Competitive Integration of Visual and Preparatory Signals in the Superior Colliculus during Saccadic Programming

Abstract

Efficient behavior requires that internally specified motor plans be integrated with incoming sensory information. Motor preparation and visual signals converge in the intermediate and deep layers of the superior colliculus (SC) to influence saccade planning and execution; however, the mechanism by which these sometimes conflicting signals are combined remains unclear. We studied this issue by presenting visual distractors as monkeys prepared saccades toward an upcoming target whose timing and location were fully predictable. Monkeys made more distractor-directed errors when the spatial location of visual distractors more closely coincided with the saccadic goal. Concomitant pretarget activity of SC visuomotor neurons, whose response fields were centered on the saccadic goal, was similarly increased by the presentation of nearby distractors and inhibited by the presentation of distant distractors. Finally, subthreshold microstimulation of the SC shifted the pattern of distractor-directed errors away from the saccadic goal toward that specified by the site of stimulation. Together, our results suggest that the likelihood of saccade generation is influenced by the spatial register of internal motor preparation signals and external sensory signals across the topographically organized SC map.

Role of the Superior Colliculus in Choosing Mixed-Strategy Saccades

“…10), which indicates that the SCi is causally involved in selecting strategic saccades. Previous work has shown that artificially manipulating SCi activity can bias the selection of perceptually guided saccades; that is, alter the probability of choosing a target stimulus that differs from distracting stimuli based on some sensory feature McPeek and Keller, 2004;Dorris et al, 2007). This study extends these previous findings in two important respects.…”

“…This transient burst had to be at least 50 spikes/s above the activity during preparatory period outlined above and be initiated within 100 ms after presentation of the target (Dorris et al, 2002). This visual activity was not contaminated by saccade-related bursts because the initiation of saccades was delayed during the mixed-strategy task presumably because of the competitive interactions between the two simultaneously presented targets (Dorris et al, 2007). Last, all microstimulation experiments were conducted within SCi regions with identified saccade-related activity.…”

Optimal Sensorimotor Control in Eye Movement Sequences

“…Numerous cortical areas are implied in the cortical network of saccadic movement such as frontal eye field (FEF), supplementary eye field, dorsolateral prefrontal cortex, parietal eye field, cerebellum and different subcortical regions as the superior colliculus and the brainstem reticular formation (Gaymard et al, 1998;Quaia et al, 1999;Munoz and Fecteau, 2002;Dorris et al, 2007). Previous studies suggest that the forward and inverse models used for sensory-motor control involve the cerebellum and parietal cortex (Zee et al, 1980;Imamizu et al, 2004;Bursztyn et al, 2006).…”

A competitive integration model of exogenous and endogenous eye movements

“…Visual, DLPFC, and FEF inputs to SC show a coarse topology, in that cortical cells tend to project to many neighboring neurons in SC (Funahashi et al 1990;Komatsu and Suzuki 1985;Lock et al 2003;Sommer and Wurtz 2001). This implies that collicular neurons have relatively broad visual fields, which is indeed the case (Dorris et al 2007;Ottes et al 1986;Schiller et al 1980). The spatial shape of the inputs to SC was a Gaussian around an SC location receiving maximum input l max .…”