Assessment of Audio-Tactile Sensory Substitution Training in Participants with Profound Deafness Using the Event-Related Potential Technique.

This paper examines the application of electroencephalogram-based methods to assess the effects of audio-tactile substitution training in young, profoundly deaf (PD) participants, with the aim of analyzing the neural mechanisms associated with vibrotactile complex sound discrimination. Electrical brain activity reflects dynamic neural changes, and the temporal precision of event-related potentials (ERPs) has proven to be key in studying time-locked processes while performing behavioral tasks that involve attention and working memory. The current protocol was designed to study electrophysiological activity in PD subjects while they performed a continuous performance task (CPT) using complex-sound stimuli, consisting of five different animal sounds delivered through a portable stimulator system worn on the right index finger. As a repeated-measures design, electroencephalogram (EEG) recordings in standard conditions were performed before and after a brief training program (five 1 h sessions over 15 days), followed by offline artifact correction and epoch averaging, to obtain individual and grand-mean waveforms. Behavioral results show a significant improvement in discrimination and a more robust P3-like centroparietal positive waveform for the target stimuli after training. In this protocol, ERPs contribute to the further understanding of learning-related neural changes in PD subjects associated with audio-tactile discrimination of complex sounds.

Quantitative EEG measures in profoundly deaf and normal hearing individuals while performing a vibrotactile temporal discrimination task.

Challenges in early oral language acquisition in profoundly deaf individuals have an impact on cognitive neurodevelopment. This has led to the exploration of alternative sound perception methods involving training of vibrotactile discrimination of sounds within the language spectrum. In particular, stimulus duration plays an important role in linguistic categorical perception. We comparatively evaluated vibrotactile temporal discrimination of sound and how specific training can modify the underlying electrical brain activity. Fifteen profoundly deaf (PD) and 15 normal-hearing (NH) subjects performed a vibrotactile oddball task with simultaneous EEG recording, before and after a short training period (5 one-hour sessions; in 2.5-3 weeks). The stimuli consisted of 700 Hz pure-tones with different duration (target: long 500 ms; non-target: short 250 ms). The sound-wave stimuli were delivered by a small device worn on the right index finger. A similar behavioral training effect was observed in both groups showing significant improvement in sound-duration discrimination. However, quantitative EEG measurements reveal distinct neurophysiological patterns characterized by higher and more diffuse delta band magnitudes in the PD group, together with a generalized decrement in absolute power in both groups that might reflect a facilitating process associated to learning. Furthermore, training-related changes were found in the beta-band in NH. Findings suggest PD have different cognitive adaptive mechanisms which are not a mere amplification effect due to greater cortical excitability.

Sustained attention in schoolchildren with type-1 diabetes. A quantitative EEG study.

OBJECTIVE: Type-1 diabetes (T1D) is a disruptive metabolic disease that has an impact on neurodevelopment through its effects on the structure and function of the brain. One of the cognitive domains affected by T1D is sustained attention. The aim of this study was to analyze this process in children with T1D and compare their results to those of healthy controls. METHODS: Seventeen T1D children attending regular primary school and a similar group of healthy children matched by gender, age, handedness, and educational level were evaluated while identifying happy faces in a Go-NoGo task presented visually with simultaneous electrophysiological recording. RESULTS: Behavioral performance in the two groups was similar but, the T1D children showed greater prefrontal and frontoparietal spectral power in the theta and alpha bands, compared to controls. Distinct patterns of theta lateralization between groups were also observed, with a negative correlation between frontal power magnitudes in delta and theta and glycated hemoglobin levels. CONCLUSIONS: These results seem to reflect the early deleterious effects of T1D on neurodevelopment, which affects mainly attention allocation processes and the neurofunctional substrates that underlie them. SIGNIFICANCE: This phenomenon emphasizes the need for studies on neural-specific targets in which T1D affects neurodevelopment.

A brain connectivity characterization of children with different levels of mathematical achievement based on graph metrics.

Recent studies aiming to facilitate mathematical skill development in primary school children have explored the electrophysiological characteristics associated with different levels of arithmetic achievement. The present work introduces an alternative EEG signal characterization using graph metrics and, based on such features, a classification analysis using a decision tree model. This proposal aims to identify group differences in brain connectivity networks with respect to mathematical skills in elementary school children. The methods of analysis utilized were signal-processing (EEG artifact removal, Laplacian filtering, and magnitude square coherence measurement) and the characterization (Graph metrics) and classification (Decision Tree) of EEG signals recorded during performance of a numerical comparison task. Our results suggest that the analysis of quantitative EEG frequency-band parameters can be used successfully to discriminate several levels of arithmetic achievement. Specifically, the most significant results showed an accuracy of 80.00% (α band), 78.33% (δ band), and 76.67% (θ band) in differentiating high-skilled participants from low-skilled ones, averaged-skilled subjects from all others, and averaged-skilled participants from low-skilled ones, respectively. The use of a decision tree tool during the classification stage allows the identification of several brain areas that seem to be more specialized in numerical processing.

A step forward in the quest for a mobile EEG-designed epoch for psychophysiological studies.

The aim of this study was to compare a reconfigurable mobile electroencephalography (EEG) system (M-EMOTIV) based on the Emotiv Epoc® (which has the ability to record up to 14 electrode sites in the 10/20 International System) and a commercial, clinical-grade EEG system (Neuronic MEDICID-05®), and then validate the rationale and accuracy of recordings obtained with the prototype proposed. In this approach, an Emotiv Epoc® was modified to enable it to record in the parieto-central area. All subjects (15 healthy individuals) performed a visual oddball task while connected to both devices to obtain electrophysiological data and behavioral responses for comparative analysis. A Pearson's correlation analysis revealed a good between-devices correlation with respect to electrophysiological measures. The present study not only corroborates previous reports on the ability of the Emotiv Epoc® to suitably record EEG data but presents an alternative device that allows the study of a wide range of psychophysiological experiments with simultaneous behavioral and mobile EEG recordings.

Type 1 diabetes and working memory processing of emotional faces.

Several executive functions decline with the development of type-1 diabetes (T1D), particularly working memory (WM). In adults, WM ensures efficient cognitive processing by focusing on task-relevant information while suppressing distractors. It has been well documented that WM can be influenced by emotional stimuli, which may facilitate the retention of information, interfere with uptake, or even affect its capacity. We evaluated the effect of T1D on visual WM processing using emotional faces as stimuli, in young patients with satisfactory clinical evolution, and matched controls without T1D. All subjects performed a 2-back task detecting facial identity using neutral, happy or fearful faces in a block design for fMRI. Behavioral performance was similar with the exception that patients responded significantly slower. Most importantly, between-group differences were found in patterns of brain activation. In comparison, more widespread brain activation -predominantly prefrontal- was found in the participants with T1D when processing neutral faces, while a decrease was observed when processing happy and fearful ones. Statistical contrasts demonstrated significantly-different activation patterns between groups when processing emotional faces, as controls exhibited greater activation in the cuneus, posterior cortex and parahippocampal gyrus, while the patients showed greater activation in the prefrontal structures. Results may reflect compensatory efforts made to minimize the deleterious effects of disease development on attention allocation processes and the operational efficiency of WM. The results suggest that emotional parameters should be periodically assessed in individuals with T1D in order to anticipate the emergence of attention and WM impairment.

Dataset on the EEG time-frequency representation in children with different levels of mathematical achievement.

This article presents the data related to the research paper entitled "The analysis of EEG coherence reflects middle childhood differences in mathematical achievement" (González-Garrido et al., 2018). The dataset is derived from the electroencephalographic (EEG) records registered from a total of 60 8-9-years-old children with different math skill levels (High: HA, Average: AA, and Low Achievement: LA) while performing a symbolic magnitude comparison task. The average brain patterns are shown through Time-Frequency Representations (TFR) for each group, and also grand-mean amplitudes within specific EEG epochs in a 19-electrode array are provided. Making this information publicly available for further analyses could significantly contribute to a better understanding on how math achievement in children associates with cognitive processing strategies.

Is sex an influential factor in type-1 diabetes neurofunctional development? A preliminary study.

The aim of the study was to evaluate the neurofunctional effect of gender in Type-1 Diabetes Mellitus (T1DM) patients during a Visual Spatial Working Memory (VSWM) task. The study included 28 participants with ages ranging from 17-28 years. Fourteen well-controlled T1DM patients (7 female) and 14 controls matched by age, sex, and education level were scanned performing a block-design VSWM paradigm. Behavioral descriptive analyses and mean comparisons were done, and between-group and condition functional activation patterns were also compared. Whole-brain cumulative BOLD signal (CumBS), voxel-wise BOLD level frequency, Euclidean distance, and divergence indices were also calculated. There were no significant differences between or within-group sex differences for correct responses and reaction times. Functional activation analyses showed that females had activation in more brain regions, and with larger clusters of cortical activations than males. Furthermore, BOLD activation was higher in males. Despite the preliminary nature of the present study given the relatively small sample size, current results acknowledge for the first time that sex might contribute to differences in functional activation in T1DM patients. Findings suggest that sex differences should be considered when studying T1DM-disease development.

The analysis of EEG coherence reflects middle childhood differences in mathematical achievement.

Symbolic numerical magnitude processing is crucial to arithmetic development, and it is thought to be supported by the functional activation of several brain-interconnected structures. In this context, EEG beta oscillations have been recently associated with attention and working memory processing that underlie math achievement. Due to that EEG coherence represents a useful measure of brain functional connectivity, we aimed to contrast the EEG coherence in forty 8-to-9-year-old children with different math skill levels (High: HA, and Low achievement: LA) according to their arithmetic scores in the Fourth Edition of the Wide Range Achievement Test (WRAT-4) while performing a symbolic magnitude comparison task (i.e. determining which of two numbers is numerically larger). The analysis showed significantly greater coherence over the right hemisphere in the two groups, but with a distinctive connectivity pattern. Whereas functional connectivity in the HA group was predominant in parietal areas, especially involving beta frequencies, the LA group showed more extensive frontoparietal relationships, with higher participation of delta, theta and alpha band frequencies, along with a distinct time-frequency domain expression. The results seem to reflect that lower math achievements in children mainly associate with cognitive processing steps beyond stimulus encoding, along with the need of further attentional resources and cognitive control than their peers, suggesting a lower degree of numerical processing automation.

Analysis of Pseudohomophone Orthographic Errors through Functional Magnetic Resonance Imaging (fMRI).

The study of orthographic errors in a transparent language such as Spanish is an important topic in relation to writing acquisition because in Spanish it is common to write pseudohomophones as valid words. The main objective of the present study was to explore the possible differences in activation patterns in brain areas while processing pseudohomophone orthographic errors between participants with high (High Spelling Skills (HSS)) and low (Low Spelling Skills (LSS)) spelling orthographic abilities. We hypothesize that (a) the detection of orthographic errors will activate bilateral inferior frontal gyri, and that (b) this effect will be greater in the HSS group. Two groups of 12 Mexican participants, each matched by age, were formed based on their results in a group of spelling-related ad hoc tests: HSS and LSS groups. During the fMRI session, two experimental tasks were applied involving correct and pseudohomophone substitution of Spanish words. First, a spelling recognition task and second a letter searching task. The LSS group showed, as expected, a lower number of correct responses (F(1, 21) = 52.72, p <.001, η2 = .715) and higher reaction times compared to the HSS group for the spelling task (F(1, 21) = 60.03, p <.001, η2 = .741). However, this pattern was reversed when the participants were asked to decide on the presence of a vowel in the words, regardless of spelling. The fMRI data showed an engagement of the right inferior frontal gyrus in HSS group during the spelling task. However, temporal, frontal, and subcortical brain regions of the LSS group were activated during the same task.

Vibrotactile Discrimination Training Affects Brain Connectivity in Profoundly Deaf Individuals.

Early auditory deprivation has serious neurodevelopmental and cognitive repercussions largely derived from impoverished and delayed language acquisition. These conditions may be associated with early changes in brain connectivity. Vibrotactile stimulation is a sensory substitution method that allows perception and discrimination of sound, and even speech. To clarify the efficacy of this approach, a vibrotactile oddball task with 700 and 900 Hz pure-tones as stimuli [counterbalanced as target (T: 20% of the total) and non-target (NT: 80%)] with simultaneous EEG recording was performed by 14 profoundly deaf and 14 normal-hearing (NH) subjects, before and after a short training period (five 1-h sessions; in 2.5-3 weeks). A small device worn on the right index finger delivered sound-wave stimuli. The training included discrimination of pure tone frequency and duration, and more complex natural sounds. A significant P300 amplitude increase and behavioral improvement was observed in both deaf and normal subjects, with no between group differences. However, a P3 with larger scalp distribution over parietal cortical areas and lateralized to the right was observed in the profoundly deaf. A graph theory analysis showed that brief training significantly increased fronto-central brain connectivity in deaf subjects, but not in NH subjects. Together, ERP tools and graph methods depicted the different functional brain dynamic in deaf and NH individuals, underlying the temporary engagement of the cognitive resources demanded by the task. Our findings showed that the index-fingertip somatosensory mechanoreceptors can discriminate sounds. Further studies are necessary to clarify brain connectivity dynamics associated with the performance of vibrotactile language-related discrimination tasks and the effect of lengthier training programs.

Electrophysiological dynamic brain connectivity during symbolic magnitude comparison in children with different mathematics achievement levels.

Children with mathematical difficulties usually have an impaired ability to process symbolic representations. Functional MRI methods have suggested that early frontoparietal connectivity can predict mathematic achievements; however, the study of brain connectivity during numerical processing remains unexplored. With the aim of evaluating this in children with different math proficiencies, we selected a sample of 40 children divided into two groups [high achievement (HA) and low achievement (LA)] according to their arithmetic scores in the Wide Range Achievement Test, 4th ed.. Participants performed a symbolic magnitude comparison task (i.e. determining which of two numbers is numerically larger), with simultaneous electrophysiological recording. Partial directed coherence and graph theory methods were used to estimate and depict frontoparietal connectivity in both groups. The behavioral measures showed that children with LA performed significantly slower and less accurately than their peers in the HA group. Significantly higher frontocentral connectivity was found in LA compared with HA; however, when the connectivity analysis was restricted to parietal locations, no relevant group differences were observed. These findings seem to support the notion that LA children require greater memory and attentional efforts to meet task demands, probably affecting early stages of symbolic comparison.

Analysis of pseudohomophone orthographic errors through Functional Magnetic Resonance Imaging (fMRI)

The study of orthographic errors in a transparent language such as Spanish is an important topic in relation to writing acquisition because in Spanish it is common to write pseudohomophones as valid words. The main objective of the present study was to explore the possible differences in activation patterns in brain areas while processing pseudohomophone orthographic errors between participants with high (High Spelling Skills (HSS)) and low (Low Spelling Skills (LSS)) spelling orthographic abilities. We hypothesize that (a) the detection of orthographic errors will activate bilateral inferior frontal gyri, and that (b) this effect will be greater in the HSS group. Two groups of 12 Mexican participants, each matched by age, were formed based on their results in a group of spelling-related ad hoc tests: HSS and LSS groups. During the fMRI session, two experimental tasks were applied involving correct and pseudohomophone substitution of Spanish words. First, a spelling recognition task and second a letter searching task. The LSS group showed, as expected, a lower number of correct responses (F(1, 21) = 52.72, p <.001, η2 = .715) and higher reaction times compared to the HSS group for the spelling task (F(1, 21) = 60.03, p <.001, η2 = .741). However, this pattern was reversed when the participants were asked to decide on the presence of a vowel in the words, regardless of spelling. The fMRI data showed an engagement of the right inferior frontal gyrus in HSS group during the spelling task. However, temporal, frontal, and subcortical brain regions of the LSS group were activated during the same task (AU)

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Visual processing in a facial emotional context: an ERP study.

Facial emotional processing can be bypassed when faces are task-irrelevant and attention is diverted, although this effect has not been examined when cognitive task occurs within a facial background. Event-related potential (ERP) measures were obtained to evaluate the influence of different irrelevant facial emotional contexts on a simultaneous "ear-size" detection task performance in five processing contexts: (1) neutral face, (2) happy face, (3) fearful face, (4) facial contour, and (5) non-facial context. Reaction times were longer when visual processing occurred in a facial context, regardless of its emotional content. The context of neutral faces also demonstrated a lower number of correct responses, with fewer incorrect responses found during the presentation of fearful faces compared to the neutral facial context. ERP morphology was similar across all conditions, but ERP amplitude from components for the non-facial context was larger than that of the alternative conditions from 100 to 300 ms, with a similar N170-like potential also observed. The findings suggest that simultaneous irrelevant emotional facial stimuli may affect cognitive processing by altering two temporarily overlapped neural mechanisms: one responsible for earlier face detection, and the other involved in emotional recognition. The first might delay simultaneous cognitive actions by diverting attention, whereas while the latter may enhance the availability of processing resources through the participation of a subcortical pathway.

Hijos de madres adictas con síndrome de abstinencia en Terapia Intensiva Neonatal / Neonatal abstinence syndrome in a Neonatal Intensive Care Unit

Introducción. En años recientes, se ha incrementado el consumo de drogas en mujeres mexicanas durante la gestación, surgiendo como entidad el síndrome del feto adicto y el síndrome de abstinencia en el neonato (SAN). Objetivo: caracterizar una muestra de neonatos, hijos de madres adictas a drogas ilícitas y que desarrollaron síndrome de abstinencia, así como conocer la respuesta terapéutica del fenobarbital en estos pacientes. Métodos. Se aplicó en forma prospectiva un cuestionario estructurado sobre la madre y el producto de todos los hijos de madres consumidoras de drogas ilegales que ingresaron a la Unidad de Cuidados Intensivos Neonatales Externos del Antiguo Hospital Civil de Guadalajara "Fray Antonio Alcalde" entre el 1 de enero de 2003 y el 20 de diciembre de 2007, por presentar SAN. Resultados. Noventa y dos neonatos desarrollaron SAN durante el período evaluado. La media de la edad materna fue de 22 años, con un bajo nivel educacional. La droga más utilizada por las madres fue la cocaína, y 10 de ellas resultaron VIH-positivas. La edad gestacional promedio fue de 37 semanas. El peso al nacer, la talla corporal y el conteo de Apgar promedios fueron de 2 600 g, 47 cm y 9 puntos, respectivamente. El síntoma más frecuente fue la irritabilidad (77% de la muestra), y en todos los casos el tratamiento con fenobarbital resultó adecuado para el control clínico de los síntomas y signos. Conclusiones. El SAN constituyó 3.5% del total de ingresos en nuestra institución durante un período de 4 años. En general, los neonatos mostraron cortejo sintomático similar al reportado previamente en la literatura. Se observó una alta incidencia de infecciones concurrentes -en particular, VIH- y un predominio de la cocaína y la marihuana como las drogas más consumidas por las madres. El tratamiento con fenobarbital resultó exitoso para el control de síntomas y signos en todos los casos. Dada su incidencia e importancia clínica, el uso de drogas durante el embarazo y sus consecuencias sobre el producto merecen un estudio más consistente e intensivo en México.

Introduction. To our knowledge, in spite of the increasing drug-abuse statistics in Mexican pregnant women, there are no published clinical researches approaching this issue in our country. We describe the characteristics of neonatal abstinent infants admitted in the Neonatal Intensive Care Unit (NICU) located at the Hospital Civil of Guadalajara. Objective: To describe the characteristics of a sample of neonatal abstinent children as well as the efficacy of phenobarbital as a pharmacological alternative. Methods. Children from drug dependent mothers who were admitted to NICU from January 1st 2003 to December 20th 2007 and developed the neonatal abstinence syndrome (NAS) were prospectively evaluated with a structured feedback form including parental data. Results. Ninety two NAS cases (3.5% of the total) were recruited in the assessed period. Mother's mean age was about 22 years with a low educational profile. The most common drug consumed by the mothers was cocaine (35%). Ten mothers had HIV-positive results, while the neonatal averaged gestational age was 37 weeks. Birth weight, corporal size and Apgar score mean values were 2 600 g, 47 cm and 9 points, respectively. The most common symptom was irritability in 77% of the patients. All the cases were treated with phenobarbital reaching a successful clinical remission of the symptoms. Conclusions. NAS represented the 3.5% of all the neonate patients admitted in NICU throughout 4 years. Our observations correspond to those previously reported in the literature. High incidence of concomitant infectious conditions was observed -especially HIV- and the predominant used drugs were cocaine and marijuana. Due to its high incidence and clinical relevance, drug-abuse during pregnancy ought to have further study in our country.

Event-related brain potentials in reading disabled children during an inverse serial digit detection task.

It has been reported that limitations in different components of working memory could underlie reading disabilities. In addition, reading-disabled (RD) children seem to perform worse when digit name processing is required. With the purpose to explore further these assumptions one inverse serial digit detection task was evaluated using event-related brain potentials in fifteen 8-year-old RD children and a control group (CG). CG obtained significantly more correct responses than RD, but had similar reaction times. The experimental task performance significantly correlated with the performance on reading tests. Difference event-related potentials showed a voltage component peaking at 160 ms over frontocentral leads (P160d) that reached significantly higher amplitude in RD group, and was interpreted as an index of the amount of neural resources involved in visual working memory load. The amplitude of P160d significantly correlated with reading speed, the backward digit span and with the experimental task performance. Present results point out that highly demanding working memory tasks reveal behavioral and electrophysiological differences in RD children with respect to healthy controls.

Análisis cuantitativo del electroencefalograma para confirmar trastorno funcional frontal en niños con trastorno por déficit de atención con hiperactividad / Quantitative electroencephalogram analysis confirms the presence of frontal lobe deficit among attention deficit disorder with hyperactivity children

Antecedentes: En 1997, Barkley postuló un modelo funcional del trastorno por déficit de atención con hiperactividad (TDAH) basado en la presencia de un déficit central que afecta el desempeño de las funciones ejecutivas. Hallazgos neuroanatómicos y neurofisiológicos relacionan la afectación de los lóbulos frontales con los procesos cognitivos y conductuales de sujetos con TDAH. Objetivo: Evaluar electrofisiológicamente la teoría de Barkley (1997). Sujetos y métodos: Se estudiaron niños entre 7 y 11 años de edad con TDAH (subtipo inatento) y un grupo control. Se compararon los registros electroencefalográficos obtenidos durante la ejecución de una tarea de estimación del tiempo (ES) con el estado de reposo con ojos abiertos (RA). Se conformaron 42 matrices con 5 tipos diferentes de datos electroencefalográficos (19 derivaciones: sistema 10/20) en tres condiciones: RA, ES y ES-RA (potencia absoluta y potencia relativa). Se utilizaron dos métodos de clasificación. Resultados: El análisis de varianza reveló diferencias significativas en el cociente de anterioridad bajo la condición ES-RA. La clasificación con análisis discriminante reportó una efectividad superior a 80%, mientras que una nueva propuesta de clasificación lineal realizó una clasificación superior a 80% con sólo dos derivaciones. Conclusión: Los resultados apoyan las hipótesis de Barkley y sugieren el uso del cociente de anterioridad referido a temporales para caracterizar electrofisiológicamente el TDAH en niños en edad escolar.

BACKGROUND: The Attention Deficit Disorder with Hyperactivity (ADDH) Barkley model predicts concomitant deficits in working memory and in the development of a sense of time as a consequence of poor behavioral inhibition. Objective: To evaluate electrophysiologically Barkley's theory (1997). SUBJECTS AND METHODS: We studied the electroencephalogram (EEG) of fifteen right-handed, normal limit IQ ADDH children (inattentive subtype), aged 7-11 years, and a control group. Subjects were studied at rest, with the eyes open (RO) while performing a time estimation task (ET). Forty-two data matrices were analyzed in three conditions: RO, ET and ET-RO, to assess broad-band spectral parameters; the anteriority, temporal-referenced and laterality quotients (Aq, Aqt and Lq, respectively); and the theta/alpha and theta/beta ratios. RESULTS: Analyses of variance revealed significant differences for ES-RA, in absolute (Aq &Aqt) and relative powers (Aq). Discriminant function analysis was able to predict group membership with an accuracy over 80%, but it decreased slightly when the leave-one-out method was applied Linear discrimination based on right hemisphere Aqt values showed the highest discrimination accuracy. CONCLUSIONS: These results support Barkley's theory, suggesting further evaluation of the temporal-referenced anteriority quotient as a promising electrophysiological tool for the diagnosis and follow up of ADDH children.

Visual verbal working memory processing may be interfered by previously seen faces.

Processing and maintenance in working memory involve active attention allocation; consequently, it is possible that a recognition process could interfere with the performance of highly demanding working memory tasks. Event-related brain potentials (ERPs) were recorded while fourteen healthy male adults performed a visual verbal dual working memory task. Three conditions were examined: A) reference (with no preceding stimuli); B) happy, angry or neutral faces presented 250 ms prior to task onset for 30 ms; and, C) visual noise control condition. Behavioral results showed that reaction times were significantly longer in the condition preceded by the presentation of faces, regardless of their emotional content. ERPs showed a predominantly right temporo-occipital negative component at around 170 ms during conditions B and C (higher amplitude in B), which probably reflects the pre-categorical structural encoding of the face. Succeeding task-onset, an early positive right temporo-parietal component (P380) appeared during condition B, probably reflecting a delayed reallocation of working memory attentional resources to carry out the task requirements. Afterwards, two other main fronto-parietal components were observed in the three conditions: a positive wave that peaked at around 410 ms, and a subsequent negative component (N585). This latter waveform reached a significantly higher amplitude during the reference condition (A) and was interpreted as mirroring the phonologic-lexical manipulation of the stimuli in working memory. These results suggest that early face detection could induce an attentional decrement that interfere a subsequent visual verbal working memory task performance. They also suggest that while face detection and facial emotional content analysis might be parallel processes, they are not onset-synchronized.

[Quantitative electroencephalogram analysis confirms the presence of frontal lobe deficit among attention deficit disorder with hyperactivity children]. / Análisis cuantitativo del electroencefalograma para confirmar trastorno funcional frontal en niños con trastorno por déficit de atención con hiperactividad.

BACKGROUND: [corrected] The Attention Deficit Disorder with Hyperactivity (ADDH) Barkley model predicts concomitant deficits in working memory and in the development of a sense of time as a consequence of poor behavioral inhibition. OBJECTIVE: To evaluate electrophysiologically Barkley's theory (1997). SUBJECTS AND METHODS: We studied the electroencephalogram (EEG) of fifteen right-handed, normal limit IQ ADDH children (inattentive subtype), aged 7-11 years, and a control group. Subjects were studied at rest, with the eyes open (RO) while performing a time estimation task (ET). Forty-two data matrices were analyzed in three conditions: RO, ET and ET-RO, to assess broad-band spectral parameters; the anteriority, temporal-referenced and laterality quotients (Aq, Aqt and Lq, respectively); and the theta/alpha and theta/beta ratios. RESULTS: Analyses of variance revealed significant differences for ES-RA, in absolute (Aq &Aqt) and relative powers (Aq). Discriminant function analysis was able to predict group membership with an accuracy over 80%, but it decreased slightly when the leave-one-out method was applied Linear discrimination based on right hemisphere Aqt values showed the highest discrimination accuracy. CONCLUSIONS: These results support Barkley's theory, suggesting further evaluation of the temporal-referenced anteriority quotient as a promising electrophysiological tool for the diagnosis and follow up of ADDH children.

Hypercalculia in savant syndrome: central executive failure?

BACKGROUND: The existence of outstanding cognitive talent in mentally retarded subjects persists as a challenge to present knowledge. We report the case of a 16-year-old male patient with exceptional mental calculation abilities and moderate mental retardation. METHODS: The patient was clinically evaluated. Data from standard magnetic resonance imaging (MRI) and two 99mTc-ethyl cysteine dimer (ECD)-single photon emission computer tomography (SPECT) (in resting condition and performing a mental calculation task) studies were analyzed. RESULTS: Main neurologic findings were brachycephalia, right-side neurologic soft signs, obsessive personality profile, low color-word interference effect in Stroop test, and diffuse increased cerebral blood flow during calculation task in 99mTc-ECD SPECT. MRI showed anatomical temporal plane inverse asymmetry. CONCLUSIONS: Evidence appears to support the hypothesis that savant skill is related to excessive and erroneous use of cognitive processing resources instigated by probable failure in central executive control mechanisms.