Spatial interactions in the superior colliculus predict saccade behavior in a neural field model.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Vision Science

Background:

• Eye movements are controlled by top-down (goal-related) and bottom-up (stimulus-related) neural signals.
• These signals converge in the superior colliculus intermediate layers (SCi), a midbrain structure crucial for saccades.
• The precise interaction of these signals within the SCi map and their influence on saccadic behavior is actively debated.

Purpose of the Study:

• To investigate the spatial interaction of top-down (TD) and bottom-up (BU) signals within a computational model of the SCi.
• To understand how these interactions influence saccadic reaction time (SRT).

Main Methods:

• Developed a two-dimensional dynamic winner-take-all neural field model of the SCi.
• Used physiological measurements of population activity on the SC map to inform model parameters.
• Simulated interactions by manipulating signal size, magnitude, number, and spatial separation.

Main Results:

• The model demonstrated nonlinear interactions between TD and BU signals within the SCi map.
• These interactions influenced SRT by altering spatial extent, peak magnitude, number, and separation of signals.
• The model successfully reproduced and reconciled inconsistencies in previous behavioral studies on TD and BU influences on SRT.
• Showed how spatial interactions can lead to either increases or decreases in SRT depending on experimental conditions.

Conclusions:

• Dynamic two-dimensional winner-take-all modeling with local excitation and distal inhibition accurately reflects SCi physiological activity.
• This modeling approach accounts for observed behavioral changes in SRT resulting from TD and BU signal manipulations.
• The findings provide a framework for understanding how neural signal interactions in the SCi govern saccadic eye movements.