Aging effects on dual-route speech processing networks during speech perception in noise

Area of Science:

• Neuroscience
• Cognitive Aging
• Speech Processing

Background:

• Healthy aging alters speech processing networks, especially in noisy environments.
• The compensatory mechanisms within dual-route neural networks during aging are not well understood.
• Previous research suggests increased brain activity in dorsal and ventral streams to offset peripheral decline.

Purpose of the Study:

• To investigate the compensatory mechanisms of dual-route functional connectivity in relation to healthy aging.
• To examine how speech perception in varying signal-to-noise ratios (SNR) is affected by age.
• To analyze age-related changes in the efficiency and nodal characteristics of speech processing networks.

Main Methods:

• Utilized functional near-infrared spectroscopy (fNIRS) to study functional connectivity.
• Employed a speech perception task with healthy young, middle-aged, and older adults across different SNRs.
• Applied graph-theoretical network analysis to assess network efficiency and nodal characteristics.

Main Results:

• Speech perception scores decreased significantly with age as SNR reduced.
• Functional connectivity increased between Wernicke's area and its homolog with age.
• Network efficiency increased with age, with significant age-related differences in Wernicke's area and its homolog under noise.

Conclusions:

• Wernicke's area acts as a key hub for maintaining speech processing network efficiency during healthy aging.
• Older adults recruit homologous Wernicke's area resources to compensate for speech decoding in noisy environments.
• Findings offer new insights into compensatory theories of aging's modulation of dual-route speech processing networks.