Figure 4.

Cross-depletion experiments reveal that EPSC trains deplete only a subset of the sucrose-accessible pool. A, The areas of EPSCs (open bar) and sucrose responses (filled middle bar) were measured at 0.5 s after high-frequency stimulation (100 pulses at 20 Hz) and compared with the areas of original responses. ^*p < 0.001 (n = 9 for EPSCs and 8 for sucrose). In separate cells, the sucrose response 0.5 s after a 40 pulse, 20 Hz train (n = 10) showed ∼25% depression, consistent with RRP discrepancies in Figure 3. B, The difference in inhibition at various times after 100 stimuli at 20 Hz (n = 3 for each point). Recovery from inhibition was fit with a single exponential; τ = 1.09 s (EPSCs; open circles) and 1.28 s (sucrose; filled circles). Fits were constrained to a maximum of 100%. C, The areas of paired EPSCs (open circles) and sucrose responses (filled circles) were measured at various times after an initial pair of responses (n = 5 for each point). Recovery from inhibition was fit with a single exponential; τ = 9.94 s (EPSCs) and 7.85 s (sucrose). Fits were constrained to a maximum of 100%. Error bars represent SEM.