GSTM1 and major depressive disorder: Numerous studies using multi-channel near-infrared spectroscopy (NIRS), a noninvasive functional neuroimaging technique measuring the spatiotemporal characteristics of brain function, have consistently reported that oxygenated-hemoglobin [oxy-Hb] activation during a verbal fluency task (VFT) significantly decreased in patients with MDD compared with healthy controls (HC) in the fronto-temporal brain regions [11–14].