Epigenetics

This blog post is another in the series inspired by the book, The Scientific American Brave New Brain.1 That book presents a table contrasting the way the brain once was regarded, the way it is presently regarded, and some conjectures about what tomorrow might hold. According to Brave New Brain, we once thought that environment determines mental potential and that today we think that genes determine mental potential. Here I must take strong exception to Brave New Brain. There were some philosophical arguments that the mind began as a blank plate, tabula rasa, and that experience was written on that plate. The father of behaviorism, John Watson, argued that he could take an infant and raise it to be anything, a butcher, a baker, a candlestick maker, a physician, a lawyer, another psychologist. For him the environment determined everything and that if the proper environments were provided a child could become anything.

Even before Mendel discovered genes, there was the notion of blood and royalty. Certain people were regarded as inherently superior to others. When genes were discovered, some thought that there might be a scientific basis for this superiority, and that genetics could account for individual differences. According to Brave New Brain, that is the current belief. This is certainly not the case. Early in the twentieth century intelligence tests were developed. Arguments as to know much intelligence is attributable to genetics and how much intelligence is attributable to the environment raged. Charges of racism entered these arguments and charges and evidence that IQ tests were culturally biased raged. It should be noted that there are statistical techniques and research designs (controlled identical twins studies, for example) that allow estimates of what percentage of intelligence is genetically determined and what percentage is due to the environment. But these are statistical abstractions. Nature (genetics) and nurture (environment) are inextricably intertwined; they never appear in isolation.

The recent birth of the study of epigenetics has highlighted the interaction between the environment and genetics. The genome cannot be considered alone. Another layer of information stored with the genome is called the epigenome. It is a chemical switch that determines which genes are activated and which genes remain dormant. It does not alter the genetic code, but affects the specific expression of genes. It shuts down or revs up the production of proteins that affect mental states.

Today we know the role of epigenetics. The question for the future is how well can we develop our understanding of epigenetics and whether we can use it to enhance brain function. Research using mice provides reasons for optimism. One study involved mice that were born with genetic disorder resembling mental retardation. They were given a drug that activated epigenetic activity three hours before a training session. They exhibited no learning problems. So perhaps someday mental retardation might be remedied via epigenitic manipulation.

Drugs are not necessarily required for epigenitic manipulation. Researchers at MIT restored mouse memories by enriching the rodents environment. Not only were memories restored but evidence of epigenetic activity was found. Research on the benefits of enriching environments was done years ago, but that was before anyone had ever heard of an epigenome.

1Horstman, J. (2010). San Franciscoā€¯ Jossey-Bass.

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