TITLE:
Dissociation of the N400 component between linguistic and non-linguistic processing: A source analysis study
AUTHORS:
Anne Gallagher, Renée Béland, Phetsamone Vannasing, Maria Luisa Bringas, Pedro Valdes Sosa, Nelson J. Trujillo-Barreto, John Connolly, Maryse Lassonde
KEYWORDS:
Event-Related Potentials; Incongruity; Semantic; Environmental Sounds; Distributed Source Model; BMA
JOURNAL NAME:
World Journal of Neuroscience,
Vol.4 No.1,
January
20,
2014
ABSTRACT: The
N400 component is commonly associated with the detection of linguistic
incongruity. A few studies have shown that the N400 can also be elicited by non-linguistic
stimuli. Different spatiotemporal patterns were observed between the typical
Linguistic N400 and the Non-linguistic N400, suggesting distinct brain
generators. The aim of this study was to investigate the presence of an N400 in
response to linguistic and non-linguistic stimuli, and to specify anatomical
sources of both N400s using a novel analysis method: the Bayesian Model
Averaging (BMA) distributed source model.
Picture-word and environmental soundpicture associations, either
congruent or incongruent, were presented to
ten young healthy adults while highdensity ERP recordings were made.
Standard electrophysiological analyses confirmed that the N400 was not specific
to linguistic incongruity but was also elicited by environmental sound-picture
incongruities. Different topographic distributions were obtained for the
Linguistic N400 and Non-linguistic N400. BMA
analysis showed that the Linguistic N400 generators were mostly located in the
left superior temporal gyrus, whereas the sources of the Non-linguistic N400
were identified mostly in the right middle
and superior temporal gyri. Detection of linguistic incongruities recruited cerebral
areas commonly associated with language processing, whereas non-linguistic incongruities
recruited right cerebral regions usually associated with auditory processing of
non-linguistic stimuli. The Linguistic and Non-linguistic N400s appear to be
elicited by similar cognitive mechanisms assumed by different cerebral areas
depending on the type of material to be processed. The present findings support
the existence of parallel pathways for the processing of linguistic and non-linguistic
incongruities.