Search Abstracts | Symposia | Slide Sessions | Poster Sessions
Mu and Beta oscillatory correlates of action-related perception and language processing.
Poster Session F, Friday, October 2, 2:45 - 4:45 pm, Wangari Maathai
Jessica White1, Fiadhnait O'Keeffe2, Patricia Gough1,3, Klaus Kessler1; 1University College Dublin, 2University College Cork, 3National College of Ireland
Action execution, action observation, graspable objects and their linguistic counterparts have all been proposed to engage sensorimotor systems (Fox et al., 2015; Lewis et al., 2006; Moreno et al., 2013). The present study examined whether action-related visual and linguistic stimuli elicit modulate motor-related oscillations within the mu and beta frequency bands. Participants underwent EEG recording while completing four experimental conditions involving action execution, action observation, object perception and word perception. Conditions included: (1) hand-action videos compared with natural scene motion and moving dots; (2) hand-action verbs (e.g., grasp) compared with abstract verbs (e.g., think); (3) graspable objects (e.g., hammer) compared with non-graspable objects (e.g., cloud); (4) graspable nouns (e.g., pencil) compared with non-graspable nouns (e.g., planet or idea). Participants performed overt hand movements during action execution, while all other conditions involved passive viewing. Oscillatory activity was examined within lower mu (8-10hz), higher mu (10-15hz), lower beta (15-20hz) and higher beta (20-25hz) frequency bands. Two complementary analyses were conducted. First, non-parametric cluster-based permutation tests (Oostenveld et al., 2011) were conducted as a data driven approach across the whole scalp to detect spatiotemporal effects. Second, a targeted region of interest (ROI) analysis, informed by prior research (Fox et al., 2015; Moreno et al., 2013), was used to examine mean oscillatory power at predefined left (C1, C3, FC3, CP3) and right (C2, C4, FC4, CP4) sensorimotor electrodes. Preliminary analyses revealed expected desynchronisation effects during both execution and observation, evident in both analyses. However, cluster-based analyses indicated widespread desynchronisation extending beyond sensorimotor regions. No significant effects were identified for graspable compared with non-graspable object imges. While ROI analyses of linguistic stimuli revealed no significant effects, cluster-based permutation tests identified greater desynchronisation for action-related words within parietal, posterior and central electrode clusters. Action-related verbs elicited significant effects in both beta bands, whereas graspable nouns showed effects exclusively in the lower mu band. The absence of significant ROI effects alongside significant cluster-based effects suggests that action-related language processing may recruit distributed networks extending beyond traditional sensorimotor regions (Barsalou, 2008; Gallese & Lakoff, 2005). This pattern is consistent with accounts proposing that embodied semantic processing involves large-scale sensorimotor integration rather than focal motor cortex activation alone. Parietal and posterior desynchronisation may reflect visuomotor imagery and action representation processes associated with action perception (Binkofki & Buccino, 2018; Urgen et al., 2019) and tool-related semantics (Binkofki & Buccino, 2018; Ishibashi et al., 2016). Beta-band desynchronisation for action verbs may reflect covert motor simulation (Moreno et al., 2013), whereas lower mu effects for graspable nouns may indicate indirect activation of motor representations through object affordances or manipulation knowledge (Bechtold et al., 2018; Martin 2007). The absence of effects for graspable objects alongside significant effects for graspable nouns might suggest that motor-related oscillatory modulation may depend more strongly on semantic-conceptual processing than on passive visual affordance perception alone (Bechtold et al., 2018). The relatively subtle and spatially distributed effects for linguistic stimuli suggest that motor-system involvement in language processing may be graded, context-dependent, and less robust than action execution or observation.
Topic Areas: Meaning: Lexical Semantics,