Effect of light on stochastic phase synchronization in the crayfish caudal photoreceptor

Phase synchronization between the firing of the crayfish caudal photoreceptor (CPR) and an applied periodic hydrodynamic stimulus is investigated. It is shown that the CPR firing synchronizes with a periodic stimulus over a range of frequencies corresponding to the known sensitivity range of the crayfish to hydrodynamic stimuli. This synchronization is quantified using previously developed measures of synchronization such as the synchronization index; multiple stimulus-response locking ratios occur in this system that are consistent with theoretical predictions based on the theory of synchronization of noisy oscillators. The maximal synchronization for various locking ratios is shifted to higher frequencies in the presence of light.