Somatosensory attending to the lower back is associated with response speed of movements signaling back pain

Abstract

The present study investigated if preparing a movement that is expected to evoke pain results in hesitation to initiate the movement (i.e., avoidance) and, especially, if the allocation of attention to the threatened body part mediates such effect. To this end, healthy volunteers (N = 33) performed a postural perturbation task recruiting lower back muscles. In 'threat trials', the movement was sometimes followed by an experimental pain stimulus on the back, whereas in 'no-threat trials', a non-painful control stimulus was applied. Electroencephalography (EEG) was used to assess attending to the lower back. Specifically, somatosensory evoked potentials (SEPs) to task-irrelevant tactile stimuli administered to the lower back were recorded during movement preparation. Reaction times (RTs) were recorded to assess movement initiation. The results revealed faster responses and enhanced somatosensory attending to the lower back on threat trials than on no-threat trials. Importantly, the amplitude of the N95 SEP component predicted RTs and was found to partially mediate the effect of pain anticipation on movement initiation. These findings suggest that somatosensory attending might be a potential mechanism by which pain anticipation can modulate motor execution.