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Short-latency fixational saccades induced by luminance increments
Gregory D Horwitz1, Thomas D Albright
1Howard Hughes Medical Institute and Vision Center Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA. horwitz@salk.edu
Journal of Neurophysiology
|August 9, 2003
Summary
Peripheral visual stimulation, specifically luminance increases, can trigger small, natural eye movements called fixational saccades. This study in macaque monkeys reveals a consistent link between visual stimuli and these involuntary saccades.
Area of Science:
- Neuroscience
- Ophthalmology
- Visual Perception
Background:
- During visual fixation, small, involuntary eye movements known as saccades naturally occur.
- The influence of peripheral visual stimuli on these fixational saccades is not fully understood.
Purpose of the Study:
- To investigate the impact of peripheral visual stimulation on naturally occurring, small-amplitude saccades during fixation.
- To determine if changes in peripheral stimulus intensity can evoke fixational saccades and characterize the response properties.
Main Methods:
- Two macaque monkeys were trained to maintain fixation on a central target.
- A colorful stimulus was presented in the visual periphery with random flickering.
- Reverse correlation analysis was used to link stimulus patterns to saccade occurrences.
Main Results:
- A reliable relationship was found between stimulus sequences and saccade occurrences.
- A transient increase in peripheral stimulus intensity evoked saccades with a latency of approximately 70 ms.
- The spectral tuning of the evoked saccades suggested a response to luminance changes, though not exclusively.
Conclusions:
- Peripheral luminance increases are capable of evoking fixational saccades.
- These findings contribute to understanding the mechanisms controlling eye movements during fixation.
- The study highlights the sensitivity of the oculomotor system to peripheral visual events.