STDP at CA3-CA1 synapses with a single pre-synaptic spike and two post-synaptic spikes (the triplet protocol).

(A) Data reproduced from [19], fit with a difference of Gaussians (least squares fit). refers to time between the pre-synaptic spike and the second post-synaptic spike. (B) An inter-pairing frequency of produced a ‘symmetric’ STDP curve, where a narrow LTP window is shifted in the causal (pre-before-post) direction, surrounded by two latency-dependent LTD windows (solid black). An inter-pairing frequency of 0.5 Hz produced a depression-only curve (dotted grey). The post-synaptic spikes were separated by 10 ms. (C) Mean value of the dynamic time constant for each value of in panel B (corresponding curves).