Abstract
The retina of adult salamander eyes always degenerates and is replaced by regeneration from surviving peripheral cells when the eye is grafted, 1 , 2 , 3 even repeatedly, 4 or when its blood supply is temporarily interrupted. 5 If the optic nerve is cut without interfering with the blood supply the retina survives and the nerve immediately regenerates. 5 This offers unusual opportunity to test the functional quadrants of the retina.
When Sperry first reported 6 reversed visoumotor responses in salamanders after optic nerve regeneration in eyes rotated in situ, I examined the effects of various types of rotation on vision in 100 grafted adult Triturus viridescens eyes in which a new functioning retina could be tested.
Normal visuomotor responses in salamanders are demonstrated when the animal moves toward, snaps at and follows a lure approaching any of the 4 quadrants in the field of vision. The animal also automatically moves head and body In the same direction with a rotating black and white drum only if it passes posteroanteriorly through the field of vision of an eye 7 , 8 , 9 (clockwise for a left eye and counterclockwise for a right eye). These compensatory movements are not elicited when the drum moves anteroposteriorly through the vision field of either eye.
The right or left eye was roated 180° in situ and fixed in place after cutting conjunctival and muscular attachments. The optic nerve and blood supply was left intact to preserve the original retina. The results were the same as in similar experiments by Sperry. All quardrants of the original intact retina were functionally reversed. After removing the normal eye on the opposite side the animals tended to swim and walk in circles toward the eyeless side.
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