Frequently Asked Questions🔗

Please see instructions for data access here.

HBCD data are openly available to qualified researchers who have a legitimate research purpose and are affiliated with an institution that holds an active Federal Wide Assurance, a designation held by numerous institutions worldwide.

Please also see Executive Order 14117 that may cause data access issues for users within certain countries.

There is no direct cost or fee for HBCD data access.

The HBCD Administrative Core (HCAC) and the HBCD Data Coordinating Center (HDCC) do not provide letters that could be interpreted as endorsements for specific applications or projects proposing secondary analyses of HBCD Study data. However, we are committed to fostering open communication with the broader scientific community. To support this, we can provide a letter outlining our commitment to facilitating access to information about the HBCD Data Resource, helping researchers obtain the details they need to pursue their specific aims. To request such a letter, please contact Lilly Tureaud at ltureaud@health.ucsd.edu.

Each institution has their own definitions and requirements surrounding whether the use of the de-identified HBCD data is considered to be human subjects research. Please consult directly with your IRB.

It is prohibited to input HBCD data into generative AI tools (e.g., ChatGPT) because doing so would violate the terms of the data use agreement. These agreements strictly limit access to approved individuals to protect sensitive information. Generative AI tools process input data in ways that may result in unauthorized access or unintended use, making them unsuitable for handling restricted data.

Protocol information is provided in multiple locations as follows. Note that specific measures for proprietary instruments are generally not available.

• https://hbcdstudy.org/study-protocols/ (main study site)
• NBDC Data Access Platform Query Wizard shows survey questions and response options
• Instrument documentation pages on this site include links to source documentation and available surveys
• DCN Special Issue on HBCD: articles include descriptions of design and protocol development for certain measures

HBCD Study data includes data in both tabulated and file-based formats - see the Data Structure Overview for an explanation of how these file types.

The source element in the NBDC Data Dictionary indicates whether the data came from the caregiver, child, etc. Source is also typically included in the table name itself, with some exceptions - see Naming Conventions for details. Note that, in the HBCD Study, all data are collected under the child’s subject ID, even when provided by the birth parent or another caregiver. This is because most information collected from caregivers pertains to the child. Please see details of the design logic here.

See Age Variable Definitions for full documentation. In brief:

• Global, single-point variables in Basic Demographics represent static age values.
• Instrument-specific variables represent age at the time of administration and may vary across instruments.
• Raw BIDS metadata (MRI, EEG, and wearable sensor data) age fields report age based on the date of data acquisition.

Instrument table and field names may contain either single or double underscores. Single underscores separate main naming components (e.g. the domain or source of the data) while double underscores separate subcomponents that provide additional details nested within the main naming components. See Naming Conventions for full details.

Please see HBCD Study MRI Protocols.

MRI scanner information, including scanner manufacturer, model, software, and serial_number, can be found in the raw BIDS data, including the session-level scans TSV files (sub-[ID]_ses-[V0X]_scans.tsv) and imaging file JSON metadata. Scanner information may be additionally provided as tabulated data in a future release.

Please refer to the HBCD Processing Pipelines for an overview of the pipelines and software standards. For full documentation on how each pipeline was used for HBCD processing, please visit the external HBCD Processing page.

FreeSurfer outputs, generated as part of Infant-fMRIPrep pipeline processing, are included in the data release within the freesurfer/ folder of the derivatives. However, note that an alternative surface reconstruction workflow optimized for neonates, M-CRIB-S, is used in place of FreeSurfer for processing visit V02 data. The V02 FreeSurfer files are therefore derived from the M-CRIB-S outputs, remapped into FreeSurfer-compatible format.
See M-CRIB-S & FreeSurfer Surface Reconstruction Methods for details.

Unprocessed raw imaging DICOM files will be made publicly available in a future release. However, raw data converted to the Brain Imaging Data Structure (BIDS) standard is currently available - see Raw BIDS.

Raw dMRI gradient tables are located in the raw BIDS data - see Raw BIDS Files (dwi/). Processed gradient tables, adjusted for head rotation, are additionally provided in the QSIPrep derivatives.

HBCD image processing pipelines use field maps to perform distortion correction for structural and functional MRI data. Most researchers will likely use the processed data for their analyses and therefore do not need to use the fieldmaps for anything, as all pipeline output derivatives are already distortion corrected. However, if using the raw BIDS data for your research, note that each fMRI acquisition will have a specific pair of fieldmaps associated with it, acquired in AP and PA phase encoding directions, located under fmap/. The matching EPI fieldmaps can easily be identified by the run number, specified by run-[X] in the filename (see details).

Quality control (QC) metrics derived from automated and manual raw data QC procedures (described in the section Raw MR Data QC) are provided for each scan in session-level sub-[ID]_ses-[V0X]_scans.tsv files. A sampling approach was used to select a subset of data for manual review based on the automated QC metrics. Therefore, while automated QC metrics are available for all scans, not all will include manual QC metrics. Also note that although the QC field is the overall manual QC score of 1 (pass) or 0 (fail), this field will automatically have a score of 1 if only automated QC was performed.

In some dMRI and fMRI acquisitions, limited brain coverage can cause the superior or inferior portions of the brain to fall outside the slice stack, referred to as field of view (FOV) cutoff. FOV cutoff is evaluated through both automated and manual QC procedures.

If the cutoff is severe (>30%), the dMRI or fMRI series fails QC. Mild (<10%) to moderate (10–30%) cutoff does not lead to QC failure, but regions outside the FOV will have missing values in the tabulated imaging data. The remaining brain areas remain usable.

All QC metrics are provided to help researchers make informed decisions about data inclusion. If FOV cutoff is a potential issue for your analysis, refer to the scans TSV file for automated and manual FOV cutoff metrics.