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Poster B14, Wednesday, November 8, 3:00 – 4:15 pm, Harborview and Loch Raven Ballrooms

Neural correlates of processing case and inflection: fMRI evidence from Russian

Anna Chrabaszcz1, Maxim Kireev2, Svyatoslav Medvedev2, Kira Gor3;1University of Pittsburgh, 2N. P. Bechtereva Institute of the Human Brain, 3University of Maryland

The mechanisms underlying processing of morphologically complex words are still a matter of debate. According to the whole-word storage view, inflected words are stored and retrieved from memory as whole units (Butterworth, 1983). Conversely, the decompositional account claims that inflected words are decomposed into constituent morphemes and are computed using combinatorial mechanisms (Fruchter & Marantz, 2015; Taft, 2004). However, when it comes to processing inflected nouns, very often it is not easy to isolate decompositional processes because case and inflection are often confounded. E.g., in a study by Szlachta et al. (2012) nouns with zero inflection had the form of the Nominative case, while nouns with overt inflection were used in the oblique case. The goal of the present study is to differentiate neural correlates associated with processing of case (Nominative vs. Genitive) and inflection (zero vs. overt -a) using inflected nouns in Russian—a language with rich morphology (e.g., -a.NOM/-a.GEN/-ø.NOM/-ø.GEN). The effect of case is taken as evidence of the role of case hierarchy in the nominal inflectional paradigm (Nominative > Genitive). The effect of inflection is taken as evidence of morphological decomposition, or affix stripping. Eighteen monolingual adult Russian speakers (mean age = 25, male = 12) performed a visual lexical decision task adapted from Gor et al. (2017) while their BOLD signal was recorded (Philips 3T Achieva, event-related design). Stimuli consisted of 280 Russian nouns broken down into four critical conditions and counterbalanced between two presentation lists. Additional 70 words were added as fillers. Nonce words were added to each list to counterbalance the number of real words. Analysis of error rate and reaction time indicated that nouns in the Nominative case were processed faster and more accurately compared to nouns in the Genitive case regardless of the type of inflection, although within the Nominative case, nouns with zero inflection were processed faster than nouns with overt inflection. Whole-brain analyses of the changes in the BOLD signal established an increased activation for overtly compared to zero-inflected nouns in several brain areas including left inferior frontal gyrus, and—bilaterally—supplementary motor area, pre- and postcentral gyri, fusiform gyrus, and cerebellum. These results provide evidence in favor of the decompositional account in morphological processing – more resources are needed to decompose the noun into a stem and an affix. In terms of case effects, an increased BOLD signal was revealed for nouns in the Genitive case compared to Nominative case in the clusters located in the left postcentral gyrus and left insula, right MTG and STG, right fusiform gyrus, and supramarginal gyrus bilaterally. These data suggest that accessing the Genitive form within the nominal paradigm in the mental lexicon is more effortful compared to the retrieval of the Nominative form. Combined with behavioral results, the study supports morphological decomposition of inflected nouns and the special status of the citation—Nominative—form in visual word recognition by differentiating the neural correlates involved in the processing of case and inflection.

Topic Area: Grammar: Morphology

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