The olivocochlear reflex strength in awake chinchillas is relevant for behavioural performance during visual selective attention with auditory distractors

Macarena Bowen,Paul H Delano,Felipe N Moreno-Gómez,Luis Robles,Macarena Ipinza,Sergio Vicencio,Gonzalo Terreros

doi:10.1038/s41598-020-71399-8

Macarena Bowen, Paul H Delano + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-71399-8

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Abstract

The auditory efferent system comprises descending projections from the cerebral cortex to subcortical nuclei, reaching the cochlear receptor through olivocochlear fibres. One of the functions attributed to this corticofugal system is to suppress irrelevant sounds during selective attention to visual stimuli. Medial olivocochlear neurons can also be activated by sounds through a brainstem reflex circuit. Whether the individual variability of this reflex is related to the cognitive capacity to suppress auditory stimuli is still controversial. Here we propose that the individual strength per animal of the olivocochlear reflex is correlated with the ability to suppress auditory distractors during visual attention in awake chinchillas. The olivocochlear reflex was elicited with a contralateral broad-band noise at ~ 60 dB and ipsilateral distortion product otoacoustic emissions were obtained at different frequencies (1–8 kHz). Fourteen chinchillas were evaluated in a behavioural protocol of visual attention with broad-band noise and chinchilla vocalizations as auditory distractors. Results show that the behavioural performance was affected by both distractors and that the magnitudes of the olivocochlear reflex evaluated at multiple frequencies were relevant for behavioural performance during visual discrimination with auditory distractors. These results stress the ecological relevance of the olivocochlear system for suppressing natural distractors.

Highlights

The auditory efferent system comprises descending projections from the cerebral cortex to subcortical nuclei, reaching the cochlear receptor through olivocochlear fibres
The linear mixed effects models (LMM) analysis showed a significant effect of the stage of behavioural protocol (X2(2) = 9.671, p = 0.008), where the only significant pairwise difference was obtained between BL1 and VOC1 latencies (Table 1)
We provide evidence that the effects of contralateral noise suppression on distortion product otoacoustic emissions (DPOAE) at multiple frequencies in awake chinchillas are significant predictors of the behavioural performance during a visual discrimination task in the presence of auditory distractors. This evidence suggests that the individual variability in the strength of the olivocochlear reflex is an important factor that aids in the ability to ignore auditory stimuli during visual selective attention

Summary

Introduction

The auditory efferent system comprises descending projections from the cerebral cortex to subcortical nuclei, reaching the cochlear receptor through olivocochlear fibres. The auditory efferent system is a neural network that comprises descending projections from the auditory cortex to the inferior colliculus, cochlear nucleus and superior olivary c omplex[10,11,12], from where the medial olivocochlear (MOC) bundle emerges making synapses directly with outer hair cells of the c ochlea[13] The functionality of these corticofugal pathways has been demonstrated in bats, chinchillas and h umans[14,15,16,17], and these descending projections are proposed to be the mediators of selective attention top-down effects on the cochlear receptor[18,19]. Whether the correlations between the individual strength of the olivocochlear reflex and the cognitive capacity to avoid auditory distractors are frequency specific or greater with ecologically relevant auditory distractors is unknown

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