Investigation of noun-verb dissociation based on EEG source reconstruction

To clarify whether grammatical category or semantic meaning is the underlying determinant of noun-verb dissociation in the brain topography, this study recorded 128-channel electroencephalographic (EEG) signals from the scalps of 22 subjects when they listened to auditory (i) unambiguous nouns (UN), (ii) unambiguous verbs (UV), (iv) noun-biased ambiguous words (AN) and (v) verb-biased ambiguous words (AV). Then the current density source reconstruction algorithm with a standardized low-resolution electromagnetic tomography constraint was applied to the EEG signals to uncover the brain dynamics during the word processing. In our results, the noun-verb dissociation appeared in the periods of 150–250 ms and 380–450 ms, during which activation differences in the visual occipital cortex and motor frontal cortex were observed in both UN-UV and AN-AV contrasts. The results suggest that semantic differences might lead to the noun-verb dissociation.