Motivational modulation of endogenous inputs to the superior colliculus

Proper initiation of saccadic eye movements depends on an intricate balance between exogenous and endogenous control mechanisms. The superior colliculus (SC) is a major site of signal integration that has been shown to drive the initiation of saccades in the brainstem. Previous work has shown that a winner-take-all mechanism implemented with a continuous attractor neural network (CANN) can explain and reproduce a multitude of behavioural findings, including the gap effect and the production of express saccades by K. Kopecz (1995) and by T.P. Trappenberg (2001). This investigation advances the CANN model of saccade initiation in several important ways in order to account for trial by trial adaptation of saccadic reaction times in a biologically plausible manner. A key hypothesis is that endogenous inputs to the intermediate layer of the SC can be adapted through motivationally-based feedback from other areas of the brain such as the basal ganglia or higher cortical areas.