Structural Analysis of fMRI Data Revisited: Improving the Sensitivity and Reliability of fMRI Group Studies (original) (raw)

Group studies of functional MRI datasets are usually based on the computation of the mean signal across subjects at each voxel (Random Effects Analyses), assuming that all subjects have been set in the same anatomical space (normalization). Although this approach allows for a correct specificity (rate of false detections), it is not very efficient, for three reasons: i) its underlying hypotheses, perfect coregistration of the individual datasets and normality of the measured signal at the group level, are frequently violated ; ii) the group size is small in general, so that asymptotic approximations on the parameters distributions do not hold ; iii) the large size of the images requires some conservative strategies to control the false detection rate, at the risk of increasing the number of false negatives.