RESUMO
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.
