Application of evoked response audiometry for specifying aberrant gamma oscillations in schizophrenia

Abstract

Gamma oscillations probed using auditory steady-state response (ASSR) are promising clinical biomarkers that may give rise to novel therapeutic interventions for schizophrenia. Optimizing clinical settings for these biomarker-driven interventions will require a quick and easy assessment system for gamma oscillations in psychiatry. ASSR has been used in clinical otolaryngology for evoked response audiometry (ERA) in order to judge hearing loss by focusing on the phase-locked response detectability via an automated analysis system. Herein, a standard ERA system with 40- and 46-Hz ASSRs was applied to evaluate the brain pathophysiology of patients with schizophrenia. Both ASSRs in the ERA system showed excellent detectability regarding the phase-locked response in healthy subjects and sharply captured the deficits of the phase-locked response caused by aberrant gamma oscillations in individuals with schizophrenia. These findings demonstrate the capability of the ERA system to specify patients who have aberrant gamma oscillations. The ERA system may have a potential to serve as a real-world clinical medium for upcoming biomarker-driven therapeutics in psychiatry.

Evaluating delay of gamma oscillations in patients with schizophrenia using evoked response audiometry system

“…In the case of a standard device for ERA, Audera, the modified set for 40-Hz ASSR consists of tone stimuli with 100% amplitude and 10% frequency modulation rate at 46 Hz. In our previous application study with the ERA device, several patients with schizophrenia did not show the phase-locked response due to aberrant gamma oscillations in the ASSR elicited by a basic 40-Hz tone and the modified 46-Hz tone preset in the device 24 . This finding opens up the availability of ERA system to identify the impairments of ASSR with approximately 40 Hz stimulation in patients with schizophrenia.…”

“…ASSR measurements were performed using Audera (Grason-Stadler Inc., MN), the standard device for ERA, in accordance with the custom protocol of this device with a minor modification. Details of the ASSR measurements are described in our previous study 24 . Briefly, the ASSR was performed with an instruction to sit and relax on a chair, keep their eyes closed, and remain motionless to avoid muscular artifact generation.…”