[Functional connections between the suprapharyngeal ganglion and segmental motor centers of the cockroach Periplaneta americana].

Studies have been made of non-specific influences of supraesophageal ganglion on the excitability of the segmental centers in the cockroach P. americana. It was shown that electrical stimulation of the mushroom bodies decreases the frequency of the background discharges which are observed in the neuropile of the central body, decreasing simultaneously the activity of motor fibers of the Vth nerve. On the contrary, stimulation of the central body increases the frequency of the spontaneous activity in motor output. It is suggested that the inhibitory influences from the mushroom bodies upon the segmental motor apparatus may spread both directly and in a stepwise fashion, i. e. via the intermediate structure of the central body. The latter is involved into the control of muscle tonus in the cockroach.