FitzHugh-Nagumo model and signal processing in the visual cortex of fly

In this paper, FitzHugh-Nagumo equations are used to model the dynamics of tangential cells in fly's visual cortex. Membrane current produced by the visual stimuli is modelled as the external input. An asympototic method is used to show that the amplitude of the oscillation depends critically on the magnitude of the external input. Furthermore, in a neighborhood of a bifurcation, the amplitude increases monotonically as a function of the external input. This result helps to explain how the visual cortex of fly encodes visual stimulus and detects motion.