r Seghier et al. r Figure 2. Relationship between global LI values and the parameter estimates vention on axial slices (top) and 3D-rendering volume (bottom). of each voxel for the contrast ‘‘semantic word matching versus Signiﬁcant effects are shown at P < 0.05 corrected (for height or perceptual matching on unfamiliar greek letters.’’ Positive (red) size). [Color ﬁgure can be viewed in the online issue, which is and negative (blue) relationships are shown in neurological con- available at wileyonlinelibrary.com.] language function. Speciﬁcally, the demonstration that inter-subject variability in language lateralization is pri- marily driven by right rather than left hemisphere activa- tion indicates that right lateralization does not imply that the left hemisphere has a redundant role in language func- tion. On the contrary, our ﬁndings from a reasonably large population of subjects indicate that two patients with dif- ferent global laterality values could have identical left hemisphere activation. In this case, the left hemisphere may be as essential for language processing in the patient with weaker left hemisphere language lateralization as a patient with strong left hemisphere language lateralization. Conversely, two patients with identical global LI values may differ in their dependency on left hemisphere activa- tion. This is consistent with prior claims that superior lin- guistic capability in the left hemisphere does not imply that the right hemisphere is irrelevant for language (for a review see [Lindell, 2006]). Understanding the relative contributions of the left and right hemisphere in language processing is also important for understanding the different intra- and inter-hemispheric mechanisms of recovery after brain insult [Cousin et al., 2008; Lazar et al., 2000; Rosenberger et al., 2009; Seghier et al., 2001], particularly the interpretation of laterality indices after brain damage (e.g., [Knecht et al., 2002]). For example, given the normal inter-subject variability that we observed in the r 1608 r