Psychopathy and the mirror neuron system: preliminary findings from a non-psychiatric sample

Recent advances in social neuroscience suggest a link between empathy and the mirror neuron system (MNS). Impaired empathy is one of the core diagnostic features of psychopathic personality disorder. In the present study, we investigated whether psychopathic personality traits in a non-psychiatric sample were related to MNS function. Healthy participants viewed short videos known to activate the sensorimotor MNS for pain (a needle penetrating a human hand) while transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEP) were recorded as a measure of motor cortex excitability. Individual psychopathic personality traits were assessed using the Psychopathic Personality Inventory (PPI) and correlated with the MEP findings. Consistent with previous data, observation of the painful stimulus was associated with a significant reduction in the amplitude of the TMS-induced MEP. Interestingly, the level of corticospinal excitability modulation was positively correlated with individual scores on the coldheartedness subscale of the PPI, such that individuals with the greatest MEP reduction were the ones scoring highest on the coldheartedness measure. These data suggest the existence of a functional link between 'motor empathy' and psychopathy.