Brain electrophysiological responses associated with the retrieval of temporal and spatial contexts in episodic memory.

Episodic memory allows us to remember three main elements regarding an event: what (it is), where (it is in space), and when (it appears). The brain's electrical activity signaling the occurrence of these processes has been studied separately, revealing different patterns of ERP components and changes in the EEG theta band amplitude. However, how these patterns signal the retrieval of the temporal and spatial contexts of the same episode is unknown. The objective of this study was to evaluate the ERP components and the EEG theta band in association to the retrieval of the what, where, and when of the same episode through a source memory task. Three types of trials were identified here: total retrieval (what, where, and when), spatial retrieval (what and where), and correct rejections (correctly identified as new items). Attentional components, N200 and P300, and theta band were sensitive to the amount of information retrieved from episodic memory. Total retrieval and spatial trials elicited higher mean amplitude of FN400 and LPC, familiarity and recollection markers, respectively, than correct rejections. Our results suggest that early attention mechanisms can discern the strength of retrieval; in turn, familiarity and recollection mechanisms participate in the retrieval of the main contexts of episodic memory, but not in a cumulative way.

Funciones cognoscitivas y ejecutivas en el TDAH / Cognitive and executive functions in ADHD

Introducción. Se han observado alteraciones en diferentes funciones cognoscitivas en niños con Trastorno por Déficit de Atención con Hiperactividad (TDAH) y recientemente se ha propuesto que la causa que subyace a toda la sintomatología es una deficiencia en las funciones ejecutivas (FE), no obstante, existen muchas discrepancias en los hallazgos. Objetivo. Realizar una evaluación amplia de las funciones cognoscitivas y FE en niños con TDAH tipos hiperactivo impulsivo y combinado (TDAH/HI-C) para conocer sus características neuropsicológicas y analizar que funciones pueden relacionarse con su conducta hiperactivo-impulsiva. Metodología. Se aplicó una Batería Neuropsicológica y los Test de Stroop, de Clasificación de tarjetas de Wisconsin (WCST) y Torre de Londres a 51 niños de 7 a12 años de edad (25 control y 26 con TDAH). Resultados. El grupo TDAH/HI-C tuvo peor resultado en atención sostenida, denominación serial rápida de figuras y colores, comprensión de órdenes escritas, dictado de palabras, comparación de números, problemas aritméticos, memoria de trabajo visual y de largo plazo y en el WCST. Los errores y velocidad en denominación serial rápida de colores y figuras, comprensión de órdenes escritas, problemas aritméticos, y del WCST errores totales, perseverativos y respuestas perseverativas, fueron las variables que se relacionaron con la hiperactividad-impulsividad. Conclusiones. Los niños con TDAH/HI-C tienen una gran variedad de deficiencias cognoscitivas y solamente en algunas áreas de las FE. Estas deficiencias explican en alguna medida el comportamiento hiperactivo-impulsivo (AU)

Introduction. Some studies have reported that attention-deficit/hyperactivity disorder (ADHD) children show alterations in different cognitive functions. Recently, a deficiency in the executive functions (EF) is proposed as the cause underlying all of these symptoms. However discrepancies exist about these findings. Objective. Assessment of cognitive and executive functions of subjects with both ADHD hyperactive-impulsive type and combined type, in order to reveal their neuropsychological characteristics and analyze if those functions are related to hyperactive-impulsive behavior. Method. Neuropsychological Battery, Stroop test, Wisconsin Card Sorting test and London Tower test were applied to 51children between 7 and 12 years old (25 controls and 26ADHD). Results. ADHD children showed worst performance in sustained attention, rapid serial naming of figures and colors, comprehension of written instructions, word dictation, number comparison, arithmetical problems, visual working memory, long term memory and the scores of WCST. Variables related to hyperactivity-impulsivity were: errors and decreased velocity in rapid serial naming of colors and figures, comprehension of written instructions, arithmetical problems and the scores of total errors, perseverating errorsand perseverating responses of WCST. Conclusion. ADHD children show a great variety of cognitive deficiencies and had deficit only in some domains of executive functions. These deficiencies could explain to some extent the hyperactive and impulsive behavior (AU)

Cognitive and executive functions in ADHD.

INTRODUCTION: Some studies have reported that attention-deficit/hyperactivity disorder (ADHD) children show alterations in different cognitive functions. Recently, a deficiency in the executive functions (EF) is proposed as the cause underlying all of these symptoms. However discrepancies exist about these findings. OBJECTIVE: Assessment of cognitive and executive functions of subjects with both ADHD hyperactive-impulsive type and combined type, in order to reveal their neuropsychological characteristics and analyze if those functions are related to hyperactive-impulsive behavior. METHOD: Neuropsychological Battery, Stroop test, Wisconsin Card Sorting test and London Tower test were applied to 51 children between 7 and 12 years old (25 controls and 26 ADHD). RESULTS: ADHD children showed worst performance in sustained attention, rapid serial naming of figures and colors, comprehension of written instructions, word dictation, number comparison, arithmetical problems, visual working memory, long term memory and the scores of WCST. Variables related to hyperactivity-impulsivity were: errors and decreased velocity in rapid serial naming of colors and figures, comprehension of written instructions, arithmetical problems and the scores of total errors, perseverating errors and perseverating responses of WCST. CONCLUSION: ADHD children show a great variety of cognitive deficiencies and had deficit only in some domains of executive functions. These deficiencies could explain to some extent the hyperactive and impulsive behavior.

An ERP study of agreement features in Spanish.

The goal of the present study was to investigate whether two morphological agreement features, Person and Number, play a different role in the agreement process. According to the Feature Hierarchy hypothesis, different nominal agreement features have different degrees of cognitive strength (e.g., Person>Number). Event-related potentials (ERPs) were collected from Spanish speakers while they read sentences in which either Person Disagreement (PD; e.g., Tú salto en el patio [You (2ndPerSing) jump (1stPerSing) in the backyard]), Number Disagreement (ND; e.g., Nosotros salto en el patio [We (1stPerPl) jump (1stPerSing) in the backyard]) or both Person and Number Disagreement (NPD; e.g., Ustedes salto en el patio [You (2ndPerPl) jump (1stPerSing) in the backyard]) relationships were manipulated. ND, PD and NPD all elicited an anterior negativity (AN) and P600 pattern. An AN effect was only found in the NPD with a different topography from the classic LAN effect as it was lateralized to right and central sites. The P600 effect elicited by the NPD condition was larger than the agreement condition and that of ND and PD in the first window 500-700, while the three disagreement conditions elicited larger P600 amplitudes than the agreement condition in the second window 700-900. There were no differences between the processing of person and number. Thus, the combination of number and person disagreement could be solved in parallel through an additive mechanism of the two features. These results do not support the Feature Hierarchy hypothesis.

Sentence processing in 30-month-old children: an event-related potential study.

In a previous event-related brain potential study, we provided evidence that preschoolers display different brain electrical patterns to semantic content and syntactic structure processing. In the present study, we aimed to determine the time-course of these event-related potential effects in 30-month-old children, using the same syntactically anomalous, semantically anomalous and control sentences that we used in our previous study. The results show that semantic violations elicit a frontal negativity peaking around 600 ms, whereas the morphosyntactic violations elicit a slow positive shift peaking around 800 ms with a frontocentral distribution. Our findings replicate the event-related potential patterns previously observed in young children and indicate that the neural signatures of sentence processing can be observed at an early point in development.