DESCRIPTION: The proposed experimental program is designed to assess changes in brain function that occur with fearful anticipation of a painful stimulus. Its principal aim is to determine the relationship between activity in specific brain structures (as defined by changes in regional blood flow), reports of fear arousal, and the electrocortical, visceral, and somatic responses that occur when expecting a painful stimulus. This research is driven by a motivational theory of human emotion that is founded on behavioral, psychophysiological, and neurophysiological research. The proposed studies are intended to explicate neural mechanisms that mediate fear of pain in normal humans, and furthermore, to examine possible individual differences in anticipation of pain between men and women, and between those who are low or high in dental fear. The specific aim of the proposed research is to map neural activation in the brain during fearful anticipation evoked by imminent painful stimulation, and to relate the obtained brain maps to psychophysiological patterns of fear reactivity. Three primary independent variables are assessed: 1) The type of anticipated stimulus (electric shock or nonpainful vibrotactile); 2) Dental fear level of the subject (low, high); and 3) Sex of the subject. Each of these eight studies (2 stimulus type x 2 fear groups x 2 sex) will be conducted once in the magnetic resonance imaging (MRI) context to assess functional brain activity, and once (with new participants) in a simulated MRI context to acquire autonomic, somatic, and central (i.e., EEG) physiological measures of anticipatory fear. The proposed research will address questions concerning the neural and psychophysiological organization of fear associated with imminent pain, as well as how individual differences in fear and/or sex affect these reactions. The proposed methodology is, furthermore, adaptable and can be used subsequently to address other facets (sensory and emotional) of the pain experience.