Consequences of unilateral hearing loss: cortical adjustment to unilateral deprivation.
The effect of unilateral hearing loss on 2-deoxyglucose (2-DG) uptake in the central auditory system was studied in postnatal day 21 gerbils. Three weeks following a unilateral conductive hearing loss (CHL) or cochlear ablation (CA), animals were injected with 2-DG and exposed to an alternating auditory stimulus (1 and 2kHz tones). Uptake of 2-DG was measured in the inferior colliculus (IC), medial geniculate (MG), and auditory cortex (fields AI and AAF) of both sides of the brain in experimental animals and in anesthesia-only sham animals (SH). Significant differences in uptake, compared to SH, were found in the IC contralateral to the manipulated ear (CHL or CA) and in AAF contralateral to the CHL ear. We hypothesize that these findings may result from loss of functional inhibition in the IC contralateral to CA, but not CHL. Altered states of inhibition at the IC may affect activity in pathways ascending to auditory cortex, and ultimately activity in auditory cortex itself. Altered levels of activity in auditory cortex may explain some auditory processing deficits experienced by individuals with CHL.
Hutson
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Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, Duke University Medical Center, Box 3805, Durham, NC 27710, USA.
Durham
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Imig
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Tucci
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D000223:Adaptation, Psychological / Q000502:physiology*; D000818:Animals; D000963:Antimetabolites / Q000493:pharmacokinetics; D001303:Auditory Cortex / Q000502:physiology; D001306:Auditory Pathways / Q000502:physiology; D003051:Cochlea / Q000601:surgery; D003714:Denervation; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004195:Disease Models, Animal; D005829:Geniculate Bodies / Q000502:physiology; D005849:Gerbillinae; D006314:Hearing Loss, Conductive / Q000503:physiopathology*; D046088:Hearing Loss, Unilateral / Q000503:physiopathology*; D007245:Inferior Colliculi / Q000502:physiology
D000963:Antimetabolites; D003847:Deoxyglucose