P08Session 2 (Friday 12 January 2024, 09:00-11:30)Neural correlates of the McGurk illusion in age-related hearing loss assessed by fMRI and EEG
Previous research investigating cortical plasticity in age-related hearing loss provides evidence for cross-modal reorganization in the auditory cortex, additional recruitment of the frontal lobe, and increased coupling of the visual and auditory cortices for matching audiovisual input. These changes already begin to occur when hearing impairment is only mild to moderate. In addition, hard of hearing people are more prone to the McGurk illusion than those with normal hearing. Using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), we here investigated the influence of mild to moderate hearing impairment on neural correlates of the McGurk illusion. Twenty-eight participants aged between 50 and 80 years participated in the study. They either had normal hearing abilities or showed a uniformly varying degree of mild to severe and symmetrical age-related hearing loss. None of them had any experience with hearing aids. The measurements taken included the McGurk illusion in the MRI (sparse-sampling approach) and in the EEG (64-channels), along with an assessment of hearing abilities by a pure tone audiometry and speech reception thresholds. In the McGurk task, we presented the syllables ‘ba’, ‘da’, and ‘ga’ in an auditory only, visual only, audiovisual congruent, and audiovisual incongruent conditions. The latter is supposed to initiate the McGurk illusion, typically achieved by presenting a visual ‘ba’ and an auditory ‘ga’, leading to the illusory percept of ‘da’. Analysis of the behavioral data indicate a mean fusion response (i.e. that participants perceived the McGurk illusion) of 70% (range 0-100%). However, there was no significant correlation between the number of perceived McGurk illusions and hearing loss. Neural data relating hearing loss, McGurk illusion perception and cross-modal reorganization of the auditory cortex measured by fMRI and EEG are currently analyzed.