Resonance induced by mixed couplings in a three-node motif

Inspired by the coexistence of excitatory and inhibitory neurons in real neural networks, we propose a motif of three coupled nodes, one with positive coupling and two with negative couplings, for signal amplification. Utilizing the bistable overdamped oscillator as well as the excitable neuron models, we show that the response of the motif is optimized for an intermediate range of coupling strength, i.e., coupling-induced resonance. Through theoretical analyses, we find that the underlying mechanism for the resonance is an abrupt pitchfork bifurcation caused by the mixed positive and negative couplings.