FIGURE 3.

Neocortical LTD in L5 PCs is presynaptically expressed. (A) LTD expression at 20 Hz with Δt = −25ms like in Figure 2B was robust across paired recordings, while no-induction controls were stable (LTD, blue triangles; 65 ± 5%, n = 9 versus control, gray circles; 97 ± 2%, n = 8, p < 0.001). (B) Coefficient of variation analysis consistently suggested a presynaptic locus of LTD expression, as all paired recordings gave rise to data points below the diagonal (angle φ = 16° ± 2°, n = 9, p < 0.001; see Figure 1).