Cochlear Neuropathy and the Coding of Supra-threshold Sound

Frontiers in Systems Neuroscience

Hari M Bharadwaj¹  Barbara G Shinn-Cunningham¹  M. Charles eLiberman²  Luke eShaheen³  Sarah eVerhulst⁴ 

[1] Boston University;Harvard University;Massachusetts Eye and Ear Infirmary;Oldenburg University;

关键词: Aging;    individual differences;    temporal coding;    auditory nerve;    Temporary Threshold Shifts;    frequency-following response (FFR);   

DOI  :  10.3389/fnsys.2014.00026

来源: DOAJ

【 摘 要 】

Many listeners with hearing thresholds within the clinically normal range nonetheless complain of difficulty hearing in everyday settings and understanding speech in noise. Converging evidence from human and animal studies points to one potential source of such difficulties: differences in the fidelity with which supra-threshold sound is encoded in the early portions of the auditory pathway. Measures of auditory subcortical steady-state responses in humans and animals support the idea that the temporal precision of the early auditory representation can be poor even when hearing thresholds are normal. In humans with normal hearing thresholds, behavioral ability in paradigms that require listeners to make use of the detailed spectro-temporal structure of supra-threshold sound, such as selective attention and discrimination of frequency modulation, correlate with subcortical temporal coding precision. Animal studies show that noise exposure and aging can cause a loss of a large percentage of auditory nerve fibers without any significant change in measured audiograms. Here, we argue that cochlear neuropathy may reduce encoding precision of supra-threshold sound, and that this manifests both behaviorally and in subcortical steady-state responses in humans. Furthermore, recent studies suggest that noise-induced neuropathy may be selective for higher-threshold, lower-spontaneous-rate nerve fibers. Based on our hypothesis, we suggest some approaches that may yield particularly sensitive, objective measures of supra-threshold coding deficits that arise due to neuropathy. Finally, we comment on the potential clinical significance of these ideas and identify areas for future investigation.

【 授权许可】

Unknown