A Framework to Support Automated Classification and Labeling of Brain Electromagnetic Patterns

This paper describes a framework for automated classification and labeling of patterns in electroencephalographic (EEG) and magnetoencephalographic (MEG) data. We describe recent progress on four goals: 1) specification of rules and concepts that capture expert knowledge of event-related potentials (ERP) patterns in visual word recognition; 2) implementation of rules in an automated data processing and labeling stream; 3) data mining techniques that lead to refinement of rules; and 4) iterative steps towards system evaluation and optimization. This process combines top-down, or knowledge-driven, methods with bottom-up, or data-driven, methods. As illustrated here, these methods are complementary and can lead to development of tools for pattern classification and labeling that are robust and conceptually transparent to researchers. The present application focuses on patterns in averaged EEG (ERP) data. We also describe efforts to extend our methods to represent patterns in MEG data, as well as EM patterns in source (anatomical) space. The broader aim of this work is to design an ontology-based system to support cross-laboratory, cross-paradigm, and cross-modal integration of brain functional data. Tools developed for this project are implemented in MATLAB and are freely available on request

Development of Neural Electromagnetic Ontologies (NEMO): Ontology-based Tools for Representation and Integration of Event-related Brain Potentials

We describe a first-generation ontology for
representation and integration of event-related brain potentials (ERPs). The ontology is designed following OBO “best practices” and is augmented with tools to perform ontology-based labeling and annotation of ERP data, and a database that enables semantically based reasoning over these data. Because certain high-level concepts in the ERP domain are illdefined, we have developed methods to support coordinated updates to each of these three components. This approach consists of “top-down” (knowledge-driven) design and implementation, followed by “bottom-up” (data-driven) validation and refinement. Our goal is to build an ERP ontology that is logically valid, empirically sound, robust in application, and transparent to users. This ontology will be used to support sharing and meta-analysis of EEG and MEG data collected within our Neural Electromagnetic Ontologies (NEMO) project

Hierarchical Event Descriptors (HED): Semi-Structured Tagging for Real-World Events in Large-Scale EEG.

Real-world brain imaging by EEG requires accurate annotation of complex subject-environment interactions in event-rich tasks and paradigms. This paper describes the evolution of the Hierarchical Event Descriptor (HED) system for systematically describing both laboratory and real-world events. HED version 2, first described here, provides the semantic capability of describing a variety of subject and environmental states. HED descriptions can include stimulus presentation events on screen or in virtual worlds, experimental or spontaneous events occurring in the real world environment, and events experienced via one or multiple sensory modalities. Furthermore, HED 2 can distinguish between the mere presence of an object and its actual (or putative) perception by a subject. Although the HED framework has implicit ontological and linked data representations, the user-interface for HED annotation is more intuitive than traditional ontological annotation. We believe that hiding the formal representations allows for a more user-friendly interface, making consistent, detailed tagging of experimental, and real-world events possible for research users. HED is extensible while retaining the advantages of having an enforced common core vocabulary. We have developed a collection of tools to support HED tag assignment and validation; these are available at hedtags.org. A plug-in for EEGLAB (sccn.ucsd.edu/eeglab), CTAGGER, is also available to speed the process of tagging existing studies

AN INTEGRATIVE MACHINE LEARNING APPROACH FOR SMALL SAMPLES AND HIGH-DIMENSIONAL IMBALANCED DATA IN PSYCHOLOGICAL EXPERIMENT

Machine learning for classification may not be immediately useful for many contexts seen in psychology. Psychological data often limit its efficacy due to small sample size, high dimensionality, and class imbalance. The current study presents an integrative machine learning approach that can be a useful solution to the challenges encountered when the aforementioned issues are inherent in psychological data. The tested approach consists of three consecutive steps – feature selection, minority oversampling, and predictive modeling. To begin with, feature selection tackles high dimensionality and extracts important features out of original predictors, using elastic net logistic regression. Then, synthetic minority oversampling technique addresses class imbalance, generating new observations primarily for the minority class. Finally, supervised machine learning algorithms build predictive models, using the oversampled feature set. The algorithms employed in this study include support vector machine, extreme gradient boosting, deep neural network, and logistic regression. They fully exploit the small sample with leave-one-out cross-validation. The current study demonstrates the utility of the integrative classification approach with an empirical analysis on predicting suicide attempt by a sample of patients diagnosed with bipolar I disorder, using their event-related potentials (ERPs). The study shows how prediction can be improved by the integrative modeling as the first two analytical steps being added to the generic process of predictive modeling.Master of Art