Relationship between N100 amplitude and T1w/T2w-ratio in the auditory cortex in schizophrenia spectrum disorders

Abstract

Schizophrenia spectrum disorders (SCZspect) are associated with altered function in the auditory cortex (AC), indicated by reduced N100 amplitude of the auditory evoked potential (AEP). While the neural substrate behind reduced N100 amplitude remains elusive, myelination in the AC may play a role. We compared N100 amplitude and magnetic resonance imaging (MRI) T1 weighted and T2 weighted ratio (T1w/T2w-ratio) as a proxy of myelination, in the primary AC (AC1) and secondary AC (AC2) between SCZspect (n = 33, 48% women) and healthy controls (HC, n = 144, 49% women). Further, we examined associations between N100 amplitude and T1w/T2w-ratios in SCZspect and HC. We finally explored N100 amplitude and T1w/T2w-ratios in the AC1/AC2 and association between N100 amplitude and T1w/T2w-ratios between male and female SCZspect and HC. N100 amplitude did not differ between SCZspect and HC or between female SCZspect and female HC, but was significantly reduced in male SCZspect compared to male HC (est = 4.3, se = 1.63, t = 2.63, p = 0.010). Further, T1w/T2w ratios in the AC1/AC2 did not differ between any groups. Finally, N100 amplitude was not associated with T1/T2-ratios in the AC1/AC2 in any groups. Reduced N100 amplitude in male SCZspect compared to male HC, suggest that sex-specific effects should be considered in research on SCZspect neurophysiology. Our findings did not support the hypothesis that reduced myelination in the AC1/AC2, as indexed by T1w/T2w-ratio, underlies N100 abnormalities in SCZspect. However, more precise estimates of intracortical myelin are needed to confirm this.