title: Connectivity in Language Areas of the Brain in Cochlear Implant Users as Revealed by fNIRS.
abstract: Many studies, using a variety of imaging techniques, have shown that deafness induces functional plasticity in the brain of adults with late-onset deafness, and in children changes the way the auditory brain develops. Cross modal plasticity refers to evidence that stimuli of one modality (e.g. vision) activate neural regions devoted to a different modality (e.g. hearing) that are not normally activated by those stimuli. Other studies have shown that multimodal brain networks (such as those involved in language comprehension, and the default mode network) are altered by deafness, as evidenced by changes in patterns of activation or connectivity within the networks. In this paper, we summarise what is already known about brain plasticity due to deafness and propose that functional near-infra-red spectroscopy (fNIRS) is an imaging method that has potential to provide prognostic and diagnostic information for cochlear implant users. Currently, patient history factors account for only 10 % of the variation in post-implantation speech understanding, and very few post-implantation behavioural measures of hearing ability correlate with speech understanding. As a non-invasive, inexpensive and user-friendly imaging method, fNIRS provides an opportunity to study both pre- and post-implantation brain function. Here, we explain the principle of fNIRS measurements and illustrate its use in studying brain network connectivity and function with example data.
authors.affiliation: The Bionics Institute of Australia, Melbourne, Australia. cmckay@bionicsinstitute.org.|Department of Medical Bionics, The University of Melbourne, Melbourne, Australia. cmckay@bionicsinstitute.org.
authors.forename: Colette M
authors.initials: CM
authors.lastname: McKay
authors.affiliation: The Bionics Institute of Australia, Melbourne, Australia.|Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, Australia.
authors.forename: Adnan
authors.initials: A
authors.lastname: Shah
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, Australia.
authors.forename: Abd-Krim
authors.initials: AK
authors.lastname: Seghouane
authors.affiliation: The Bionics Institute of Australia, Melbourne, Australia.|Department of Medical Bionics, The University of Melbourne, Melbourne, Australia.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.affiliation: The Bionics Institute of Australia, Melbourne, Australia.|Department of Medicine, The University of Melbourne, Melbourne, Australia.
authors.forename: William
authors.initials: W
authors.lastname: Cross
authors.affiliation: Waisman Center, The University of Wisconsin-Madison, Madison, USA.
authors.forename: Ruth
authors.initials: R
authors.lastname: Litovsky
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003054:Cochlear Implants; D006801:Humans; D007804:Language Development; D009473:Neuronal Plasticity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013067:Speech Perception / Q000502:physiology*
keywords: Brain plasticity; Cochlear implants; Connectivity in brain networks; Deafness; fNIRS