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Functional and neuronal binocularity in kittens raised with rapidly alternating monocular occlusion
L Altmann1, H J Luhmann, J M Greuel
1Max Planck Institute for Brain Research, Frankfurt, Federal Republic of Germany.
Journal of Neurophysiology
|November 1, 1987
Summary
Kittens can develop normal binocular vision even with several hundred milliseconds of asynchronous visual input. This suggests the kitten visual system is flexible in developing binocularity.
Area of Science:
- Neuroscience
- Developmental Biology
- Vision Science
Background:
- Binocularity, the coordinated use of both eyes, is crucial for depth perception and visual processing.
- The critical period for visual development in kittens requires specific patterns of binocular input for normal maturation.
Purpose of the Study:
- To investigate the degree of synchrony in binocular visual activation necessary for the development of normal binocularity in kittens.
- To determine the impact of varying intervals of alternating monocular occlusion on visual functions and cortical development.
Main Methods:
- Kittens were reared with rapidly alternating monocular occlusion using microprocessor-controlled shutters, with varying occlusion intervals (50-1,000 ms).
- Control groups included normally reared kittens and those with synchronous occlusion.
- Evaluations included binocular depth discrimination, pupillary light reflex for luminance summation, and single-cell recordings in the visual cortex.
Main Results:
- A strong correlation was observed between the degree of binocular experience asynchrony, impaired depth discrimination, and reduced percentages of binocular neurons.
- Kittens reared with alternation rates up to 400 ms showed normal binocularity, similar to controls.
- Alternation rates of 500 ms or longer impaired depth discrimination and luminance summation, and reduced cortical binocularity.
Conclusions:
- The kitten visual system can tolerate significant asynchrony (several hundred milliseconds) in binocular activation while still developing normal binocularity.
- Depth discrimination, binocular luminance summation, and the percentage of binocular neurons exhibit a linear relationship with the degree of binocular synchrony.