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

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.

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.

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).

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