Ear-specific neuroplasticity for sound localization in individuals with single-sided deafness

Studies on cortical plasticity in individuals with single-sided deafness (SSD) show increased activity in the auditory cortex ipsilateral to the hearing ear, impacting auditory localization and rehabilitation outcomes. However, the direct relationship between neuroplastic changes and binaural processing in SSD remains unclear, as does the specificity of plasticity to the affected ear. In this study, two groups of SSD patients (left [Lt] SSD, 17; right [Rt] SSD, 18) of postlingual onset and 13 normal-hearing controls (NC) underwent fMRI during an auditory localization task. The NC group was also treated with earplugs to simulate acute monaural hearing. We compared the cortical networks involved in auditory localization and conducted correlation analyses to identify neural activity associated with SSD duration and localization performance. The response laterality in the auditory cortex was analyzed and compared across groups. Results indicated that extended SSD modulates auditory cortical response in the right primary auditory cortex. The posterior superior temporal gyrus and cingulo-opercular network were linked to improved localization performance. Findings suggest that cortical attentional resources are crucial for auditory spatial behavior in SSD, especially when the left ear is impaired.