title: Monaural Congenital Deafness Affects Aural Dominance and Degrades Binaural Processing.
abstract: Cortical development extensively depends on sensory experience. Effects of congenital monaural and binaural deafness on cortical aural dominance and representation of binaural cues were investigated in the present study. We used an animal model that precisely mimics the clinical scenario of unilateral cochlear implantation in an individual with single-sided congenital deafness. Multiunit responses in cortical field A1 to cochlear implant stimulation were studied in normal-hearing cats, bilaterally congenitally deaf cats (CDCs), and unilaterally deaf cats (uCDCs). Binaural deafness reduced cortical responsiveness and decreased response thresholds and dynamic range. In contrast to CDCs, in uCDCs, cortical responsiveness was not reduced, but hemispheric-specific reorganization of aural dominance and binaural interactions were observed. Deafness led to a substantial drop in binaural facilitation in CDCs and uCDCs, demonstrating the inevitable role of experience for a binaural benefit. Sensitivity to interaural time differences was more reduced in uCDCs than in CDCs, particularly at the hemisphere ipsilateral to the hearing ear. Compared with binaural deafness, unilateral hearing prevented nonspecific reduction in cortical responsiveness, but extensively reorganized aural dominance and binaural responses. The deaf ear remained coupled with the cortex in uCDCs, demonstrating a significant difference to deprivation amblyopia in the visual system.
authors.affiliation: Cluster of Excellence Hearing4all, Institute of AudioNeuroTechnology and Department of Experimental Otology of the ENT Clinics, Hannover Medical School, Hannover, Germany Department of Otorhinolaryngology, J.W. Goethe University, Frankfurt am Main, Germany MED-EL GmbH, Innsbruck, Austria.
authors.forename: Jochen
authors.initials: J
authors.lastname: Tillein
authors.affiliation: Cluster of Excellence Hearing4all, Institute of AudioNeuroTechnology and Department of Experimental Otology of the ENT Clinics, Hannover Medical School, Hannover, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Hubka
authors.affiliation: Cluster of Excellence Hearing4all, Institute of AudioNeuroTechnology and Department of Experimental Otology of the ENT Clinics, Hannover Medical School, Hannover, Germany School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA.
authors.forename: Andrej
authors.initials: A
authors.lastname: Kral
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000503:physiopathology*; D001306:Auditory Pathways / Q000503:physiopathology; D002415:Cats; D003051:Cochlea / Q000503:physiopathology; D003054:Cochlear Implants; D003638:Deafness / Q000151:congenital / Q000503:physiopathology*; D004558:Electric Stimulation; D007839:Functional Laterality; D013017:Sound Localization / Q000502:physiology*
keywords: asymmetric hearing; auditory development; binaural cochlear implants; interaural time difference; sensory deprivation