Astrocyte on Neuronal Phase Synchrony in CMOS

CMOS neuromorphic circuits are proposed to emulate the role of astrocytes in phase synchronization of neuronal activity. We emulate, to a first order, the ability of slow inwards currents (SICs) evoked by the astrocyte, acting on extrasynaptic N-methyl-D-aspartate receptors (NMDAR) of adjacent neurons, as a mechanism for phase synchronization. We do an experiment incorporating two small networks of neurons interacting with astrocytic microdomains. Upon enough synaptic activity, the microdomains interact with each other, generating SIC events on synapses of adjacent neurons. Since the amplitude of SICs is several orders larger compared to synaptic currents, a SIC event drastically enhances the excitatory postsynaptic potential on adjacent neurons simultaneuously. This causes neurons to fire synchronously in phase. Phase synchrony holds for a duration of time proportional to the time constant of SIC decay.