Figure 3.

Tuning curves and preferred directions of individual muscles. (A) Example of tuning curves for two muscles (first row: PectMajClav, second row: DeltA) of subject 3 estimated from different blocks (blue markers and lines) compared to the tuning curve of the muscles calculated from the pooled data of all baseline blocks (reference blocks, gray markers and lines). As for PectMajClav, the changes in preferred direction (PD, blue radial segment) of many muscles with respect to the PD in the reference blocks were similar to the initial direction angle errors. However, the activation of some muscles such as DeltA was not cosine tuned and those muscles were excluded from analysis. (B) Examples of the mean PD-change of three muscles across subjects and grand mean of the PD-change across muscles and subjects (rightmost panel). The PD changes of the muscles (blue) was not statistically different from the initial direction angle error (red).