Premium
Effects of aging on peripheral and central auditory processing in rats
Author(s) -
Costa Margarida,
Lepore Franco,
Prévost François,
Guillemot JeanPaul
Publication year - 2016
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13302
Subject(s) - inferior colliculus , audiology , brainstem , cochlear nucleus , superior olivary complex , presbycusis , auditory system , neuroscience , population , psychology , hearing loss , superior colliculus , auditory brainstem response , perception , sound localization , cochlea , medicine , nucleus , environmental health
Hearing loss is a hallmark sign in the elderly population. Decline in auditory perception provokes deficits in the ability to localize sound sources and reduces speech perception, particularly in noise. In addition to a loss of peripheral hearing sensitivity, changes in more complex central structures have also been demonstrated. Related to these, this study examines the auditory directional maps in the deep layers of the superior colliculus of the rat. Hence, anesthetized Sprague–Dawley adult (10 months) and aged (22 months) rats underwent distortion product of otoacoustic emissions ( DPOAE s) to assess cochlear function. Then, auditory brainstem responses ( ABR s) were assessed, followed by extracellular single‐unit recordings to determine age‐related effects on central auditory functions. DPOAE amplitude levels were decreased in aged rats although they were still present between 3.0 and 24.0 kH z. ABR level thresholds in aged rats were significantly elevated at an early (cochlear nucleus – wave II ) stage in the auditory brainstem. In the superior colliculus, thresholds were increased and the tuning widths of the directional receptive fields were significantly wider. Moreover, no systematic directional spatial arrangement was present among the neurons of the aged rats, implying that the topographical organization of the auditory directional map was abolished. These results suggest that the deterioration of the auditory directional spatial map can, to some extent, be attributable to age‐related dysfunction at more central, perceptual stages of auditory processing.