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Tuesday, July 25, 2023

Missing Brain Parts

One of the most astonishing developments in neuroscience in recent years is the growing number of instances of researchers discovering cases of people who are missing parts of their brains that are responsible for certain functions but who are not missing the functions.

Denyse O'Leary writes about an example at Evolution News in which a girl lacks olfactory bulbs in her brain but nevertheless still has the ability to smell:
Ever since neuroscientists started imaging the brain, they’ve been turning up cases where people are missing brain parts we would expect them to need in order to do something — but they are doing that very thing anyway. One example, written up in Live Science in 2019, concerns women who are missing their olfactory bulbs but can still smell.

Researchers have discovered a small group of people that seem to defy medical science: They can smell despite lacking “olfactory bulbs,” the region in the front of the brain that processes information about smells from the nose.

It’s not clear how they are able to do this, but the findings suggest that the human brain may have a greater ability to adapt than previously thought.

The story is all the more remarkable when we consider that her sense of smell was especially good; that was why she had signed up for the Israeli researchers’ study. Deciding to pursue the matter, the researchers tested other women. On the ninth try, they found another left-handed woman who could smell without an olfactory bulb.
Missing olfactory bulbs are only one example of the brain's ability to adapt and compensate: Last year, Medical Express reported on a woman who lacked a left temporal lobe, believed to be the language area of the brain:
[The woman] told Fedorenko and her team that she only came to realize she had an unusual brain by accident—her brain was scanned in 1987 for an unrelated reason. Prior to the scan she had no idea she was different.

By all accounts she behaved normally and had even earned an advanced degree. She also excelled in languages — she speaks fluent Russian — which is all the more surprising considering the left temporal lobe is the part of the brain most often associated with language processing.

Eager to learn more about the woman and her brain, the researchers accepted her into a study that involved capturing images of her brain using an fMRI machine while she was engaged in various activities, such as language processing and math.

In so doing, they found no evidence of language processing happening in the left part of her brain; it was all happening in the right. They found that it was likely the woman had lost her left temporal lobe as a child, probably due to a stroke. The area where it had been had become filled with cerebrospinal fluid.

To compensate, her brain had developed a language network in the right side of her brain that allowed her to communicate normally.

The researchers also learned that [the woman] had a sister who was missing her right temporal lobe, and who also had no symptoms of brain dysfunction — an indication, the researchers suggest, that there is a genetic component to the stroke and recovery process in the two women.

It’s also come out that one in 4000 people lacks a corpus callosum. That’s the structure of neural fibers that transfers information between the brain’s two hemispheres. It would seem a pretty important part of the brain yet 25 percent of those who lack it show no symptoms. The others suffer mild to severe cognitive disorders.
Remarkably, some people have been found to be missing almost their entire cerebral cortex and are still leading normal lives. I wrote about one such case on VP some time ago here.

O'Leary believes that these phenomena are evidence that the brain is not all there is to our cognitive experience, that in addition to the material gray matter we also possess an immaterial mind. She concludes:
Neuroplasticity is perhaps best understood as the human mind reaching out past physical gaps and barriers in any number of inventive ways. And it raises a question: If the mind is merely what the brain does, as many materialist pundits claim, what is the mind when the brain … doesn’t? At times, the mind appears to be picking up where the brain left off.
Of course, if we do possess an immaterial mind then the metaphysical view called materialism, the belief that everything in the universe is just a manifestation of matter and energy, is wrong, and since materialism is a pillar of modern atheism, atheism cannot afford for materialism to be refuted.