Superposition of the deformations evoked by motoneurons innervating different muscle fiber classes.A, Optical flow after circular motoneuron 112 stimulation with a current pulse lasting 5 sec and evoking a spike discharge of ∼28 Hz. B, Optical flow after longitudinal motoneuron 5 stimulation with a current pulse lasting 5 sec and evoking a spike discharge of ∼42 Hz. C, Optical flow after identical simultaneous stimulation of both motoneurons. D, Sum of the optical flows shown inA and B (red) compared with the optical flow shown in C (black).E, Elementary deformations computed for the optical flows shown in A and B (112, gray bars; 5, white bars). F, Sum of the elementary deformations of motoneurons 112 and 5 (red bars) compared with the elementary deformations of the optical flow shown in C (gray bars). The width of the annuli in A–D is ∼1 mm. Equal normalization in E and F.