Fig. 4. (A) Tetanus-induced short-term depression followed by lasting augmentation. Depression induced in this unidentified alpha lobe-extrinsic neuron lasted for about 30 s and was followed by augmentation. Similar time courses of depression and augmentation were seen in three other neurons; none was identified as a PE1 neuron. (B) Spike trains of this neuron 70 s after tetanus. The stimulus artefacts mark the test pulses. (C) Average time course of depression in five PE1 neurons. Notice the different time scale in A and C. The ordinates give the number of spikes elicited by a single stimulus (± S.D. in C.) and the abscissa time in s (A) or min (C).