The Evidence: In footnote 35 relating to Chapter 2, Shenk
cites a study conducted by Eleanor Maguire of taxi drivers in London, proving
that establishing spatial relationships of the representation of London has a
physical impact on the brain, specifically by increasing the tissue volume of
the posterior hippocampus. In addition, the physical impact of further
developing “The Knowledge” is elevated with time and better understanding of
spatial relationships. Analyze how the relationship between “The Knowledge” and
the physical composition of the posterior hippocampus fit the GxE model and
explain how the “fine-tuning of the spatial representation of London” makes
intelligence a process that has a physical effect. Relate your response to the
biological concept of how structure fits function and to the ability of animals
to establish cognitive maps in the nervous system, as detailed in Chapter 51.2
of Campbell.
Nick Sotos (nsotos13@gmail.com)
Nick Sotos (nsotos13@gmail.com)
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ReplyDeleteThe correlation between experience as a London taxi driver and the enlargement of the posterior hippocampus fits Shenk's GxE model because it shows how the environment has a major impact on traits. In GxE, "genes, proteins, and environmental signals...constantly interact with one another, and this interactive process influences the production of proteins, which then guide the functions of cells, which form traits" (31). The perplexing environment of London causes a change in the shape of the brain to increase volume size of the posterior hippocampus which is responsible for recalling spatial representations. As such, the environment clearly had an impact on the final trait which would be impossible under the old G+E model. This also proves that intelligence is a process and not a fixed-quantity because if intelligence was a fixed-quantity, that would not explain how London taxi drivers with more experience have an even larger posterior hippocampus than newer London taxi drivers. Clearly the taxi drivers' intelligence is increasing with time which shows it is a process.
ReplyDeleteThe ability of the brain to change shape in order to meet an individual's environmental demands is called plasticity. The structure of the brain changes in order to match the required function. For example, right-handed string players have a larger cortical representation for their left little finger and conductors have an altered auditory cortex.
http://journals.cambridge.org/action/displayAbstract;jsessionid=0FBC9C3E57505A1D8E76B1A1AFDBB1B0.journals?fromPage=online&aid=364346 This human brain plasticity is what allows the brain in London taxi drivers to enlarge its posterior hippocampus to allow for the spatial recognition of all the streets in London. The plasticity of the human brain allows people to become what they want to be and prevents the argument that only those born with a special gene can become great at something. Because the human brain is always changing to counteract environmental constraints, it is always changing which further proves that intelligence is a process and not a fixed quantity. Plasticity of the brain is also a perfect example of the biological theme of structure matching function. The theme says that the structure of an object will match the function of that object. The brain changes its structure which also changes its function in order to adapt to the environmental demands.
A cognitive map is “a representation in the nervous system of the spatial relationships between objects in an animal’s surroundings” (Campbell 1127). In the case of organisms that can guide their activity by cognitive mapping, that most likely does not relate with plasticity but with chunking. Shenk states "great minds don't recall more raw data than others; rather they recognize patterns faster and form chunks more efficiently" (53). Similarly, organisms that use cognitive mapping do not memorize every object's specific location and landmarks but relate the landmark positions to one another. For example, nutcrackers memorize pine seed hiding places by identifying the halfway point between landmarks (Campbell 1127). This method of memorization is much more efficient and allows for the organism to memorize many more locations than if it were to memorize the exact locations of each of the seeds.
-Josh Choi (joshchoi95@yahoo.com)
Studies showed that the taxi drivers who consistently navigate London’s enigmatic streets have enlarged hippocampi, suggesting that navigational experience as a whole is associated with grey matter size in the hippocampus. Contrary to Josh’s statements, Shenk’s assertion, and previous studies, another study was performed in London in 2003 that measured a connection between hippocampus grey matter volume and navigational experience but suggested there was “no association between expertise and posterior hippocampal grey matter volume (or, indeed, grey matter volume throughout the brain)” (http://brainimaging.waisman.wisc.edu/~chung/hippocampus/papers/hoppocampus-covariates-VBM.pdf). The disparity between these results was puzzling even to those performing the experiment who proposed that navigational may result in different structural changes to the hippocampus such as density or that those who are more experienced navigators have a more active hippocampus during the activity. Still, the taxi drivers perform the task of navigating all day for much greater period of time than “experienced navigators” used in the study who were strictly non-taxi drivers, so it is still possible that after continuous use, the need for greater function begets a change in brain structure such as increased volume of grey matter.
ReplyDeleteAll throughout the human body, it is evident that structure fits function, and that greater experience can cause these changes by a principle known as plasticity. Campbell explains that the “capacity for the nervous system to be remodeled, especially in response to its own activity, is call neural plasticity” (1079). By creating more internal connections and to other regions of the brain, synapses in the hippocampus can become “stronger” by becoming more voluminous. The structure of becoming more voluminous allows for the function of making cognitive connections faster, allowing taxi-drivers to better utilize cognitive maps.
Cognitive maps are “a representation in the nervous system of the spatial relationships between objects in an animal’s surroundings” (Campbell 1127). Taxi drivers need to be able to navigate the spaces in their environments and understand directions at quick speeds, and constant exposure to their surroundings reinforces the cognitive maps that the drivers use for navigation. Cognitive maps function by means of a place system, which is the relationship between objects and space as they are and have been, and a misplace system, which notes the lack or change of the spaces or objects in an environment (http://www.cognitivemap.net/HCMpdf/HCMComplete.pdf). These systems used in tandem would allow a cab driver to navigate to a known part of the city even if the path that he or she would normally use to get there is no longer an option.
-Kyle Mueting (kylemueting@comcast.net)