Reduced Cortical Inhibition in Violent Offenders: A Study with Transcranial Magnetic Stimulation

Abstract

<i>Background:</i> Aggression and violent behaviour are often regarded as a threat to society. Therefore, understanding violent behaviour has high social relevance. We performed a study with transcranial magnetic stimulation on a sample of violent offenders in order to measure cortical inhibition in the motor neuron system that is part of the frontal cortex. <i>Methods:</i> To investigate intracortical inhibition and intracortical facilitation, we conducted paired-pulse stimulation according to the technique of Kujirai and his group (see Method). The investigation sample comprised 62 right-handers: 32 prisoners who had committed severe violent crimes and 30 controls with no history of violence. All subjects were male and matched for age. <i>Results:</i> Using the paired-pulse paradigm with interstimulus intervals (ISI) of 1–15 ms, a reduced cortical inhibition (ISI: 3 ms) was found in the left cortex of violent offenders compared with control subjects. <i>Conclusions:</i> These findings corroborate the hypothesis of inhibition deficits and frontal cortex dysfunction in violent offenders when compared with non-violent control subjects.

Methods in cognitive neuroscience: a primer for forensic psychologists

“…As one example for an application in forensic psychology, a study used the stimulation to investigate cortical inhibition capacities in violent offenders compared to a control group (Philipp-Wiegmann et al, 2011). They used paired contralateral stimulation of the motor cortex, measuring the magnetically evoked potential provoked by the stimulation on the scalp.…”