title: Combined neural and behavioural measures of temporal pitch perception in cochlear implant users.
abstract: Four experiments measured the perceptual and neural correlates of the temporal pattern of electrical stimulation applied to one cochlear-implant (CI) electrode, for several subjects. Neural effects were estimated from the electrically evoked compound action potential (ECAP) to each pulse. Experiment 1 attenuated every second pulse of a 200-pps pulse train. Increasing attenuation caused pitch to drop and the ECAP to become amplitude modulated, thereby providing an estimate of the relationship between neural modulation and pitch. Experiment 2 showed that the pitch of a 200-pps pulse train can be reduced by delaying every second pulse, so that the inter-pulse-intervals alternate between longer and shorter intervals. This caused the ECAP to become amplitude modulated, but not by enough to account for the change in pitch. Experiment 3 replicated the finding that rate discrimination deteriorates with increases in baseline rate. This was accompanied by an increase in ECAP modulation, but by an amount that produced only a small effect on pitch in experiment 1. Experiment 4 showed that preceding a pulse train with a carefully selected "pre-pulse" could reduce ECAP modulation, but did not improve rate discrimination. Implications for theories of pitch and for limitations of pitch perception in CI users are discussed.
authors.affiliation: MRC Cognition & Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, England.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Carlyon
authors.affiliation: MRC Cognition & Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, England.
authors.forename: John M
authors.initials: JM
authors.lastname: Deeks
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001306:Auditory Pathways / Q000502:physiology*; D003054:Cochlear Implants; D003638:Deafness / Q000503:physiopathology / Q000628:therapy; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004867:Equipment Design; D005072:Evoked Potentials, Auditory; D006801:Humans; D008875:Middle Aged; D009474:Neurons / Q000502:physiology; D010898:Pitch Perception / Q000502:physiology*; D011571:Psychoacoustics; D013997:Time Factors