The [oxy-Hb] responses on both sides of PFC are stronger than middle PFC from healthy controls, which implies deeper light penetration in the interhemispheric fissure that causes the fewer backscattered photons to be received. Furthermore, the [oxy-Hb] mapping of schizophrenic case is significantly weaker than normal on PFC and no significant difference is found among right, left, and middle forehead areas. It indicates the task-dependent profile of functional abnormalities can be observed from the brain metabolism on schizophrenic PFC. Also, the fOT measurement may offer a good potential to detect the structural change of brain. To our knowledge, we are the first to report the significant difference regions of PFC by utilizing discriminant analysis between schizophrenic and healthy subjects based on fOT monitoring. Although Azechi et al. used prefrontal activation with frontal lobe tasks for discriminant analyzing between schizophrenic and healthy subjects,39 they did not provide the significant difference regions of PFC for discriminating schizophrenia. In this study, we pointed out the significant difference regions of PFC between schizophrenia and healthy controls. Figure 2 shows the group-level of [oxy-Hb] in right, left, and middle PFC that is significantly different between schizophrenia and healthy controls. According to two-sample K-S test, the channels of significant difference are analyzed on left PFC. Abnormal structural and/or functional hemisphere asymmetries in schizophrenia disorders have been assessed based on fOT.18,40 In an fMRI study, reduced activation of the left frontal regions during word production was found in schizophrenia patients compared with normal.41 The other study shows that schizophrenia produces a failure of attentional modulation that leads to a breakdown in the selective enhancement or inhibition of semantic/lexical representations, whose biological substrata are widely distributed across left (dominant) temporal and frontal lobes.42 These findings can be interpreted as a sign of reduced specific lateralized PFC reactivity, possibly based on a left hemisphere functional deficit between schizophrenia and normal. Our result of the significant difference regions on left PFC is in agreement with previous studies. Therefore, the left PFC shows a great potential of feature region for discriminant analysis of schizophrenia. Table 2 demonstrates the accuracy of classification by applying six significant channels, which is better than 52 channels. Therefore, the significant channels in fOT can be used for schizophrenia diagnosis with discriminant analysis. However, the limitation of this study must be taken into account. Discriminant analysis with fOT can reveal significant differences between the probability distributions of signals in healthy and diseased groups, but cannot provide an individual diagnosis. Nevertheless, optical imaging with fOT can still be used as an auxiliary tool in schizophrenia diagnosis.