Auditory efferent system: new insights from cortex to cochlea

Abstract

The main function of the sensory systems is the transducing of external stimuli into bioelectrical signals, which are conducted through afferent pathways from sensory epithelia to the brain. However, it is known that descending projections are ubiquitous in the different sensory modalities, and in the case of auditory efferents connect the cerebral cortex with sensory receptor cells. The auditory efferent pathway is constituted by descending projections from pyramidal neurons located in layer V and VI of the primary auditory cortex and directed to the thalamus, inferior colliculus, cochlear nucleus and olivocochlear (OC) neurons. In addition, lateral and medial OC fibers innervate auditory-nerve fibers and outer hair cells of the cochlea respectively. Several functions have been attributed to the efferent system, including protection to acoustic trauma, unmasking of auditory stimuli in background noise, balance of interaural sensitivity and some cognitive functions like modulation of cochlear sensitivity during selective attention to auditory or visual stimuli. In addition there is evidence of a possible involvement of the efferent system in the etiology or treatment of some clinical pathologies like tinnitus, selective mutism and others. This call for papers is for any original work or review in auditory efferent functioning. Some of the proposed topics, but not limited to, are: neuroanatomical pathways from cortex to cochlea, pharmacology of the efferent system, cortical modulation of cochlear responses, olivocochlear functioning in different cortical states (awake, sleep, anesthetized), modulation of cochlear sensitivity during selective attention, human studies of auditory efferent functioning, and clinical pathologies related to the efferent system. This Research Topic will be a great contribution to the understanding of the efferent system in mammals, giving a more systemic point of view and merging auditory-cortex literature with classical studies mainly performed in the olivocochlear system.