This article aims to provide an introduction to neurolinguistics, a subcategory of linguistics which is broadly concerned about the structure and use of language . It is also related to psycholinguistics, which focuses on the relationship between language and psychological processes such as language acquisition . This article explores brain structures involved in language production and comprehension, disorders of those structures, prominent research in the field, and areas where there is a lot more to be discovered.
Brain Structures Associated With Language
The two parts of the brain that are most often associated with language are Wernicke's area, which is in the temporal lobe on the left side of the brain and is responsible for the comprehension of speech, and Broca's area, which is in the frontal lobe and is involved in the production of speech. Recent evidence, however, suggests that language in the brain is much more complex and plastic, being processed in many different areas. Even a single word can engage multiple parts of the brain: we use sensory cues, emotional cues, and context cues to think of and verbalize a particular word, all of which occur in different areas of the brain. Interestingly, the majority of the parts of the brain linked to both spoken and written language are in the left hemisphere of the brain, regardless of what language one reads and how it is written. This is most notably demonstrated by the fact that aphasia, or cognitive language loss, is almost always caused by injury to the left hemisphere, not to the right hemisphere. This observation can be seen across different languages and different reading/writing abilities .
A prominent condition associated with neurolinguistics is aphasia, the cognitive loss of language. It can develop suddenly, such as in the cases of a stroke or sudden head trauma, or over time, such as due to a brain tumor or progressive neurological disease. The disorder affects all aspects of language: comprehension, speech, reading, and writing. It may interact with other neurological disorders. Aphasia typically affects the middle-aged and elderly, but it can occur in anyone. It currently affects about three-thousandths of the US population .
There are many types of aphasia, including Wernicke's aphasia (caused by damage to Wernicke’s area), where the patient may speak in long, nonsensical (but often grammatically correct) sentences embellished with superfluous or even made-up phrases. Patients’ ability to comprehend spoken and written language is usually severely impaired, however. Something someone with Wernicke’s aphasia might say is "You know that smoodle pinkered and that I want to get him round and take care of him like you want before," which could simply mean, “I want to walk the dog.” Damage to Broca’s area results in Broca’s aphasia. Patients retain relatively normal levels of comprehension, in contrast to Wernicke’s area, but are only able to produce short, broken phrases . Those with Broca’s aphasia are also more likely to be aware of their speech issues, so they can be more frustrated. An example of a sentence that someone with Broca’s aphasia might say is “Walk dog,” which could mean “I walked the dog,” “You should walk the dog,” or something similar .
The brain is remarkable in its ability to heal itself, but still, people may require extra measures to live comfortably with a disorder like aphasia. Speech-language therapy is often used in aiding patients to learn how to communicate again. This includes the encouragement of using remaining communication methods and acquiring new methods of communication. The brain’s plasticity helps communication abilities to return to normal even though some brain areas may be damaged. Responsibilities may be shifted to other brain areas, but aphasia can never be fully cured .
Another familiar linguistic disorder thought to have neurological origins is dyslexia, or difficulty reading or interpreting text while being generally intelligent. It affects 20 percent of the population and represents 80 to 90 percent of all those with learning disabilities. Individuals with dyslexia use different parts of the brain to process text than those without it, and these parts do not function as efficiently during reading as the parts of the brain that non-dyslexics use. Specifically, the occipito-temporal, temporo-parietal, and inferior frontal cortices, which are involved in reading, are altered in individuals with dyslexia; less gray and white matter volume can be found in these areas .
Like aphasia, dyslexia cannot be cured, but with the correct accomodations, it can be effectively adapted into one’s lifestyle. Those with dyslexia often require extra, distraction-free time on tests, text-to-speech technology, and the ability to write notes on laptops in order to succeed in a classroom environment. Teachers can facilitate reading in children with dyslexia by emphasizing speech sounds in words (called phonemic awareness) and letter-sound correspondences (called phonics) . It is important to note that the manifestation of the disorder can widely vary, and current dyslexic theories are being considerably upended as a result of new perspectives and findings.
Developments and Frontiers
Before the development of modern technologies, important discoveries in neurolinguistics were made through lesion analysis, or examining the behaviors of individuals with brain lesions. Broca’s and Wernicke’s areas were discovered through this method. Still, because of the potential ethical issues involved in these study methods, the number of subjects for such studies were limited, and broad conclusions could not be made. Since then, scientists have engaged in more rigorous studies of the brain, using advanced imaging techniques that allow active, instead of deceased, brains to be studied. Many emerging methods (e.g., PET, fMRI, magnetoencephalography, high field event-related encephalography, and optical imaging) allow healthy brains to be studied directly, eliminating the potential misconceptions produced from applying conclusions from lesioned-brain data sets to normal-brain data sets .
One of the more modern, practical aspects of neurolinguistics is the studies of the effects of multilingualism. In this globalized economy, being fluent in more than one language is an asset for job prospects and cultural undertakings. Research now corroborates the value of multilingualism in cognitive realms as varied as standardized test-taking to decision-making . Additionally, researchers found that the earlier and more languages a child learns, the more quickly and efficiently they will be disposed to learn new information and the more adaptable their brain will be to such incoming information . This information is useful to parents and educators who seek to broaden children’s cultural horizons as well as employers who look to expand businesses to places where languages other than English are spoken.
The future of neurolinguistics is rather promising. Exciting research is being done in relation to music and other forms of expressions as well as brain structures previously thought to control only language abilities . There is more work to be done in regard to the understanding of the physiology of brain structures and processes implicated in linguistics, including those at the microscopic level (e.g. neurons and synapses). While neurolinguistic research was previously constrained by technology and ethics, it has been growing exponentially over the last four decades . With jobs in education, research, advertising/marketing, and technology, the field of neurolinguistics presents many exciting, interdisciplinary job prospects for the future and will continue to grow in prominence as a promising field of study.
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