Fig. 4. Intrinsic plasticity and synergistic concomitance in TS-PCM.
a Illustration of neuron composed of dendrites, soma, and axon. A specific region of AIS is located between the soma and axon that integrates input signals into AP spikes. b Intrinsic plasticity by AIS structure. (i) AIS regulates the threshold of AP generation, modulating the firing frequency of the neuron. (ii) Elongation of AIS leads to extension of the excitable region, resulting in increment of the firing frequency. c, d Intrinsic plasticity of TS-PCM based on the Vth modulation in the bottom TS layer. Upon the same input current of 2.5 μA, the firing frequency increases from 287.5 Hz to 462.5 Hz by the application of pre-stimulations. Five cycles of pre-stimulations with a two second time interval prevents the complete diffusion of the Ag filament in the TS layer, leading to a decreased Vth and increased firing frequency. e Time interval dependency of intrinsic plasticity. The change of the firing rate exponentially decays with the increase of pre-stimulation time intervals, with a time coefficient of 4.90 s. Each data point indicates the mean value and the error bars indicate the standard deviation. f Schematic diagram of neuronal excitability curve with E-S coupling. The excitability curve is translated by the LTP and LTD of the synapse, presenting the synergistic interaction between intrinsic and synaptic plasticity. g Emulation of LTP-IE using TS-PCM based on the simultaneous implementation of synaptic and intrinsic plasticity. The firing frequency increases from 30.5 Hz to 109.8 Hz by the LTP of TS-PCM from 4.1 × 105 Ω to 8.3 × 104 Ω. h Intrinsic excitability curve of TS-PCM verifying the emulation of LTP-IE. Inset graph shows the excitability curve of a biological neuron. (Inset of Fig. 4h was reproduced with permission from [Campanac E. and Debanne D. Spike-timing-dependent plasticity: a learning rule for dendritic integration in rat CA1 pyramidal neurons.] 66. Copyright © 2008 The Physiological Society).