People who have been blind since birth are just as proficient in numerical reasoning skills as sighted people, according to a new study at Johns Hopkins University (JHU). The findings contradict the popular belief that basic number sense — shared by humans and even animals — has evolved primarily as a result of looking at the world and trying to quantify the sights.
The neuroscientists also found that the visual cortex in blind people is highly involved in doing math, suggesting the brain is far more adaptable than previously believed.
“The number network develops totally independently of visual experience,” said lead author Shipra Kanjlia, a graduate student in JHU’s Department of Psychological and Brain Sciences. “These blind people have never seen anything in their lives, but they have the same number network as people who can see.”
For the study, both born-blind participants and sighted participants wearing blindfolds solved math equations and answered language questions while having a brain scan. With the math problems, participants heard pairs of increasingly complicated recorded equations and were asked to tell whether 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, became very active as participants solved the math problems.
Meanwhile, in blind participants only, regions of the visual cortex also responded as they did math. In fact, the more complicated the math, the greater the activity in the vision center.
Although it has been a common belief that brain regions, including the visual cortex, had entrenched functions that could change slightly but not fundamentally, these findings confirm recent research showing just the opposite: The visual cortex is extremely plastic and, when it isn’t processing sight, can handle a variety of tasks, including responding to spoken language and math problems.
The findings suggest that the brain as a whole could be extremely adaptable, almost like a computer. Depending on data coming in, the brain could reconfigure to handle almost limitless types of tasks, say the researchers. In fact, it could someday be possible to reroute functions from a damaged area to a new spot in the brain.
“If we can make the visual cortex do math, in principle we can make any part of the brain do anything,” said co-author Dr. Marina Bedny, an assistant professor of psychological and brain sciences.
This study is the first to show that this repurposed vision center in blind people is not just responding to new functions haphazardly. The cortex in blind people has essentially become specialized with some parts of this area doing math, while other parts are doing language, etc.
Even in a resting state, brain scans show these new brain regions connect to traditional parts of the brain responsible for math and language in sighted people.
The findings are published online in the journal Proceedings of the National Academy of Sciences.
Source: Johns Hopkins University