Conceptual conditioning: Mechanisms mediating conditioning effects on pain

摘要

Classical conditioning can profoundly modify subsequent pain responses, but the mechanisms driving this effect are unresolved. Pain-conditioning studies typically condition cues to primary aversive reinforcers; hence, subsequent pain modulation could reflect learned pre-cognitive associations and/or expectancies that are conceptual in nature. We isolated conceptual contributions using a thermal pain-conditioning procedure in which different cues (CShigh and CSlow) were repeatedly paired with symbolic representations of high and low noxious heat, respectively. In a subsequent test phase, identical noxious stimuli evoked larger skin-conductance responses (SCRs) and pain ratings when preceded by CShigh than CSlow cues. These effects were mediated by participants’ self-reported expectancies. CShigh cues also evoked larger anticipatory SCRs, but larger anticipatory SCRs predicted smaller subsequent heat-evoked SCRs. These results provide novel evidence that conditioned modulation of pain physiology can be acquired through purely conceptual processes, and that self-reported expectancies and physiological threat responses have opposing effects on pain.