Impact of Experimental Tonic Pain on Corrective Motor Responses to Mechanical Perturbations

Figure 4

Average traces of elbow angular position (a), velocity (b), acceleration (c), and muscle responses (d) for Biceps (left) and Triceps (right) during experimental trials (average of P, VPc, and VPi sensory conditions). The short-latency (SL) response, occurring from 20 to 50 ms, provides information on spinal mechanisms and depends exclusively on proprioceptive signals. The long-latency response (LL; 50 to 100 ms) reflects both spinal and transcortical processes related to the integration of proprioceptive signals, especially by the cerebellum. The early voluntary response (EV; 100 to 150 ms) results from a visuomotor control related to the integration of visual and proprioceptive afferent signals at the cortical level. The period between 150 ms and 600 ms, during which participants were actively maintaining their index on the initial target against the perturbation, was not included in the analyses as this represents voluntary muscle activity. MVC = maximal voluntary contraction.