Medical Bionics - Research Publications

Permanent URI for this collection

http://hdl.handle.net/11343/45239

Filters

2016 - 2018 3
Reset filters

Settings
Statistics
Citations
Start date: 2003 × Author: McKay, Colette × Author: Zhou, Xin ×

Search Results

Now showing 1 - 3 of 3
  • Item
    Thumbnail Image
    Cortical Processing Related to Intensity of a Modulated Noise Stimulus-a Functional Near-Infrared Study
    Weder, S ; Zhou, X ; Shoushtarian, M ; Innes-Brown, H ; McKay, C (SPRINGER, 2018-06)
    Sound intensity is a key feature of auditory signals. A profound understanding of cortical processing of this feature is therefore highly desirable. This study investigates whether cortical functional near-infrared spectroscopy (fNIRS) signals reflect sound intensity changes and where on the brain cortex maximal intensity-dependent activations are located. The fNIRS technique is particularly suitable for this kind of hearing study, as it runs silently. Twenty-three normal hearing subjects were included and actively participated in a counterbalanced block design task. Four intensity levels of a modulated noise stimulus with long-term spectrum and modulation characteristics similar to speech were applied, evenly spaced from 15 to 90 dB SPL. Signals from auditory processing cortical fields were derived from a montage of 16 optodes on each side of the head. Results showed that fNIRS responses originating from auditory processing areas are highly dependent on sound intensity level: higher stimulation levels led to higher concentration changes. Caudal and rostral channels showed different waveform morphologies, reflecting specific cortical signal processing of the stimulus. Channels overlying the supramarginal and caudal superior temporal gyrus evoked a phasic response, whereas channels over Broca's area showed a broad tonic pattern. This data set can serve as a foundation for future auditory fNIRS research to develop the technique as a hearing assessment tool in the normal hearing and hearing-impaired populations.
  • Item
    Thumbnail Image
    Cortical Speech Processing in Postlingually Deaf Adult Cochlear Implant Users, as Revealed by Functional Near-Infrared Spectroscopy
    Zhou, X ; Seghouane, A-K ; Shah, A ; Innes-Brown, H ; Cross, W ; Litovsky, R ; McKay, CM (SAGE PUBLICATIONS INC, 2018-07-19)
    An experiment was conducted to investigate the feasibility of using functional near-infrared spectroscopy (fNIRS) to image cortical activity in the language areas of cochlear implant (CI) users and to explore the association between the activity and their speech understanding ability. Using fNIRS, 15 experienced CI users and 14 normal-hearing participants were imaged while presented with either visual speech or auditory speech. Brain activation was measured from the prefrontal, temporal, and parietal lobe in both hemispheres, including the language-associated regions. In response to visual speech, the activation levels of CI users in an a priori region of interest (ROI)-the left superior temporal gyrus or sulcus-were negatively correlated with auditory speech understanding. This result suggests that increased cross-modal activity in the auditory cortex is predictive of poor auditory speech understanding. In another two ROIs, in which CI users showed significantly different mean activation levels in response to auditory speech compared with normal-hearing listeners, activation levels were significantly negatively correlated with CI users' auditory speech understanding. These ROIs were located in the right anterior temporal lobe (including a portion of prefrontal lobe) and the left middle superior temporal lobe. In conclusion, fNIRS successfully revealed activation patterns in CI users associated with their auditory speech understanding.
  • Item
    No Preview Available
    Connectivity in Language Areas of the Brain in Cochlear Implant Users as Revealed by fNIRS
    McKay, CM ; Shah, A ; Seghouane, A-K ; Zhou, X ; Cross, W ; Litovsky, R ; VanDijk, P ; Baskent, D ; Gaudrain, E ; DeKleine, E ; Wagner, A ; Lanting, C (SPRINGER-VERLAG BERLIN, 2016)
    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.