Study of Neuroplasticity on Depressed Patients : Modulation of MEP Induced by Theta Burst Stimulation

The study is lead with patients suffering from a MDD. All patients are drug free. Patients are compared to a control group of healthy subjects The protocol has 2 sessions. During the first session, After determining the parameters of stimulation (stimulated target : part of the left motor cortex responsible for the contraction of the right first dorsal interosseous muscle ; Activity Motor Threshold (AMT) ; Intensity of Stimulation providing a Motor Evoked Potential (MEP) with an Amplitude of 1mV (MEP 1mV)), a Baseline consisting of 15 MEP (intensity MEP 1mV) is measured. Then each subjet receive a TBS protocol (cTBS or iTBS) (intensity of stimulation 80% of AMT). After receiving the stimulation, sets containing 10 MEP are regularly measured by each subject. During a second session, the same protocol is done again with the other TBS stimulation (cTBS or iTBS) the subject didn't get during the first session. A neuronavigation device is used to determine precisely the area of stimulation.