[ENH] BEP044 - Stim-BIDS

mkdocs.yml

@@ -20,6 +20,7 @@ nav:
           - Near-Infrared Spectroscopy: modality-specific-files/near-infrared-spectroscopy.md
           - Motion: modality-specific-files/motion.md
           - Magnetic Resonance Spectroscopy: modality-specific-files/magnetic-resonance-spectroscopy.md
+          - Stimuli: modality-specific-files/stimuli.md
       - Derivatives:
           - BIDS Derivatives: derivatives/introduction.md
           - Common data types and metadata: derivatives/common-data-types.md

src/modality-specific-files/stimuli.md

@@ -0,0 +1,161 @@
+# Stimuli
+
+## Stimulus Files Organization
+
+Stimulus files MUST be stored in the `/stimuli` directory under the root directory of the dataset.
+The `/stimuli` directory can contain subdirectories to organize the stimulus files.
+Stimulus files MUST follow the BIDS naming conventions and are referenced in the `events.tsv`
+file using the `stim_id` column.
+
+The standardization of stimulus files and their annotations within BIDS offers several key benefits:
+
+1.  **Consistency**: Ensures uniform storage and referencing across datasets
+1.  **Reusability**: Enables stimulus reuse across studies through standardized structure
+1.  **Efficiency**: Minimizes redundancy by centralizing annotations
+1.  **Flexibility**: Facilitates dataset reuse with alternative annotations
+
+To preserve backward compatibility with existing datasets (see the Legacy section below), the use of these specifications for `/stimuli` directory and the `stim_id` column in the `events.tsv` files is RECOMMENDED but not required. Researchers are encouraged to follow these guidelines to enhance the interoperability and reproducibility of their studies.
+
+Following these guidelines will help ensure that stimulus files and their annotations are stored and referenced consistently across different datasets, facilitating data sharing, reuse, and reproducibility.
+
+## File Organization
+
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+   "stimuli": {
+    "stimuli.tsv": "",
+    "stimuli.json": "",
+    "[stim-<label>[_part-<label>]_<suffix>.<extension>]": "",
+    "[stim-<label>[_part-<label>]_<suffix>.json]": "",
+    "[[stim-<label>_]annotations.tsv]": "",
+    "[[stim-<label>_]annotations.json]": "",
+    "[stim-<label>[_part-<label>]_annot-<label>_events.tsv]": "",
+    "[stim-<label>[_part-<label>]_annot-<label>_events.json]": ""
+    }
+  }) }}
+
+Note: The presence of `stimuli.tsv` file indicates that the content of the `/stimuli` directory follows this BIDS specification for stimulus organization. This structure is planned to become mandatory in BIDS 2.0.
+
+### Stimulus File Formats
+
+The following table lists the supported stimulus file formats and their corresponding suffixes. The suffixes are used to identify the type of stimulus file and are appended to the `stim-<label>` prefix in the file name.
+
+| suffix      | extensions                      | description                  |
+| ----------- | ------------------------------- | ---------------------------- |
+| audio       | `.wav`, `.mp3`, `.aac`, `.ogg`  | Audio-only stimulus files    |
+| image       | `.jpg`, `.png`, `.svg`          | Static visual stimulus files |
+| video       | `.mp4`, `.avi`, `.mkv`, `.webm` | Video-only stimulus files    |
+| audiovideo  | `.mp4`, `.avi`, `.mkv`, `.webm` | Combined audio-visual files  |
+
+## Stimulus description (`stim-<label>_<suffix>.json`)
+
+The `stim-<label>_<suffix>.json` file provides metadata about the _singular_ stimulus file.
+The following fields are defined to describe the stimulus file:
+
+<!-- This block generates a metadata table.
+These tables are defined in
+  src/schema/rules/sidecars
+The definitions of the fields specified in these tables may be found in
+  src/schema/objects/metadata.yaml
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_sidecar_table("stimuli.Stimuli") }}
+
+In some cases, such as observing the copyright of a stimulus file, the actual stimulus file may not be shared. In such cases, the `stim-<label>_<suffix>.json` file SHOULD be used to provide metadata about the stimulus file, including the license, copyright, URL, and description.
+
+### Example `stim-<label>_<suffix>.json`
+
+```JSON
+{
+    "License": "CC-BY-4.0",
+    "Copyright": "Lab 2023",
+    "URL": "https://example.com/stimuli/",
+    "Description": "Collection of face images, tones, and movie clips used in the experiment"
+}
+```
+
+## Stimuli Description (`stimuli.tsv`)
+
+The `stimuli.tsv` files are used to provide information about the stimuli based on their `stim_id`. This file is similar in usage as `participants.tsv`, `scans.tsv` and `sessions.tsv`, which list descriptions about subjects, scans and sessions, respectively. The `stimluli.tsv` files MUST be placed in the `/stimuli` directory.
+
+The `stimuli.tsv` file contains information about each stimulus, including stimulus ID, type, URL, and other relevant details. The following table describes the REQUIRED, RECOMMENDED, and OPTIONAL columns for the `stimuli.tsv` file:
+
+<!-- This block generates a columns table.
+The definitions of these fields can be found in
+  src/schema/rules/tabular_data/*.yaml
+and a guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_columns_table("stimuli.Stimuli") }}
+
+### Example `stimuli.tsv`
+
+```Text
+stimulus_id    type     URL                                     license      copyright    description                                  present
+stim-face01   image    https://example.com/faces/face01.jpg    CC-BY-4.0   Lab 2023    A female face with neutral expression       true
+stim-tone01   audio    https://example.com/tones/tone01.wav    CC-BY-4.0   Lab 2023    A 440Hz pure tone                          true
+stim-movie01  video    https://example.com/movies/movie01.mp4  n/a         Studio XYZ  A clip from copyrighted movie              false
+```
+
+The `stimuli.json` file provides detailed descriptions of the columns in the `stimuli.tsv` file. There MAY be extra entries in the `stimuli.json` in addition to the columns in the `stimuli.tsv` to provide more details about the stimulus.
+
+In cases where the stimulus is not shared, the `stimuli.tsv` file can be used to provide metadata about the stimuli, including the license, copyright, URL, and description. This is similar to the use of `stim-<label>_<suffix>.json` files for individual stimuli files. In the case of conflict between the metadata in the `stimuli.tsv` and `stim-<label>_<suffix>.json` files, the metadata in the `stim-<label>_<suffix>.json` file takes precedence.
+
+## Stimulus Annotations
+
+Annotations of the still images or general description of the stimuli (such as frequency and duration of a beep sound) can be stored in the `stimuli.tsv` as an additional column or `stim-<label>_<suffix>.json` as described above. Here is an example of how annotations can be stored in the `stimuli.tsv` file for an image from the Natural Scene Dataset (NSD):
+
+| stimulus_id   | type  | description                                           | HED                                                                                                                                                               | NSD_id | COCO_id |
+| ------------- | ----- | ----------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------ | ------- |
+| stim-nsd02951 | image | an open market full of people and piles of vegetables | ((Item-count, High), Ingestible-object), (Background-view, ((Human, Body, Agent-trait/Adult), Outdoors, Furnishing, Natural-feature/Sky, Urban, Man-made-object)) | 2951   | 262145  |
+
+However, for time-varying stimuli, such as audio or video, it is RECOMMENDED to use specific annotations files in the form of `stim-<label>_annot-<label>_events.tsv` to store the annotations. These files have the same structure as the `events.tsv` files and are used to store annotations for the stimuli. There can be multiple annotation files for a single stimulus file, each with a unique annotation label. The annotation files MUST be stored in the `/stimuli` directory.
+
+## Annotation Description (`annotations.tsv`)
+
+The `annotations.tsv` file contains additional metadata about stimulus annotations. There MAY be a single `annotations.tsv` file for all the stimuli or separate `stim-<label>_annotations.tsv` files for each stimulus.
+The following columns are defined for the `annotations.tsv` file:
+
+<!-- This block generates a columns table.
+The definitions of these fields can be found in
+  src/schema/rules/tabular_data/*.yaml
+and a guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_columns_table("stimuli.Annotations") }}
+
+### Example `*_annotations.tsv`
+
+```Text
+annot_id     description
+face01_emo   Emotion annotation for face01 stimulus
+face01_gen   Gender annotation for face01 stimulus
+face01_age   Age group annotation for face01 stimulus
+```
+
+## Referencing Stimulus Identifiers in `events.tsv`
+
+To reference stimulus identifiers in the `events.tsv` file, use the `stim_id` column. The values in the `stim_id` column should represent unique identifiers for the stimuli. Stimulus ID (`stim_id`) should correspond to the unique identifier of the stimulus file in the /stimuli directory and expands to all files (both stimulus and annotation files) that share the same stimulus ID.
+
+Example `events.tsv` file:
+
+| onset | duration | trial_type | response_time | stim_id        |
+| ----- | -------- | ---------- | ------------- | -------------- |
+| 1.23  | 0.65     | start      | 1.435         | `stim-<label>` |
+| 5.65  | 0.65     | stop       | 1.739         | `stim-<label>` |
+| 12.1  | 2.35     | n/a        | n/a           | `stim-<label>` |
+
+In the accompanying JSON sidecar, the `stim_id` column might be described as follows:
+
+```JSON
+{
+    "stim_id": {
+        "LongName": "Stimulus identifier",
+        "Description": "Represents a unique identifier for the stimulus presented at the given onset time."
+    }
+}
+```

src/modality-specific-files/task-events.md

@@ -400,3 +400,106 @@ A guide for using macros can be found at
 Additional metadata may be included as in
 [any TSV file](../common-principles.md#tabular-files) to specify, for
 example, the units of the recorded time series for each column.
+
+## Standardization of Stimulus Files and Annotations
+
+To ensure consistency and facilitate reuse, the BIDS specifications provide guidelines for standardizing stimulus files and their annotations. This section outlines the recommended practices for storing and referencing stimulus files within a BIDS dataset.
+
+### Storing Stimulus Files
+
+Stimulus files should be stored in the `/stimuli` directory under the root directory of the dataset. The `/stimuli` directory can contain subdirectories to organize the stimulus files. There are no restrictions on the file formats of the stimulus files.
+
+Example directory structure:
+
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+  "stimuli": {
+    "images": {
+      "cat01.jpg": "",
+      "cat02.jpg": "",
+    },
+    "videos": {
+      "movie01.mp4": "",
+      "movie02.mp4": "",
+    },
+  },
+}) }}
+
+### Referencing Stimulus Files in `events.tsv`
+
+To reference stimulus files in the `events.tsv` file, use the `stim_file` column. The values in the `stim_file` column should represent the relative path to the stimulus file within the `/stimuli` directory.
+
+Example `events.tsv` file:
+
+```Text
+onset	duration	trial_type	response_time	stim_file
+1.23	0.65	start	1.435	images/cat01.jpg
+5.65	0.65	stop	1.739	images/cat02.jpg
+12.1	2.35	n/a	n/a	videos/movie01.mp4
+```
+
+In the accompanying JSON sidecar, the `stim_file` column might be described as follows:
+
+```JSON
+{
+    "stim_file": {
+        "LongName": "Stimulus file",
+        "Description": "Represents the location of the stimulus file (such as an image, video, or audio file) presented at the given onset time. The values correspond to a path relative to the /stimuli directory."
+    }
+}
+```
+
+### Referencing Stimulus Identifiers in `events.tsv`
+
+To reference stimulus identifiers in the `events.tsv` file, use the `stim_id` column. The `stim_id` corresponds to the unique identifier of the stimulus files and their annotations stored under the `/stimuli` directory. This allows linking each event to multiple related files associated with that stimulus.
+
+Example `events.tsv` file:
+
+```Text
+onset	duration	trial_type	response_time	stim_id
+1.23	0.65	start	1.435	stim-face01
+5.65	0.65	stop	1.739	stim-face02
+12.1	2.35	n/a	n/a	stim-video01
+```
+
+In the accompanying JSON sidecar, the `stim_id` column might be described as follows:
+
+```JSON
+{
+    "stim_id": {
+        "LongName": "Stimulus identifier",
+        "Description": "Represents a unique identifier for the stimulus presented at the given onset time. Links to files and annotations in the /stimuli directory."
+    }
+}
+```
+
+The `stim_id` in the events file links to corresponding files:
+
+```Text
+stimuli/
+├── stim-face01_image.jpg
+├── stim-face01_image.json
+├── stim-face01_annotations.tsv
+├── stim-face02_image.jpg
+├── stim-face02_image.json
+├── stim-face02_annotations.tsv
+├── stim-face02_annotations.tsv
+├── stimuli.tsv
+└── stimuli.json
+```
+
+By using `stim_id`, multiple annotations and stimulus files associated with the same identifier can be efficiently linked to events in the `events.tsv` file. The `stim_id` is a unique identifier for the stimulus that can be used to reference the stimulus files, annotations, and metadata stored in `stimuli.tsv` and `stimuli.json`. For more information on the structure of stimulus files and annotations, refer to the [Stimuli](./stimuli.md) BIDS specifications.
+
+### Advantages of Standardization
+
+Standardizing stimulus files and their annotations within the BIDS specifications offers several advantages:
+
+1.  **Consistency**: Ensures that stimulus files are stored and referenced in a consistent manner across different datasets.
+1.  **Reusability**: Facilitates the reuse of stimulus files and annotations in other studies by providing a standardized structure.
+1.  **Efficiency**: Reduces redundancy by avoiding the need to replicate annotations across subjects, modalities, tasks, and runs.
+1.  **Flexibility**: Allows for easy modification of annotations by updating a single file, enabling the reuse of datasets with alternative annotations.
+
+By following these guidelines, researchers can enhance the interoperability and reproducibility of their studies, making it easier to share and reuse data within the scientific community.

src/schema/objects/columns.yaml

@@ -585,6 +585,15 @@ stim_file:
     For example `images/cat03.jpg` will be translated to `/stimuli/images/cat03.jpg`.
   type: string
   format: stimuli_relative
+stim_id:
+  name: stim_id
+  display_name: Stimulus identifier
+  description: |
+    Represents a unique identifier for the stimulus presented at the given onset
+    time. The `stim_id` is inclusive of the stimulus file(s), annotations
+    related to the stimulus, and the information about the stimulus present in
+    the `stimuli.tsv` file.
+  type: string
 strain:
   name: strain
   display_name: Strain

src/schema/objects/datatypes.yaml

@@ -65,3 +65,7 @@ nirs:
   value: nirs
   display_name: Near-Infrared Spectroscopy
   description: Near-Infrared Spectroscopy data organized around the SNIRF format
+stimuli:
+  value: stimuli
+  display_name: Stimulus
+  description: Stimulus

src/schema/objects/entities.yaml

@@ -194,20 +194,12 @@ part:
   name: part
   display_name: Part
   description: |
-    This entity is used to indicate which component of the complex
-    representation of the MRI signal is represented in voxel data.
-    The `part-<label>` entity is associated with the DICOM Tag
-    `0008, 9208`.
-    Allowed label values for this entity are `phase`, `mag`, `real` and `imag`,
-    which are typically used in `part-mag`/`part-phase` or
-    `part-real`/`part-imag` pairs of files.
-
-    Phase images MAY be in radians or in arbitrary units.
-    The sidecar JSON file MUST include the `"Units"` of the `phase` image.
-    The possible options are `"rad"` or `"arbitrary"`.
-
-    When there is only a magnitude image of a given type, the `part` entity MAY be
-    omitted.
+    This entity is used to indicate which component of a complex
+    representation is being stored. For MRI data, it indicates which component
+    of the complex signal is represented in voxel data. For stimulus files, it can
+    be used to distinguish different parts of a single stimulus, such as chapters
+    in an audiobook or segments of a long movie (for example, `part-1`, `part-2`,
+    `part-epilog`, `part-chapter1`).
   type: string
   format: label
   enum:
@@ -373,6 +365,19 @@ stain:
     and/or `"SampleSecondaryAntibodies"` metadata fields, as appropriate.
   type: string
   format: label
+stimulus:
+  name: stim
+  display_name: Stimulus
+  description: |
+    The `stim-<label>` entity can be used to distinguish different stimulus files
+    or annotations. The label is a unique identifier for the stimulus or annotation.
+
+    This entity represents the `"Stimulus"` metadata field and requires corresponding
+    entries in the `stimuli.tsv` file. Therefore, if the `stim-<label>` entity is
+    present in a filename, `"Stimulus"` MUST be defined in the associated metadata,
+    and a matching entry MUST exist in the `stimuli.tsv` file.
+  type: string
+  format: label
 subject:
   name: sub
   display_name: Subject
@@ -443,3 +448,13 @@ tracksys:
     may be longer and more human readable.
   type: string
   format: label
+annotation:
+  name: annot
+  display_name: Annotation
+  description: |
+    The `annot-<label>` entity accommodates multiple annotations for a single
+    (usually, but not necessarily, time-varying) stimulus id. Similar to `stimuli.tsv`,
+    there can be one or multiple `annotations.tsv` files with `annotation_id`, providing
+    a list of the annotations in the directory, or for a specific stimulus respectively.
+  type: string
+  format: label

src/schema/objects/metadata.yaml

@@ -542,6 +542,11 @@ ContrastBolusIngredient:
     # TODO: Add definitions for these values. (perhaps don't specify)
     - UNKNOWN
     - NONE
+Copyright:
+  name: Copyright
+  display_name: Copyright
+  description: Copyright information
+  type: string
 DCOffsetCorrection:
   name: DCOffsetCorrection
   display_name: DC Offset Correction
@@ -1892,6 +1897,11 @@ License:
     The corresponding full license text MAY be specified in an additional
     `LICENSE` file.
   type: string
+StimulusLicense:
+  name: License
+  display_name: License
+  description: License under which this stimulus is shared.
+  type: string
 LongName:
   name: LongName
   display_name: Long Name
@@ -3653,6 +3663,11 @@ SubjectArtefactDescription:
     If this field is set to `"n/a"`, it will be interpreted as absence of major
     source of artifacts except cardiac and blinks.
   type: string
+StimulusURL:
+  name: URL
+  display_name: URL
+  description: Location (origin) for the stimulus file.
+  type: string
 TablePosition:
   name: TablePosition
   display_name: Table Position