Figure 4.

The additional LTP elicited by HFS after applying ω-CgTX or Cd²⁺ is not due to a postsynaptic effect (e.g., saturation of current entry) or a change in inhibition. (A and B) HFS after LTP saturation and bath-application of CNQX (bar) did not yield additional LTP in a single slice (A) or for the group average (B; 3.9 ± 2.7% vs. 0.3 ± 2.2%, P = 0.64, n = 9). (C and D) HFS after LTP saturation and bath-application of 5-hydroxysaclofen (bar) also did not result in additional LTP (−4.3 ± 9.6% vs. −8.3 ± 3.2%, P = 0.70, n = 3). All experiments were performed in the presence of picrotoxin.