Difference in Perseverative Errors during a Visual Attention Task with Auditory Distractors in Alpha-9 Nicotinic Receptor Subunit Wild Type and Knock-Out Mice.

Pascal Jorratt,Paul H Delano,Gonzalo Terreros,Carolina Delgado,Alexies Dagnino-Subiabre

doi:10.3389/fncel.2017.00357

Abstract

The auditory efferent system is a neural network that originates in the auditory cortex and projects to the cochlear receptor through olivocochlear (OC) neurons. Medial OC neurons make cholinergic synapses with outer hair cells (OHCs) through nicotinic receptors constituted by α9 and α10 subunits. One of the physiological functions of the α9 nicotinic receptor subunit (α9-nAChR) is the suppression of auditory distractors during selective attention to visual stimuli. In a recent study we demonstrated that the behavioral performance of alpha-9 nicotinic receptor knock-out (KO) mice is altered during selective attention to visual stimuli with auditory distractors since they made less correct responses and more omissions than wild type (WT) mice. As the inhibition of the behavioral responses to irrelevant stimuli is an important mechanism of the selective attention processes, behavioral errors are relevant measures that can reflect altered inhibitory control. Errors produced during a cued attention task can be classified as premature, target and perseverative errors. Perseverative responses can be considered as an inability to inhibit the repetition of an action already planned, while premature responses can be considered as an index of the ability to wait or retain an action. Here, we studied premature, target and perseverative errors during a visual attention task with auditory distractors in WT and KO mice. We found that α9-KO mice make fewer perseverative errors with longer latencies than WT mice in the presence of auditory distractors. In addition, although we found no significant difference in the number of target error between genotypes, KO mice made more short-latency target errors than WT mice during the presentation of auditory distractors. The fewer perseverative error made by α9-KO mice could be explained by a reduced motivation for reward and an increased impulsivity during decision making with auditory distraction in KO mice.

Highlights

The auditory efferent system is a neural network that comprises descending projections from the auditory cortex to several subcortical nuclei, including the medial geniculate body, inferior colliculus, cochlear nucleus and superior olivary complex (Terreros and Delano, 2015)
medial OC (MOC) neurons make cholinergic synapses with outer hair cells (OHCs) through nicotinic receptors constituted by α9 and α10 subunits that mediate auditory efferent activity (Elgoyhen et al, 1994, 2001, 2009)
The number and mean latencies of incorrect and non-target error responses in wild type (WT) and KO mice were compared during the four periods of the experimental protocol (PRE, clicks and kHz tones (C+T), BBN and POST)

Summary

Introduction

The auditory efferent system is a neural network that comprises descending projections from the auditory cortex to several subcortical nuclei, including the medial geniculate body, inferior colliculus, cochlear nucleus and superior olivary complex (Terreros and Delano, 2015). The α9 subunit of nicotinic receptors is expressed in different parts of the nervous and endocrine systems, including the inner ear, pituitary gland and dorsal ganglion root neurons (McIntosh et al, 2009) This subunit has been implicated in different physiological functions, including auditory frequency discrimination (Clause et al, 2017), suppression of auditory distractors during selective attention to visual stimuli (Terreros et al, 2016), vestibular rehabilitation (Eron et al, 2015), motion sickness and balance control (Tu et al, 2017), stress responses (Colomer et al, 2010; Mohammadi et al, 2017), awake/sleep cycle and circadian rhythm regulation (Velluti et al, 1989; Madrid-López et al, 2017; Mohammadi et al, 2017), and modulation of pain and hyperalgesia (Mohammadi and Christie, 2014; Romero et al, 2017). In this line the auditory efferent system, including OC neurons are important pathways that permit filtering of cochlear and auditory nerve responses during selective attention to visual stimuli (Delano et al, 2007; Smith et al, 2012)

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Conclusion