Fig. 4: Rate-temporal fusion scheme encodes synaptic plasticity in real-time for sensing and memory.
From: An artificial visual neuron with multiplexed rate and time-to-first-spike coding
a Simplified schematic of sensitisation in the retina. b Operation scheme of optical (red line) and electrical input (blue line). UV illumination (pulse width: 5 ms, frequency: 5 Hz, intensity: 1.71 mW/cm2 at 365 nm). Electrical pulses VDD (3 V, 20 μs) are applied to evaluate the spiking behaviour at t1, t2, t3, and t4, corresponding to 0, 10, 30, and 60 s, and t5, t6, t7, and t8, corresponding to 5, 10, 15, and 25 min. The gate voltage bias VG is 5 V. c Measured output current waveforms of sensitisation (t1–t4) with increasing synaptic weights under UV light illumination. d Measured output current waveforms of memory (t5–t8) with decreasing synaptic weights after the light pulse. e, f The sensing and memory processes have a linear relationship with the (e) spike frequency and an exponential relationship with the (f) first spike latency. g, h The RTF coding scheme exhibits changes in (g) spike frequency and (h) first spike latency during the memory window after different light intensities. i Image memory with rate coding and TTFS coding for a mushroom pattern at 0, 2, 4, and 6 min after light stimuli ceased.
