Impulsivity and semantic/emotional processing: an examination of the N400 wave.

OBJECTIVE The study investigated (a) to what extent semantic/emotional processing modulates the N400 wave of the event-related potentials (ERPs) during reading, (b) the influence of impulsivity trait on neurocognitive systems underlying semantic/emotional processing related to the generation of the N400 wave. METHODS A canonical semantic sentence processing paradigm, known to selectively elicit the N400 wave was used. The ERPs were elicited to emotionally valenced (neutral, positive and negative) sentence final words that were either semantically congruent or semantically incongruent with the previous sentence context. RESULTS Congruent negatively valenced words produced longer reaction times (RTs) than congruent positive and neutral words. Incongruent words elicited more pronounced N400 peak amplitudes than congruent ones, while, for the congruent trials, the N400 amplitude was greater for negative words as compared to positive and neutral words. High impulsive participants, compared to low impulsive ones, (a) made more errors and longer reaction times in identifying incongruent words, (b) displayed more pronounced N400 peak amplitudes over fronto-central midline scalp sites. CONCLUSIONS This pattern of results indicated that the activity of fronto-central system may account for individual differences of impulsivity with high impulsive individuals showing more difficulty in integrating incongruent final words into a sentence context. SIGNIFICANCE Results open up new perspectives for future investigations on language disorders characterized by substantial impulsivity.