You are fired! Exclusion words induce cortico-spinal modulations associated with vicarious pain.

Abstract

Self- and vicarious experience of physical pain induces inhibition of the motor cortex (M1). Experience of social rejections recruits the same neural network as physical pain, however, whether social pain modulates M1 corticospinal excitability remains unclear. This study examines for the first time whether social exclusion words, rather than simulated social exclusion tasks, modulate embodied sensorimotor networks during vicarious experience of other's pain. Participants observed visual sequences of painful and functional events ending with a superimposed word with either social exclusion, social inclusion, or nonsocial meaning. Motor-evoked potentials (MEPs) to single-pulse transcranial magnetic stimulation (TMS) of the left M1 were recorded at 400 or 550 ms from word onset. MEPs tended to inhibit during observation of pain, relative to functional events. Moreover, MEPs recorded at 400 ms from word onset, during pain movies, decreased following the presentation of exclusion, relative to inclusion/neutral words. The magnitude of these two modulations marginally correlated with participants' interindividual differences in personal distress and self-esteem. These findings provide evidence of vicarious responding to others' pain in the M1 corticospinal system and enhancement of such vicarious response in the earlier phases of semantic processing of exclusion words - supporting activation of social pain embodied representations.