Selective Attention to Visual Stimuli Using Auditory Distractors Is Altered in Alpha-9 Nicotinic Receptor Subunit Knock-Out Mice

Abstract

During selective attention, subjects voluntarily focus their cognitive resources on a specific stimulus while ignoring others. Top-downfiltering of peripheral sensory responses by higher structures of the brain has been proposed as one of the mechanisms responsible forselective attention. A prerequisite to accomplish top-down modulation of the activity of peripheral structures is the presence of corticofugalpathways. The mammalian auditory efferent system is a unique neural network that originates in the auditory cortex and projectstothe cochlear receptorthroughthe olivocochlear bundle, and it has been proposedtofunction as atop-downfilter of peripheral auditoryresponses during attention to cross-modal stimuli. However, to date, there is no conclusive evidence of the involvement of olivocochlearneurons in selective attention paradigms. Here, wetrained wild-type and-9 nicotinic receptor subunit knock-out (KO) mice, which lackcholinergic transmission between medial olivocochlear neurons and outer hair cells, in a two-choice visual discrimination task andstudied the behavioral consequences of adding different types of auditory distractors. In addition, we evaluated the effects of contralateralnoise on auditory nerve responses as a measure of the individual strength of the olivocochlear reflex. We demonstrate that KO micehave a reduced olivocochlear reflex strength and perform poorly in a visual selective attention paradigm. These results confirm that anintact medial olivocochlear transmission aids in ignoring auditory distraction during selective attention to visual stimuli.