A SECOND ORDER FEEDBACK MODEL OF VISUAL TRANSDUCTION IN CONES OF THE MONKEY MACACA FASCICULARIS

A representative existing model of visual transduction in the retinal cones of the macaque monkey combines parametric curves and feedback models to give a detailed description of cone response dynamics. Here, we approximate this previous model with a second order feedback control system, capturing key dynamic characteristics of cone responses, namely, a system with a natural frequency of 5 Hz and peak response time of 50ms. Even if considerably simplified when compared to the original model, the second order feedback system is found useful as a computational tool to simulate blurring of moving visual cues. Comparison with a signal averaging model- an accepted approximation of motion blur- shows that second order feedback more closely follows visual perception of motion smear in various stimulus patterns. The finding that cone dynamics capture perceptual phenomena that has been hitherto associated with motion pathways raises questions about the neurological origins of motion blur effects. Visual transduction in rods and cones of the retina constitutes the earliest step in neural representation of optical signals in the visual system. Understanding the nature of these earl