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The site of saccadic suppression.
Kai V Thilo1, Loredana Santoro, Vincent Walsh
1University Laboratory of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, UK. kai.thilo@physiol.ox.ac.uk
Nature Neuroscience
|December 31, 2003
Summary
During rapid eye movements (saccades), vision is stabilized by reducing sensitivity. This study shows saccadic suppression occurs before the occipital cortex, protecting vision during eye movements.
Area of Science:
- Neuroscience
- Visual Perception
- Ophthalmology
Background:
- Stable vision during eye movements (saccades) relies on reducing visual sensitivity, a phenomenon known as saccadic suppression.
- The precise location within the visual pathway where saccadic suppression originates remains an open question in neuroscience.
Purpose of the Study:
- To determine the site of saccadic suppression within the human visual system.
- To differentiate between retinal and cortical contributions to saccadic suppression.
Main Methods:
- Induction of phosphenes (illusory visual perceptions) using transcranial magnetic stimulation (TMS) applied to the occipital cortex.
- Induction of phosphenes via direct retinal stimulation.
- Assessment of phosphene perception during saccades.
Main Results:
- Phosphenes generated by transcranial magnetic stimulation (TMS) of the occipital cortex were not affected by saccadic suppression.
- Phosphenes generated by direct retinal stimulation were significantly suppressed during saccades.
- This dissociation provides physiological evidence for the site of saccadic suppression.
Conclusions:
- Saccadic suppression is not a feature of the occipital cortex itself.
- Saccadic suppression occurs at a processing stage between the retina and the occipital visual cortex.
- These findings clarify the neural circuitry underlying visual stability during eye movements.