Figure 2. Modulation of a single motor unit discharge by task conditions.
A and B, the position of the finger (upper trace) and thumb levers during precision grip task performance under the most compliant (HI-COMP) and least compliant (LO-COMP) conditions, averaged across 25 trials. The scale of the lever displacement at the tip of the digit is shown to on the left. C and D, the firing of a single motor unit (SMU) under the two task conditions. Each point represents a discriminated discharge from the SMU. Data are aligned to the onset of the first hold period. Trial number increases from the bottom up. E and F, the average rectified EMGs of the 1DI muscle recorded during the task conditions. G and H, the interspike interval histogram (ISIH) calculated across the entire task for the single motor units shown in C and D. The ISIH were calculated between 0 and 400 ms and had a binwidth of 1 ms.