Short-term synaptic dynamics in compound EJP responses. A, Examples of responses to repeated train stimulations of all PY axons. Shown are the 24th and 25th trains in preparations with different numbers of PY neurons. The dashed line indicates the peak voltage of the first response in the train. B, Box and scatter plots of compound EJP amplitudes for the first and last pulses in the last (25th) train across preparations with different numbers of PY neurons (3 PY neurons: n = 7; 4 PY neurons: n = 12; 5 PY neurons: n = 16).C, Box and scatter plots of the ratios between the compound EJP amplitudes in response to the last and first pulse of the last (25th) train. *p < 0.05, **p < 0.01, ***p < 0.001.