Functional MRI will only detect brain activation very indirectly, as variations in the T2* signal, following changes in the oxyHb/deoxyHb ratio, after neurovascular coupling triggered by neuronal activity.
Data acquisition is carried out in T2*-weighted ultrafast sequences of the echo planar type, sensitive to BOLD contrast, during a succession of different repeated tasks following a paradigm.
The signal variations are very weak and their analysis is based on a statistical comparison between different states of activation.
The temporal resolution of fMRI, combined with the possibilities of morphological imaging, make MRI a modality of choice in the neurosciences.
Summary