The Level of Passive Voice Comprehension in the 4–5 Years Old Russian Children Reflects in the ERP’s

The passive voice acquisition and thematic-role assignment is the key point in the process of complex grammar comprehension. The same semantic situation can be expressed in Russian using different grammatical instruments, the mastering of which continues throughout preschool age and depends on their frequency in the language. Brain mechanisms of passive voice processing in 4–5 years old children are poorly understood. In our study, 46 4–5-years-old children with normal speech development and 26 adults performed sentence-picture matching tasks (active/passive voice) during EEG recording using 3-words sentences (NP1-V-NP2). According to the results of the thematic roles assignment in the passive voice direct word order sentences, two subgroups of children were formed: high (> 80% of correct answers, n = 17) and low (< 60%, n = 19) comprehension levels. Between groups, differences were revealed in the event-related potentials (ERPs) on the 3d word comprehension (NP2), as well as in verbal memory and the phonological awareness and lexical competence. The ERPs were obtained for frontocentral, left and right temporoparietal regions of interest (ROI) for each word in a sentence separately. In both adults and children, cerebral sensitivity to syntactical markers of grammar voice (inflection) was shown: a greater amplitude in the passive vs active voice. In adults and children with high levels of passive voice comprehension, this sensitivity was found in all ROIs, while in children with low comprehension level, there was no sensitivity in the left temporoparietal areas. Children with high comprehension level showed positivity at 200–600 ms, with the beginning in frontocentral areas spreading to the temporoparietal areas bilaterally, while children with low comprehension level showed significantly fewer differences. The sensitivity of the frontocentral and temporoparietal cortical areas bilaterally, especially the left hemisphere, to the grammatical markers of the voice could be the brain mechanism that ensures effective comprehension of complex grammar in children as early as 4–5 years of age.