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

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.

Keywords: auditory efferent; impulsivity; nicotinic receptors; olivocochlear; selective attention.

Figure 1

Difference in the number of non-target errors between wild type (WT) and knock-out (KO) mice during the C+T period. Incorrect and non-target responses are shown in red and green bars (mean ± SEM) for WT and KO mice correspondingly. (A) Number of incorrect responses. (B) Number of non-target errors. *p < 0.05.

Figure 2

Difference in the number of perseverative responses between WT and KO mice during the C+T period. The different behavioral measures in the four periods of the experimental protocol are shown in red and green bars (mean ± SEM) for WT and KO mice correspondingly. (A) Number of perseverative responses. (B) Number of intertrial interval (ITI) responses. (C) Number of premature responses. *p < 0.05.

Figure 3

Differences in the mean latency of perseverative responses between WT and KO mice during C+T and broadband noise (BBN) periods. The latencies of error responses in the four periods of the behavioral protocol are shown in red and green bars (mean ± SEM) for WT and KO mice correspondingly. (A) Mean latencies of incorrect responses. (B) Mean latencies of perseverative responses. (C) Mean latencies of ITI responses. (D) Mean latencies of premature responses. *p < 0.05.

Figure 4

Differential distribution of incorrect responses latencies between WT and KO mice during C+T and BBN periods. Density of incorrect responses latencies in the four periods of the behavioral protocol are shown in red and green lines for WT and KO mice correspondingly. Notice the presence of two peaks, around 500 ms and 1500 ms in the four periods. KO mice increase the amplitude of the first peak of incorrect responses with auditory distractors (C+T and BBN periods). (A) Pre-distractor period. (B) C+T period. (C) BBN period. (D) Post-distractor period. Kolmogorov-Smirnov test, *p < 0.05.

Figure 5

Differences in the total number of lever presses between WT and KO mice during PRE and C+T periods. The number of total lever presses in the four periods of the behavioral protocol are shown in red and green bars (mean ± SEM) for WT and KO mice correspondingly. *p < 0.05.