Figure 6.

E‐S potentiation is dependent on number of APs elicited during plasticity induction. (A) Example of a trace from the WPP protocol where APs were evoked from both the suprathreshold EPSP and as a result of current injection. (B) Plot shows P₅₀ Firing against number of APs evoked by suprathreshold EPSPs during WPP. P₅₀ Firing for CA1 neurons from pilocarpine‐treated rats (filled circles) increased with APs evoked by suprathreshold EPSPs, whereas cells from saline‐treated rats did not (crosses). (C) P₅₀ Firing exhibits a dose–response relationship with respect to APs evoked from suprathreshold EPSPs. Different symbols reflect neurons subjected to different plasticity induction protocols (see Table I). P₅₀ Firing values for CA1 neurons from: pilocarpine‐treated rats subjected to WPP (filled circles) or afferent Schaffer collateral stimulation only (open triangles). Open squares represent P₅₀ Firing values for CA1 neurons from saline‐treated rats subjected to Schaffer collateral stimulation only. Solid line indicates fit to a logistic equation (Equation 2) for all points. This analysis indicates that greater than 8.1 APs elicited from EPSPs are required to cause E‐S potentiation under these plasticity‐inducing conditions: N ₅₀ = 8.1, n = 1.7. Dashed line indicates no change in E‐S coupling after the plasticity inducing protocol.