The Generalization of Fear Condition Between Viewed and Imagined Percepts

Mental images can provoke intense emotional states (Holmes & Matthews, 2010). Imagery and perception have common neural and physiological mechanisms, including activation of the early visual areas (Albers et al., 2013). We tested the prediction that individuals can acquire fear to imagined percepts and if this fear transfers to viewing percepts, using fMRI and self-reported measures to determine participants’ fear. The participants completed a task in which they viewed and imagined two stimuli, and were fear conditioned when imagining the CS+. Participants are only told that mild electrical stimulation will be paired with one of the stimuli, but not which stimulus, viewed or imagined. Participants completed 6 runs of each task after completing 6 runs of a habituation form of each task. Behaviorally, participants report greater fear when imagining the CS+ than imagining the CS-. When acquiring fear to an imagined stimulus, we found significant activation in the right insula. These findings are consistent with previous literature indicating that this regions are involved in processes related to emotional memory, autonomic arousal, and emotion-related motivation. Behaviorally, participants also report greater fear when viewing the CS+ than when viewing the CS-, though neither is ever paired with shock. When fear is generalized from an imagined precept to a viewed one (i.e., CS+ view > CS- view), we found no significant activation. We can conclude that participants generalize the fear acquired when imagining the stimulus to viewing the stimulus. Finally, participants also show a similar level of self-reported fear to fear conditioning acquired to imagining a stimulus as to when fear is acquired to viewing a stimulus. We found insular cortex and precentral gyrus activation when investigating the similarities between these processes. These results indicate: that humans can fear condition to imagined percepts, which involves activation of anterior insula; that this fear conditioning generalizes to instances of viewing the conditioned percept; and that differential conditioning to both imagined and viewed percepts produced a similar magnitude of subjective fear along with activation of the right anterior insula.