Hysteriosis

HYSTERIOSIS, increased excitability of centers created by prolonged tetanization of an afferent nerve (Vvedensky). If an afferent nerve is stimulated for a long time, the stimulation of this nerve rather quickly ceases to produce a visible effect, and reflex muscle contractions stop. On this basis, the notion arose that sensory neurons undergo fatigue sooner than motor neurons. Vvedensky in 1910 showed that during prolonged tetanization of a sensory nerve, this stimulation, although it ceases to exert a visible reflex influence, nevertheless causes profound functional changes in the centers. Gradually (in approximately an hour), the excitability of the central nervous system, especially of the center to which the prolonged stimulation of the afferent nerve arrives, begins to increase sharply. This is manifested in a sharp drop in the stimulation thresholds for a nerve adjacent to the one undergoing prolonged tetanization. This is very clearly seen, for example, upon stimulation of the tibial nerve after prolonged tetanic stimulation of the peroneal nerve. Investigating the relationship between hysteriosis and the dominant, Ukhtomsky's school showed that during hysteriosis, the centers are incapable of summing excitation.