H-Reflex of Single Motoneurones in Man

Abstract

As early as 1918 Hoffmann described how electrical stimulation of the tibial nerve in man evokes, in addition to a direct motor response in the calf muscles, another well synchronized motor response at a latency of about 30 ms¹. He concluded that this later response was identical with the myotatic reflex, because it had the following characteristics : (1) it appears only in the muscles supplied by the stimulated nerve; (2) it can be evoked by shocks which are subliminal for motor axons and it tends to be blocked at stronger stimulus strengths; (3) it is conducted in afferent fibres of high velocity and its central delay is short enough to indicate a monosynaptic pathway; (4) it is facilitated by a voluntary contraction of the muscle involved and obliterated by a contraction of its antagonist.