Its old news that the neurogenesis of new brain cells does occur. Although, perhaps like me, you can remember arguments to the contrary.
I still remember a school friend arguing that you kill five brain cells every time you have a drink of beer and they will never grow back….
Fortunately, Argentinean Fernando Nottebohm shattered the belief that a brain gets its nerve cell quota shortly after birth and lets them die off through life.
Then of course the skepticism continued that it could not be true of humans. "Read my lips: no new neurons," stated Pasko Rakic, of Yale University.
Now I fully support the scientific method. The problem is that institutionalization is as part of science as it is in religion or politics. And as in the field of religion, I admire a man who is prepared to logically test his belief or theology and modify his view because he never stopped searching for new data.
In a world of magical thinking, where statistical association is often confused as proof of causation among new age gurus and advertising executives it is only right that science proceeds cautiously.
OK, the mating calls and territorial claims of caged canaries and finches in New York State may appear an odd place to start.
Yet neurobiologist Fred Gage of the Salk Institute in La Jolla, California, found evidence nerve cell regrowth in humans. This may potentially help treat waisted neral conditions like Parkinson’s and Alzheimer’s.
It was because Nottebohm remained open minded that a new field of health care may develop.
"Once I was in the 5 or 10 percent of scientists who believed in neurogenesis," said Nottebohm. "Now 95 percent accept that position. I rather liked it better being in the minority."
."Listening to birds was sort of my hobby," he said. "Other boys had cars, I had birds. I liked to try to identify them by their songs."
He then studied bird songs at the University of California at Berkley before moving to Rockefeller University.
Iin 1981 he demonstrated that a male canary’s brain changes seasonally in the area responsible for bird song. It grows when it is needed most to attract a mate in spring and shrinks in summer.
Nottebohm’s collegue Arturo Alvarez-Buylla, traced the new nerves to particular stem cells in the lining of the ventricles or fluid-filled cavities in the brain.
“The discovery that neurons can arise from stem cells in the brain fires hopes of a potentially limitless material for repairing damaged brain tissue” states Smithsonian Magazine. The potential will depend on the realities of further research.
In 1998, research found that a chemical called
BrdU in the hippocampus, part of the brain that lays down memories. BrdU incorporates into the DNA of dividing cells and suggested that new neurons had developed and perhaps played a role in storing information.
However, mammalian adult neurogenesis has only been found in the hippocampus which is why researches like Rakic are skeptical. Unless it is found to occur in the cerebral cortex the research may be of little value.
"We start life with a lot of uneducated neurons, but at some point they all become college graduates," states Radik. "With neurogenesis in the cerebral cortex, you would have neurons that never went to elementary school. New cells would erode all your memories. You would give up all you have labored to acquire."
On the other hand neurobiologist Elizabeth Gould, a Princeton University argues that neurogenesis would not occur in mammals without a reason. Ms Gould found neurogenesis in marmoset and other adult primates.
Nottebohm suggests that the aging brain develops new brain cells to learn new things but deletates the unnecessary files from the neural hard drive.
Nottebohm soon found evidence in birds. He researched blackcapped chickadees that hide food sources in trees. Come autumn the chickadees grow new cells in a brain center dealing with spatial memory when it is most needed.
So Gould continued research with rhesus monkeys and discovered neurogenesis in three areas of the cerebral cortex:
1. the prefrontal region, which controls executive decision making and short-term memory;
2. the inferior temporal region, which plays a crucial role in the visual recognition of objects and faces, and
3. the posterior parietal region, which is important for the representation of objects in space.
It was not discovered in the striate cortex, which handles the initial, and more rudimentary, steps of visual processing
“That contrast suggests that neurogenesis may play a role in performing higher brain functions” stated a
Princeton Press release in 1999.
More recently, a Japanese research group led by Professor Junichi Nabekura in National Institute for Physiological Sciences, NIPS, Japan, found that, after cerebral stroke in one side of the mouse brain, another side of the brain rewires its neural circuits to recuperate from damaged neural function. The report was released in the
Journal of Neuroscience, on August 12, 2009.
"We found that the active rearrangement of the neural circuits in the opposite side of the brain happens only in the specific period after strokes. Our findings can be applied to rehabilitative programs for stroke survivors", said Professor Nabekura.
Recent advances in functional imaging of human brain activity in stroke patients, such as functional magnetic resonance imaging, have revealed that cortical hemisphere contralateral to the infarction plays an important role in the recovery process. However, underlying mechanisms occurring in contralateral hemisphere during functional recovery have not been elucidated.
Perhaps this short example demonstrates how we should not be too quick to shut off areas of research, while proving we must be open to try and establish causal mechanisms.
It’s the insight of people like Nottebohm that win respect.
Sometimes people are accused of making ridiculous claims in the name of positive thinking. You have to be realistic they rightly say. They may even be rightly frustrated.
However, as New Age guru James Ray said: “Positive thinking doesn’t work, but optimists achieve more.”
I suggest we should be we should be encouraging creative research to see how far the boundaries can be pushed. I also encourage the cycnical minority of scientidfic thinkers to perhaps be a bit more tolerant of more abstract and less mechanistic ways of thinking.
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