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Interaction of the two frontal eye fields before saccade onset
J Schlag1, P Dassonville, M Schlag-Rey
1Department of Neurobiology and Brain Research Institute, UCLA School of Medicine, Los Angeles, California 90095-1763, USA.
Journal of Neurophysiology
|February 21, 1998
Summary
Scientists discovered how frontal eye field (FEF) neurons achieve consensus for saccades. Functional connections ensure cells commanding similar movements excite each other and silence conflicting ones, preventing competing eye movement commands.
Area of Science:
- Neuroscience
- Oculomotor Systems
Background:
- The brain must select a single target for gaze despite competing stimuli.
- Oculomotor neurons in central brain regions consistently agree on saccade destinations.
Purpose of the Study:
- To investigate the mechanism by which saccade-related cells in the frontal eye fields (FEF) avoid issuing competing commands.
- To elucidate how neural consensus for saccade initiation is achieved.
Main Methods:
- Unit recording and microstimulation in trained monkeys.
- Recorded presaccadic neuronal activity in one FEF while stimulating the contralateral FEF.
- Analyzed cell responses to microstimulation, including collision techniques to alter saccade vectors.
Main Results:
- 35% of cells were unaffected, 37% inhibited, and 20% excited by contralateral FEF stimulation.
- Response types (excitation/inhibition) depended on stimulation site and angular difference between movement vectors.
- A subset of cells (8%) showed vector-dependent activation or inhibition based on evoked saccades.
Conclusions:
- Functional connections between FEF cells implement a winner-take-all mechanism for saccade selection.
- Cells commanding similar movements mutually excite, while those commanding conflicting movements inhibit each other.
- This neural circuitry effectively prevents conflicting eye movement commands.