We have found increased EEG-SFC in this band in SDD and decreased in LDD compared with controls. These differences were not only seen in neighboring ROI pairs but also in remote ones, in line with the role of gamma oscillations in long-range synchronization function and dysfunction (Buzsaki and Wang, 2012; Lehmann et al., 2014). A recent study in first episode medicated SCZ using FC methods reported increased gamma activity in left hemisphere sources localized in the infero-orbitofrontal, lateral, and medial temporal and inferior parietal areas. Interestingly, SCZ with low positive and disorganization symptoms showed higher gamma connectivity (Andreou et al., 2014). The dependency of gamma band connectivity patterns on disease duration might be partially explained by differences in inhibitory/excitatory neurotransmission. Recent magnetic resonance spectroscopy studies (Kegeles et al., 2012; Natsubori et al., 2014) have shown increased prefrontal GABA and glutamate in the early stages and a decreased in chronic patients. Moreover, a recent meta-analysis showed greater age-dependent decrease in glutamate and glutamine concentration in schizophrenia compared to controls (Marsman et al., 2013). Our findings have interesting similarities with those from
