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The way our brain processes personal familiarity is still debatable. We used searchlight multivoxel pattern analysis (MVPA) to identify areas where local fMRI patterns could contribute to familiarity detection for both faces and name categories. Significantly, we identified cortical areas in frontal, temporal, cingulate, and insular areas, where it is possible to accurately cross-classify familiar stimuli from one category using a classifier trained with the stimulus from the other (i.e., abstract familiarity) based on local fMRI patterns. We also discovered several areas in the fusiform gyrus, frontal, and temporal regions-primarily lateralized to the right hemisphere-supporting the classification of familiar faces but failing to do so for names. Also, responses to familiar names (compared to unfamiliar names) consistently showed less activation strength than responses to familiar faces (compared to unfamiliar faces). The results evinced a set of abstract familiarity areas (independent of the stimulus type) and regions specifically related only to face familiarity, contributing to recognizing familiar individuals.
RESUMO
INTRODUCTION: N200 and P300 event-related evoked potentials provide sensitive measurements of sensory and cognitive function and have been used to study information processing in patients with schizophrenia and their unaffected first-degree relatives. Reduced amplitude and increased latency of N200 and P300 potentials have been consistently reported in schizophrenia. Thus, event-related evoked potentials abnormalities are promising possible biological markers for genetic vulnerability to schizophrenia. OBJECTIVE: To assess the association of changes in latency, amplitude and topographic distribution of potentials N200 and P300 of patients with paranoid schizophrenia and their healthy first-degree relatives, in families with schizophrenia multiplex. METHODOLOGY: We measured latency and amplitude of the N200 and P300 component of evoked potentials using an auditory odd-ball paradigm in 25 schizophrenic patients (probands) from 60 families multiply affected with paranoid schizophrenia, 23 of their non-schizophrenic first-degree relatives and 25 unrelated healthy controls, through a study of family association. RESULTS: Schizophrenic patients and their relatives showed significant latency prolongation and amplitude reduction of the N200 and P300 waves compared to controls. Left-temporal as compared to right-temporal N200 and P300 were significantly smaller in schizophrenic patients and their non-schizophrenic first-degree relatives than in controls. Our results suggest that event-related evoked potentials abnormalities may serve as markers of genetic vulnerability in schizophrenia. CONCLUSIONS: Confirming results of other researchers, this present study suggests that latency prolongation and amplitude reduction of the N200 and P300 waves and an altered topography at temporal sites may be a trait marker of paranoid schizophrenia.
INTRODUCCIÓN: Los potenciales relacionados a eventos N200 y P300 son herramientas sensibles para evaluar el funcionamiento sensorial y cognitivo. Debido a que, frecuentemente se reporta una prolongación de la latencia y una disminución de la amplitud de los componentes N200 y P300 en pacientes con esquizofrenia, estos potenciales constituyen marcadores biológicos de vulnerabilidad genética para este trastorno mental. OBJETIVO: Precisar la asociación de las alteraciones en la latencia, la amplitud y la distribución topográfica de los potenciales N200 y P300 de pacientes con esquizofrenia paranoide y sus familiares sanos de primer grado, pertenecientes a familias con esquizofrenia multiplex. MÉTODOS: Se utilizó un paradigma odd-ball auditivo para evaluar la latencia, la amplitud y la distribución topográfica de los componentes N200 y P300 en 25 pacientes con esquizofrenia paranoide (probandos), 23 familiares sanos de primer grado y 25 sujetos controles, mediante un estudio de asociación familiar en 60 familias afectadas con esquizofrenia multiplex. RESULTADOS: Los probandos y sus familiares mostraron una prolongación significativa de la latencia y una disminución de amplitud de las ondas N200 y P300 cuando se compararon con los sujetos sanos. De igual forma, la amplitud de los potenciales N200 y P300 resultó significativamente disminuida en regiones temporales del hemisferio izquierdo de los probandos y sus familiares con respecto al grupo control. CONCLUSIONES: En concordancia con resultados de otros investigadores, este estudio sugiere que, la prolongación de latencia, la disminución de amplitud y las alteraciones en la distribución topográficas detectadas en regiones temporales de los potenciales N200 y P300, pueden constituir por su elevada asociación familiar, marcadores de rasgo para la esquizofrenia paranoide.
