THE MOTOR PROGRAM FOR DEFENSIVE KICKING IN CRICKETS - PERFORMANCE ANDNEURAL CONTROL

Crickets can repulse sources of mechanical touch to their wings, legs or to the posterior body by kicking backwards ipsilaterally with one h indleg, The main component of a kick is the rapid extension of the fem oro-tibial (knee) joint. A kick as a defence against predators must oc cur instantly after the moment of touch, The cricket kick is completed within 60-100 ms, whereas in locusts 500-2000 ms elapses between the stimulus and the end of the kick. The rapid movement of the cricket hi ndleg was recorded with a high-resolution video technique. Cricket kic king is based on a dynamic co-contraction of the extensor and flexor t ibiae muscles during the pre-kick knee flexion period, thus differing from the static co-contraction period seen in locusts. Biomechanically , the knee joint is specialized for kicking and jumping by the specifi c leverage of tendons inserting at the knee, by a femoral ridge that m odifies the angle of attack for flexor muscular forces and by a cushio n-like swelling on the flexor tibiae tendon, Because of these structur al specialisations for rapid kicking, the neural control of the motor pattern of the muscles participating in the tibial movement can vary c onsiderably, but still produce efficient kicks, Kicking is also an ele ment of other complex behaviours.