[Responses in the superior thoracic white rami communicantes to stimulation of the dorsolateral funiculi of the spinal cord].

In anesthetized cats, the responses in T3 white rami to stimulation of the spinal dorsolateral funiculi at C5 level displayed three typical waves. The short latency first wave is the result of stimulation of descending fibres with conduction velocity over 20 m/sec, which activate some sympathetic preganglionic neurons monosynaptically. These neurons are, probably, outside of the lateral horns and have axons with conduction velocities over 10 m/sec. The second wave is associated with the discharges of lateral horn's sympathetic preganglionic neurons disynaptically activated by descending fibres with conduction velocity about 6 m/sec.