Chaos in neurobiology

Deterministic mathematical models of neural systems can give rise to complex aperiodic (`chaotic') dynamics in the absence of stochastic fluctuations (`noise') in the variables or parameters of the model or in the inputs to the system. The authors show that chaotic dynamics are expected in nonlinear feedback systems possessing time delays such as are found in recurrent inhibition and from the periodic forcing of neural oscillators. The implications of the possible occurrence of chaotic dynamics for experimental work and mathematical modeling of normal and abnormal functions neurophysiology are mentioned.