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Poster D38, Thursday, November 9, 6:15 – 7:30 pm, Harborview and Loch Raven Ballrooms

Quick and easy composition of event concepts in the left (but not the right) anterior temporal lobe

Songhee Kim1, Liina Pylkkänen1,2;1New York University, 2NYU Abu Dhabi Institute

While more and more evidence suggests that the neural representation of semantics is broadly distributed, involving many areas of at least the temporal, parietal, and frontal lobes (e.g. [1]), characterizing the precise computations carried out by this network remains a central challenge. One of the better understood nodes within this system is the left anterior temporal lobe (LATL), an integrative hub implicated for certain types of combinatory conceptual operations. Specifically, the LATL shows an early (200–250ms) amplitude increase for words in combinatory contexts if the semantic composition between the current word and its context is in some ways “simple,” involving no reference to a broader context [e.g., 2, 3]. In other words, the LATL appears to compute some type of “first-pass” conceptual combination, limited to simple, straightforwardly composable concepts. However, this type of effect has so far only been demonstrated for the composition of nouns and their modifiers. Here we asked whether a similar pattern is elicited for complex event concepts, as denoted by combinations of verbs and adverbs. Method: We measured participants’ (N = 21) MEG responses to adverb-verb combinations, in which the semantic type of the adverb varied. In the simplest case, so-called eventive adverbs, the adverb named a property of the event described by the verb: slowly paints describes a painting event that is slow. But in the other two cases, the adverb described a property of one of the arguments of the verb, which were not named in our two-word stimuli. So-called resultative adverbs described a resultant state of the object – vividly paints describes a painting event that results in a vivid picture – whereas agentive adverbs describe a property of the agent of the event, as in reluctantly paints (the painter is reluctant). A non-combinatory baseline was created by replacing the adverbs with a consonant string. If the LATL’s role is limited to simple, directly composable concepts in the verbal domain as well, only the eventive adverbs should elicit an LATL increase as compared to non-combinatory controls. Results: A cluster based permutation test (Maris & Oostenveld, 2007) on the time courses of the left BA 20, 21, and 38 revealed a reliable effect of adverb type in BA 38 at 278-291ms after the onset of the verb, driven by significantly increased activity in the eventive condition. Given prior evidence that the activity patterns of the right anterior temporal lobe may in fact positively correlate with complexity [2], we also tested the right homologues of these regions, finding increased activity for the agentive condition in right BA 21 and 38 at ~250-300ms. Conclusion: Our findings show clear evidence for “quick and easy” composition of verb phrases in the LATL and a sharply distinct effect in similarly timed right-lateral activity, suggesting a right hemisphere focus for more complex cases of conceptual combination. References: [1] Binder, J.R. Psychon Bull Rev (2016) 23: 1096. [2] Poortman, E.B., & Pylkkänen, L. Brain and language (2016) 160: 50-60. [3] Ziegler, J., & Pylkkänen, L. Neuropsychologia (2016) 89: 161-171.

Topic Area: Meaning: Combinatorial Semantics

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