The blessing of Dimensionality: Feature Selection outperforms functional connectivity-based feature transformation to classify ADHD subjects from EEG patterns of phase synchronisation

• Published in: PloS one Vol. 13; no. 8; p. e0201660
• Main Authors: Pereda, Ernesto, García-Torres, Miguel, Melián-Batista, Belén, Mañas, Soledad, Méndez, Leopoldo, González, Julián J.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.08.2018; Public Library of Science (PLoS)
• Subjects: Adolescent; Algorithms; Artificial intelligence; Attention Deficit Disorder with Hyperactivity - diagnosis; Attention Deficit Disorder with Hyperactivity - physiopathology; Attention deficit hyperactivity disorder; Biology and Life Sciences; Brain; Brain - physiopathology; Child; Children; Classification; Computer and Information Sciences; Computer engineering; Connectome - methods; Dependence; EEG; Electroencephalography; Electroencephalography Phase Synchronization; Female; Humans; Image Processing, Computer-Assisted; Indexing; Learning algorithms; Machine Learning; Male; Mathematical analysis; Matrix methods; Medical imaging; Medicine and Health Sciences; Methods; Neural networks; Neuroimaging; Neurophysiology; NMR; Nuclear magnetic resonance; Pattern classification; Pattern Recognition, Automated; Physical Sciences; Research and Analysis Methods; Signal processing; Teaching hospitals; Transformation; Tenerife; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0201660

Functional connectivity (FC) characterizes brain activity from a multivariate set of N brain signals by means of an NxN matrix A, whose elements estimate the dependence within each possible pair of signals. Such matrix can be used as a feature vector for (un)supervised subject classification. Yet if N is large, A is highly dimensional. Little is known on the effect that different strategies to reduce its dimensionality may have on its classification ability. Here, we apply different machine learning algorithms to classify 33 children (age [6-14 years]) into two groups (healthy controls and Attention Deficit Hyperactivity Disorder patients) using EEG FC patterns obtained from two phase synchronisation indices. We found that the classification is highly successful (around 95%) if the whole matrix A is taken into account, and the relevant features are selected using machine learning methods. However, if FC algorithms are applied instead to transform A into a lower dimensionality matrix, the classification rate drops to less than 80%. We conclude that, for the purpose of pattern classification, the relevant features should be selected among the elements of A by using appropriate machine learning algorithms.