Why does language laterality index vary?
Waites A, Mannfolk P, Abbott D, Jackson G, Olsrud J
Lund University Hospital
Measurement of language lateralisation is of great benefit for surgical planning. FMRI measures of laterality index (LI) are not totally concordant with Wada test, and show variability with analysis method. This study investigates the extent to which this variability depends on methodological issues, versus variability in the underlying cognitive networks. Twelve subjects performed a language fMRI study, and LI was calculated in a number of ways. Further, simulated data was investigated. LI was found to vary as a function of threshold in individual subjects, and this variation was subject-specific, making a single threshold inappropriate.