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blackvault
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Joined: Sep 10, 2001
Posts: 3660
Location: USA
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 Posted: Sat Jul 20, 2002 4:24 am Post subject: Study finds that one gene makes \'big brains\' in mice |
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When it comes to brains, is \"bigger\" always \"better\"? That\'s the question that researchers at Brigham and Women\'s Hospital and Harvard Medical School are asking, following a startling result to one of their experiments. Dr. Christopher Walsh led a team of colleagues in finding out what the effects would be if mice were given a double portion of beta-catenin. (This is what helps to control cell division in normal mice.) In their experiment, they wanted to see if having more of beta-catenin would cause the brain tissue to be overactive in development. Even they were surprised with the degree of success they achieved.
The resulting mice had brains so large that the brain had to fold up on themselves in the same way human brains do. This \'squishing\' allowed the significantly larger brain to still fit inside the skull. They bore a striking resemblance to a human brain, in fact.
Humans have disproportionately large brains for their size. Especially large is the cerebral cortex, the surface layer made up of gray matter -- the stuff involved in thought, as opposed to control of basic body functions.
\"The thinking power of the cerebral cortex is determined by surface area. It is basically a sheet,\" said Walsh, a neurologist and geneticist.
\"If unfolded, it would be 10 times bigger than our head is. But the head has to be small enough to come out of the mother\'s body at the right time.\"
What are the effects of having a drastically increased brain? Were the mice smarter? We\'ll have to wait for the answer on that, because in this study the mice were all killed shortly after birth. Dr. Christopher Walsh, who led the study, admits it\'s a question she\'d love to be able to answer herself.
\"I know the most interesting question was whether they learned to play Mozart, but we [just] don\'t know,\" she reported in a telephone interview with Fox News.
\"A bigger brain is not always good,\" he added, pointing out that a condition called megacephaly, in which the cerebral cortex grows too large, can cause mental retardation.
Walsh and colleague Anjen Chenn decided to use beta-catenin because of its unique function.
\"It is expressed in the brain in such a way that made us think it could be a regulatory switch that makes cells stop dividing ... and become a neuron,\" Walsh said. \"Because neurons don\'t divide, that has to happen for a cell to become a neuron.\"
Unlike cells in other tissues of the body, neurons stop dividing and become fully formed before birth.
One of the next things the scientists plan to do is determine whether the beta-catenin gene is abnormal in cases of mental retardation, or in cases where the brain is too big or too small for the owner.
They\'ll also genetically engineer more mice with extra beta-catenin and allow them to continue to develop, while watching them closely. They hope to be able to determine if they develop normally and how their level of intelligence has been affected by the change.
Source: Reuters
http://www3.cosmiverse.com/news/science/0702/science07190201.html
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