Fig. 4.

Effects of forces applied as ramp and hold functions and adaptation in synergist muscles. A and B: after periods of leg searching, forces applied as ramp and hold functions produced sustained bursting in the depressor muscle (DEPR TROCH) of both the front (A) and hindlegs (B). C: histograms of depressor firing to forces applied to the depressor insertion showed lower rates of discharge in front legs (top) than in hindlegs (bottom; see main text for discussion). D: adaptation. Forces applied as ramp and hold functions at the depressor insertion in a front leg produced sustained firing in the depressor but bursts in the synergist flexor (FLEXOR TIB) adapted rapidly to the stimulus. E: histogram of front leg flexor bursts applied at moderate levels (mean amplitude: 1.94 mN). Firing rapidly adapted to sustained forces. F: adaptation depends on force amplitude. Application of forces in another preparation showed adaptation in flexor firing (left) that was decreased when the force amplitude was increased (right).