Figure 2.

Intensity-amplitude relationships. (a) Intensity-amplitude relationships (I-A plots) for average synaptic amplitudes belonging to each of the STSP classes. Each dot represents an average from experimental samples. Thin lines are the fits for: IPSCAmp(I) = A _max/(1 + e − k(I − I _h)). The colored shadowed areas around the fit show the estimation errors as a function of threshold units strength. Right: fitted curves again showed differences among each other. In agreement with color: representative recordings from each type of I-A plot. Arrows point to the time of stimulus. (b) Recruitment index (slope factor divided by the stimulus necessary to attain half-maximal amplitude, k/I _h) as a function of maximal amplitude reached by the IPSCs. The red plot and dots correspond to synapses exhibiting STD; the blue plot and dots correspond to those synapses showing STF; the green plot and dots correspond to synapses exhibiting STB. Depressing connections more easily recruit release sites as a function of stimulus strength.