16 September 2014

Scientists "humanized" mice, trying to understand the origins of human speech

They didn't talk, but they got smarter

Nadezhda Markina, "Newspaper.Ru"Scientists have "humanized" mice by changing their gene responsible for human speech.

The result was that the mice were more successfully trained to find bait in the maze. Perhaps this is how scientists found changes in the mouse brain that once allowed a person to speak.

The ability to articulate speech is the main feature that distinguishes a person even from the most highly organized animals. But the speech did not arise from scratch. If man descended from a monkey, as Darwin suggested, and modern anthropology has proved, then our perfect brain is a matter of human pride, it is a product of evolution. And something like that happened to him in our ancestors, which made the appearance of speech possible. But everything that happens to the brain originates in the genes.

Modern geneticists, sorting out the human genome analysis data, pay attention to the FOXP2 gene as the closest to being called the speech gene. This gene was discovered by Swedish scientist Svante Paabo, famous for reading the genome of a Neanderthal, and then a Denisovan man.

It turned out that people whose FOXP2 gene is functionally inactive in at least one chromosome suffer from a speech disorder, both oral and written.

I must say that this "speech gene" is present not only in humans, but also in all mammals, including mice. In general, we differ very little from mice in the set of genes. But in humans, it has acquired some changes, key mutations, which make it necessary for the formation of speech skills.

Researchers from the Massachusetts Institute of Technology decided to see what would happen if these changes were made to the FOXP2 gene in mice. They made two substitutions in the mouse gene, making it human.

This operation radically affected the rodents. No, the "humanized" mice did not learn to speak, but they became smarter than their fellows, as the authors of the experiment wrote in the journal PNAS (Schreiweis et al., Humanized Foxp2 accelerates learning by enhancing transitions from declarative to procedural performance).

Ordinary mice with the human FOXP2 gene were trained to find bait in a maze in the shape of the letter T. To get it, the mice had to run either to the right or to the left when they reached the fork. The location of the bait was indicated to them by various clues.

And here the "humanized" mice showed their advantage: they learned faster and with fewer mistakes.

Next, the scientists decided to look at what changes occurred in the brains of "humanized" mice. In the most interesting areas of the brain, they analyzed all the active genes (for this they collected all the RNA that is synthesized on the DNA matrix while the gene is working). And they found that the "humanization" of one gene greatly affected the activity level of many other genes. Further, it turned out that the human gene changed the level of dopamine, the most important nerve signal transmitter in some parts of the mouse brain. And also increased the plasticity of synapses – contacts between neurons. This is the most important condition for good learning.

Mice have become more intelligent, fine. But what does it have to do with it, it would seem? But then it turned out that the changes in the brain of humanized mice concern exactly what people with the defective FOXP2 gene and speech disorders lack.

So scientists have suggested that they have managed to simulate to some extent the development of the human brain on the way to the development of articulate speech.

In general, a little more, and you can experiment to talking mice. But seriously, to understand how our ancestors managed to speak.

Portal "Eternal youth" http://vechnayamolodost.ru16.09.2014

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