Altered Neural Oscillations and Hemispheric Asymmetry in Single-Sided Deafness

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Neurophysiology

Background:

• Single-sided deafness (SSD) impairs binaural hearing and can induce cortical reorganization.
• Neural oscillatory activity changes in SSD, but side-specific effects are unclear.
• Understanding these brain changes is crucial for auditory rehabilitation.

Purpose of the Study:

• To investigate differences in resting-state electroencephalography (EEG) spectral power and hemispheric asymmetry between left SSD (LSSD), right SSD (RSSD), and normal-hearing (NH) individuals.
• To determine if the laterality of hearing loss influences cortical reorganization patterns.
• To explore potential associations between EEG measures and clinical hearing assessments.

Main Methods:

• Resting-state EEG data collected from 100 participants (32 LSSD, 31 RSSD, 37 NH).
• EEG power spectra computed across six frequency bands (delta, theta, alpha, beta, gamma1, gamma2).
• Hemispheric asymmetry quantified using a lateralization index; statistical analyses performed for group differences and correlations.

Main Results:

• Both LSSD and RSSD groups exhibited increased gamma1 (γ1) power compared to NH.
• RSSD showed additional widespread increases in theta (θ) and beta (β) power, with greater right-hemisphere dominance in delta (δ) and theta (θ) bands.
• LSSD displayed symmetric power distribution and no significant lateralization differences compared to NH.

Conclusions:

• Resting-state EEG reveals distinct, side-specific cortical reorganization in SSD.
• RSSD is associated with broader neural changes and right-hemispheric bias, suggesting different compensatory mechanisms than LSSD.
• Findings highlight potential for laterality-specific auditory rehabilitation strategies.