NIfTI Group Averaging

The NIfTI Group Averaging extension provides tools for computing group averages and statistical comparisons of NIfTI files organized by experimental groups.

Import and export participant rows

Use Import CSV/TSV, Export CSV, or Export TSV below the Subjects header. Export the current table for an editable template. The required header and an example CSV row are:

subject_id,simulation_name,group
101,L_Insula,Group1

Workflow Example

Basic Group Analysis

  1. Open tool: Extensions ▸ NIfTI group averaging in the navigation rail
  2. Configure Subjects:
    • Subject 001: Simulation “stim_A”, Group “Treatment”
    • Subject 002: Simulation “stim_A”, Group “Treatment”
    • Subject 003: Simulation “stim_B”, Group “Control”
    • Subject 004: Simulation “stim_B”, Group “Control”
  3. Set Parameters under Analysis configuration:
    • Analysis name: treatment_vs_control
    • Space: MNI volume
    • NIfTI pattern: empty (the chosen space’s file)
    • Group differences: empty (all pairs)
  4. Run Analysis: Generate group averages and differences

Space and the file it reads

Analysis configuration ▸ Space decides which file of each simulation is averaged. Leave NIfTI pattern empty to read the space’s own file (it is shown as the field’s placeholder):

Space File read from TI/niftis/
MNI volume (default) grey_{simulation_name}_TI_MNI_MNI_TI_max.nii.gz
Subject volume grey_{simulation_name}_TI_subject_TI_max.nii.gz

Output Structure

Results are saved to derivatives/ti-toolbox/nifti_average/{analysis_name}/:

treatment_vs_control/
├── average_Treatment.nii.gz                     # Group average for Treatment
├── average_Control.nii.gz                       # Group average for Control
├── difference_Treatment_minus_Control.nii.gz    # Treatment - Control
└── config.json                                  # Analysis name, pattern, space, each group's subjects, differences

Results Visualization

Each average and difference is a NIfTI on the grid of the files it averaged. Open one in TetraVox from the job’s Artifacts tab (Open in Tetravox); see Viewer.