Now Sperry combined the two procedures: he rotated the frog’s
eyeball by 180 degrees and cut the optic nerve connection between
the eyeball and the brain. Initially, of course, the frog was completely
blind, but after a few weeks the axons forming the optic nerve regrew
and reestablished connections between the eye and the brain. The
question: how would the frog see now? Will the frog’s nervous system
use the opportunity provided by regrowth of the optic nerve to form
synaptic connections that correct for the rotated eyeball, so that it
will see the world normally again. Or, will the frog see the world up-
side down and backward?
What is your prediction?
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Figure 10.6. Left: frog with normal vision. The frog sees the insect (dashed
line) and strikes out with its tongue in the direction of the insect (solid line).
Right: frog after eye is surgically rotated by 180 degrees. It apparently sees the
world upside down and backward, because it attempts to catch an insect lo-
cated above and behind its body by striking down and ahead.The result: the frog sees the world upside down and backward, as if
the eyeball had simply been rotated without the cutting and reform-
ing of the optic nerve connections. Thus, the frog did not use the
opportunity afforded by regrowing the optic nerve axons and forming
new synaptic connections in the brain to correct the damage done to