Elena I. Rodríguez-Martínez

Slow wave maturation on a visual working memory task

The purpose of the present study is to analyze how the Slow Wave develops in the retention period on a visual Delayed Match-to-Sample task performed by 170 subjects between 6 and 26 years old, divided into 5 age groups. In addition, a neuropsychological test (Working Memory Test Battery for Children) was correlated with this Event Related Potential (ERP) in order to observe possible relationships between Slow Wave maturation and the components of Baddeley and Hitchs Working Memory model. The results showed a slow negativity during the retention period in the posterior region in all the age groups, possibly resulting from sustained neural activity related to the visual item presented. In the anterior region, a positive slow wave was observed in the youngest subjects. Dipole analysis suggests that this fronto-central positivity in children (6-13 years old) consists of the positive side of the posterior negativity, once these subjects only needed two posterior dipoles to explain almost all the neural activity. Negative correlations were shown between the Slow Wave and the Working Memory Test Battery for Children, indicating a commonality in assessing Working Memory with the Slow Wave and the neuropsychological testing.

Developmental trajectories of event related potentials related to working memory

ABSTRACT Working memory is an important cognitive function, and it is crucial to better understand its neurophysiological mechanisms. The developmental trajectories of the Event Related Potentials related to this important function have hardly been studied. However, these ERPs may provide some clues about the individual state of maturation, as has been demonstrated for anatomical brain images. The present study aims to determine the behavioral and neurophysiological development of Working Memory (WM) processes. For this purpose, 170 subjects with ages ranging from 6 to 26 years performed a visual Delayed Match‐to‐Sample task (DMTS). The RTs, total errors, and Event Related Potentials (ERPs) in the phases of encoding, retention, and matching were obtained. Results revealed a decrease in the amplitude of ERPs with age, paralleled by improved performance on the DMTS task (i.e., shorter RTs and fewer errors). None of these variables were affected by gender. To determine whether memory performance was influenced by the individual pattern of maturation beyond age, the amplitude of the different ERP components was correlated with RT and errors on the WM task after removing the effect of age. Frontal N2 and posterior P1 and the Late Positive Component were the only ERPs that presented significant correlations with behavioral errors. Behavioral performance was predicted by age and by the scores on the first component extracted from Principal Component Analysis (PCA) of the ERPs. Age (under 17 years old) explained 85.04% and the PCA component explained 14.96% of the variance explained by the bivariate model predicting behavioral errors (1/age + scores of 1st PCA component). From the age of 17 on, the principal PCA component ceases to be an independent component predicting error performance. The results suggest that the individual maturation of ERP components seems to be of particular importance in controlling behavioral errors in WM, as measured by the DMTS. HIGHLIGHTSAll the ERPs related to Working Memory during development were analyzed.All ERPs presented a reduction in amplitude with age.Frontal N2, posterior P1 and the Late Positive Component are important for controlling errors,Individual brain maturation influences cognitive performance in the 6–17 year old period.

Fronto–temporo–occipital activity changes with age during a visual working memory developmental study in children, adolescents and adults

The present report analyzes differences in cerebral sources among several age groups with respect to the encoding, maintenance and recognition of stimuli during a visual working memory task. Differential intensity of involvement of anterior and posterior areas during working memory processing is expected at different ages. For that, 168 subjects between 6 and 26 years old performed a visual delayed match-to-sample task. The sample was subdivided into 5 age groups, and the cerebral sources were analyzed with sLORETA, comparing the groups two-by-two. The results showed that at younger ages more posterior regions are involved in working memory processing, while in adulthood more anterior regions are involved. Maintaining the visual item in memory showed some common activated areas with stimulus matching, indicating similar neural mechanisms involved in holding and selecting the target stimulus.

Spontaneous theta rhythm and working memory co-variation during child development

The present study examines possible relationships between changes in electroencephalogram (EEG) power and in working memory (WM) due to brain maturation. Scores on the phonological loop, visuospatial sketchpad and executive components of WM, measured by the Working Memory Test Battery for Children (WMTB-C), were correlated with the power spectral density (PSD) values on the spontaneous EEG from 1 to 46 Hz. In order to control for non-specific processes of visuomotor abilities, the reaction time (RT) variable was measured with an Oddball task. One hundred and sixty seven subjects (82 males and 85 females) between 6 and 26 years old participated in the study. Three minutes of spontaneous EEG were recorded. The WMTB-C and the Oddball task were also administered. The scores on each WM component increased and the RT in the Oddball decreased with age, while PSD values in the different frequencies decreased with age. Significant negative correlations between each of the components and the PSD were obtained. The maximal negative correlations were obtained in the theta (4-7 Hz) range. A bivariate linear model including theta PSD and RT explained most of the WM variance due to age. The results suggest that spontaneous EEG maturation is closely related to WM maturation, particularly in the theta range.

Electrophysiological Evidence of a Delay in the Visual Recognition Process in Young Children.

The present study analyzes the development of the visual recognition processing of the relevant stimulus in a Delayed Match-To-Sample (DMS) task during the matching phase. To do so, Electroencephalograms of 170 subjects between 6 and 26 years old were recorded. Behavioral responses and Event Related Potentials (ERPs) induced by the stimuli were obtained. Reaction times and errors, mainly omissions, were inversely related to age. The ERPs analysis showed a parietal negativity in the P7 and P8 electrodes when the relevant stimulus was presented in the contralateral site. This negativity resulting from the recognition and selection of the relevant stimulus was present in all age groups. However, the youngest children showed an extended latency in the recognition process. The results suggest that children and adults use similar processes to recognize the item maintained in visual short-term memory (VSTM), but children need more time to successfully recognize the memorized item.

The neurophysiology of working memory development: from childhood to adolescence and young adulthood

Abstract Working memory (WM) is an important cognitive function that is necessary to perform our daily activities. The present review briefly describes the most accepted models underlying WM and the neural networks involved in its processing. The review focuses on how the neurophysiological mechanisms develop with age in the periods from childhood to adolescence and young adulthood. Studies using behavioral, neuroimaging, and electrophysiological techniques showed the progress of WM throughout the development. The present review focuses on the neurophysiology of the basic processes underlying WM operations, as indicated by electroencephalogram-derived signals, in order to take advantage of the excellent time resolution of this technique. Children and adults use similar cerebral mechanisms and areas to encode, recognize, and keep the stimuli in memory and update the WM contents, although adults rely more on anterior sites. The possibility that a functional reorganization of WM brain processing occurs around the adolescent period is suggested, and would partly justify the high prevalence of the emergence of mental pathology in the adolescent period.

Event-Related Potentials During a Delayed Match-to-Sample Test to Evaluate Working Memory Development in Control and Attention Deficit Children and Adolescents

Working memory (WM) impairment is a core feature of attention deficit disorder (ADD). Differences in event-related potentials (ERPs) amplitude with respect to controls would permit to characterize neurophysiologically WM processing in ADD. Thirty-two ADD-diagnosed subjects and thirty-eight controls (6–17 years old) were recorded during a visual delayed match-to-sample test (DMTS). ERP amplitudes of ADD and control subjects were compared during the encoding, retention, and matching phases. Cluster mass permutation test, controlling for multiple comparisons in time and space (electrodes), showed statistically significant lower amplitude for the negative slow wave (NSW) in ADD children compared to the control group during the retention period. Electrodes CP6, P4, and P8 showed these significant differences. The lower amplitude of the NSW in ADD children suggests a dysfunctional activation of the WM, possibly related to the difficulty to focus attention during the coding and retention phases.

Spectral Power and Maturational Frequency-Coupling Differences Between Attention Deficit and Control Children and Adolescents

Present report explores the possibility that attentional deficit disorder (ADD) subjects would show a different spectral power values compared with healthy subjects and possibly a different theta-beta maturational frequency coupling. Open-eyes, resting-state EEG was recorded in a sample of 36 controls and 36 ADD subjects (6–17 years old). The power spectral density (PSD) from 0 to 46 Hz was computed. ANOVAs to compare spectral power between control and ADD subjects were obtained. PSD correlations between the whole ranges of frequencies were calculated to observe possible differences in the co-maturation of the different brain rhythms in both groups of subjects. An increase in delta power in ADD subjects with respect to control subjects was obtained, indicating a predominance of slow waves in ADD subjects. While control subjects presented a significant correlation between low-frequency rhythms and beta rhythm, ADD subjects presented a lower maturational power-to-power frequency coupling between these rhythms.

Working Memory Development in Attention Deficit Children and Adolescents

Attentional deficit disorder (ADD, ADHD) is a complex disorder in which attention and working memory (WM) are impaired. The central hypothesis is that WM behavioral performance would be impaired in ADD and would facilitate the classification of control and ADD subjects. One hundred and eighty-one control and 41 ADD children and adolescents (6–17 years old) were behaviorally recorded using the Working Memory Test Battery for Children (WMTB-C), delayed match-to-sample test (DMTS), and oddball tasks. ADD children presented a behavioral impairment in WMTB-C, DMTS, and oddball tasks. ADD obtained lower direct scores in the three subcomponents of the Baddeley’s WM model, lower d’ values, produced more errors, and presented higher variability in RTs than controls. The discriminant analysis was able to classify correctly around 70% of controls and ADD children. The results suggest that WM is a central core dysfunction in ADD and useful as a diagnostic tool.

Broad band indices of human spontaneous EEG maturational trends

matter centered at the anterior cingulate cortex were determined using LC model. Participants completed 9 subtests of the California Computerized Assessment Package (CalCAP) to assess reaction time, working-memory, and attention. Correlations between age, imaging, and cognitive measures were determined (p < 0.05 significance). The medial-orbital-frontal cortex thinned with age (r = −0.37). Improved CalCAP performance on 2 subtests (r > 0.34) and higher n-acetyl-aspartate (NAA) levels (r = −0.32) were associated with this thinning. The superior-frontal cortex also thinned with age (r = -0.45) with corresponding improved performance on 4 subtests (r > 0.33) and higher glutamate + glutamine (GLX) levels. The superior-frontal cortex volume also decreased with age (r = −0.42) and was associated with improved performance on 8 subtests (r > 0.30). Smaller volumes of the frontal pole were observed in older participants (r = −0.31), which correlated with improved performance on 1 test (r = 0.31). Smaller volumes in the medialorbital-frontal cortex correlated with improved performance on 4 subtests (r > 0.35) and higher NAA levels (r = −0.31). These results emphasize that the frontal cortex is still developing into the 3rd decade of life. In addition, our data suggest that cortical pruning (thinning and volume reductions) during periadolescent brain development is associated with increasing concentrations of neuronal markers (NAA and GLX), and improved performance on higher cognitive functions, possibly due to more compact and efficient neuronal function and enhanced neuronal integrity.