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. 1997 May 27;94(11):5888–5893. doi: 10.1073/pnas.94.11.5888

Figure 1.

Figure 1

LTP can be expressed through increases in p. (A) LTP was saturated by repeated HFS (arrows), thereby maximizing the potential contributions to LTP by increases in the three synaptic parameters p, n, and q. ω-CgTX was then applied (⇑), which decreases only p. HFS then elicited additional LTP, which should only be due to increases in p. (B) Even when less LTP was induced at saturation (25.7%), additional LTP was still elicited after applying ω-CgTX. (C) Superimposing the average, normalized HFS before ω-CgTX application (○) and the HFS with ω-CgTX (•) demonstrates the additional LTP elicited by the last HFS (24.6 ± 5.8% vs. −0.3 ± 2.2%, averages ± SEM, n = 8, P = 0.0027 by t test). (D) All slices that potentiated showed decreases in PPF (−5.7 ± 2.3%, P = 0.016 by Sign Test; all changes are in percent PPF rather than percent change), consistent with increases in p. An example is shown in D where PPF decreased from 68 to 53% with the last HFS administered to the slice in A.