Aging Affects Neural Precision of Speech Encoding
Open Access
- 10 October 2012
- journal article
- Published by Society for Neuroscience in Journal of Neuroscience
- Vol. 32 (41), 14156-14164
- https://doi.org/10.1523/jneurosci.2176-12.2012
Abstract
Older adults frequently report they can hear what is said but cannot understand the meaning, especially in noise. This difficulty may arise from the inability to process rapidly changing elements of speech. Aging is accompanied by a general slowing of neural processing and decreased neural inhibition, both of which likely interfere with temporal processing in auditory and other sensory domains. Age-related reductions in inhibitory neurotransmitter levels and delayed neural recovery can contribute to decreases in the temporal precision of the auditory system. Decreased precision may lead to neural timing delays, reductions in neural response magnitude, and a disadvantage in processing the rapid acoustic changes in speech. The auditory brainstem response (ABR), a scalp-recorded electrical potential, is known for its ability to capture precise neural synchrony within subcortical auditory nuclei; therefore, we hypothesized that a loss of temporal precision results in subcortical timing delays and decreases in response consistency and magnitude. To assess this hypothesis, we recorded ABRs to the speech syllable /da/ in normal hearing younger (18–30 years old) and older (60–67 years old) adult humans. Older adults had delayed ABRs, especially in response to the rapidly changing formant transition, and greater response variability. We also found that older adults had decreased phase locking and smaller response magnitudes than younger adults. Together, our results support the theory that older adults have a loss of temporal precision in the subcortical encoding of sound, which may account, at least in part, for their difficulties with speech perception.Keywords
This publication has 85 references indexed in Scilit:
- Functional connectivity during top-down modulation of visual short-term memory representationsNeuropsychologia, 2011
- Spatial and temporal processing of single auditory cortical neurons and populations of neurons in the macaque monkeyHearing Research, 2011
- Effects of reverberation on brainstem representation of speech in musicians and non-musiciansBrain Research, 2010
- Aging alters the perception and physiological representation of frequency: Evidence from human frequency-following response recordingsHearing Research, 2009
- Processing of broadband stimuli across A1 layers in young and aged ratsHearing Research, 2009
- Age-related changes in glycine receptor subunit composition and binding in dorsal cochlear nucleusNeuroscience, 2009
- Aging and cortical mechanisms of speech perception in noiseNeuropsychologia, 2008
- Age-related differences in sensitivity to small changes in frequency assessed with cortical evoked potentialsHearing Research, 2008
- Aged-related loss of temporal processing: Altered responses to amplitude modulated tones in rat dorsal cochlear nucleusNeuroscience, 2008
- Phase Patterns of Neuronal Responses Reliably Discriminate Speech in Human Auditory CortexNeuron, 2007