Seminars in Hearing Research at Purdue (SHRP)

Date: Thursday, September 9, 2021

Time: 10:30 – 11:20 am

Location: LYLE 1150

Title: Age-related reduction in frequency-following responses as a potential marker of cochlear neural degeneration

Speaker: Jonatan Märcher-Rørsted, PhD candidate, Technical University of Denmark (DTU)

Abstract: Previous studies have reported an age-related reduction in frequency-following responses (FFRs) in listeners with clinically normal audiometric thresholds. This has been argued to reflect an age-dependent decline in neural synchrony in the central auditory system. However, age-dependent degeneration of auditory nerve (AN) fibers may have little effect on audiometric sensitivity and may yet affect the suprathreshold coding of temporal information. This peripheral loss of temporal information may not be recovered centrally and may thus also contribute to reduced phase-locking accuracy in the auditory midbrain. Here, we investigated whether age-related reductions in the FFR could, at least in part, reflect age-dependent peripheral neural degeneration.

We combined human electrophysiology and auditory nerve (AN) modelling to investigate whether age-related changes in the FFR would be consistent with peripheral neural degeneration. A reduction in the FFR response in the older listeners was found across stimulation frequencies for both sweep and static pure-tone stimulation. Older listeners also showed significantly shallower MEMR growth level functions compared to the younger listeners, which could indicate a loss of low spontaneous rate fibers in the AN. Despite having clinically normal audiometric thresholds, the older listeners had significantly reduced sensitivity at frequencies above 8 kHz compared to the young group. The computational simulations suggested that such experimental results can be accounted for by neural degeneration already at the stage of the AN whereas a loss of sensitivity due to OHC dysfunction at higher frequencies could not explain the observed reduced FFR in the older listeners. These results are consistent with a peripheral source of the FFR reductions observed in older normal-hearing listeners, and indicate that FFRs at lower carrier frequencies may potentially be a sensitive marker of peripheral neural degeneration.

Zoom Info:

https://purdue-edu.zoom.us/j/93108158900?pwd=RDdTQ0Z4UE9Rb0JUenhjMG1SMkp2QT09

Meeting ID: 931 0815 8900

Passcode: 11501150

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The working schedule for this academic year will be available here shortly:

https://purdue.edu/TPAN/hearing/shrp_schedule

The titles and abstracts of the talks will be added here:

https://purdue.edu/TPAN/hearing/shrp_abstracts