Objective To explore the differences in brain activation related to anhedonia in patients with schizophrenia(SCZ)and major depressive disorder(MDD)during a verbal fluency task(VFT)based on functional near-infrared spectroscopy(fNIRS).Methods A total of 31 patients with first-episode SCZ,45 patients with first-episode MDD and 45 healthy controls(HC)were included.The clinical symptoms were assessed using the 17-item Hamilton depression scale(HAMD-17),the positive and negative symptom scale(PANSS)and the Snaiss-Hamilton pleasure scale(SHAPS).All subjects completed the 48-channel fNIRS-VFT and the Chinese characters"Bai","Bei",and"Da"were recorded in the VFT.The Homer2 software in Matlab was used to extract information of oxy-hemoglobin(Oxy-Hb)concentration during the task.Results In the fNIRS-VFT task,compared with HC,patients with SCZ had decreased Oxy-Hb concentration in the bilateral middle frontal gyrus,superior frontal gyrus,inferior frontal gyrus,right superior temporal gyrus,and left posterior cingulate gyrus(including 25 channels,P<0.05),compared with MDD patients,patients with SCZ exhibited significantly reduced Oxy-Hb concentration in the bilateral superior frontal gyrus,left middle frontal gyrus,and right superior temporal gyrus(including 6 channels,P<0.05).The results of the general linear model showed that SHAPS scores in the MDD group were negatively correlated with Oxy-Hb concentration in the right superior frontal gyrus(channels 26,42)(β=-5.46,P=0.02;β=-5.01,P=0.01).Conclusion Patients with first-episode SCZ and those with first-episode MDD had functional abnormalities in bilateral middle frontal gyrus,and the left superior frontal,inferior frontal gyrus and postcentral gyrus.Additionally,abnormal activation of the right superior temporal gyrus and superior frontal gyrus was neurobiological markers of SCZ,abnormal activation of the right superior frontal gyrus was associated with anhedonia in MDD.