Figure 4.

Changes in the feedforward components of the motor command. A, Change in feedforward activity of the posterior deltoid (mean ± SEM) plotted against the signed handpath error from the previous trial. The change in the feedforward activity was binned into equally sized groups depending on the signed handpath error and plotted against the mean signed handpath error of each group. *p < 0.05, **p < 0.01), ***p < 0.005, changes in feedforward activity significantly different from zero. B, Change in the feedforward activation of the pectoralis major. Both muscles showed similar responses: if the muscle either lengthened or shortened on the previous trial the feedforward command increased on the subsequent trial. However, if the signed handpath error was close to zero on the previous trial, then the feedforward command of both muscles was reduced. The dotted lines are the least squares linear fit to the positive and negative error regions of the data with a common intercept for both regions.