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Updated: Jun 4, 2026
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Investigating the Deployment of Visual Attention Before Accurate and Averaging Saccades via Eye Tracking and Assessment of Visual Sensitivity
Published on: March 18, 2019
Separate visual signals for saccade initiation during target selection in the primate superior colliculus
Brian J White1, Douglas P Munoz
1Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada. brianw@biomed.queensu.ca
Summary
The superior colliculus (SC) uses both color and brightness signals for visual orientation. Delayed color signals, compared to brightness signals, impact target selection and eye movement initiation.
Area of Science:
- Neuroscience
- Visual Processing
- Primate Behavior
Background:
- The superior colliculus (SC) orients the visual system to relevant stimuli.
- Historically, SC visual activity was thought to derive solely from achromatic pathways.
- Recent findings indicate primate SC sensitivity to chromatic pathways, with delayed signal arrival compared to luminance.
Purpose of the Study:
- Investigate the functional consequences of delayed chromatic signals in the SC.
- Examine how timing differences affect target selection and saccade initiation.
- Determine the influence of chromatic and achromatic pathways on saccade commands.
Main Methods:
- Two rhesus monkeys performed a color-singleton selection task.
- Stimuli varied in chromaticity only (isoluminant) or combined chromatic-achromatic components.
- Monitored neural activity and saccade initiation in response to visual stimuli.
Main Results:
- Visual responses were delayed for chromatic-only stimuli versus combined stimuli.
- SC neurons discriminated targets similarly across conditions when chromaticity was constant.
- Saccades were initiated faster but with more errors for chromatic-achromatic stimuli.
Conclusions:
- Luminance signals may trigger saccades prematurely before adequate color discrimination.
- Separate mechanisms in the SC may independently control saccadic commands.
- Signal arrival time and visual selection output influence saccade initiation.
