Reading NWB Files

This section provides an overview of reading and exploring NWB (Neurodata Without Borders) files with MatNWB. It serves as a reference guide to the functions and data objects you’ll interact with when working with NWB files. For detailed code examples and usage demonstrations, please refer to the tutorials.

To read an NWB file, use the nwbRead() function:

nwb = nwbRead('path/to/file.nwb');

This command performs several important tasks behind the scenes:

  1. Opens the file and reads its structure

  2. Automatically generates MATLAB classes needed to work with the data

  3. Returns an NwbFile object representing the entire file

The returned NwbFile object is the primary access point for all the data in the file. In the next section, we will examine the structure of this object in detail, covering how to explore it using standard MATLAB dot notation to access experimental metadata, raw recordings, processed data, and analysis results, as well as how to search for specific data types.

Important

Lazy Loading: MatNWB uses lazy reading to efficiently work with large datasets. When you access a dataset through the NwbFile object, MatNWB returns a types.untyped.DataStub object instead of loading the entire dataset into memory. This allows you to:

  • Work with files larger than available RAM

  • Read only the portions of data you need

  • Index into datasets using standard MATLAB array syntax

  • Load the full dataset explicitly using the .load() method

For more details, see DataStubs and DataPipes.

Note

The nwbRead() function currently does not support reading NWB files stored in Zarr format.

Next steps

The following pages provide detailed information on specific aspects of reading NWB files: