A common N400 EEG component reflecting contextual integration irrespective of symbolic form

Objective Electroencephalographic (EEG) waves modulated by context have been identified about 400 ms after presentation of a new semantic stimulus, such as a word or a number, within a prior context. However, it is not known if any component of these waves arises from a common brain system activated by different symbolic forms. Methods Multichannel EEG recordings were performed in 10 healthy subjects during the presentation of lexical and numerical series with congruent and incongruent endings. EEG was analysed using a combination of independent component and cluster analysis. Results Contextual integration of semantic stimuli elicited a negative independent component at around 400 ms that shared the same pattern of spatio-temporal covariation across numerical series and sentences within single subjects. This independent component was bigger following incongruent endings. Conclusions These data provide evidence that one element of the activity contributing to the N400 is common to different symbolic forms. Significance One component of the brain systems evaluating the semantic inter-relationship of new stimuli with prior context may be common to different symbolic forms.