Single high strength afferent volleys can produce long-term potentiation in the hippocampus in vitro.

Although hippocampal long-term potentiation (LTP) is normally elicited by tetanization of an afferent input, it may also be induced by pairing afferent volleys with strong depolarizing conditioning stimuli. In extracellular recordings made from area CA1 of hippocampal slices bathed with a picrotoxin-containing solution, long-lasting potentiation was produced by high strength single volleys alone. Potentiation occurred with intervals between high strength stimuli as great as one per minute. Tetanization-induced LTP was no greater than tetanization-induced LTP plus high strength single volley potentiation, given in either order. These data suggest that single afferent volleys can induce LTP under conditions of reduced inhibition.