Nonlinear shunting model of the pupil light reflex

Abstract

A leaky-integrator equation with shunting is introduced to represent processing at the retinal level as part of a system of delay-differential equations modelling the pupil light reflex. This system of equations exhibits the correct behaviour in response to monocular and binocular sinusoidal inputs. Understanding such behaviour can help to establish (non-invasively) the location and nature of nonlinearities in the reflex arc and how signals from the two eyes combine.

Shrewd alliances: mixed foraging associations between treeshrews, greater racket-tailed drongos and sparrowhawks on Great Nicobar Island, India

“…The sparrowhawk diverges from typical hunting techniques displayed by accipiters and exhibits a local, context-dependent foraging preference. Accipiter species in general are known to supplement about 10 per cent of their diet with small mammals (Gotmark & Post 1996) and to attack the most vulnerable group of mammals that are present in the area (Cresswell & Quinn 2004). However, the lowered chance of predation success in the presence of drongos may have led to the choice of the predator to join the group as a commensal.…”

Iris surface deformation and normalization

“…Studies of iris physiology reported that the response of the texture with respect to different intensities of light is non-linear due to the distribution of iris muscles controlling the pupil size [20]. Therefore, later works of iris normalization incorporate non-linear iris normalization.…”