Linear and nonlinear analysis of intrinsic mode function after facial stimuli presentation in children with autism spectrum disorder.

In this work, a method for classifying Autism Spectrum Disorders (ASD) from typically developing (TD) children is presented using the linear and nonlinear Event-Related Potential (ERP) analysis of the Electro-encephalogram (EEG) signals. The signals were acquired during the presentation of three types of face expression stimuli -happy, fearful and neutral faces. EEGs are first decomposed using the Multivariate Empirical Mode Decomposition (MEMD) method to extract its Intrinsic Mode Functions (IMFs), which provide information about the underlying activities of ERP components. The nonlinear sample entropy (SampEn) features, as well as the standard linear measurements utilizing maximum (Max.), minimum (Min), and standard deviation (Std.), are then extracted from each set of IMFs. These features are then evaluated by the statistical analysis tests and used to construct the input vectors for the Discriminant analysis (DA), Support vector machine (SVM), and k-Nearest Neighbors (kNN) classifiers. Experimental results show that the proposed features can differentiate the ASD and TD children using the happy stimulus dataset with high classification performance for all classifiers that reached 100% accuracy. This result suggests a general deficit in recognizing the positive expression in ASD children. Additionally, we found that the SampEn measurements computed from the alpha and theta bands and the linear features extracted from the delta band can be considered biomarkers for disturbances in Emotional Facial Expression (EFE) processing in ASD children.

Cognitive Outcome Prediction in Infants With Neonatal Hypoxic-Ischemic Encephalopathy Based on Functional Connectivity and Complexity of the Electroencephalography Signal.

Impaired neurodevelopmental outcome, in particular cognitive impairment, after neonatal hypoxic-ischemic encephalopathy is a major concern for parents, clinicians, and society. This study aims to investigate the potential benefits of using advanced quantitative electroencephalography analysis (qEEG) for early prediction of cognitive outcomes, assessed here at 2 years of age. EEG data were recorded within the first week after birth from a cohort of twenty infants with neonatal hypoxic-ischemic encephalopathy (HIE). A proposed regression framework was based on two different sets of features, namely graph-theoretical features derived from the weighted phase-lag index (WPLI) and entropies metrics represented by sample entropy (SampEn), permutation entropy (PEn), and spectral entropy (SpEn). Both sets of features were calculated within the noise-assisted multivariate empirical mode decomposition (NA-MEMD) domain. Correlation analysis showed a significant association in the delta band between the proposed features, graph attributes (radius, transitivity, global efficiency, and characteristic path length) and entropy features (Pen and SpEn) from the neonatal EEG data and the cognitive development at age two years. These features were used to train and test the tree ensemble (boosted and bagged) regression models. The highest prediction performance was reached to 14.27 root mean square error (RMSE), 12.07 mean absolute error (MAE), and 0.45 R-squared using the entropy features with a boosted tree regression model. Thus, the results demonstrate that the proposed qEEG features show the state of brain function at an early stage; hence, they could serve as predictive biomarkers of later cognitive impairment, which could facilitate identifying those who might benefit from early targeted intervention.