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Using EEG to Examine Action Semantics in Primary Progressive Aphasia
Poster Session A - Sandbox Series, Thursday, October 24, 10:00 - 11:30 am, Great Hall 3 and 4
This poster is part of the Sandbox Series.
Amy Lebkuecher1,2, Laurel Buxbaum2, Chia-Lin Lee3, Kristen Li1, Branch Coslett1; 1Laboratory for Cognition and Neural Stimulation, University of Pennsylvania, Philadelphia, PA, USA, 2Cognition and Action Laboratory, Moss Rehabilitation Research Institute, Philadelphia, PA, USA, 3Graduate Institute of Linguistics, Department of Psychology, Graduate Institute of Brain and Mind Sciences, and Neurobiology and Cognitive Neuroscience Center National Taiwan University, Taipei, Taiwan
The current study uses EEG to explore the role of action semantics in the comprehension of nouns and verbs in Primary Progressive Aphasia (PPA). PPA refers to a group of neurodegenerative diseases characterized by frank language deficits early in disease progression (Gorno-Tempini et al., 2011). Sensorimotor disruption has been proposed to explain action-related language deficits observed in other neurodegenerative disorders such as Parkinson’s Disease (see Bak, 2013 for a review), but there is little research examining action semantics in PPA. For the purposes of the current project, action semantics is defined as semantic information about actions (e.g., manual gestures) that is accessible to language and during the execution, observation, and mental simulation of actions. Specifically, this project focuses on whether there is neurophysiological and behavioral evidence that the observation of gestures facilitates language comprehension in at least some individuals with PPA. Meaningful gestures facilitate language comprehension in neurotypical individuals (Gunter, Weinbrenner, & Holle, 2015; Kelly, Özyürek, & Maris, 2010; Wu & Coulson, 2007), but this facilitation has not yet been assessed in PPA. There is an on-going theoretical debate surrounding the extent to which gesture and language access a common repository of semantic representations or separate stores of semantic knowledge (e.g., Leshinskaya & Caramazza, 2016). Studying the connection between gesture and language comprehension in PPA will further inform this debate. Our experiment uses an event-related paradigm to investigate whether observing a related manual gesture facilitates the comprehension of an auditorily presented noun or verb across 10 individuals with PPA as well as 10 age-matched neurotypical controls. To examine whether sensorimotor disruption affects this facilitation in PPA, we are evaluating event-related desynchronization of the β oscillation and µ rhythm as indicators of sensorimotor aspects of action semantics (e.g., Schaller et al., 2017). If the sensorimotor aspect of action semantics is intact, we expect to observe greater event-related desynchronization of the β oscillation or µ rhythm in response to a matching gestural prime and target word. If this desynchronization is reduced or absent, then this would suggest sensorimotor disruption may contribute to any observed action semantics deficits in PPA. We examine the N400 as an index of semantic priming across gesture and target word, as well as how this effect relates to behavioral evidence for priming (e.g., faster response time to matching gestural primes and target words). Individuals with impaired comprehension should exhibit a reduced response time benefit for trials where a matching gesture precedes the target word and a reduced or absent N400 effect in response to mismatches. Here we present preliminary findings for the project as data collection is still in progress.
Topic Areas: Meaning: Lexical Semantics, Disorders: Acquired