Spike-timing dependent plasticity (STDP) is a fundamental concept in neurobiology. Briefly, the relative timing of two neuron spikes reinforces or weakens the synapse between them, so that events caused by another should trigger spikes in a particular time order.
A reversal of this order causes the weakening of the synapse, so it penalizes the correlation. This process allows the brain to establish causal correlations from the environment and it is widely used in computational neuroscience.
Now, Yu Chen et al. have found that the photoconductive properties of quantum wells at the LaAlO3/SrTiO3 interface mimic STDP, using time correlations in optical pulses. More specifically, the conductance of the quantum well is increased or decreased depending on the relative timing of optical pulses of short- (blue, B) and long- (red, R) wavelengths (Figure). The sensitivity of the conductance to these correlations opens up fascinating perspectives on the use of optical synapses for neuromorphic devices based on these photoconductive systems.
Photoinduced persistent electron accumulation and depletion in LaAlO3/SrTiO3 quantum wells
Yu Chen, Yoann Lechaux, Blai Casals, Bruno Guillet, Albert Minj, Jaume Gázquez, Laurence Méchin, and Gervasi Herranz.
Phys. Rev. Lett. 124, 246804 – Published 19 June 2020