PT  - JOURNAL ARTICLE
AU  - Kay Robbins
AU  - Dung Truong
AU  - Stefan Appelhoff
AU  - Arnaud Delorme
AU  - Scott Makeig
TI  - Capturing the nature of events and event context using Hierarchical Event Descriptors (HED)
AID  - 10.1101/2021.05.06.442841
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.05.06.442841
4099  - http://biorxiv.org/content/early/2021/05/07/2021.05.06.442841.short
4100  - http://biorxiv.org/content/early/2021/05/07/2021.05.06.442841.full
AB  - Because of the central role that event-related data analysis plays in EEG and MEG (MEEG) experiments, choices about which events to report and how to annotate their full natures can significantly influence the reliability, reproducibility, and value of MEEG datasets for further analysis. Current, more powerful annotation strategies combine robust event description with details of experiment design and metadata in a human-readable as well as machine-actionable form, making event annotation relevant to the full range of neuroimaging and other time series data. This paper dissects the event design and annotation process using as a case study the well-known multi-subject, multimodal dataset of Wakeman and Henson (openneuro.org, ds000117) shared by its authors using Brain Imaging Data Structure (BIDS) formatting (bids.neuroimaging.io). We propose a set of best practices and guidelines for event handling in MEEG research, examine the impact of various design decisions, and provide a working template for organizing events in MEEG and other neuroimaging data. We demonstrate how annotations using the new third-generation formulation of the Hierarchical Event Descriptors (HED-3G) framework and tools (hedtags.org) can document events occurring during neuroimaging experiments and their interrelationships, providing machine-actionable annotation enabling automated both within- and across-study comparisons and analysis, and point to a more complete BIDS formatted, HED-3G annotated edition of the MEEG portion of the Wakeman and Henson dataset (OpenNeuro ds003645).Competing Interest StatementThe authors have declared no competing interest.