Fig. 6.

In the hippocampus, LTP uniformly potentiates all EPSPs of a train. A, Two different protocols were used to induce LTP. Depolarization was paired either with the first five pulses (early) or last five pulses (late). Each trace shows the average of four separate experiments before (black) and after (gray) the induction of LTP. Thin lines represent the SEM. In both groups, potentiation was uniform across the length of the train. B,Top traces represent the average baseline and posttest trace from all eight cells. Middle traces are the same as those shown above after scaling. Note that the overlap of the normalized traces indicate potentiation was the same across all EPSPs.Bottom trace shows the subtraction of the baseline from the posttest traces. C, In the unpaired pathway there were no significant changes before and after the induction of LTP.