Why ROI ? (Region Of Interest) 1.To explore one’s data (difficult to discern patterns across whole brain) To control for Type 1 error and limit the number of statistical tests by using pre-defined knowledge: 2.Anatomical landmarks 3.separate functional localizer

Anatomical landmarks FDR Peak of Activation ROI??? Group selection AnatomicalFunctional Individually FunctionalAnatomical

Individually Vs. Group replication across groups and not across subjects? Different location and/or size of activations between subjects? Experimenter bias? Anatomical Vs. Functional Using orthogonal contrast Including only relevant voxels? Relevant in what contrast? Experimenter bias?

How ROI ? (Region Of Interest) 1.To explore one’s data (difficult to discern patterns across whole brain) peak of activation (sphere) masked with the threshold activation map -orthogonal contrast To control for Type 1 error and limit the number of statistical tests by using pre-defined knowledge: 2.Anatomical landmarks Using individual subject’s anatomy for detention – not Talairach 3.separate functional localizer Orthogonal contrasts in a factorial design (Poldrack, 2007)

Conclusions No one good way to extract ROI : There has not been a systematic study of the power of one approach in comparison with the other Different brain regions may require different methods Different protocols may require different methods Voxels count have been shown to be an unreliable measure of activation compared to signal change (Cohen & Dubois, 1999) Tip - using ROI to remove outliers (Wager et al., 2005)