Emotion-induced changes in human medial prefrontal cortex: I. During cognitive task performance

Regional cerebral blood flow (BF) was examined in regions of the medial pre frontal cortex (MPFC) with positron-emission tomography while subjects perf ormed two cognitive tasks, reading nouns aloud and generating appropriate V erbs for the same nouns. The control task was passive viewing of the same w ords. BF was reduced in regions of the MPFC during word reading and naive v erb generation, relative to a control state in which the subjects passively viewed nouns. Practicing verb generation produced improved performance, as measured by response time, which was strongly correlated with further redu ctions in MPFC and hypothalamic BF, After practice, when verb generation wa s performed on a novel list of words, reaction times slowed and the pattern of MPFC BF reverted to that seen in the word reading and naive conditions. A separate behavioral study of the verb-generation task indicated that anx iety, high during naive use-generation as measured by heart rate and self-r eport, decreased with practice on the task but returned with the introducti on of a novel list of words. Taken together, these results suggest that the MPFC is part of a network, including the hypothalamus and brainstem, whose activity reflects a dynamic interplay between cognitive task performance a nd emotion.