Collective chaos is shown to emerge, via a period-doubling cascade, from quasiperiodic partial synchronization in a population of identical inhibitory neurons with delayed global coupling. This system is thoroughly investigated by means of an exact model of the macroscopic dynamics, valid in the thermodynamic limit. The collective chaotic state is reproduced numerically with a finite population, and persists in the presence of weak heterogeneities. Finally, the relationship of the model’s dynamics with fast neuronal oscillations is discussed.

We thank Hugues Chaté for valuable comments. D. P. acknowledges support by MINECO (Spain) under the Ramón y Cajal Programme. We acknowledge support by MINECO (Spain) under Project No. FIS2014-59462-P, and by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant No. 642563.