A bifurcation of a synchronous oscillations into a torus in a system of two mutually inhibitory aVLSI neurons: experimental observation

We studied a system of two ‘identical’ oscillatory aVLSI neurons with mutually inhibitory connections. The system demonstrates different oscillatory behaviors depending on the strength of the inhibitory connections: anti-phasic, synchronous, phase-shifted, and quasiperiodic oscillations. We experimentally observed a bifurcation of synchronous oscillations into quasiperiodic oscillations with two independent frequencies. This bifurcation was confirmed by the analysis of the phase between neuronal outputs, the cross-correlation function, the amplitude spectrum, and the correlation dimension. The observation of this bifurcation in a physical system suggests that this scenario might also occur in living half-center oscillators, such as those found in central pattern generators.