Neurophysiological investigation of transcranial magnetic stimulation’s antidepressant effects

Treatment resistant depression (TRD) is a form of major depressive disorder (MDD) that involves non-response to at least 2 antidepressant treatment trials. Depression is associated with reduced cortical excitability and dysfunctional autonomic nervous system balance. Repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex is an effective intervention for TRD. While rTMS is hypothesized to enhance the cortical excitability of the site of stimulation, current methods are confounded by the use of the motor system and complex experimental setups. Moreover, it is unclear how rTMS modulates the autonomic nervous system balance due to its effects on the prefrontal cortices.