Emotion facilitates action: A transcranial magnetic stimulation study of motor cortex excitability during picture viewing

Emotional stimuli capture attention, receive increased perceptual processing resources, and alter peripheral reflexes. In the present study, we examined whether emotional stimuli would modulate the magnitude of the motor evoked potential (MEP) elicited in the abductor pollicus brevis muscle by transcranial magnetic stimulation (TMS) delivered to the motor cortex. The electromyogram (EMG) was recorded from 16 participants while they viewed six blocks of pleasant, neutral, and unpleasant images; 36 TMS pulses at increasing intensities were delivered during each block. The TMS-induced MEP was reliably larger while participants viewed pleasant and unpleasant compared to neutral images. There were no differences in the pre-TMS EMG activity as a function of emotional stimuli. Thus, viewing arousing stimuli, regardless of valence, increased motor cortex excitability. Implications and directions for future research are discussed.