Effect of repetitive stimulation (20 msec interstimulus interval) on excitatory postsynaptic currents (eEPSC) peak. (A) Example of a depressing EPSC, average of four stimulus presentations, from a control cell. (B) Example of a response that depresses little with successive stimuli, average of four stimulus presentations from a 2 d intact cell. (C) Mean eEPSC peak relative to first eEPSC peak for stimuli 2–4. Control and axotomized cells show depressing pattern, while intact cells depress little. Only cells with either no action potential or in which the eEPSC peak could be clearly distinguished from an earlier action potential were used for this analysis. n=9 control, nine 1 d axotomized, six 2 d axotomized, four 1 d intact, and three 2 d intact cells.