From this perspective, the psychophysiologies of human emotions are action dispositions ( Lang et al., 1997 see also Frijda, 1987), that is, states of heightened vigilance and physiological mobilization that are primitively associated with survival goals and occur in mammals when overt action is delayed or inhibited. Lang, Bradley, and Cuthbert (1997) proposed that humans viewing aversive, unpleasant picture stimuli are engaged by these cues in the same way that nonhuman mammals are engaged by a threatening stimulus seen at a distance. Thus, the confrontation between predator and prey can be seen as an antagonistic dance, involving common actions and competing motives that may be part of humans’ mixed emotional inheritance. Furthermore, research on anticipated reward has implicated many of the same brain structures activated in defense (e.g., the amygdala Zald, 2003), as well as other structures (e.g., nucleus accumbens and medial prefrontal cortex see Schultz, 2000) that may be unique to reward. The reactions of a stalking predator are similar to the anticipatory responses of threatened prey-in the initial inhibition of movement and augmented vigilance, but also in physiological mobilization with increasing proximity as the predator approaches the strike zone, instead of fight or flight, there is a final rush to capture. With close confrontation (the circa-strike zone), prey show active defense (fight or flight), mediated by the dorsal central gray ( Fanselow, 1994). This “alarm” reaction ( Masterson & Crawford, 1982) involves yet higher vigilance, sympathetic activation of glands and smooth muscles, movement of blood to the gross muscles, and cardiac acceleration. Davis (1998), who demonstrated that fearful animals were hyperreactive to startling stimuli presented during conditioned fear cues-a response also mediated by projections from the amygdala.Īs the distance from the predator is further reduced, prey animals increasingly mobilize for action. Further understanding of this defense circuit was provided by M. Studying conditioned fear, Fanselow (1994) found that initial motor “freezing” depended on projections from the amygdala to the brain’s ventral central gray, and Kapp, Whalen, Supple, and Pascoe (1992) found that bradycardia evoked by a fear cue covaried closely with cell firing in the amygdala. When prey animals perceive a predator in the distance, limbic circuitry in their brains initiates a range of defensive reactions, including motor inhibition, focused attention to the threat, and decelerating heart rate ( fear bradycardia Campbell, Wood, & McBride, 1997) if the predator gets closer, these reactions are augmented. Research with animals shows that brain and reflex reactions change systematically with the proximity of aversive cues.
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