Effect of age on lateralized auditory processing

• Published in: Hearing research 2023-07, Vol.434, p.108791-108791, Article 108791
• Main Authors: Stadler, Jörg, Brechmann, André, Angenstein, Nicole
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation - methods; Aging; Auditory cortex; Auditory Perception; Categorization; Diffusion Tensor Imaging; Functional Laterality; Functional magnetic resonance imaging; Hemispheric specialization; Magnetic Resonance Imaging - methods; Noise - adverse effects; Sequential processing
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/j.heares.2023.108791

•Older adults stronger involve auditory cortex during auditory processing despite same performance.•Involvement is especially increased during a task that strongly requires hemispheric interaction.•In older adults, connectivity of auditory cortex with other cortical areas is increased.•Older adults have reduced anatomical interhemispheric connections indicated by DTI. The lateralization of processing in the auditory cortex for different acoustic parameters differs depending on stimuli and tasks. Thus, processing complex auditory stimuli requires an efficient hemispheric interaction. Anatomical connectivity decreases with aging and consequently affects the functional interaction between the left and right auditory cortex and lateralization of auditory processing. Here we studied with magnetic resonance imaging the effect of aging on the lateralization of processing and hemispheric interaction during two tasks utilizing the contralateral noise procedure. Categorization of tones according to their direction of frequency modulations (FM) is known to be processed mainly in the right auditory cortex. Sequential comparison of the same tones according to their FM direction strongly involves additionally the left auditory cortex and therefore a stronger hemispheric interaction than the categorization task. The results showed that older adults more strongly recruit the auditory cortex especially during the comparison task that requires stronger hemispheric interaction. This was the case although the task difficulty was adapted to achieve similar performance as the younger adults. Additionally, functional connectivity from auditory cortex to other brain areas was stronger in older than younger adults especially during the comparison task. Diffusion tensor imaging data showed a reduction in fractional anisotropy and an increase in mean diffusivity in the corpus callosum of older adults compared to younger adults. These changes indicate a reduction of anatomical interhemispheric connections in older adults that makes larger processing capacity necessary when tasks require functional hemispheric interaction.