Learned Symptom-Specific Fear Toward a Visceral Sensation and Its Impact on Perceptual Habituation.

Abstract

Objective: Impaired habituation of bodily sensations has been suggested as a contributing factor to chronic pain. We examined in healthy volunteers the influence of fear learning toward a nonpainful sensation in the esophagus on the perceptual habituation of this sensation.

Methods: In a homoreflexive fear learning paradigm, nonpainful electrical sensations in the esophagus were used as a conditioned stimulus (CS). This sensation was presented 42 times before, during, and after fear learning. In the fear learning group ( n = 41), the CS was paired with a painful electrical sensation in the esophagus (unconditioned stimulus [US]). In the control group ( n = 41), the CS was not paired with the US. Ratings for CS intensity, US expectancy, startle electromyogram (EMG), skin conductance responses (SCR), and event-related potentials (ERPs) to the CS were assessed.

Results: Compared to the control group, fear learning was observed in the fear learning group as evidenced by potentiated startle responses after the CS relative to ITI ( t (1327) = 3.231, p = .001) and higher US expectancy ratings ( t (196) = 3.17, p = .002). SCRs did not differ between groups ( F1,817 = 1.241, p = .33). Despite successful fear learning, the fear learning group did not show a distinct pattern of habituation to the visceral CS relative to the control group (intensity ratings: F1,77.731 = 0.532, p = .47; ERPs: F1,520.78 = 0.059, p = .94).

Conclusion: Acquired fear to nonpainful esophageal sensations does not affect their perceptual habituation patterns.