Shenk cites in footnote 32 (198-199) in his book a study done by neurologist Eleanor Maguire regarding MRI scans that were conducted on London cabbies. When their MRI scans were compared with the MRI scans of others, there was a large contrast between the sizes of the posterior hippocampus. The fact that the increase of posterior hippocampus in size is directly related to the duration of the driving career shows that there is "functional differentiation within the hippocampus." Is there a limit to how large the posterior hippocampus can grow and ,therefore, a limit to how strong the spatial memory can be or how many spatial representations we can recall? Even though this knowledge has already been stored in the cabby's mind, do you think it's possible that if the cabby forgets this knowledge that the size of the posterior hippocampus will decrease afterwards? Is this a evolutionary adaptation that the brain has aquired over the years? Can the brain physcially adapt to all forms of intelligence?
(Yanfei Gao, feifeiyg@yahoo.com)
The study done by Eleanor Maguire and her team found that the size of the posterior hippocampus increased depending on how long a subject was a cab driver. This discovery proved the posterior hippocampus to be related and able to grow based on spatial navigation skills. Though the two were found to be related, no maximum size was obtained, only an increase based on time (http://www.pnas.org/content/97/8/4398.long). The hippocampus is involved in short-term and long-term memory. Information for short-term memory is accessed by the cerebral cortex through the hippocampus. When transferred to long-term memory, the connections made in the hippocampus are replaced with more permanent links in the cerebral cortex. This makes the hippocampus necessary to acquire new information for memories but is not needed to maintain them (Campbell 1079). Therefore, forgetting the information that the cabbies know about their routes will not affect the size of the hippocampus because once the information is taken in, the hippocampus is not used to keep it. If the cabby were to quit and no longer need his spatial navigation skills as much, his hippocampus would most likely adapt and shrink because it is not being used as much anymore. The brain has shown the ability to adapt for different uses in many parts. Studies of Albert Einstein’s brain showed an abnormally large parietal lobe. The parietal lobe is significant in the development of visuo-spacial and mathematic skills (http://serendip.brynmawr.edu/bb/neuro/neuro01/web2/Iskander.html). When a skill is introduced or practiced repeatedly, neurons along with the connections between neurons and other brain cells multiply and grow stronger, resulting in growth of the brain. While researching the brains of animals, children, and adults, scientists have discovered the brain works more like a muscle than previously known. With continuous practice and repetition, the brain can grow and become stronger, similar to how muscles do during steady exercise. To verify this, a study was performed using adults who could not juggle. Half of the subjects were taught how to juggle and practiced for an extended period of time. The other half were not taught how to juggle and, therefore, did not practice. Comparisons of brain scans from before and after the experiment showed growth in sections of the brain that controlled visual and motor abilities only in those who learned and practiced juggling. (http://www.medicalnewstoday.com/releases/5615.php). The brain has shown the ability to grow and adapt for different forms of intelligence depending on what the individual does. This discovery proves that the intelligence one is born with is not permanent; it can be changed if the individual decides to work hard and change it. No longer does one inherit any sort of intelligence but learn and develop it over time.
ReplyDeleteJenna Sherman (jsherm013@aol.com)