The Beginning of the Reading

So far the beginning of my reading has been quite interesting.  The first paper I read was a journal article that discussed the sections of the brain that were active in twins, either 13 or 19, when they were given a task in Japanese, their first language, and in English, their second language.  When given a task in Japanese the section of the brain that was activated was very specific and when they were given the same task in English the activation was more widespread, but the areas of activation were similar between the two possibly suggesting that the cortical plasticity, or the reorganization of neural connections, for second language acquisition occurs in a way to match the specialization of first language activation.  This makes sense as the brain is using the preexisting, strong neural connections from the primary language to help learn and remember the secondary language better and it also displays that there are certain areas of the brain that are activated depending on whether the task is sentence construction, syntax or grammar.  I found it interesting that these researchers and others suggest that there is a sensitive period from birth until puberty where there is increased neural plasticity and flexibility that then declines after puberty due to aphasia, or the loss of ability to understand speech.  Also, in this paper they showed a possible network of linguistic functions including sentence comprehension, syntax, phonology, and lexico-semantics, which I thought was very intriguing.  Another paper provided a possible hypothesis as to the greater ability of infants to learn languages, and that is that when babies are born their brains are wired to understand any language and as parents and others talk to them they start to distinguish different phonemes before they are even able to speak.  Another curious hypothesis that this researcher proposed is that there is a social “gate” which explains why other animals who have very powerful computing systems are not able to speak and it provides a possible explanation for why those with autism  have deficits in social cognition and language.  When the researchers looked at 7.5 month old children and observed their brain waves when given phonetic sounds of their native and nonnative language they looked at the mismatch negativity, which is how well the children were able to detect odd phonemes.  If a child had better native phonetic discrimination this allows them to detect words and leads them towards language, but if they had better nonnative discrimination then that signified the infant was at an earlier stage in development.  The ability of the infant to recognize phonetic units in their native language while inhibiting their attention towards phonetic units that don’t work in this language is what allows them to proceed towards language themselves.  In a separate study 9 month old infants took 12 sessions with either a native Mandarin speaker or a native English speaker and after these sessions each infant was tested using the Mandarin phonetic units that were different from English and those that had Mandarin exposure had a much higher ability to recognize these units and therefore they concluded that infants are still able to learn even when their brain starts to differentiate into their native language.  They also found that when the infants were taught through audiotapes or TV they did not learn and were equivalent to those that were exposed to only the native English speakers.  One other paper discussed the gray matter volume, the tissue in the brain that contains the neuron bodies and synapses, in the language associated areas in the brain in multilinguals, those that spoke 3 or more languages.  They hypothesized that there would be higher levels of gray matter in those that learned the languages successively, meaning they learned one at a young age, another at a later point in their life and the third much later, compared to those that learned their first two languages simultaneously and the third later in life.  This hypothesis suggests that those who learned two languages simultaneously had a more efficient neural networks and they are able to better incorporate a second language into the same network as the first language instead of the brain creating all new connections.  They found that there was greater gray matter volume in those that learned their languages successively in regions that are associated with language in the brain.  Their results were bilateral, in that they had similar results in the right and left hemispheres of the brain, while other previous studies had found that there was only an increase in gray matter density in the left hemisphere.  This paper was interesting because it investigates essentially the efficiency of language processing in those that have learned languages when they were young or as they aged.  In one review they researched the functional and anatomical alterations that occur in the brain and they found different evidence for the gray matter changes in the previously discussed paper in this post.  Other studies have looked into cortical thickness or white matter integrity.  One article included in this review observed bilinguals and measured their gray matter density in one area of the brain that is associated with vocabulary and found that there was more gray matter in bilinguals compared to monolinguals and the more vocabulary they learned the more gray matter was present.  Another article looked at white matter integrity and found that there was higher white matter integrity in the monolinguals compared to bilinguals in older subjects while the opposite was true in younger subjects.  Suggesting that the age of acquisition is an important factor in learning languages.  It was suggested in one paper that there is usually gray matter atrophy in Alzheimer’s patients and that those who are bilingual with greater white matter integrity can compensate for this loss and therefore is a deterrent for the disease.   Most of these articles from the review looked at bilinguals who had a longterm experience with the second language, however the researchers wanted to look into those who learned languages in the short-term and found there was increased white matter in those that took a Chinese course for 9 months compared to those who didn’t.  Another study took monolingual English speakers and taught them pseudowords and they found that the more successful learners had more focused activation in the phonological processing center while the less successful learners had a more diffuse network.  For more successful learners, they had more white matter volume and density compared to slower, less successful learners.  Overall, the papers I have read so far have given me much insight into the studies that have been and are currently being conducted to answer the questions that I and many others have asked.