Implantable Organic Artificial Synapses Exhibiting Crossover between Depressive and Facilitative Plasticity Response

Organic neuromorphic devices mimic signal processing features of biological synapses, with short-term plasticity, STP, modulated by the frequency of the input voltage pulses. Here, an artificial synapse, made of intracortical microelectrodes, is demonstrated that exhibits either depressive or facilitative STP. The crossover between the two STP regimes is controlled by the frequency of the input voltage. STP features are described with an equivalent circuit where an inductance component is introduced in parallel with the RC circuit associated with poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS)||electrolyte interface. The proposed RLC circuit explains the physical origin of the observed STP and its two timescales in terms of charge build up in PEDOT/PSS.

Automated summary

This study demonstrates an artificial synapse made of intracortical microelectrodes that exhibits either depressive or facilitative short-term plasticity (STP), controlled by the frequency of the input voltage. The proposed RLC circuit, including an inductance component, explains the physical origin of the observed STP and its two timescales related to charge accumulation in PEDOT/PSS.