Behavioral and neural spatial acuity can be persistently reduced by early temporary hearing loss

Abstract

Children experiencing asymmetrical hearing early in life, typically due to conductive hearing loss (CHL) associated with ear infection, often display reduced behavioral spatial acuity that persists long after hearing is restored, suggesting abnormal central auditory development. We hypothesized that persistent CHL disrupts the experience-dependent fine-tuning of binaural hearing necessary in the developing auditory system to support normal behavioral spatial acuity. Using an animal model (the guinea pig), we found that chronic unilateral CHL during development (induced by an earplug) caused the brain to generate a less precise representation of auditory space. When the hearing loss was reversed by simply removing the earplug, both the spatial acuity of single neurons in the inferior colliculus and behavioral performance in a simple sound location acuity task were ~threefold worse than animals that had not worn earplugs, as if the sense of auditory space had been blurred. Overall, the results suggest that experiencing even temporary hearing loss during early development can persistently alter the normal maturation of the auditory brain circuits that are necessary to support good spatial acuity. Thus, the maladaptive plasticity in these circuits due to temporary hearing loss during development can place limitations on spatial acuity in adulthood. [Support: R01-DC011555, T32-DC012280, F31-DC014219.]