title: Neural adaptation and behavioral measures of temporal processing and speech perception in cochlear implant recipients.
abstract: The objective was to determine if one of the neural temporal features, neural adaptation, can account for the across-subject variability in behavioral measures of temporal processing and speech perception performance in cochlear implant (CI) recipients. Neural adaptation is the phenomenon in which neural responses are the strongest at the beginning of the stimulus and decline following stimulus repetition (e.g., stimulus trains). It is unclear how this temporal property of neural responses relates to psychophysical measures of temporal processing (e.g., gap detection) or speech perception. The adaptation of the electrical compound action potential (ECAP) was obtained using 1000 pulses per second (pps) biphasic pulse trains presented directly to the electrode. The adaptation of the late auditory evoked potential (LAEP) was obtained using a sequence of 1-kHz tone bursts presented acoustically, through the cochlear implant. Behavioral temporal processing was measured using the Random Gap Detection Test at the most comfortable listening level. Consonant nucleus consonant (CNC) word and AzBio sentences were also tested. The results showed that both ECAP and LAEP display adaptive patterns, with a substantial across-subject variability in the amount of adaptation. No correlations between the amount of neural adaptation and gap detection thresholds (GDTs) or speech perception scores were found. The correlations between the degree of neural adaptation and demographic factors showed that CI users having more LAEP adaptation were likely to be those implanted at a younger age than CI users with less LAEP adaptation. The results suggested that neural adaptation, at least this feature alone, cannot account for the across-subject variability in temporal processing ability in the CI users. However, the finding that the LAEP adaptive pattern was less prominent in the CI group compared to the normal hearing group may suggest the important role of normal adaptation pattern at the cortical level in speech perception.
authors.affiliation: Department of Communication Sciences and Disorders, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Fawen
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Communication Sciences and Disorders, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Benson
authors.affiliation: Department of Communication Sciences and Disorders, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Dora
authors.initials: D
authors.lastname: Murphy
authors.affiliation: Department of Communication Sciences and Disorders, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Melissa
authors.initials: M
authors.lastname: Boian
authors.affiliation: Department of Audiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Scott
authors.affiliation: Department of Communication Sciences and Disorders, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Robert
authors.initials: R
authors.lastname: Keith
authors.affiliation: Neurology Division, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America.
authors.forename: Jing
authors.initials: J
authors.lastname: Xiang
authors.affiliation: Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Paul
authors.initials: P
authors.lastname: Abbas
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003054:Cochlear Implants; D005072:Evoked Potentials, Auditory; D005260:Female; D034381:Hearing Loss / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D065855:Spatial Processing; D013067:Speech Perception