - A PETINVESTIGATION

CEREBRAL blood flow was recorded (using positron emission tomography) while middle-aged subjects viewed or visualized pictures of neutral or aversive stimuli, and then determined whether auditorily presented st atements correctly described the stimuli. Visualizing aversive stimuli enhanced cerebral blood flow, relative to visualizing neutral stimuli , in areas 17 (right) and 18 (bilateral), as well as the anterior insu la (bilateral) and middle frontal cortex (left). Areas 17 and 18 have been identified as supporting the representations that underlie the ex perience of imagery, and the anterior insula is a major cortical recip ient of input from the autonomic nervous system. Perceiving aversive s timuli enhanced cerebral blood flow, relative to neutral stimuli, in a rea 46, the angular gyrus and area 19, area 47, and the middle tempora l gyrus (all in the left hemisphere). All of these areas have previous ly been implicated in visual object identification. It is striking tha t negative emotion did not modulate activation in any areas in the sam e way during imagery and perception.