Neural correlates of fear: insights from neuroimaging

Fear in the human brain Garfinkel & Critchley 2 1.0 Abstract Fear anticipates a challenge to one's wellbeing and is a reaction to the risk of harm. The expression of fear in the individual is a constellation of physiological, behavioral, cognitive and experiential responses. Fear indicates risk, and will guide adaptive behavior, yet fear is also fundamental to the symptomatology of most psychiatric disorders. Neuroimaging studies of normal and abnormal fear in humans extend knowledge gained from animal experiments. Neuroimaging permits the empirical evaluation of theory (emotions as response tendencies, mental states and valence and arousal dimensions) and improves our understanding of mechanisms of how fear is controlled by both cognitive processes and bodily states. Within the human brain, fear engages a set of regions that include insula and anterior cingulate cortices, amygdala and dorsal brainstem centres such as periaqueductal gray matter. This same fear matrix is also implicated in attentional orienting, mental planning, interoceptive mapping, bodily feelings, novelty and motivational learning, behavioral prioritization and the control of autonomic arousal. The stereotyped expression of fear can thus be viewed as a special construction from combinations of these processes. An important motivator for understanding neural fear mechanisms is the debilitating clinical expression of anxiety. Neuroimaging studies of anxiety patients highlight the role of learning and memory in pathological fear. Post-traumatic stress disorder is further distinguished by impairment in cognitive control and contextual memory. These processes ultimately need to be targeted for symptomatic recovery. Neuroscientific knowledge of fear has broader relevance to understanding human and societal behavior. As yet only some of the insights into fear, anxiety and avoidance at the individual level extrapolate to groups and populations, and can be meaningfully applied to economics, prejudice and politics. Fear is ultimately a contagious social emotion. Fear in the human brain Garfinkel & Critchley 4 2.0 Emotions and fear Emotions can be viewed as transient stereotyped reactions to motivationally-salient events or stimuli. These reactions reprioritise perceptual, cognitive and behavioral states. Emotions have psychological (cognitive, perceptual and experiential), physiological (bodily arousal), and behavioral (expressions and action tendencies) dimensions. Most formulations of emotion also emphasize a social role, where motivational states such as hunger and thirst are conceptualized at a lower level.