title: Auditory cortex activation to natural speech and simulated cochlear implant speech measured with functional near-infrared spectroscopy.
abstract: The primary goal of most cochlear implant procedures is to improve a patient's ability to discriminate speech. To accomplish this, cochlear implants are programmed so as to maximize speech understanding. However, programming a cochlear implant can be an iterative, labor-intensive process that takes place over months. In this study, we sought to determine whether functional near-infrared spectroscopy (fNIRS), a non-invasive neuroimaging method which is safe to use repeatedly and for extended periods of time, can provide an objective measure of whether a subject is hearing normal speech or distorted speech. We used a 140 channel fNIRS system to measure activation within the auditory cortex in 19 normal hearing subjects while they listed to speech with different levels of intelligibility. Custom software was developed to analyze the data and compute topographic maps from the measured changes in oxyhemoglobin and deoxyhemoglobin concentration. Normal speech reliably evoked the strongest responses within the auditory cortex. Distorted speech produced less region-specific cortical activation. Environmental sounds were used as a control, and they produced the least cortical activation. These data collected using fNIRS are consistent with the fMRI literature and thus demonstrate the feasibility of using this technique to objectively detect differences in cortical responses to speech of different intelligibility.
authors.affiliation: Abramson Center for the Future of Health and Department of Engineering Technology, University of Houston, 300 Technology Building, Suite 123, Houston, TX 77204, USA. Electronic address: lpollonini@uh.edu.
authors.forename: Luca
authors.initials: L
authors.lastname: Pollonini
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA. Electronic address: ceo@stanford.edu.
authors.forename: Cristen
authors.initials: C
authors.lastname: Olds
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA. Electronic address: habaya@ohns.stanford.edu.
authors.forename: Homer
authors.initials: H
authors.lastname: Abaya
authors.affiliation: Department of Psychology, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT 06269-1020, USA. Electronic address: heather.bortfeld@uconn.edu.
authors.forename: Heather
authors.initials: H
authors.lastname: Bortfeld
authors.affiliation: Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, 6431 Fannin St., Suite MSB 7.046, Houston, TX 77030, USA. Electronic address: Michael.S.Beauchamp@uth.tmc.edu.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Beauchamp
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA. Electronic address: joghalai@ohns.stanford.edu.
authors.forename: John S
authors.initials: JS
authors.lastname: Oghalai
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001302:Audiometry, Speech; D001303:Auditory Cortex / Q000502:physiology*; D001309:Auditory Threshold; D001931:Brain Mapping / Q000379:methods*; D003054:Cochlear Implants; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared; D013065:Speech Intelligibility; D013067:Speech Perception; D013997:Time Factors; D055815:Young Adult