In foot note 35, Shenk reproduces
Eleanor Maguire’s ideas saying that only certain people can take on the ‘task’
of being a London taxi driver (198). Shenk, throughout his argument, explains
that everyone has the capability to develop abilities through their environment
in a GxE model where environment plays a significant role in the development of
a human. According to Shenk, it is
possible to change the environment such that one may attempt to successfully
acquire a skill they desire but, as explained by Maguire, the physical
structure of the posterior hippocampus determines if a person may take on the
skill in question. Explain how the structure of the brain can be affected by
desires to excel in certain areas—i.e. if a person wanted to be a London taxi
driver, could they do it even if their genes do not aid in the production of
the necessary hippocampus. Is it possible for the environment to change the structure, hence altering the function, of certain regions in the brain for desired effects? If a person changes their own environment to
correctly tweak their “knobs and switches“ (19), can they excel in their
desired field? Relate your answer to the different mechanisms of gene operation
in Chapter 18 of Campbell and to human behavior as explained in Chapter 51 of Campbell.
-Jesse Pukshansky (jesse.pukshansky@gmail.com)
-Jesse Pukshansky (jesse.pukshansky@gmail.com)
The notion that only specific people can become certain things is the same thing that Shenk is arguing is false. Shenk uses Maguire's findings to support his idea of human brain plasticity; the idea that the human brain changes in order to meet an individual's specific demands. For example, in footnote 35 Eisenberg writes, "magnetoencephalographic recordings from experienced violinists... [had] more brain area dedicated to representation of fingers...than in the...nonmusicians" (199).
ReplyDeleteShenk's "GxE" model states that "Genes, proteins, environmental signals...constantly interact with one another, and this interactive process influences the production of proteins, which then guide the function of cells, which form traits" (31). In the specific case of the London taxi driver the enlargement of posterior hippocampus, the part of the brain that specializes in recalling spacial representations, is so they can memorize the plethora of streets in London. Therefore, it is not our genes that allow us to have a specialized brain to allow us to perform specific tasks while preventing us from doing others.
One particular method by which developmental brain plasticity is done by a process called synaptic pruning. Over the first few years of life, the brain grows rapidly. By the time one is two or three years old, the number of synapses is 15,000 per neuron, twice the amount of an average adult brain. As one ages, the environment eliminates unnecessary synapses while keeping and strengthening the ones that the individual needs. By this process, the brain adapts itself to the environment. http://faculty.washington.edu/chudler/plast.html Ergo, it is the environment that causes changes to the brain in order to change to what we demand of it. So yes, if one desires to be a London taxi driver, then he or she can became one through experience as the brain will alter itself to enlarge its posterior hippocampus to increase spatial recognition.
Another method that this could be possible is through the regulation of chromatin structure. If the necessary genes that encode for a larger posterior hippocampus are turned off prior to the environment requiring those genes, then through histone acetylation those genes can be turned on again. The attachment of acetyl groups (¬-COCH3) to histone tails, their positive charges are neutralized and no longer bind to nearby nucleosomes. This loosening of chromatin more easily allows for transcription proteins to access the genes in those acetylated regions. This also relates to the biological theme of regulation as the body can do the opposite through DNA methylation. The attachment of methyl groups (-CH3) to histone tails promotes the condensation of chromatin which prevents transcription. This allows the body to save energy and use the ATP where the body needs it more rather than wasting it on transcribing unnecessary genes.
- Josh Choi (joshchoi95@yahoo.com)