Prediction and action in cortical pain processing

Predicting that a stimulus is painful facilitates action to avoid harm. But how distinct are the neural processes underlying the prediction of upcoming painful events, and those taking action to avoid or prevent them? In this fMRI experiment, we addressed this by investigating brain activity as a function of current and predicted painful or nonpainful thermal stimulation, and the ability of voluntary action to affect the duration of the upcoming stimulation. Participants (n = 30) performed a task which involved the administration of a painful or nonpainful stimulus (S1), which predicted an immediately subsequent very painful or nonpainful stimulus (S2). On action-effective trials, pressing a response button within a specified time window during S1 reduced the duration of the upcoming stimulation in S2. On action-ineffective trials, pressing the button had no effect on upcoming stimulation. Predicted pain increased activation in regions including anterior cingulate cortex (ACC), midcingulate cortex (MCC), and insula; however, activation in ACC and MCC depended on whether a meaningful action was performed, with MCC activation showing a direct relationship with motor output. Region-of-interest analyses revealed that insulas responses for predicted pain were also modulated by potential action consequences, especially in the left hemisphere, albeit without a direct relationship with motor output. Taken together, these findings suggest that cortical pain processing is not specifically tied to the sensory stimulus, but instead depends on the consequences of that stimulus for sensorimotor control of behavior. Significance statementDuring acute pain, the processing of an acute sensory event likely occurs in parallel with predictive processing about its relevance for current and upcoming voluntary behavior. Here, we temporally separated the functional processes underlying current and predicted pain and found that activation in regions typically implicated in acute pain is modulated both by the noxious nature of upcoming events and by the possibility to affect those events via voluntary action (a button press). Our findings suggest that cortical pain processing is not specifically tied to the sensory stimulus, but instead is processed in "consequence-level" terms based on what the stimulus implies for sensorimotor control of behavior.