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Influence of eye position on activity in monkey superior colliculus
A J Van Opstal1, K Hepp, Y Suzuki
1Neurology Department, University Hospital, Zürich, Switzerland.
Journal of Neurophysiology
|October 1, 1995
Summary
The superior colliculus (SC) uses an eye position signal for eye movement generation. This research found that SC neuron activity is modulated by the eyes' position in the orbit, influencing saccade commands.
Area of Science:
- Neuroscience
- Ophthalmology
- Motor Control
Background:
- The superior colliculus (SC) is crucial for generating eye movements.
- Previous studies suggested SC cell activity represents a fixed saccadic vector command.
- However, anatomical and lesion data implied SC access to eye position information.
Purpose of the Study:
- To investigate whether SC neuronal activity is influenced by eye position during saccade generation.
- To test the hypothesis that the SC integrates eye position signals into its motor commands.
Main Methods:
- Recorded activity from presaccadic burst neurons in the SC of alert rhesus monkeys.
- Monkeys performed rapid eye movements across a wide oculomotor range.
- Analyzed neuronal firing rates and characterized eye position dependence using model-independent and quantitative (gain field) descriptions.
Main Results:
- Activity of 30 out of 57 recorded SC neurons was significantly influenced by eye position.
- While saccade tuning remained consistent, peak firing rates varied systematically with eye position.
- Gain fields showed varied alignment of eye position sensitivity relative to saccade direction.
Conclusions:
- The SC demonstrably has access to a signal encoding eye position in the orbit.
- This eye position signal likely modulates the neural code for saccadic eye movements.
- Further research is needed to elucidate the functional role of this signal within the SC's motor map.