The association between subcortical and cortical fMRI and lifetime noise exposure in listeners with normal hearing thresholds
Rebecca S. Dewey,
Susan T. Francis,
Hannah Guest,
Garreth Prendergast,
Rebecca E. Millman,
Christopher J. Plack,
Deborah A. Hall
Affiliations
Rebecca S. Dewey
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK; National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham, NG1 5DU, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, NG7 2UH, UK; Corresponding author. National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham, NG1 5DU, UK.
Susan T. Francis
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK; Corresponding author. Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK.
Hannah Guest
Manchester Centre for Audiology and Deafness (ManCAD), University of Manchester, Manchester Academic Health Science Centre, M13 9PL, UK
Garreth Prendergast
Manchester Centre for Audiology and Deafness (ManCAD), University of Manchester, Manchester Academic Health Science Centre, M13 9PL, UK
Rebecca E. Millman
Manchester Centre for Audiology and Deafness (ManCAD), University of Manchester, Manchester Academic Health Science Centre, M13 9PL, UK; National Institute for Health Research (NIHR) Manchester Biomedical Research Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, M13 9WL, UK
Christopher J. Plack
Manchester Centre for Audiology and Deafness (ManCAD), University of Manchester, Manchester Academic Health Science Centre, M13 9PL, UK; National Institute for Health Research (NIHR) Manchester Biomedical Research Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, M13 9WL, UK; Department of Psychology, Lancaster University, LA1 4YF, UK
Deborah A. Hall
National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham, NG1 5DU, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, NG7 2UH, UK; University of Nottingham Malaysia, Jalan Broga, 43500, Semeniyh, Selangor Darul Ehsan, Malaysia
In animal models, exposure to high noise levels can cause permanent damage to hair-cell synapses (cochlear synaptopathy) for high-threshold auditory nerve fibers without affecting sensitivity to quiet sounds. This has been confirmed in several mammalian species, but the hypothesis that lifetime noise exposure affects auditory function in humans with normal audiometric thresholds remains unconfirmed and current evidence from human electrophysiology is contradictory. Here we report the auditory brainstem response (ABR), and both transient (stimulus onset and offset) and sustained functional magnetic resonance imaging (fMRI) responses throughout the human central auditory pathway across lifetime noise exposure. Healthy young individuals aged 25–40 years were recruited into high (n = 32) and low (n = 30) lifetime noise exposure groups, stratified for age, and balanced for audiometric threshold up to 16 kHz fMRI demonstrated robust broadband noise-related activity throughout the auditory pathway (cochlear nucleus, superior olivary complex, nucleus of the lateral lemniscus, inferior colliculus, medial geniculate body and auditory cortex). fMRI responses in the auditory pathway to broadband noise onset were significantly enhanced in the high noise exposure group relative to the low exposure group, differences in sustained fMRI responses did not reach significance, and no significant group differences were found in the click-evoked ABR. Exploratory analyses found no significant relationships between the neural responses and self-reported tinnitus or reduced sound-level tolerance (symptoms associated with synaptopathy). In summary, although a small effect, these fMRI results suggest that lifetime noise exposure may be associated with central hyperactivity in young adults with normal hearing thresholds.
