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Cortical responses to speech stimuli in hearing impaired infants measured by fMRI and auditory evoked potentials

Cahill, Lisa D.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1273174165

Abstract Details

2010, PhD, University of Cincinnati, Allied Health Sciences : Communication Science and Disorders.
The overall aim of the present research was to perform an exploratory analysis of the relationship between the P1 auditory evoked potential response and residual auditory cortical function as shown by fMRI activation maps in moderate or severe to profoundly hearing impaired subjects. Electrophysiologic and functional neuroimaging evaluations using speech stimuli were conducted on fourteen subjects ages 9-24 months with residual hearing ranging from 85 dBHL to 100 dBHL pure tone average (PTA), in the .5 to 2 KHz range. Electrophysiological testing included evaluation of P1 cortical auditory evoked response with a hearing aid on using a Klatt generated /ba/ stimulus in the soundfield at 75 dBSPL. Subjects unable to wear an amplification device during the testing were stimulated using an Eartone 3A insert earphone at a minimum of 10 dB sensation level based on aided audiometric results. An fMRI paradigm consisting of Narrow Band Noise (NBN) and stories was administered under sedation at the end of a clinical scan in a 3 Tesla system using sound presentation levels of 10 dB sensation level based on audiometric results. Stimuli were interleaved with silence in a block-periodic counterbalanced fMRI design with 30-second on-off intervals. Results were subjected to a correlation analysis to search for a relationship between P1 characteristics and the number of activated fMRI pixels detected within specified regions of interest in the auditory cortex. In addition, a multiple regression analysis was conducted to assess the prediction of the P1 latency in our sample based on duration of hearing aid use and age at the time of the fitting. Results indicated that although fMRI activation patterns do not exhibit a predictive relationship with P1 latency (r(10) = .038, p = .456), the strength of the auditory BOLD response was inversely correlated with P1 amplitude (rS = -.85, p = .001), suggesting more localized regions of cortical responsivity in subjects with robust P1 waveforms. This finding was difficult to interpret in light of fMRI sedation effects, and may be a reflection of normal cortical maturational processes that are known to influence the anatomical generators of the P1 response. Group and individual maps of BOLD activation were markedly dissimilar from what has been observed in normal hearing subjects within the same age range (Smith, et al., 2008). In all subjects, common areas of BOLD activity outside of auditory regions included positive BOLD within the medial frontal gyrus and anterior cingulate cortex, and negative BOLD responses in the inferior frontal gyrus. Areas that were shown to possess a positive correlation with shifts in P1 latency included the left middle frontal gyrus and inferior frontal gyrus, the anterior cingulate, and bilaterally in insular and occipital areas. In order to verify and further characterize a possible inverse connection between neural and vascular activity in thalamocortical and primary auditory cortical regions, more information is needed regarding developmental effects auditory deprivation on P1 amplitude.
Robert Keith, PhD (Committee Chair)
David Brown, PhD (Committee Member)
Scott Holland, PhD (Committee Member)
Peter Scheifele, PhD (Committee Member)
164 p.
Audiology
congenital sensorineural hearing loss; cochlear implants; fMRI; auditory evoked potentials; auditory plasticity

Recommended Citations

Citations

  • Cahill, L. D. (2010). Cortical responses to speech stimuli in hearing impaired infants measured by fMRI and auditory evoked potentials [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1273174165

    APA Style (7th edition)

  • Cahill, Lisa. Cortical responses to speech stimuli in hearing impaired infants measured by fMRI and auditory evoked potentials. 2010. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1273174165.

    MLA Style (8th edition)

  • Cahill, Lisa. "Cortical responses to speech stimuli in hearing impaired infants measured by fMRI and auditory evoked potentials." Doctoral dissertation, University of Cincinnati, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1273174165

    Chicago Manual of Style (17th edition)

ucin1273174165
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This open access ETD is published by University of Cincinnati and OhioLINK.