Epigenetics and the Human Brain Where Nurture Meets Nature

I covered this earlier here; but it bears more publicity, ask your researcher about it.
http://oc1dean.blogspot.com/2011/04/epigenics-of-stroke-rehabilitation.html

http://www.dana.org/news/cerebrum/detail.aspx?id=32670

Since the discovery of DNA in the 1950s, one of the primary goals of geneticists has been to understand how differences in the DNA sequence can influence human health and lead to diseases. After several decades of intense research, two conclusions are clear: (1) in most cases, it is difficult to establish a direct link between any specific gene(s) and specific biological processes or diseases, and (2) most traits and pathologies are associated with more than just one gene and have complex mechanisms. Discovering that such complexity is at play led researchers to acknowledge that the genome on its own is likely not sufficient to sustain all biological functions, and that another level of regulation is contributing. They proposed the epigenome as one of these additional levels.

Tightly associated with the genome, the epigenome represents an ensemble of biochemical marks present on the DNA itself. These marks modulate the DNA’s activity and functions, but occur without any change in the DNA sequence. Instead, various enzymes add epigenetic marks to the DNA. The marks stamp genes with a unique signature that signals the gene to be active or silent.

Unlike the DNA sequence, epigenetic processes are dynamic and not fixed, although some can persist for long periods of time, up to several years or a lifetime. Further, they are strongly influenced by the environment and by exposure to external factors like diet, living conditions, exercise, stress, chemicals, drugs, and toxins. Both positive and negative factors can modulate the epigenome. For instance, positive factors such as enriched living conditions, like social interactions, physical activity, and changing surroundings, can promote beneficial epigenetic marks, while severe stress or agricultural chemicals can permanently alter some marks.1,2 These modifications can impact various aspects of an organism’s life during any phase of development, and can increase the susceptibility to diseases. For example, traumatic events and severe chronic stress in early life can alter the epigenome in a persistent and sometimes heritable fashion.3-5 Many cancers are also associated with epigenetic alterations induced by factors such as poor diet and toxins.6,7