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Poster E39, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Evidence for a causal link between left temporo-parietal alpha-beta desynchronisation and context-driven word production

Vitoria Piai1,2, Joost Rommers1, Robert Knight3;1Radboud University, Donders Institute for Brain, Cognition and Behaviour, 2Radboudumc, Department of Medical Psychology, 3University of California, Berkeley, Helen Wills Neuroscience Institute and Department of Psychology

Different frequency bands in the electroencephalogram have been postulated to support distinct language functions. For example, alpha- and beta-band power decreases during language production were initially linked to speech motor function. However, recent studies have suggested that alpha-beta power decreases may also index word-retrieval processes. In a paradigm designed to elicit context-driven word production, participants hear lead-in sentences that either constrain the final word of the sentence (“He locked the door with the”) or not (“She walked in here with the”). The last word is shown as a picture that has to be named. Previous studies have consistently found faster picture-naming response times (RTs) for constrained relative to unconstrained sentences (i.e., the context effect), suggesting that the picture name can be retrieved before picture presentation. In the electroencephalogram, the context effect is associated with left-lateralised alpha-beta power decreases pre-picture onset, suggesting that word retrieval may be associated with power decreases in those frequency bands. This oscillatory effect has been localised to the lateral temporal, inferior parietal, and lateral frontal lobes. However, the relative contribution of temporo-parietal versus frontal areas to the alpha-beta power decreases is unknown. We recorded the electroencephalogram from patients with stroke lesions to the left-lateral posterior cortex (N = 8) or left-lateral frontal lobe, including the inferior frontal gyrus (N = 5) and from matched controls (N = 13). Individual-participant analyses indicated a behavioural context effect in all participants, except for in the two patients with extensive lesions to the temporo-parietal cortex (P7 and P9). We replicated the alpha-beta power decreases pre-picture onset in the control group and in all patients, except for in P7 and P9. Hierarchical clustering analyses of the patients’ lesion profiles, and behavioural and oscillatory effects indicated that P7 and P9 had a unique combination of lesion distribution, and lack of behavioural and oscillatory context effects. These results provide evidence for a causal link between alpha-beta power decreases in the left temporal and inferior parietal lobes and context-driven word production.

Topic Area: Meaning: Lexical Semantics

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