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Dynamic dissociation of visual selection from saccade programming in frontal eye field.
A Murthy1, K G Thompson, J D Schall
1Vanderbilt Vision Research Center, Department of Psychology, Vanderbilt University, Nashville, Tennessee 37240, USA.
Journal of Neurophysiology
|November 8, 2001
Summary
Neurons in the frontal eye fields select conspicuous visual targets, not just prepare eye movements (saccades). This selection reflects image interpretation, not an automatic saccade command.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Visual Perception
Background:
- Previous research in frontal eye fields (FEF) identified a selection process before saccades during visual search.
- The exact nature of this selection process remains debated: is it stimulus-driven or movement-related?
Purpose of the Study:
- To differentiate between stimulus-based selection and saccade preparation in FEF neurons.
- To investigate whether FEF neuronal activity reflects the salience of a visual stimulus or the motor command for an upcoming saccade.
Main Methods:
- A novel 'search-step' task was developed for visual search experiments.
- This task involved a singleton visual search array where the target's location unpredictably switched with a distractor.
- This allowed for trials where the same stimulus was either a target or a distractor, eliciting saccades towards or away from it.
Main Results:
- Visually responsive neurons in the frontal eye fields consistently selected the current location of the conspicuous target.
- This selection occurred even when the participant's gaze shifted to the distractor's location.
Conclusions:
- The findings demonstrate a dissociation between stimulus selection and saccade preparation in FEF.
- Neuronal selection in FEF appears to be an explicit interpretation of visual input, rather than an obligatory saccade command.