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This study explores the relationship between retinal neuron firing and iris muscles in the context of the pupil control system. Three models are presented, with a focus on exploring the effects of different parameters and the introduction of a delay. The findings have potential applications in eye disease detection.
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Assumptions • The light has constant intensity and is shone constantly into the pupil • The light is shone on the edge of the pupil and the location of the light does not change • Direct relation between retinal neuron firing and iris muscles • Parameters (Rmin, Rmax, R1, R2) for models 2 and 3
MODEL 1 • Equations: • Firing rate is dependent on: • pupil radius • amount of light that has contact with pupil • df/dt= a*G(r)*Intensity Change in radius of pupil • Firing rate • dr/dt= -b*f
WRONG AND A DAY LOST!!! • a*G(r)*Intensity is not a rate; it is actually the number of neurons firing • Assuming instantaneous results; no delay rate -The model does not yield oscillating results; get decaying results -Delay: 200 ms • Different constants for pupil constriction and dilation
Introducing A Delay – Model 2 & 3 F0 – Optimal number of neurons firing F1 – Number of neurons that will fire as a result of incident light. k – scaling parameter g(r) – Fraction of F1 actually making it through iris at radius r.
Model 2 • Assume a form for g(r) • Some analysis -Analytical solution? yup -only oscillatory solutions -prediction for delay
Model 3 • Assume a form for g(r) • Analysis -Analytical solution? no -Can find linear stability
Conclusions • Evolutionary reason for rate of constriction/dilation of eye! • Why should damping exist? • Application: eye disease detection