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Detecting Narrative Language Deficits in Aphasia Using Continuous EEG During Speech Production
Poster Session D, Saturday, September 13, 5:00 - 6:30 pm, Field House
This poster is part of the Sandbox Series.
Willem van Boxtel1, Ally Miller1; 1Louisiana State University
Background: Assessing narrative deficits in stroke-induced aphasia is a laborious and time-consuming process. Developing objective, efficient assessments for narrative speech in aphasia therefore remains a highly relevant objective. Recent studies have leveraged continuous electroencephalography (EEG) recordings during speech comprehension to assess the presence and severity of narrative deficits, but this has not been applied to speech production. Given that some persons with aphasia (PWA) may demonstrate impaired production, but preserved comprehension, or vice versa, determining the neurophysiological correlates of speech production in PWA is highly warranted. This study aims to (1) determine whether continuous EEG recordings during spontaneous speech production can detect the presence of aphasia, and (2) to evaluate whether behavioral narrative speech metrics correlate with neuroelectrical activity patterns in PWA. Specifically, we hypothesize that theta and delta band activity may be less powerful in PWA compared to controls, and may be related to narrative speech characteristics. Methods: Data collection is ongoing. Final samples will comprise a group of PWA exhibiting varying narrative speech deficits, and a group of age-matched neurotypical controls. Participants are first asked to sit with eyes closed, then with eyes open, for five minutes each, to establish resting-state EEG activity. They then take part in an expressive language task, including open questions (e.g., “Tell me about your stroke”), and a variety of widely used picture prompts (including pictures from the Western Aphasia Battery, Boston Diagnostic Aphasia Examination, and a Cinderella story). Participants must produce at least 10 minutes of speech to ensure sufficient data generation. During speech production, EEG signals are recorded using 64 scalp electrodes, and these continuous signals are assessed for oscillatory power in each of six activity bands identified in previous research (alpha, beta, low gamma, high gamma, delta, theta; ~1-100 Hz). Narrative quality metrics (mean length of utterances [MLU], words per minute [WPM] and correct information units [CIU]) are extracted from participants’ language samples to compare complexity of narratives to the strength of oscillations in each band. Results: Preliminary findings from two neurotypical controls highlight the roles of the Delta (1-4Hz) band: power in this band was significantly higher during speech production than during resting-state EEG (F(5) = 3.273, p < .01; Tukey’s adjusted post-hoc, speech v. resting, p <.001). In addition, visual indications for differences in the theta (4-8Hz) and low gamma (30-70Hz) bands were present, though these were not statistically reliable with the current dataset. Given that both participants were neurotypical controls, no correlational analyses between measures of narrative ability and EEG power have been made thus far. Preliminary Conclusions: Continuous EEG detected differences between narrative and resting-state activity in neurotypical pilots, suggesting this method is sensitive to language production. While the delta band has been comparatively under-highlighted in behavioral and cognitive research, some previous literature has emphasized the role of this band in semantic tasks and inhibitory control. This paradigm is therefore highly promising for application to the assessment of speech and narrative deficits. Ongoing data collection including PWA and age-matched controls will elucidate this further.
Topic Areas: Disorders: Acquired, Language Production