Efferent activity during fictitious scratch reflex in the cat.

Abstract

The efferent activity of muscle nerves was recorded during the fictitious scratch reflex in decerebrate curarized cats. The nerves that became tonically active during the postural stage of the reflex had long bursts of activity during the rhythmical stage. Definite phase shifts were found between the onsets of bursts in different nerves. The shape of the burst in different nerves was also different. The nerves, which were not active during the postural stage of the reflex, has short bursts of activity during the rhythmical stage. These bursts were not synchronized but had definite phase shifts in relation to each other Exteroceptive stimulation of the foot during scratching resulted in considerable change in the activity of nerves of certain double-joint muscles: discharges in n. [nervus] rectus femoris decreased or even disappeared while discharges in n. biceps posterior and n. semitendinosus increased and became longer. Such stimulation did not affect the activity of the nerves of pure flexors and extensors. Both the timing of efferent activity in the cycle and the effects of exteroceptive stimulation were similar to those found in the study of locomotion. The central mechanisms of scratching and locomotion are probably basically identical.