Skip to main content
. 1998 Feb 3;95(3):1283–1288. doi: 10.1073/pnas.95.3.1283

Figure 1.

Figure 1

LTD accompanies a reduction in the pool size of readily releasable vesicles. (A, B) LTD was induced in an autapse in a small single cell island (B, Top); the synaptic strength ratio was 0.33 relative to the baseline synaptic responses. Note that autaptic responses gradually decreased over time before and after LTD induction: a response washout. (B, Bottom) The time course of the same experiment after correcting for the washout. The average rate of washout—i.e., the slope correction—was 0.017 of normalized synaptic strength per min. Hypertonic solution was applied to the entire autapse before and after LTD induction (B, arrows). LTD (synaptic strength ratio) of autaptic response was 0.33 of baseline values and the response to application of 0.5 M sucrose solution after LTD induction was 0.27 of the response elicited prior to LTD. Typical traces obtained before and after induction of LTD, in superposition, are shown for autapse (A, Left) and for hypertonic solution-induced response (A, Right). The autaptic cell was used after 9 days in culture, and extracellular recording solution contained 2 mM Mg2+ and 3 mM Ca2+. (C) Summary of LTD in single cell autapses in which the readily releasable pool size was monitored before and after induction of LTD (n = 13). Each point represents the relative autaptic response after LTD/before LTD (synaptic strength ratio) as function of the corresponding ratio of hypertonic solution-induced responses (after/before). The depression of the autaptic response and the hypertonic solution-evoked response paralleled each other, indicating that LTD involves an alteration in the mechanism(s) regulating the size of readily releasable vesicles.