Folders¶

The BIDS format is essentially a way to structure your data / metadata within a hierarchy of folders. This makes it easy to browse from a computer, as well as to automatically parse a BIDS folder with a program. The BIDS structure makes minimal assumptions about the tools needed to interact with the data that’s inside.

The files in present in BIDS dataset are organized into a hierarchy of folders that have specific naming conventions.

The rest of this page describes how these folders are structured.

Overview¶

There are four main levels of the folder hierarchy, these are:

project/
└── subject
    └── session
        └── datatype

With the exception of the top-level project folder, all sub-folders have a specific structure to their name (described below). Here’s an example of how this hierarchy looks:

myProject/
└── sub-01
    └── ses-01
        └── anat

Here is the folder name structure of each level:

project¶

Can have any name, this should be descriptive for the dataset contained in the folder.

subject¶

Structure: sub-<participant label>

One folder per subject in this dataset. Labels should be unique for each subject.

session¶

Structure: ses-<session label>

In general, a session represents a recording session, and subjects will stay in the scanner or headset during that session. You might have multiple sessions per subject if you collected data from them on several occasions. If there is only a single session per subject, this level of the hierarchy may be omitted.

For more details, refer to this section of the FAQ.

datatype¶

Represents different types of data. Must be one of:

anat: anatomical MRI data
func: functional MRI data
fmap: fieldmap data
dwi: diffusion MRI data
perf: arterial spin labeling data
eeg: electroencephalography data
meg: magnetoencephalography data
ieeg: intracranial EEG data
beh: behavioral data
pet: positron emission tomography data
micr: microscopy data
nirs: near-infrared spectroscopy data
motion: motion capture data

The name for the datatype depends on the recording modality.

	modality
datatype	MRI	PET	meeg	behavioral	microscopy	NIRS	motion
	anat	pet	eeg	beh	micr	nirs	motion
	func		meg
	dwi		ieeg
	perf

BIDS folder example¶

Below is the folder hierarchy for one of the BIDS example datasets. It has multiple subjects of data, and includes metadata files (.tsv and .json) both between- and within-subjects.

Note that it has one session per subject, so this level is omitted.

ds001
├── dataset_description.json
├── participants.tsv
├── sub-01
│   ├── anat
│   │   ├── sub-01_inplaneT2.nii.gz
│   │   └── sub-01_T1w.nii.gz
│   └── func
│       ├── sub-01_task-balloonanalogrisktask_run-01_bold.nii.gz
│       ├── sub-01_task-balloonanalogrisktask_run-01_events.tsv
│       ├── sub-01_task-balloonanalogrisktask_run-02_bold.nii.gz
│       ├── sub-01_task-balloonanalogrisktask_run-02_events.tsv
│       ├── sub-01_task-balloonanalogrisktask_run-03_bold.nii.gz
│       └── sub-01_task-balloonanalogrisktask_run-03_events.tsv
├── sub-02
│   ├── anat
│   │   ├── sub-02_inplaneT2.nii.gz
│   │   └── sub-02_T1w.nii.gz
│   └── func
│       ├── sub-02_task-balloonanalogrisktask_run-01_bold.nii.gz
│       ├── sub-02_task-balloonanalogrisktask_run-01_events.tsv
│       ├── sub-02_task-balloonanalogrisktask_run-02_bold.nii.gz
│       ├── sub-02_task-balloonanalogrisktask_run-02_events.tsv
│       ├── sub-02_task-balloonanalogrisktask_run-03_bold.nii.gz
│       └── sub-02_task-balloonanalogrisktask_run-03_events.tsv
...
...
└── task-balloonanalogrisktask_bold.json

BIDS starter kit

Folders

Contents