EEG-BIDS, an extension to the brain imaging data structure for electroencephalography

Abstract

The Brain Imaging Data Structure (BIDS) project is a rapidly evolving effort in the human brain imaging research community to create standards allowing researchers to readily organize and share study data within and between laboratories. Here we present an extension to BIDS for electroencephalography (EEG) data, EEG-BIDS, along with tools and references to a series of public EEG datasets organized using this new standard.

Fig. 1

Exemplary EEG-BIDS dataset with previews of EEG files. The left side of the figure shows a standard BIDS directory tree with the root containing files describing the dataset in general (“README”, “dataset_description.json”), a file describing the participants (“participants.tsv”), and as several JSON files (“participants.json”, “task-TASKNAME_events.json”), which contain the description necessary to understand the contents of the TSV files. Note that JSON files at high levels get inherited by lower levels unless overridden (the Inheritance Principle). Next to the files at the root, there is a stimuli and a sourcedata directory that can be used to save the respective study data. Most important are the subject directories named “sub-  ” for each study participant. Nested in the subject directories are all recorded data split over modalities (eeg and anat, for the EEG and structural MRI data respectively). The right side of the figure shows the contents of the eeg modality directory, including the raw EEG data (1) and associated metadata (2). An events.tsv file (3) specifies all events that were recorded during the session and can reference presented stimuli with the stimuli directory of the dataset (see stim_file column). A “channels.tsv” file (4) provides further information about the raw EEG data and can contain information not present in the raw EEG data file such as filter settings and channel status (good/bad). Finally, an “electrodes.tsv” file (5) and an accompanying “coordsystem.json” file (6) provide electrode locations and specify which coordinate framework to use to interpret the electrode locations (for example with respect to a T1 weighted MRI scan).