Memory-like effects in fly vision: Spatio-temporal interactions in a wide-field neuron

摘要

In earlier papers the correlation model for the perception of movement was shown to be a powerful tool in the description and prediction of the spike activity of the movement detectors in the lobula complex of the fly as evoked by a wide variety of continuously or stepwise moving visual patterns. In this paper we use the correlation model to predict the responses elicited by a pattern which alternates stepwise movements with stepwise intensity changes. The experimental results violate these predictions as long as the two alternating stimuli-movement and flickerare treated separately, i.e. as long as in the estimation of a flicker response no remainder effect of the preceding stimulus (a movement step) is taken into account and vice versa. It is shown that introduction in the model calculations of a memory-like term which carries information concerning the immediate past of the stimulusevent space of the neuron, generalizes the correlation model in such a way that the movementflicker experiments can be satisfactorily understood. The time constant of the memorylike performance of the movement detectors can take values of the order of magnitude of a few minutes.