Figure 7.

Pattern decomposition shows clear evidence for nonlinear bimanual tuning of voxels in the functionally defined bimanual ROI in pre- and postcentral gyri. (A) For the bimanual patterns, the variance estimate for the contralateral component is relatively strong and equivalent for uni- and bimanual movements. (B) The variance of the ipsilateral component effect is reduced for the bimanual movement compared with unimanual. However, a substantial interaction effect between ipsi- and contralateral fingers (white bar) is observed. (C) For contralateral fingers (red), there is a high correlation between the unimanual and bimanual pattern components of the same finger. For ipsilateral finger presses (blue), there is no systematic relationship. Box plots extend from the 25th to the 75th percentile. Whiskers indicate the full range of the data, with circle indicating data points that are further away from the median than 1.5 the times the box length (intraquartile range). (D) The classification accuracy for the ipsilateral finger during bimanual actions correlates with the size of the interaction effect. Values for the bimanual area within the left and right precentral and postcentral ROIs are shown for each participant. (E) Classification accuracy does not correlate with the size of a pattern component related to the ipsilateral main effect. Error bars indicate between-participant SE.