title: Plasticity in human pitch perception induced by tonotopically mismatched electro-acoustic stimulation.
abstract: Under normal conditions, the acoustic pitch percept of a pure tone is determined mainly by the tonotopic place of the stimulation along the cochlea. Unlike acoustic stimulation, electric stimulation of a cochlear implant (CI) allows for the direct manipulation of the place of stimulation in human subjects. CI sound processors analyze the range of frequencies needed for speech perception and allocate portions of this range to the small number of electrodes distributed in the cochlea. Because the allocation is assigned independently of the original resonant frequency of the basilar membrane associated with the location of each electrode, CI users who have access to residual hearing in either or both ears often have tonotopic mismatches between the acoustic and electric stimulation. Here we demonstrate plasticity of place pitch representations of up to three octaves in Hybrid CI users after experience with combined electro-acoustic stimulation. The pitch percept evoked by single CI electrodes, measured relative to acoustic tones presented to the non-implanted ear, changed over time in directions that reduced the electro-acoustic pitch mismatch introduced by the CI programming. This trend was particularly apparent when the allocations of stimulus frequencies to electrodes were changed over time, with pitch changes even reversing direction in some subjects. These findings show that pitch plasticity can occur more rapidly and on a greater scale in the mature auditory system than previously thought possible. Overall, the results suggest that the adult auditory system can impose perceptual order on disordered arrays of inputs.
authors.affiliation: Department of Otolaryngology, Oregon Health and Science University, Portland, OR, USA; Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA. Electronic address: reiss@ohsu.edu.
authors.forename: L A J
authors.initials: LA
authors.lastname: Reiss
authors.affiliation: Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA; Department of Otolaryngology, University of Iowa, Iowa City, IA, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Turner
authors.affiliation: Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Karsten
authors.affiliation: Department of Otolaryngology, University of Iowa, Iowa City, IA, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Gantz
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001703:Biophysics; D003051:Cochlea / Q000502:physiology*; D003054:Cochlear Implants; D004558:Electric Stimulation; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D010898:Pitch Perception / Q000502:physiology*; D011571:Psychoacoustics; D011594:Psychometrics; D055815:Young Adult
keywords: CI; HA; HF; HL; cochlear implant; electro-acoustic stimulation; hearing aid; hearing loss; high-frequency; hybrid; pitch; plasticity; tonotopic map