Harmonized-Multinational qEEG norms (HarMNqEEG).

This paper extends frequency domain quantitative electroencephalography (qEEG) methods pursuing higher sensitivity to detect Brain Developmental Disorders. Prior qEEG work lacked integration of cross-spectral information omitting important functional connectivity descriptors. Lack of geographical diversity precluded accounting for site-specific variance, increasing qEEG nuisance variance. We ameliorate these weaknesses. (i) Create lifespan Riemannian multinational qEEG norms for cross-spectral tensors. These norms result from the HarMNqEEG project fostered by the Global Brain Consortium. We calculate the norms with data from 9 countries, 12 devices, and 14 studies, including 1564 subjects. Instead of raw data, only anonymized metadata and EEG cross-spectral tensors were shared. After visual and automatic quality control, developmental equations for the mean and standard deviation of qEEG traditional and Riemannian DPs were calculated using additive mixed-effects models. We demonstrate qEEG "batch effects" and provide methods to calculate harmonized z-scores. (ii) We also show that harmonized Riemannian norms produce z-scores with increased diagnostic accuracy predicting brain dysfunction produced by malnutrition in the first year of life and detecting COVID induced brain dysfunction. (iii) We offer open code and data to calculate different individual z-scores from the HarMNqEEG dataset. These results contribute to developing bias-free, low-cost neuroimaging technologies applicable in various health settings.

Volume Reduction Techniques for the Classification of Independent Components of rs-fMRI Data: a Study with Convolutional Neural Networks.

In the last decade, neurosciences have had an increasing interest in resting state functional magnetic resonance imaging (rs-fMRI) as a result of its advantages, such as high spatial resolution, compared to other brain exploration techniques. To improve the technique, the elimination of artifacts through Independent Components Analysis (ICA) has been proposed, as this can separate neural signal and noise, opening possibilities for automatic classification. The main classification techniques have focused on processes based on typical machine learning. However, there are currently more robust approaches such as convolutional neural networks, which can deal with complex problems directly from the data without feature selection and even with data that does not have a simple interpretation, being limited by the amount of data necessary for training and its high computational cost. This research focused on studying four methods of volume reduction mitigating the computational cost for the training of 3 models based on convolutional neural networks. One of the reduction techniques is a novel approach that we call Reduction by Consecutive Binary Patterns (RCBP), which was shown to preserve the spatial features of the independent components. In addition, the RCBP showed networks in components associated with neuronal activity more clearly. The networks achieved accuracy above 98 % in classification, and one network was even found to be over 99 % accurate, outperforming most machine learning-based classification algorithms.

Neurophysiological changes associated with training in laparoscopic surgery using EEG: a pilot study.

Laparoscopy is a minimally invasive technique that requires surgeons to acquire special motor skills derived from an extensive training. This work focuses on exploring the neurophysiological changes associated with motor learning. Electroencephalographic (EEG) signals were recorded from eight subjects while performing a bimanual coordination task in a laparoscopic simulator. Spectral power measurements in theta, alpha and beta bands during four training sessions were calculated. Power indices, task score and perception of mental workload were evaluated using analysis of variance to show the effect of training session. Results show improvements in task performance and changes in power measurements associated with the training process. This work opens the possibility to assess the training performance of surgical residents using electrophysiological recordings.

Quantitative EEG analysis disease during resting and memory task in carriers and non-carriers of PS-1 E280A mutation of familial Alzheimer's / Análisis del EEG cuantitativo durante tareas de memoria y reposo en portadores y no portadores de la mutación PS-1 E280A de la enfermedad de Alzheimer

ABSTRACT Background: Alzheimer's disease is the most leading cause of dementia in the world; the mutation PS-1 E280A alters the gene of the Presenilin-1 and causes an early onset familial Alzheimer's disease. This mutation has been found in large kindred of Antioquia, Colombia. The objective of this study was to find differences revealed by electroencephalogram between healthy subjects and asymptomatic carriers that can be used as clinical markers of the disease in this population. Methods: EEG was recorded in 15 asymptomatic E280A carriers and 15 healthy non carriers during resting and a memory task using 64 channels amplifier. Two conditions in the memory task were analyzed: encoding and retrieval, the process of recording and evocating information, respectively. Power spectrum was calculated in delta (0. 5-4. 0 Hz), theta (4. 0-8. 0 Hz), alpha-1 (8. 0-10. 0 Hz), alpha-2 (10. 0-13. 0 Hz), beta (13. 0-25. 0 Hz) and gamma (25. 0-50 Hz) frequency bands for four regions of interest. Changes were evaluated in different conditions by ANOVA analysis.. Results: In resting condition a significant decrease was found in theta (p=0. 0001) and an increase in alpha-2 frequencies (p=0.037) in carriers compare with controls. During encoding of the memory task theta was significantly lower in carriers compared with controls (p=0. 008) and comparing resting versus retrieval process for each group, there was more theta synchronization in carriers. Conclusions: Early changes in theta frequencies were observed in the EEG recordings, it could be use as clinical markers in this population. Also it seems carriers activate additional cortical regions in order to conserve successful cognitive functions before clinical impairment.

RESUMEN Introducción: la enfermedad de Alzheimer es la principal causa de demencia en el mundo; la mutación PS-1 E280A altera el gen presenilin-1 y causa una variante familiar de la enfermedad que se caracteriza por una aparición temprana. La mutación se ha descubierto en un grupo de familias de Antioquia, Colombia. El objetivo de este estudio fue encontrar diferencias, a partir de registros electroencefalográficos de personas portadores de la mutación en una etapa asintomática y sujetos sanos para evaluar si pueden ser utilizadas como un marcador temprano de la enfermedad en la población portadora de la mutación. Metodología: se realizaron registros EEG en 15 portadores asintomáticos de la mutación E280A y 15 personas sanas no portadoras durante una tarea de memoria y en reposo utilizando un amplificador de 64 canales. En la tarea de memoria se evaluaron dos condiciones: codificación y evocación; el proceso de memorizar y recuperar la información, respectivamente. La potencia espectral fue calculada en las bandas de frecuencia delta (0,5-4,0 Hz), teta (4,0-8,0 Hz), alfa-1 (8,0-10,0 Hz), alfa-2 (10,0-13,0 Hz), beta (13,0-25,0 Hz) y gamma (25,0-50 Hz) para cuatro regiones de interés. Los cambios del espectro fueron evaluados por análisis de varianza ANOVA. Resultados: bajo la condición de reposo se encontró una disminución importante en la potencia de la banda teta (p=0,0001) y un incremento en la banda alfa-2 (p=0,037) en portadores comparados con controles. Durante la tarea de codificación, los portadores mostraron una disminución significativa en la banda teta (p=0,008). Al comparar reposo contra memoria de evocación se encontró una mayor sincronización en teta en los portadores de la mutación. Conclusión: se encontraron cambios tempranos de la potencia en la banda teta que pueden ser utilizados como un marcador clínico de la enfermedad en esta población. Una hipótesis adicional basada en los resultados es que los portadores necesitan ...