Photons are captured by rhodopsin in rod outer segments, where they are converted into an electrical signal. Modeling the light-sensitive electrical behavior of rods can reveal their biophysical mechanisms. However, most rod cell models are empirically based and lack biophysical meanings. In this paper, a model for rod cells based on the protein cascade transduction process and ion channels is presented. Based on the biochemical cascade of phototransduction in the rod outer segment, the model describes the formation of photocurrent and simulates the photocurrent response to different light stimuli. In addition, the model analyses the contribution of ion channels to light-response processes in photoreceptors and determines the relationship between light intensity and photovoltage response amplitude. This study presents an effective strategy for probing the internal phototransduction mechanism of rod cells. Furthermore, the model also provides an objective and quantitative description method for monitoring retinal diseases.
Neuromorphic computing system inspired by the human brain has the capability of breaking through the von Neumann bottleneck, which can improve the efficiency of data processing. To deploy efficient neuromorphic systems, the development of synaptic devices is imperative. However, achieving tunable synaptic behaviors in a single transistor remains challenging. In this work, a silicon nanowire-based photoelectronic synaptic transistor is developed to achieve tunable synaptic behaviors. Using the floating-body effect and a cylindrical surrounding double-gate (CSDG) structure, we simulated excitatory and inhibitory synaptic plasticity in a single device. Additionally, our device also simulated various synaptic characteristics by modulating the bias voltages and light pulses, such as excitatory and inhibitory postsynaptic current (PSC), short-term potentiation (STP), short-term depression (STD), long-term potentiation (LTP), and forgetting behavior. This study provides an effective strategy for developing tunable photoelectronic synapses. Furthermore, Si processing compatibility also makes the synaptic device a promising contender for the implementation of neuromorphic computing.
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