The Neurodata Without Borders (NWB) data standard provides neuroscientists with a common standard to share, archive, use, and analyze neurophysiology data. NWB supports a wide range of neurophysiology data and metadata, including from intracellular and extracellular electrophysiology and optical physiology experiments. However, as new experimental and analytical methods are developed, researchers require ways to represent data from these methods within NWB. To support these novel and specialized data types, NWB allows users to create formal extensions to the core data standard.

To facilitate the development and use of NWB extensions, we present the Neurodata Extensions Catalog, a novel web archive and associated tools that enable users to easily create, search for, test, review, and install NWB extensions. As particular extensions gain traction within the community, there may be a need to integrate these extensions into the core NWB format for broader use and standardization. We have developed a formal process for reviewing proposed changes to the core NWB format so that NWB can adapt to evolving data needs in neuroscience. Finally, to demonstrate the usage of NWB extensions, the novel Neurodata Extensions Catalog, and the proposal review process, we present extensions for storing 1) hierarchical metadata for intracellular electrophysiology data and 2) task events and TTL pulses, and we discuss the current status of integrating these extensions into the core NWB format.