ERPs and contextual semantic discrimination hypothesis: N400 deficits of different degrees of congruency in probands and first degrees relatives from multiplex schizophrenia families

AGUSTÍN IBÁÑEZ; MARTÍN REYES MIGDYRAI; RIVEROS RODRIGO; ESTEBAN HURTADO; VIVIANA VERGARA; FACUNDO MANES

Chicago

Encuentro; 39th Annual Meeting of the Society for Neuroscience; 2009

Society for Neuroscience

Endophenotypes is one emerging strategy in schizophrenia research that is being used to identify the functional importance of genetically transmitted, brain-based deficits present in this disease. Currently, event-related potentials (ERPs) are timely used in this search. Recently, we report the first evidence of N400 deficits (significantly reduced N400 amplitude for congruent categories) in probands and first degree relatives in a picture semantic-matching task suggesting a probable contextual semantic deficit [Guerra, S, Ibañez, A, Bobes, A., Martin, M et al. (In press). Brain and Cognition, 10.1016/j.bandc.2009.02.004]. In order to directly test the hypothesis of contextual semantics deficits as a probable endophenotype, unaffected first-degree relatives of patients, DSM-IV diagnosed schizophrenia probands, and control subjects, matched by age, gender and educational level performed an contextual task with four degrees of contextual congruency, previously reported by our team [Ibáñez, A., Lopez, V., Cornejo, C. (2006). Brain and Language, 98, (3), 264-275.]. Results support the idea of N400 contextual deficits in semantic integration as possible endophenotype candidate: Compared to control, N400 from relatives only discriminate congruent of incongruent target, but not partially contextual incongruent targets. Compared to controls and relatives, N400 from probands failed to discriminate partially and totally incongruent categories from congruent trials. These results demonstrate an electrophysiological deficit in contextual semantic discrimination in clinically unaffected first degree relatives and probands with schizophrenia from multiplex families, confirming a possible use of this marker as endophenotype.