The overall purpose of this proposal is to explore relationships between the reception of spoken language and the functional neuroanatomy of brain responses to speech listening by combining traditional measures of speech perception with state-of-the-art brain imaging with Single Photon Emission Computed Tomography (SPECT). Studies included in this proposal aim to identify cortical regions that subserve or participate in the reception of spoken language. The biological bases of spoken language reception will be explored by investigating regional cerebral blood flow (rCBF) in individuals with normal hearing and individuals who experience difficulty with the reception of spoken language because of varying degrees of hearing impairments. Several key questions will be addressed including: 1) what brain regions are activated in individuals with normal hearing and language reception versus individuals who experience difficulty with language reception because of hearing impairments, and 2) how do abnormalities in cortical activation responses related to clinical measures of audiometric performance , auditory evoked potentials, speech perception performance, communication difficulty indices, and lipreading capability, as well as to demographic variables such as age of hearing loss onset, etiology, and type of hearing loss intervention.
The specific aims are to: 1) document cerebral neural circuitry activated during spoken language reception in individuals with normal hearing in response to normal or acoustically manipulated signals, 2) determine if rCBF responses to speech stimuli are blunted in magnitude and/or altered in neuroanatomic distribution in individuals with varying degrees of hearing impairments, 3) examine if abnormal rCBF responses occur even when auditory evoked responses are intact, 4) characterize relationships between clinical measures of speech perception and rCBF responses, and 5) explore how demographic variables relate to rCBF changes. RCBF will be measured under three tasks: Full audio (presented either binaurally or monoaurally), degraded audio (incorporating manipulations to the spectral and temporal and content of the signals), and visual only presentations. Data from these studies will address several key areas in the NIDCD Strategic Plan including the development and application of """"""""novel techniques, e.g., functional imaging to assess structural and functional plasticity"""""""" and the NIH Consensus Development Conferences on Cochlear Implants in Adults and Children which called for """"""""new tools, such as functional brain imaging, to be applied to unexplored variables such as the ability of the implant to activate the central auditory system.""""""""
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