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The study of neurolinguistics is concerned with the relationship between language and the brain. The ultimate aim in this discipline is to discover the neurological foundations both for our knowledge of language and for our ability to use language. The initial impetus in the field was provided by the study of language pathology, in which language disorders are explained in terms of underlying neurological dysfunctions. Language disorders which have been acquired (either through disease or accident) provided many early insights in the sub-discipline of aphasiology. Other disorders can often be traced to difficulties arising from around the time of birth, either due to problems during pregnancy, in the delivery process, or in the postnatal period. Language disorders are commonly classified in terms of a predictable group of symptoms, known as a syndrome, which can often allow the patient\'s unusual language behaviour to be traced back to specific types and regions of damage to the brain.
A prevalent assumption in neurolinguistics is that language occupies distinct mental faculties, and that individual aspects of language are located in a number of distinct modules, each with a distinct physical and mental realization. However, this concept of modularity is by no means an inevitable outcome of neurolinguistic research and it remains somewhat controversial.
Recently, pathological research has been complemented by investigations of language functioning in people with normal, undamaged brains. Several ingenious techniques have been developed which provide the researcher with a window on the relationship between brain and language. For example, it is now well established that the two hemispheres of the brain are specialized for certain cognitive functions. In general, it has been found that the core aspects of language, namely, phonology, syntax and semantics, are located in the left hemisphere of most people. (For a minority of people, these aspects of language are processed in the right hemisphere, but the principle of specialization holds true).
One of the techniques which helped establish this finding is the so-called Wada technique. In this method, sodium amytal is injected into either the left or the right carotid artery of the neck. The result is the temporary immobilization of one side of the brain. And while one half of the brain is inactive, researchers can conduct various tests in order to establish which particular language functions have been lost. Using this technique, the broad discovery of left hemisphere dominance has been supplemented by more subtle findings. For example, it has emerged that the right hemisphere is used in the processing of concrete lexical items whose referents can be easily visualized (for example, table, dog), while more abstract words are processed in the left hemisphere (such as truth or goodness). The Wada technique is just one method which has allowed many startling discoveries to be made in the field of neurolinguistics, although we must acknowledge that huge advances are still necessary in order to fully illuminate the neurological foundations of language. MS
Further reading D. Crystal, An Introduction to Language Pathology; , M.L.E. Espir and , F.C. Rose, The Basic Neurology of Speech and Language. |
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