title: Rapid Increase in Neural Conduction Time in the Adult Human Auditory Brainstem Following Sudden Unilateral Deafness.
abstract: Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.
authors.affiliation: School of Psychological Sciences, University of Manchester, A3.11 Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: M R D
authors.initials: MR
authors.lastname: Maslin
authors.affiliation: Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: S K
authors.initials: SK
authors.lastname: Lloyd
authors.affiliation: Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: S
authors.initials: S
authors.lastname: Rutherford
authors.affiliation: Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: S
authors.initials: S
authors.lastname: Freeman
authors.affiliation: Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: A
authors.initials: A
authors.lastname: King
authors.affiliation: School of Psychological Sciences, University of Manchester, A3.11 Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK.|Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Moore
authors.affiliation: School of Psychological Sciences, University of Manchester, A3.11 Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK. kevin.j.munro@manchester.ac.uk.|Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK. kevin.j.munro@manchester.ac.uk.
authors.forename: K J
authors.initials: KJ
authors.lastname: Munro
mesh_terms: D000328:Adult; D000368:Aged; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D046088:Hearing Loss, Unilateral / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D011930:Reaction Time
keywords: acoustic neuroma; auditory brainstem response; deafferentation; disinhibition; neural plasticity; unilateral deafness