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Gap-induced inhibition of the post-auricular muscle response in humans and guinea pigs
Journal article   Open access   Peer reviewed

Gap-induced inhibition of the post-auricular muscle response in humans and guinea pigs

Caroline A Wilson, Joel I Berger, Jessica de Boer, Magdalena Sereda, Alan R Palmer, Deborah A Hall and Mark N Wallace
Hearing research, Vol.374, pp.13-23
03/15/2019
DOI: 10.1016/j.heares.2019.01.009
PMCID: PMC6408328
PMID: 30685571
url
https://doi.org/10.1016/j.heares.2019.01.009View
Published (Version of record) Open Access

Abstract

A common method for measuring changes in temporal processing sensitivity in both humans and animals makes use of GaP-induced Inhibition of the Acoustic Startle (GPIAS). It is also the basis of a common method for detecting tinnitus in rodents. However, the link to tinnitus has not been properly established because GPIAS has not yet been used to objectively demonstrate tinnitus in humans. In guinea pigs, the Preyer (ear flick) myogenic reflex is an established method for measuring the acoustic startle for the GPIAS test, while in humans, it is the eye-blink reflex. Yet, humans have a vestigial remnant of the Preyer reflex, which can be detected by measuring skin surface potentials associated with the Post-Auricular Muscle Response (PAMR). A similar electrical potential can be measured in guinea pigs and we aimed to show that the PAMR could be used to demonstrate GPIAS in both species. In guinea pigs, we compare the GPIAS measured using the pinna movement of the Preyer reflex and the electrical potential of the PAMR to demonstrate that the two are at least equivalent. In humans, we establish for the first time that the PAMR provides a reliable way of measuring GPIAS that is a pure acoustic alternative to the multimodal eye-blink reflex. Further exploratory tests showed that while eye gaze position influenced the size of the PAMR response, it did not change the degree of GPIAS. Our findings confirm that the PAMR is a sensitive method for measuring GPIAS and suggest that it may allow direct comparison of temporal processing between humans and animals and may provide a basis for an objective test of tinnitus. •Myogenic potentials from the guinea pig pinna show gap induced pre-pulse inhibition.•Startle inhibition is also shown by gaps in background noise using the Preyer reflex.•Startle potentials recorded behind the human pinna show gap-induced inhibition.•Human post-auricular muscle potentials may form an objective test for tinnitus.
Acoustic startle reflex Eye-blink reflex Gap-pre-pulse inhibition Preyer reflex Tinnitus

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