Figure 4. Microstructural correlates of NMRP activity.

A. Statistical parametric map (SPM) of significant correlations between individual subject expression of the normal motor-related activation pattern (NMRP) and the corresponding maps of fractional anisotropy (FA) generated by 3T magnetic resonance (MR) diffusion tensor imaging (DTI) acquired in nine DYT1 mutation carriers. Significant regions were thresholded at p<0.001, uncorrected and superimposed on a single-subject MRI T1 template. A significant correlation between NMRP expression and FA was identified in the dorsal aspect of the upper brainstem in the vicinity of the superior cerebellar peduncle. B. Post-hoc analysis of the significant cluster identified in (A). An inverse correlation was present between NMRP expression in the non-movement audiovisual (AV) condition and local FA values such that reduced microstructural integrity in brainstem pathways was associated with relatively greater network activity. We note that the non-manifesting (NM) carrier with the “protective” 216H allele (arrow) was normal with respect to both variables. Nonetheless, the correlation remained significant following the exclusion of this subject (R²=0.62, p<0.02).