The 'optic chiasm' (
Greek χίασμα, "crossing", from the Greek χλαζειν 'to mark with an X', after the Greek letter '
Χ', ''chi'') is the part of the
brain where the
optic nerves partially cross.
Pathways
Specifically, the nerves connected to the right eye that attend to the left visual field cross with the nerves from the left eye that attend to the right visual field.
The parts of both
eyes that attend to the right visual field are processed in the left
visual system in the brain, and vice versa.
Optic chiasm in cats
In
Siamese cats with certain
genotypes of the
albino gene, this wiring is disrupted, with less of the nerve-crossing than is normal, as a number of scholars have reported.
[1] To compensate for lack of crossing in their brains, they cross their eyes (
strabismus).
[2]
This is also seen in albino
tigers, as Guillery & Kaas report.
[3]
Additional images
References
1. OMIA
2. R. W. Guillery; J. H. Kaas. Genetic Abnormality of the Visual Pathways in a "White" Tiger. ''Science''. 1973 Jun 22;180(92):1287-9. GS
3. Guillery, R. Visual pathways in albinos. ''Scientific American'' 1974 May;230(5):44-54. PubMed
★ Jeffery, Glen.
Architecture of the Optic Chiasm and the Mechanisms That Sculpt Its Development ''Physiol Rev'', Oct 2001; 81: 1393 - 1414.
External links
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