A CA2+ Dynamics Model of the STDP Symmetry-to-Asymmetry Transition in the CA1 Pyramidal Cell of the Hippocampus

Recent experimental evidence has reported that the profiles of spike-timing-dependent plasticity (STDP) in the CA1 pyramidal neuron can be classified into two types depending on the location along the stratum radiatum (SR) dendrite: (1) A symmetric STDP profile centered at 0 ms (largest LTP value) with two distinct LTD windows at about ±20ms in the proximal SR dendrite, and (2) an asymmetric one in the distal SR dendrite. Bicuculline application revealed that GABAA is responsible for the symmetry of the STDP curve. We investigate via computer simulations the STDP symmetry-to-asymmetry transition in the proximal SR dendrite. Our findings indicate the transition from symmetry-to-asymmetry is indeed due to decrease of GABAA, but the simulated symmetrical STDP profile is centered at +10ms (and not at 0ms) with two distinct LTD tails at -10ms and +40ms (and not at ±20ms). The simulated LTD tails are strongly dependent on the GABAA conductance.