Journal
NEUROBIOLOGY OF AGING
Volume 73, Issue -, Pages 30-40Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.neurobiolaging.2018.08.023
Keywords
Inferior colliculus; Voice onset time; Evoked potentials; Hearing loss
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Funding
- NIDCD [DC-011580]
- Canada First Research Excellence Fund BrainsCAN postdoctoral fellowship
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Hearing impairment in older people is thought to arise from impaired temporal processing in auditory circuits. We used a systems-level (scalp recordings) and a microcircuit-level (extracellular recordings) approach to investigate how aging affects the sensitivity to temporal envelopes of speech-like sounds in rats. Scalp-recorded potentials suggest an age-related increase in sensitivity to temporal regularity along the ascending auditory pathway. The underlying cellular changes in the midbrain were examined using extracellular recordings from inferior colliculus neurons. We observed an age-related increase in sensitivity to the sound's onset and temporal regularity (i.e., periodicity envelope) in the spiking output of inferior colliculus neurons, relative to their synaptic inputs (local field potentials). This relative enhancement for aged animals was most prominent for multi-unit (relative to single-unit) spiking activity. Spontaneous multi-unit, but not single-unit, activity was also enhanced in aged compared with young animals. Our results suggest that aging is associated with altered sensitivity to a sound's temporal regularities, and that these effects may be due to increased gain of neural network activity in the midbrain. (C) 2018 Elsevier Inc. All rights reserved.
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