Mechanically evoked cerebral potentials and long-latency muscle responses in the evaluation of afferent and efferent long-loop pathways in humans.

Standing humans were subjected to sudden tilts of a platform toe-up. This resulted in a long-latency response in the anterior tibial muscle with a mean latency of 132 ms. The same physiological stimulus was applied to evoke cerebral potentials. The mechanically evoked potential was characterized by a positive peak with a mean latency of 76.4 ms. Absolute peak latencies were variable between subjects but the side difference after separate stimulation of both legs was only around 2 ms. The recording of both, mechanically evoked long-latency muscle responses and cerebral potentials allows a separate evaluation to be made of afferent and efferent central pathways.