  This paper indicates causality as the tool that unifies the analysis of both
activations and connectivity of brain areas, obtained with fMRI data. Causality
analysis is commonly applied to study connectivity, so this work focuses on
demonstrating that also the detection of activations can be handled with a
causality analysis. We test our method on finger tapping data, in which GLM and
Granger Causality approaches are compared in finding activations. Granger
causality not only performs the task well, but indeed we obtained a better
localization (i.e. precision) of activations. As a result we claim that
causality must be the main tool to investigate activations, since it is a
measure of "how much" the stimulus influences the BOLD signal, and since it
unifies connectivity and activations analysis under the same area.
