Abstract
Healthy aging is accompanied by listening difficulties, including decreased speech comprehension, that stem from an ill-understood combination of sensory and cognitive changes. Here, we use electroencephalography to demonstrate that auditory neural oscillations of older adults entrain less firmly and less flexibly to speech-paced (∼3 Hz) rhythms than younger adults’ during attentive listening. These neural entrainment effects are distinct in magnitude and origin from the neural response to sound per se. Non-entrained parieto-occipital alpha (8–12 Hz) oscillations are enhanced in young adults, but suppressed in older participants, during attentive listening. Entrained neural phase and task-induced alpha amplitude exert opposite, complementary effects on listening performance: higher alpha amplitude is associated with reduced entrainment-driven behavioural performance modulation. Thus, alpha amplitude as a task-driven, neuro-modulatory signal can counteract the behavioural corollaries of neural entrainment. Balancing these two neural strategies may present new paths for intervention in age-related listening difficulties.
Highlights
Healthy aging is accompanied by listening difficulties, including decreased speech comprehension, that stem from an ill-understood combination of sensory and cognitive changes
Gap durations were individually adjusted using an adaptive-tracking procedure; mean performance was near threshold and did not differ significantly between age groups (hit rates: t(38) 1⁄4 À 1.62, P 1⁄4 0.11, re 1⁄4 0.25
The current work demonstrates that neural entrainment to environmental rhythms is weaker in older compared to younger adults, while they perform a difficult gap-detection task
Summary
Healthy aging is accompanied by listening difficulties, including decreased speech comprehension, that stem from an ill-understood combination of sensory and cognitive changes. We use electroencephalography to demonstrate that auditory neural oscillations of older adults entrain less firmly and less flexibly to speech-paced (B3 Hz) rhythms than younger adults’ during attentive listening These neural entrainment effects are distinct in magnitude and origin from the neural response to sound per se. The current electroencephalography (EEG) study examined the dynamic relationship between neural entrainment to stimulus rhythm (during active and passive listening) on the one hand and task-induced alpha modulations on the other, that is, between rhythmic- and continuous-mode processing during vigilance-style monitoring of a rhythmic stimulus. We recorded event-related potentials (ERPs) in response to tone sequences that had presentation rates and spectral ranges matched to the frequency-modulated sounds The reason for this was to rule out the possibility that weaker entrainment for older compared to younger adults could be attributed to overall decreases in auditory cortical responsiveness with age
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