The thought of spending 10 days holed up in a dark room is
unpleasant. The thought of kittens holed up in a dark room for
10 days seems cruel, until one learns that the kittens entered
the room visually impaired and emerged from it with their vision
restored. The kittens in question suffered from the equivalent
of a human condition known as amblyopia, commonly referred to as
“lazy eye.” Amblyopia is associated with unusual changes in the
visual cortex of the brain, which arise from the difference in
the degree to which each eye is used. The changes are
characterized primarily by the suppression of neural pathways
associated with visual input from the weak eye and consolidation
of the pathways from the favored eye. Remarkably, these changes
can be undone through forced use of the suppressed eye (in other
words, covering the favored eye to prevent its use). But age
plays a critical role in recovery, because after the first few
years of life, the brain is less able to alter its neural
connections to process info