When the stimulus intensity is a half of the value that induced the largest response of synapses, the paired-pulse stimulation of 75-ms interval produced a stable PPD while the stimulation of 150-ms or 300-ms produced a stable PPF.

• 在1/2最大反应强度为检测刺激时，间隔为75ms时可产生稳定的PPD，而间隔为150ms和300ms时则可产生稳定的PPF。