Tuesday, October 14, 2014

The biological transmission of memory.

Article: Phobias may be memories passed down in genes from ancestors
In the study, which is published in the journal of Nature Neuroscience, the researchers trained mice to fear the smell of cherry blossom using electric shocks before allowing them to breed. 
The offspring produced showed fearful responses to the odour of cherry blossom compared to a neutral odour, despite never having encountered them before. 
The following generation also showed the same behaviour. This effect continued even if the mice had been fathered through artificial insemination.The researchers found the brains of the trained mice and their offspring showed structural changes in areas used to detect the odour.
Up until recently, this would have been considered nonsense. Classical evolution and genetics stated that the experiences of the parent could not be transmitted to offspring. At its most extreme, evolution was seen as favoring only those genes that were most successful in passing themselves onto offspring. Genes could affect behavior, but not the other way around.
The DNA of the animals also carried chemical changes, known as epigenetic methylation, on the gene responsible for detecting the odour. 
This suggests that experiences are somehow transferred from the brain into the genome, allowing them to be passed on to later generations. 
The researchers now hope to carry out further work to understand how the information comes to be stored on the DNA in the first place. 
They also want to explore whether similar effects can be seen in the genes of humans.
We now know that this mechanism exists, though not how it works. How does changes in the brain change the DNA in cells of the ovary and testes that become eggs and sperm?
He added: "It addresses constitutional fearfulness that is highly relevant to [human] phobias, anxiety and post-traumatic stress disorders, plus the controversial subject of transmission of the ‘memory’ of ancestral experience down the generations.

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