The Concept of Contexts in Pain: Generalization of Contextual Pain-Related Fear Within a de Novo Category of Unique Contexts

The experience of unpredictable pain fluctuations can trigger anticipatory pain-related fear. When discrete predictors for pain are lacking, fear typically accrues to the broader environmental context: a phenomenon referred to as contextual pain-related fear. We examined whether conceptual similarity between discrete contexts facilitates pain-related fear generalization; this mechanism is known as category-level fear generalization. Using a voluntary joystick movement paradigm, pain-free participants performed movements in 2 contexts (within-subjects design); context was manipulated by varying background color screens. In the predictable context, one movement predicted pain and another did not. In the unpredictable context, 2 other movements never predicted pain but pain was unpredictably delivered during the context. Participants subsequently learned to categorize novel background colors (ie, generalization contexts) as being similar to either the unpredictable or predictable pain context. Then we tested fear generalization to these novel contexts. We measured self-reported pain related fear, expectancy, and eyeblink startle. Results indicated higher pain-related fear reports, but no elevated startle responses, for generalization contexts that were trained to be similar to the original unpredictable context rather than the predictable pain context. This highlights a potential pathway through which neutral contexts can elicit pain-related fear and motivate avoidance behavior associated with chronic pain disability. Perspective: Self-reported pain-related fear and expectancy of painful outcome in response to a context associated with unpredictable pain generalizes to perceptually distinct contexts that are trained to be conceptually similar to the unpredictable pain context. Category-level generalization may be a pathway contributing to spreading of fear and avoidance in chronic pain. (C) 2017 by the American Pain Society