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Differential involvement of prefrontal cortex in the processing of case agreement attraction in Russian: an fMRI study
Grammatical agreement often becomes the subject of experimen- tal studies: this is one of basic linguistic operations that exhibits interesting cross-linguistic similarities and differences and allows exploring how linguistic dependencies are established and how different features (number, gender, person etc.) are represented and manipulated in the mental grammar. However, most experiments use behavioral methods so far, a number of studies relies on EEG, and neuroimaging experiments are still very infrequent. They revealed a number of facts regarding different functional roles played by the brain areas comprising the frontotemporal language processing brain system: their involvement in semantic or syntactic analysis, in person and number agreement error detection etc.
Nineteen healthy right-handed subjects (23±4 years old) partici- pated in the current fMRI study aimed to extend these findings focusing on adjective-noun agreement, which has not been studied before, and on a novel feature: case. Russian has six cases, and adjectives agree with nouns in case, as well as in number and gender (in singular). Grammatically correct sentences as well as sentences with two types of agreement errors were compared: involving or not involving agreement attraction (attraction in subject-predicate number and gender agreement has been extensively studied using behavioral methods and EEG, but not using fMRI). All adjective-noun pairs were introduced by prepositions that unambiguously indicated which case should be used.
We found that the left inferior frontal gyrus (LIFG, BA 45/47) and the supplementary motor area were involved in error processing in all conditions (with or without attraction). At the same time, the relative
decrease in local activity within the left middle frontal gyrus (LMFG, BA 10) was demonstrated for the sentences with attraction errors. The revealed differential involvement of the LIFG and LMFG in the processing of agreement errors supports the domain general role of the LIFG and the language-specific involvement of the LMFG sensitive to morphological features of the form-to-meaning mapping process.