I am analyzing two different fMRI datasets one on dyslexia in adults (morphosem) and one in dyslexia in children (dyschildren). They both have control subjects. The children are aged 8 to 9 years old and the adults are all university students of similar age. I have already preprocessed and ran 1st level analysis the data for all 40 subjects (morphosem) and 41 subjects (dyschildren) in each dataset in FSL. I ran 2nd level analysis for dyschildren which has 41 subjects and 3 runs using the following models:
The task is event related. Here is the exact description from the OpenNeuro page: “Stimuli consisted of 60 words and 60 matched pseudohomophones of three to eight letters. Each stimulus was presented alone in white on a black background for 3s in an event-related design. After it disappeared, a fixation cross was displayed. The presentation of the fixation cross was jittered between 2000 and 6000 ms (M = 4000 ms). To prevent fatigue effects in children, stimuli were presented over three consecutive runs of 40 items each, separated by short breaks of 3-5 min. Children were instructed to read aloud the stimuli appearing on the screen.”
I do have one question, there are quite a lot of brain maps from the first run that don’t have any activation clusters. I believe this is what influenced the 2nd Level analysis results. Is not having any activation an error?
The steps you took. e.g., what regressors were used in your first-level model, were data smoothed at all, what was the contrast, etc
Hard to say without knowing how first-level models were made.
These brains look like they have a lot of anatomical warping near the front. If you can preprocess again with some form of susceptibility distortion correction (e.g., --use-syn-sdc in fMRIPrep) that might be helpful. Also I see a lot of frontal activation whereas reading is typically associated most strongly with with visual and left occiptotemporal activation. Knowing what contrast you used for first-level analyses would help decide if your maps are plausible.