Data of main experiment for the fast fMRI project

This BIDS dataset contains data collected at 7T in 4 subjects, over three sessions each. Each subject was shown naturalistic image stimuli from the THINGS dataset at three different presentation rates (0.5s, 1s, 4s), with a fixed (0.35s) or relative (75% of SOA) stimulus duration. Each run used one SOA and one duration type. Runs included a 6s ramp-up and 10s cool-down. Participants performed a fixation color-change task. TR=0.5s.

We used a total of 642 stimuli, with 55 test stimuli that were shown 6 times in the 4s condition, 24 times in the 1s condition and 48 times in the 0.5s condition. The remaining 587 stimuli were shown 1 time, 4 times and 8 times in the 4s, 1s and 0.5s conditions, respectively.

Notes

Session 1 additionally contains a structural T1w image and a whole-brain single-volume reference EPI (in func). Sessions 2 and 3 contain two fLoc localizer runs each (in func). After each functional run, short PA EPI fieldmap data were collected for distortion correction. JSON sidecars include the presentation rate per run (key: SOA).

participants.tsv contains which subjects used fixed vs relative durations; this can also be inferred from the stimulus durations in the events.tsv files.

Acquisition summary

• TR: 0.5s, TE: 22ms, FA: 40°, multiband: 4, GRAPPA: 2
• 40 interleaved slices; partial FoV covering occipital and temporal cortex
• Fixation color-change task (0.5s red flashes, random 2–7s intervals)
• No null trials

Derivatives

• derivatives/basic_preproc_v2 custom preprocessing (motion correction, distortion correction with PA EPIs, alignment to T1w and MNI). Outputs include space-T1w and space-MNI preprocessed BOLD, masks, and transforms.
• derivatives/floc_preprocessed preprocessing outputs and events for fLoc runs.
• derivatives/single_trial_betas single-trial beta estimates (LSS) and analysis outputs.
• derivatives/decoding pairwise decoding accuracy maps per SOA.
• derivatives/spose_rsa_sl searchlight RSA (SPoSE/object-dimensions) results.
• derivatives/localizer localizer-based maps/ROIs derived from the main experiment.
• derivatives/atlases auxiliary atlases and masks (Harvard-Oxford, Neurosynth LOC, object parcels).