ABSTRACT
A circuit model of the postsynaptic membrane of a neuron is developed for simulation of inhibition and sustained excitation. The model is simulated using SPICE (Simulation Program with Integrated Circuit Emphasis). The circuit uses MOSFETs (metal-oxide-semiconductor field-effect transistors) as an analog of the conductance of receptor-gated ion channels in the postsynaptic membrane. Transmitter-receptor binding activity serves as the input to the system and is simulated by an electrical signal. In the model, sustained excitation is a result of biochemical feedback from the postsynaptic to presynaptic neuron. This feedback can maintain the release of excitatory neurotransmitter. Postsynaptic inhibition is then demonstrated as a plausible mechanism for limiting the duration of sustained excitation in the nervous system within individual neurons.
