Introduction The medial orbitofrontal cortex (mOFC) and rostral part of the anterior cingulate cortex (rACC) are brain regions that are important in the neural network involving emotional processing and decision making, as well as playing an important role in social behavior and interaction. Considering the schizophrenia dysconnectivity hypothesis, observed abnormalities in emotional response and social behavior in schizophrenia might be associated with connectivity abnormalities between mOFC and rACC. Methods Twenty-seven patients with chronic schizophrenia and 26 healthy controls were examined using Diffusion Tensor Imaging (DTI). White matter properties in bilateral mOFC-rACC connections were examined using stochastic tractography, which has been shown to be among the most effective DTI methods for examining tracts between adjacent gray matter regions. Results Reductions in fractional anisotropy (FA) were observed in left anterior mOFC-rACC connections (p<0.0001), and bilateral posterior mOFC-rACC connections (left: p<0.0001; right: p<0.0001) in patients compared to controls. In addition, reduced FA in left posterior mOFC-rACC connections were associated with more severe anhedonia-asociality (R=−0.396, P=0.041) and avolition-apathy (R=−0.426, p=0.027) using the Scale for the Assessment of Negative Symptoms. Discussion White matter abnormalities within connections between mOFC and rACC are associated with more severe anhedonia-asociality and avolition-apathy, which suggest that these brain regions may be important in understanding abnormal emotional responses and social behavior in patients with schizophrenia.

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We investigated whether the gray matter volume of primary auditory cortex (Heschl’s gyrus [HG]) was associated with abnormal patterns of auditory γ activity in schizophrenia, namely impaired γ synchronization in the 40-Hz auditory steady-state response (ASSR) and increased spontaneous broadband γ power. (The γ data were previously reported in Hirano et al, JAMA Psychiatry, 2015;72:813-821). Participants were 24 healthy controls (HC) and 23 individuals with chronic schizophrenia (SZ). The ASSR was obtained from the electroencephalogram to click train stimulation at 20, 30, and 40 Hz rates. Dipole source localization of the ASSR was used to provide a spatial filter of auditory cortex activity, from which ASSR evoked power and phase locking factor (PLF), and induced γ power were computed. HG gray matter volume was derived from structural magnetic resonance imaging at 3 T with manually traced regions of interest. As expected, HG gray matter volume was reduced in SZ compared with HC. In SZ, left hemisphere ASSR PLF and induced γ power during the 40-Hz stimulation condition were positively and negatively correlated with left HG gray matter volume, respectively. These results provide evidence that cortical gray matter structure, possibly resulting from reduced synaptic connectivity at the microcircuit level, is related to impaired γ synchronization and increased spontaneous γ activity in schizophrenia.