Sunday, 31 December 2006
Some processes in nervous tissue are essentially discontinuous in nature, others, like heat and carbon dioxide production, and positive after-potential, are cumulative; they tend to develop in some relation to the number of impulses carried, not infrequently to appear in measurable form only after a number of actions have been compressed into a limited time. In such conditions of activity not only are cumulative processes demonstrable in nerve, but indications of their influence may be found in the altered responsiveness of simple synaptic relays and of neuromuscular junctions. The usual sequel to a period of tetanic stimulation in junctional tissues is a more or less prolonged increase in the transmitted response to standard, iterative, but infrequently elicited pre-junctional nerve volleys into which train of volleys the tetanus has been interpolated (2, 7, 10, 11, 23, 35, etc.). The observed phenomena have been called post-tetanic facilitation, or post-tetanic potentiation; the latter designation is to be preferred. This article by Lloyd, 1949 describes this process (full access).