Human babies and even animals
have a basic number sense that many believe evolves from seeing the world and
trying to quantify all the sights. But vision has nothing to do with it --
Johns Hopkins University neuroscientists have found that the brain network
behind numerical reasoning is identical in blind and sighted people. The
researchers also found the visual cortex in blind people is highly involved in
doing math, suggesting the brain is vastly more adaptable than previously
believed. The findings are published online in the journal Proceedings of the
National Academy of Sciences. The researchers had congenitally blind people and
sighted people wearing blindfolds solve math equations and answer language
questions while having a brain scan. With the math problems, participants heard
pairs of increasingly complicated recorded equations and responded if the value
for "x" was the same or different.
The participants also heard pairs
of sentences and responded if the meaning of the sentences was the same or
different. With both blind and sighted participants, the key brain network
involved in numerical reasoning, the intraparietal sulcus, responded robustly
as participants considered the math problems. Meanwhile, in blind participants
only, regions of the visual cortex also responded as they did math. And the
visual cortex didn't merely respond -- the more complicated the math, the
greater the activity in the vision center. Although it had been thought that
brain regions including the visual cortex had entrenched functions that could
change slightly but not fundamentally, these findings underscore recent
research that showed just the opposite: The visual cortex is extremely plastic
and, when it isn't processing sight, can respond to everything from spoken
language to math problems.
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