Identifying auditory cortex encoding abnormalities in schizophrenia: The utility of low-frequency versus 40 Hz...

Area of Science:

• Neuroscience
• Psychiatry
• Biomedical Engineering

Background:

• Magnetoencephalography (MEG) and electroencephalography (EEG) show inconsistent auditory encoding abnormalities in schizophrenia (SZ).
• Previous studies reported both positive and negative findings regarding low-frequency and 40 Hz steady-state auditory encoding in SZ.
• Discrepancies may stem from variations in data collection and analysis strategies, including sensor versus source-space measures.

Purpose of the Study:

• To investigate factors contributing to inconsistencies in auditory encoding measures between healthy controls (HC) and individuals with schizophrenia (SZ).
• To compare group differences in MEG and EEG source space versus EEG sensor space for auditory encoding.
• To determine optimal methods for assessing auditory encoding abnormalities in SZ.

Main Methods:

• Simultaneous whole-head MEG and EEG recordings were obtained from 55 HC and 41 chronic SZ participants.
• Participants were presented with 500 Hz sinusoidal stimuli modulated at 40 Hz.
• MEG and EEG source models (superior temporal gyrus dipoles) and various EEG sensor analysis strategies were employed to evaluate auditory encoding.

Main Results:

• Poststimulus low-frequency auditory encoding group differences were consistently observed across all methods.
• Forty Hz steady-state auditory encoding group differences were only significant in younger participants and were most pronounced in source-space analyses.
• Age-related decreases in left superior temporal gyrus 40 Hz steady-state activity were noted in HC, differing from SZ.

Conclusions:

• Optimal data collection and analysis methods for auditory encoding in schizophrenia depend on the specific measure of interest.
• Low-frequency auditory encoding group differences between HC and SZ are robust across modalities and analysis strategies.
• Forty Hz steady-state auditory encoding group differences are highly dependent on the analysis strategy, with source-space measures offering superior group differentiation.