[12a-PA4-1~9] 31.1 Focused Session "AI Electornics"

[12a-PA4-6] Mathematical analysis of the frequency-dependent synaptic plasticity in vivo

〇Katsuhiko Hata^1,2,3,4, Osamu Araki⁵, Tatsuya Saka^2,3, Osamu Yokoi^2,3, Tetsuro Nikuni⁴ (1.S&MS, Kokushikan Univ., 2.DPEMS, Kokushikan Univ., 3.Res.Cent. for Math.Med., 4.Phys.TUS, 5.Ap.Phys.TUS)

Keywords:synaptic plasticity, in vivo, synapse

Two elements for neural information processing are currently proposed, that is, firing rate and spike timing of neurons. In the case of synaptic plasticity, although spie-timing-dependent plasticity (STDP) depending on presynaptic and postsynaptic spike times had been considered the most common synaptic plasticity rule, recent studies have shown the inhibitory nature of the brain in vivo for precise spike timing which is key to the STDP. Thus, the importance of the firing frequency in the synaptic plasticity in vivo has been recognized again. It is poorly understood, however, whether in vivo characteristic factors such as the variation of firing pattern, the difference of intracellular parameters and internal noise are involved in the frequency-dependent synaptic plasticity (FDP). Here, we focused on the presynaptic input pattern, the intracellular calcium decay time constants and the background synaptic activity, which vary depending on neuron types, anatomical and physiological environment in the brain. By analyzing ``calcium based model'', we found that the synaptic weight differs depending on them even if neurons receive the same input rate. This finding suggests an involvement of multifaceted factors other than input frequency in FDP and even neural coding in vivo.