fMRI study design
Designing your MRI experiment is not an easy task to do. There are many factors that need to be considered and depending on what your research question is and how good your equipment is, you'll have to make adaptions to the standard fMRI acquisition.
General Advice for your Study Design¶
Scan Duration and Number of Participants¶
- Scan as long as possible each participant (max. 40-60 min)
- rough guidelines are 2 min per condition, 12 min per run
- The more number of scans the better the signal-to-noise ratio (SNR)
- If group analysis is relevant, then the power of the study depends on the number of participants, the more participants the better.
Task¶
- Minimize the time of when participant is inactive
- Keep inter-trial interval (ITI) as short as possible
- Longer ITIs can be added for measuring baseline/ Null events
- Avoid taking breaks! As these:
- Disrupt the spin equilibrium (more dummy scans are needed)
- Reduce the efficiency of temporal filtering
- Contain session effect
Contrasting¶
- If you are using high-pass filter, do not contrast trials far apart in time
- In block design: Do not use too long blocks (>50sec), best block length is about 16 sec long
Randomization¶
- If the time between different trials is blow 20 sec then
- either use a fixed ITI with different order of conditions
- or use the same order with different ITI
Resources¶
Amaro Jr, E., & Barker, G. J. (2006). Study design in fMRI: basic principles. Brain and cognition, 60(3), 220-232.
Last updated 03.06.2024, Elina Stocker