Brain response to subject-verb agreement during grammatical priming.

In this study, we explored cerebral mechanisms during the computation of subject-verb agreement by measuring event-related potentials after French verb and pseudoverb targets preceded by various contexts. In auditory grammatical priming, the targets were either related to a congruent predictive pronoun prime (nous prêtons we lend) or an incongruent predictive pronoun prime (vous prêtons you lend) or a nonpredictive prime (zous prêtons zous lend). Whereas an early anterior negativity (LAN) and a parietal positivity were modulated by the preceding context for verb targets, only the early negativity was sensitive to the context for pseudoverb targets. Interestingly, for verbs, the LAN response was larger at left frontocentral sites around 100ms after the onset of the recognition point of verbal inflection in the incongruent predictive condition relative to two other conditions. This finding was in line with the behavioral results, suggesting that top-down processes of the computation of the subject-verb agreement occur. Moreover, at 160-210ms after the onset of the recognition point of verbal inflection, the parietal positivity was smaller in amplitude at left centroparietal sites for the incongruent predictive and nonpredictive conditions. This was interpreted as reflecting bottom-up processes of the computation of the subject-verb agreement. All findings thus suggest that top-down and bottom-up processes of the computation of the subject-verb agreement occur with distinctive temporal properties.