title: Using acoustic reflex threshold, auditory brainstem response and loudness judgments to investigate changes in neural gain following acute unilateral deprivation in normal hearing adults.
abstract: Unilateral auditory deprivation induces a reduction in the acoustic reflex threshold (ART) and an increase in loudness. These findings have been interpreted as a compensatory change in neural gain, governed by changes in excitatory and inhibitory neural inputs. There is also evidence to suggest that changes in neural gain can be measured using the auditory brainstem response (ABR). The present study extended Munro et al. (2014) [J. Acoust. Soc. Am. 135, 315-322] by investigating changes after 4 days of unilateral earplug use to: (i) ART, (ii) ABR and (iii) loudness. Because changes may occur during the post-deprivation test session (day 4), ART measurements were taken 1 h and 2 h post-earplug removal. There was a significant reduction in ART in the treatment ear immediately after the removal of the earplug, which is consistent with a compensatory increase in neural gain. A novel finding was the significant return of ARTs to baseline within 2 h of earplug removal. A second novel finding was a significant decrease in the mean amplitude of ABR wave V in the treatment ear, but a significant increase in the control ear, both after 4 days of deprivation. These changes in the ABR are in the opposite direction to those predicted. We were unable to replicate the change in loudness reported in previous deprivation studies; however, the short period of earplug use may have contributed to this null finding.
authors.affiliation: Manchester Centre for Audiology and Deafness, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, United Kingdom. Electronic address: hannah.brotherton@manchester.ac.uk.
authors.forename: Hannah
authors.initials: H
authors.lastname: Brotherton
authors.affiliation: Manchester Centre for Audiology and Deafness, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, United Kingdom; Department of Psychology, Lancaster University, Lancaster, LA1 4YF, United Kingdom. Electronic address: chris.plack@manchester.ac.uk.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Plack
authors.affiliation: Ear Institute, University College London, London, WC1X 8EE, United Kingdom. Electronic address: r.schaette@ucl.ac.uk.
authors.forename: Roland
authors.initials: R
authors.lastname: Schaette
authors.affiliation: Manchester Centre for Audiology and Deafness, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, United Kingdom; Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WK, United Kingdom. Electronic address: kevin.j.munro@manchester.ac.uk.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Munro
mesh_terms: D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000223:Adaptation, Psychological; D000328:Adult; D001306:Auditory Pathways / Q000502:physiology*; D001309:Auditory Threshold; D004430:Ear Protective Devices; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006309:Hearing; D006801:Humans; D007600:Judgment; D008144:Loudness Perception; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity; D020127:Recovery of Function; D012022:Reflex, Acoustic; D012683:Sensory Deprivation; D013997:Time Factors; D055815:Young Adult
keywords: Neural gain; Subcortical plasticity; Unilateral deprivation