Predictions for STDP curves at CA3-CA1 synapses when a single pre-synaptic spike is paired with more than two post-synaptic spikes at inter-pairing frequencies lower than the theta band.

(A) 75 pairings under the quadruplet protocol (3 post-synaptic spikes) at frequencies of 2 Hz (dotted grey) and 3 Hz (solid black). (B) 75 pairings under the quintuplet protocol (4 post-synaptic spikes) at 1 Hz and 2 Hz. The curves are indistinguishable. (C) The dynamic time constant under the quintuplet and sextuplet (5 post-synaptic spikes) protocols at 1 Hz. Post-synaptic spiking followed the pre-synaptic spike by 5 ms. (D) transients, where curves correspond to in panel C. The horizontal line shows the LTP threshold. In panels A and B, is defined as the time between the pre-synaptic spike and the last post-synaptic spike. In panels C and D, black and grey curves correspond to the quintuplet and sextuplet protocols respectively. Post-synaptic spikes were separated by 10 ms under all protocols.