Redes neurales de la atencion en pacientes con esquizofrenia y sus familiares no afectados de primer grado: un endofenotipo potencial / Attentional network task in schizophrenic patients and theirs unaffected first degree relatives: a potential endofenotype

Introducción. Existe un notable incremento de reportes sobre déficit atencionales en pacientes con esquizofrenia y sus familiares de primer grado, incluyendo un gran esfuerzo por la búsqueda de endofenotipos para llegar a genes específicos responsables de la enfermedad. Posner y col. Desarrollaron una prueba para explorar las redes neurales de la atención (ANT). Esta provee mediciones por separado para cada una de las tres redes neurales anatómicamente definidas(alerta, orientación y control ejecutivo).Metodología: Investigamos a través de un estudio de asociación familiar el desempeño atencional en 32 pacientes con esquizofrenia, 29 familiares sanos y 29 controles utilizando el ANT. Examinamos segregadamente la eficiencia para las redes del control ejecutivo, la alerta y la orientación, evaluando como los tiempos de reacción eran modificados por la posición de la señal orientadora (“cue”) y la congruencia contextual del estímulo (“flanker”). También exploramos la asociación familiar de estas alteraciones atencionales. Resultados: Un ANOVA reveló un efecto principal del “flanker” y la condición del “cue” y una interacción significativa entre el “flanker” y los grupos estudiados. Los pacientes con esquizofrenia y sus familiares tienen un tiempo de reacción medio superior al grupo control. Los probandos y sus familiares difieren significativamente del grupo control en términos de resolución de conflictos, sin embargo, la alerta aparece conservada. Conclusiones: Nuestros resultados apoyan la tesis de un déficit atencional específico en la esquizofrenia y evidencian la segregación de las tres redes neuro-atencionales. La asociación familiar de estas alteraciones soporta la idea de un endofenotipo potencial en la esquizofrenia (AU)

Introduction. In recent years, reports of attention deficits in schizophrenic patients and in their biological relatives have rapidly increased, including an important effort to search for the endophenotypes in order to link specific genes to this illness. Posner et al. developed a test, the Attention Network Test (ANT), to study the neural networks. This test provides a separate measure for each one of the three anatomically-defined attention networks (alerting, orienting and executive control). Methodology. In this paper, we investigate the attentional performance in 32 schizophrenic patients, 29 unaffected first degree relatives and 29 healthy controls using the ANT through a study of family association. We have studied the efficiency of the segregated executive control, alerting and orienting networks by measuring how response latencies (reaction time) were modified by the cue position and the flanking stimuli. We also studied the familial association of these attentional alterations. Results. The ANOVA revealed main effects of flanker and cue condition and a significant interaction effect between flanker and groups studied. The schizophrenic patients and their relatives had a longer median reaction time than the control group. The probands and their relatives significantly differed from the healthy controls in terms of their conflict resolution; however, the alerting network appeared to be conserved. Conclusions. Our results support the thesis of a specific attentional deficit in schizophrenia and show the segregation of the three attentional networks. The family association of these reported alterations supports the idea of a potential endophenotype in schizophrenia (AU)

Searching for face-specific long latency ERPs: a topographic study of effects associated with mismatching features.

In a previous study [E. Olivares, M.A. Bobes, E. Aubert, M. Valdés-Sosa, Associative ERPs effects with memories of artificial faces, Cogn. Brain Res. 2 (1994) 39-48] we reported the presence of a negativity associated with mismatching features when subjects carried out a face-feature matching task whilst their evoked potentials were recorded. Since the stimuli used were learned faces (realistic drawings), for which the subjects possessed no semantic information or associated verbal labels, the mismatch negativity obtained was considered a face-specific N400. In this work we present a new experiment to study the topographic distribution of these mismatch effects. As in the above-mentioned study, in each trial the subjects observed previously an incomplete (without the eyes/eyebrows fragment) familiar face, which served as a structural context for the face recognition. The face was then completed by grafting either matching (learned) features or mismatching features (from another face). In line with neuropsychological studies on prosopagnosia and electrophysiological findings in humans and non-human primates, we found as one of the most relevant items of data that the most-posterior (principally, left occipital) cortices appear to be a region in which are located the possible neural generators of the negativity associated with the detection of incongruencies in the structure of familiar faces. We also reported a late positivity, distributed in more anterior regions, which follows the mismatch negativity. This complex N-P is interpreted as reflecting a dual process of retrieval and integration of information in memory.