Abstract
The nonlinear dynamics of neuronal firing play a key role in understanding modulation mechanisms in excitable systems. In this work, a dual-state generic memristor is proposed, in which two internal variables represent antagonistic facilitation-like and inhibition-like drives within a phenomenological framework. Coupling this device with the Hindmarsh-Rose neuron yields a four-dimensional DSGM-HR system with bidirectional feedback. Equilibrium analysis, bifurcation diagrams, and Lyapunov exponents reveal transitions among periodic and chaotic firing regimes, as well as multistability under varying coupling strength and external input. A DSP implementation further confirms hardware reproducibility. Pain-related terminology is adopted only as a conceptual narrative to interpret antagonistic modulation, rather than to quantify subjective pain intensity.