title: Neuroimaging with near-infrared spectroscopy demonstrates speech-evoked activity in the auditory cortex of deaf children following cochlear implantation.
abstract: Cochlear implants (CI) are commonly used to treat deafness in young children. While many factors influence the ability of a deaf child who is hearing through a CI to develop speech and language skills, an important factor is that the CI has to stimulate the auditory cortex. Obtaining behavioral measurements from young children with CIs can often be unreliable. While a variety of noninvasive techniques can be used for detecting cortical activity in response to auditory stimuli, many have critical limitations when applied to the pediatric CI population. We tested the ability of near-infrared spectroscopy (NIRS) to detect cortical responses to speech stimuli in pediatric CI users. Neuronal activity leads to changes in blood oxy- and deoxy-hemoglobin concentrations that can be detected by measuring the transmission of near-infrared light through the tissue. To verify the efficacy of NIRS, we first compared auditory cortex responses measured with NIRS and fMRI in normal-hearing adults. We then examined four different participant cohorts with NIRS alone. Speech-evoked cortical activity was observed in 100% of normal-hearing adults (11 of 11), 82% of normal-hearing children (9 of 11), 78% of deaf children who have used a CI > 4 months (28 of 36), and 78% of deaf children who completed NIRS testing on the day of CI initial activation (7 of 9). Therefore, NIRS can measure cortical responses in pediatric CI users, and has the potential to be a powerful adjunct to current CI assessment tools.
authors.affiliation: Bobby R. Alford Department of Otolaryngology - Head and Neck Surgery, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Alexander B G
authors.initials: AB
authors.lastname: Sevy
authors.forename: Heather
authors.initials: H
authors.lastname: Bortfeld
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Huppert
authors.forename: Michael S
authors.initials: MS
authors.lastname: Beauchamp
authors.forename: Ross E
authors.initials: RE
authors.lastname: Tonini
authors.forename: John S
authors.initials: JS
authors.lastname: Oghalai
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001299:Audiometry; D001303:Auditory Cortex / Q000503:physiopathology*; D001309:Auditory Threshold; D001931:Brain Mapping / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D019929:Cochlear Implantation; D012048:Correction of Hearing Impairment / Q000523:psychology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared; D013067:Speech Perception; D013997:Time Factors; D055815:Young Adult