Compensatory Mechanisms for Preserving Speech-in-Noise Comprehension Involve Prefrontal Cortex in Older Adults

The capacity of comprehending others amidst noise is essential for human communication. However, it presents significant challenges for the elderly who often face progressive declines in the peripheral auditory system and the whole brain. While previous studies have suggested the existence of neural reserve and neural compensation as potential mechanisms for preserving cognitive abilities in aging, the specific mechanisms supporting speech-in-noise comprehension among the elderly remain unclear. To address this question, the present study employs an inter-brain neuroscience approach by analyzing the neural coupling between brain activities of older adults and those of speakers under noisy conditions. Results showed that the neural coupling encompassed more extensive brain regions of older listeners compared to young listeners, with a notable engagement of the prefrontal cortex. Moreover, the neural coupling from prefrontal cortex was coordinated with that from classical language-related regions. More importantly, as background noise increases, the older listeners speech comprehension performance was more closely associated with the neural coupling from prefrontal cortex. Taken together, this study reveals the compensatory recruitment of neurocognitive resources, particularly within the prefrontal cortex, to facilitate speech processing in the aging brain, and further highlights the critical role of prefrontal cortex in maintaining the elderlys ability to comprehend others in noisy environments. It supports the neural compensation hypothesis, extending the knowledge about the neural basis that underlies cognitive preservation in the aging population.