Cross-modal symbolic processing can elicit either an N2 or a protracted N2/N400 response.

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Cross-modal symbolic processing can elicit either an N2 or a protracted N2/N400 response.

Psychophysiology. 2016 Jul;53(7):1044-53

Authors: Griffiths O, Le Pelley ME, Jack BN, Luque D, Whitford TJ

Abstract
A cross-modal symbolic paradigm was used to elicit EEG activity related to semantic incongruence. Twenty-five undergraduate students viewed pairings of visual lexical cues (e.g., DOG) with congruent (50% of trials) or incongruent (50%) auditory nonlexical stimuli (animal vocalizations; e.g., sound of a dog woofing or a cat meowing). In one condition, many different pairs of congruent/incongruent stimuli were shown, whereas in a second condition only two pairs of stimuli were repeatedly shown. A typical N400-like pattern of incongruence-related activity (including activity in the N2 time window) was evident in the condition using many stimuli, whereas the incongruence-related activity in the two-stimuli condition was confined to differential N2-like activity. A supplementary analysis excluded stimulus characteristics as the source of this differential activity between conditions. We found that a single individual performing a fixed task can demonstrate either a protracted N400-like pattern of activity or a more temporally focused N2-like pattern of activity in response to the same stimulus, which suggests that the N2 may be a precursor to the protracted N400 response.

PMID: 27006093 [PubMed - indexed for MEDLINE]

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