Earplug-Induced Changes in Acoustic Reflex Thresholds Suggest that Increased Subcortical Neural Gain May Be Necessary but Not Sufficient for the Occurrence of Tinnitus

Publication date: Available online 16 March 2019Source: NeuroscienceAuthor(s): Hannah Brotherton, Charlotte Turtle, Christopher J. Plack, Kevin J. Munro, Roland SchaetteAbstractThe occurrence of tinnitus is associated with hearing loss and neuroplastic changes in the brain, but disentangling correlation and causation has remained difficult in both human and animal studies. Here we use earplugs to cause a period of monaural deprivation to induce a temporary, fully reversible tinnitus sensation, to test whether differences in subcortical changes in neural response gain, as reflected through changes in acoustic reflex thresholds (ARTs), could explain the occurrence of tinnitus.Forty-four subjects with normal hearing wore an earplug in one ear for either 4 (n = 27) or 7 days (n = 17). Thirty subjects reported tinnitus at the end of the deprivation period. ARTs were measured before the earplug period and immediately after taking the earplug out. At the end of the earplug period, ARTs in the plugged ear were decreased by 5.9 ± 1.1 dB in the tinnitus-positive group, and by 6.3 ± 1.1 dB in the tinnitus-negative group. In the control ear, ARTs were increased by 1.3 ± 0.8 dB in the tinnitus-positive group, and by 1.6 ± 2.0 dB in the tinnitus-negative group. There were no significant differences between the groups with 4 and 7 days of auditory deprivation.Our results suggest that either the subcortical neurophysiological changes underlying the ART...

Source: Neuroscience - March 17, 2019 Category: Neuroscience Source Type: research