Temporal asymmetry in Hebbian regulation of pulse coupling in the network of excitable chemical cells

The effect of temporal asymmetry of pre- and postsynaptic spiking on the dynamics of a neuromorphic chemical network that incorporates Hebbian regulation of coupling strength is considered both theoretically and experimentally. The system under study mimics the synaptically coupled neuronal unit by four interconnected excitable chemical cells in which the Belousov–Zhabotinsky occurs. The key feature consists of incorporating a “presynaptic structure” (so-called “M”-point), which is positioned before the chemical synapse and realizes specific time delays between the occurrence of a spike in the cell representing the “presynaptic chemical neuron” and the corresponding perturbation of its recipient cell (“postsynaptic chemical neuron”). Being combined with the pulsatory modulations from two additional cells, the considered system exhibits a rich variety of dynamic modes. Their manifestation is explored by numerical simulation of the chemically relevant nonlinear dynamical system with two control parameters (the localization of the “M” point and the period of external excitation). The theoretical predictions are validated by direct experimental investigation. It confirmed that the existence of the Hebb mode can be determined by the localization of point “M”, which allows for manipulating by desired features of memory formation in the chemical neuromorphic system.