Spatiotemporal processing in neural networks with random synaptic background activity

Nonlinear shunting model of the pupil light reflex

“…An immediate consequence of the shunting effect is that it provides a logarithmic-like compression of retinal response that is consistent with the Weber-Fechner law (Grossberg 1988;Bressloff 1995). (There is also log arithmic compression of light at the photoreceptor level.)…”

“…We therefore extend the model by introducing an additional dynamical variable that represents the membrane potential of the retinal ganglion cells within a population model. We assume that evolves according to the standard leaky-integrator shunting equation (Grossberg 1988;Bressloff 1994Bressloff , 1995:…”

“…In this paper, we extend the Longtin-Milton model to include a phenomenological representation of the dynamics of the retinal system in the form of a leakyintegrator shunting equation (Bressloff 1994(Bressloff , 1995Grossberg 1988). We show how the flux-dependent modulation of the effective time constant of the system (due to shunting), combined with the various nonlinearities of the system, can account for the following observed features: (i) there is a frequency-dependent shift in the average pupil response when a constant light stimulus is modulated by a sinusoidal input; and (ii) there is a nonlinear summation of signals from left and right eyes (binocular versus monocular sinusoidal response).…”