Vicente Guerrero

Electroencephalographic coherences discriminate between children with different pedagogical evaluation

The relationship of reading-writing ability and EEG coherences was studied in 84 subjects from two age groups 7.0-8.9 and 9-11.2 years old. All children were divided into three groups according to their performance on a pedagogical test: ped1, normal children; ped2, children with mild problems; ped3, children with reading-writing disability. The following results were obtained: in general, children showed higher coherences in groups with poor performance in the delta, theta and beta bands. In the alpha band, higher coherence values were related to better performance. The exceptions to this general pattern were rare. Group ped2 had higher coherences in delta, theta and alpha bands than ped1 and ped3, in left temporal leads. In older children the same tendency was observed, but group differences in the theta, alpha and beta bands were few. In this age range, the significant group differences were almost all interhemispheric coherences. The discriminant analysis that classified subjects by their coherence values gave very good results, fact that demonstrates, that EEG coherence is a highly sensitive measurement indicating not only the existence of a reading-writing problem, but also the degree of its severity.

Auditory event-related potentials in poor readers

Although poor readers (PR) are considered the major group among reading-disabled children, there are not event-related potentials (ERP) studies reported of PR on the subject. In this study, attentional and memory processes were studied in an auditory oddball task in PR and normal controls. ERP to auditory stimuli were recorded in 19 leads of the 10/20 system, using linked earlobes as references, in 20 normal children (10 female) and 20 PR (10 female) of the same age (10-12 years old). Two pure tones (1000 and 3000 Hz) were used in an oddball paradigm. No significant differences were observed in the amplitudes and latencies of N100 between the groups. However, N200 to frequent stimuli and P200 to both frequent and infrequent stimuli were of higher amplitude in poor readers than in normal children. There were no differences between groups in the latency and amplitude of P300. The results suggest that PR use more attentional resources in the components occurring before P300 to both frequent and infrequent stimuli than the normal children, and this finding is particularly marked for PR girls.

Broad Band Spectral Eeg Parameters Correlated with Different IQ Measurements

The relationship of IQ (measured by WAIS and all its subscales) and EEG broad band spectral parameters were studied in 40 right-handed, male volunteers ranging in age from 20 to 25 years old. EEGs were recorded in 20 derivations during rest with eyes opened. The results obtained reveal positive and negative correlations with abundant frontal participation in all bands. Mean frequency data show a frequency shift in a very narrow range suggesting that more relations in narrow band could be achieved. These results highlight the need of psychological tests that measure more homogeneous abilities and finer measurement technique to reveal clearly explainable correlations and demonstrate that EEG recordings do reflect intellectual abilities.

A follow-up study of EEG coherences in children with different pedagogical evaluations

A follow-up study on EEG coherence values was carried out with 46 school-age children divided into three pedagogical groups considering their reading and writing abilities (normal subject and children with mild and with serious reading-writing problems). EEGs were recorded at rest, with eyes closed in 15 referential derivations that gave 105 possible coherence values. Coherence was calculated after the elimination of the average reference. Repeated Measure ANOVAs were calculated to evaluate the effects of time, sex, reading-writing problems and their interactions. The second EEG recordings were taken 2-3 years after the first. The results revealed significant increase of coherence values during the time lapse studied, consisting of an increase of frontal coherences in all bands, with the exception of the theta band. The most numerous changes occurred in the alpha band. Very few differences in coherence values were observed between the two EEG recordings by pedagogical groups and by sex suggesting a similar but not igual maturation of coherences of boys and girls and of the three pedagogical groups, in this age range studied. These findings suggests an abnormal coherence development for the reading disabled group, as well as different coherence maturation for boys and girls in this time lapse studied.

Event-related potentials findings differ between children and adults during arithmetic-fact retrieval

Some cognitive abilities of arithmetical calculation depend on retrieval of arithmetic facts from long-term memory. Arithmetic-fact retrieval has been studied in adults through Event-Related Potentials (ERP) experiments. Such information in children, however, has been scarce. It has been reported that from the age of 9 years, children employ a memory retrieval strategy for solving simple multiplication problems. The present study compared arithmetical-fact retrieval in children and adults while they were being subjected to ERP recording. The subjects were asked to make judgments about solutions to simple multiplication problems. Both groups of participants displayed the so-called arithmetic N400 effect for incorrect solutions relative to correct solutions. Adults showed a posterior N400 effect, while children showed a widely distributed N400 effect. Children displayed a larger amplitude and longer latency arithmetic N400 component than adults; this observation could be due to children exerting greater effort involving more widespread cortical activation than adults to solve the experimental problems. The Late Positive Component (LPC), which follows the arithmetic N400 and has been described previously in adult subjects, was observed in the present adult subjects, but was present in children only for correct solutions. These results may indicate that, relative to adults, children showed slower memory retrieval and a different pattern of a verification mechanism for correct and incorrect solutions.

Poor reading skills may involve a failure to focus attention

A source localization analysis was carried out to provide brain functional and structural assessments of individuals with poor reading skills. Standardized low-resolution brain electromagnetic tomography was used to locate sources of P2 and P3 event-related potential components in normal readers and in poor reader children performing a cued continuous performance task. Cue-elicited P2 sources in the right superior parietal gyrus were smaller in 37 poor readers than in 40 normal readers. Poor readers showed a higher P3 activation in response to a false target in frontal and frontorbital regions than normal readers. These results suggest that reading disabilities may be attributed to failures in attentional focalization for incoming stimuli.

Adaptación de las pruebas de procesamiento fonológico de una batería neuropsicológica en niños de 5 a 7 años

Resumen Se ha descrito la importancia de las habilidades de procesamiento fonológico y en especial el de la sensibilidad fonológica, en la adquisición de la lectura, por lo) que es muy importante evaluar estas habilidades en niños preescolares. El objetivo del presente trabajo fue realizar una adaptación de las pruebas de procesamiento fonológico de la Batería Neuropsicológica para la Evaluación de Niños con trastornos del Aprendizaje de la Lectura (BNTAL) para niños mexicanos preescolares y de primer grado escolar. Participaron 165 niños de 5.5 a 7.4 años, de preescolar y primer grado. Los resultados mostraron un nivel de consistencia interna bastante aceptable para las pruebas de sensibilidad fonológica, además se observaron significativamente mejores ejecuciones en los niños de primer grado escolar con relación a los preescolares en la mayoría de las pruebas de sensibilidad fonológica. Se concluye que el instrumento de medición obtenido es confiable para medir el procesamiento fonológico de los niños de estas edades.

Visual Evoked Potentials, Attention and Mnemonic Abilities in Children

We analyzed the correlation between attention and mnemonic processes and different visual evoked potential (VEP) parameters. A group of 34 children between 9 and 13 years old was studied. VEPs were recorded in C3, C4, P3, P4, O1, O2, T5 and T6 with linked ear lobes as reference. Two different types of stimuli were used: flash and checkerboard pattern. The power of VEPs was calculated as the sum of the square amplitude values for different time epochs. Correlation coefficients between left and right homologous VEPs were also computed. A visual selective attention task divided into 5 items of increasing difficulty and the Sternberg paradigm were applied. The performance was automatically evaluated by the computer, giving the number of correct responses (NCR) and other measures of performance. Correlation coefficients between VEP parameters and the scores obtained in the performance of tasks were calculated. It was observed that power in P3, P4, T5, and T6 and the correlation coefficients between central, parietal and temporal VEPs were positively correlated with NCR of both tasks. However, power in O1 and O2 was negatively correlated with NCR.

Quantitative spectral EEG assessments during affective states evoked by the presentation of the international affective pictures

Resumen en: This study was carried out to find changes in EEG power during emotions of positive and negative valence evoked by the International Affective Pictures. ...