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Poster D75, Thursday, November 9, 6:15 – 7:30 pm, Harborview and Loch Raven Ballrooms

Brain lesion associated with impaired sensorimotor processing of speech auditory feedback in aphasia

Roozbeh Behroozmand1, Lorelei Phillip2, Karim Johari1, Leonardo Bonilha3, Chris Rorden4, Gregory Hickok5, Julius Fridriksson2;1Speech Neuroscience Lab, Department of Communication Sciences and Disorders, University of South Carolina, 1224 Sumter Street, Columbia, SC 29201, USA, 2The Aphasia Lab, Department of Communication Sciences and Disorders, University of South Carolina, 915 Greene St., Columbia, SC 29208, USA, 3Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA, 4Department of Psychology, University of South Carolina, Columbia, SC 29208, USA, 5Department of Cognitive Sciences, University of California, Irvine, Irvine CA 92697, USA

The present study sought to illuminate the brain network involved in speech sensorimotor processing by studying patients with post-stroke aphasia using the altered auditory feedback (AAF) paradigm. We utilized the combination of neuroimaging-based lesion-symptom-mapping analysis and behavioral testing to examine the pervasiveness of speech sensorimotor deficit and its relationship to the brain regions implicated. We recruited 16 patients with aphasia and 16 age-matched healthy control subjects to complete a speech task under AAF. The task involved producing a steady vowel sound while listening to the pitch-shifted real-time feedback of their speech. The implementation of this task allowed us to develop an objective biomarker of speech sensorimotor impairment by measuring the degree to which each subject behaviorally responded to AAF stimuli to compensate for errors in their speech auditory feedback signal. Results indicated that compensatory speech responses to AAF were significantly diminished in patients with aphasia compared with the control group (F(1,30) = 16.02, p < 0.001). The correlation analysis revealed a strong and direct relationship (r = 0.6, p = 0.015) between AAF responses and speech repetition ability, as indexed by the Western Aphasia Battery (WAB) scores. A region-of-interest lesion-symptom-mapping analysis revealed that the early phase (50-150 ms) of diminished AAF responses in aphasia were correlated with damage to auditory cortical regions within the superior and middle temporal gyrus, whereas the middle (150-250 ms) and late (250-350 ms) phases of diminished AAF responses were correlated with damage to the inferior frontal gyrus and supramarginal gyrus areas, respectively. These findings suggest that damage to the auditory, motor and auditory-motor integration networks are associated with impaired sensorimotor function for speech error processing in patients with aphasia. In addition, based on the results of the correlation analysis, we argue that specific aspects of language impairment (i.e. speech repetition deficit) are accounted for by dysfunctions of the speech sensorimotor integration network as revealed by diminished responses to AAF. These findings provide new insights into the connection between pathologically-diminished integrative function underlying speech auditory feedback processing and the implicated brain lesions associated with language deficits in patients with post-stroke aphasia.

Topic Area: Speech Motor Control and Sensorimotor Integration

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