Figure 2. Amplitudes of illusory movements evoked when skin stretch was applied over the dorsal aspect of the MCP joint of digit IV in one subject.

A, raw data from a single subject when skin stretch was applied over the dorsum of the MCP joint of digit IV. The top two traces show the time course of the application of the vibration to the finger extensor tendons at the wrist and the skin stretch over the MCP joint. The bottom three traces show the resulting illusory movements at the MCP joints as indicated by the voluntary movements of the matching hand. The digit at which the skin stimulation was applied is indicated with a double underline. Flexion at the MCP joint is shown as a downward deflection. B, mean amplitude (±s.e.m.) of the illusory movements from all cycles of each type of stimulation from the data shown in A (n = 10 for each mean). Data shown for vibration as open bars, skin stretch as hatched bars, and vibration combined with skin stretch as filled bars. The skin stimulation was applied at digit IV as indicated by the horizontal line. *Significant differences between vibration and the combined stimulation.