We report our results from the study of the dynamics of electron-trapping materials (ETM's) under simultaneous illumination of pulsed blue light and constant IR light. By combining the dynamic property of ETM with the S-shaped nonlinear I-V characteristic of a programmable unijunction transistor, we produce an optoelectronic pulsating neuron. A proof-of-concept experiment successfully produces oscillations and demonstrates the great potential of using ETM's to implement dense arrays of pulsating neurons.