Neurolinguistics

Neurolinguistics is the science concerned with the human brain mechanisms underlying the comprehension, production and abstract knowledge of language, be it spoken, signed or written. As an interdisciplinary endeavor, this field straddles the borders between linguistics, cognitive science, neurobiology and computer science, among others. Researchers are drawn to the field from a variety of backgrounds, bringing along a variety of experimental techniques as well as widely varying theoretical perspectives. Neurolinguistics has highlighted the special role of that part of the human brain known as Broca's area in crucial aspects of human language, namely syntax: the component of language that involves recursion.

History
Historically, the term neurolinguistics has been most closely associated with aphasiology, the study of linguistics deficits, and spared abilities, occurring as the result of brain damage. (This field is considered in a separate article).

Although aphasiology is the historical core of neurolinguistics, in recent years the field has broadened considerably, as new technologies have emerged. Language is a fundamental topic of interest in cognitive neuroscience, and modern brain imaging techniques have contributed greatly to a growing understanding of the anatomical organization of linguistic functions. Such techniques include PET and fMRI, which provide high spatial resolution images of energy utilized in various brain regions during language processing tasks. To date, the results of these techniques have not contradicted the existing results from aphasiology. Unfortunately, the techniques do not allow for high temporal resolution of brain activity as the comprehension or production of sentences unfolds. As temporal resolution is of utmost importance in these questions, researchers also employ the gross electrophysiological techniques EEG and MEG. These provide resolution during milliseconds, but the exact nature of brain mechanisms generating the electrical signals on the scalp is not known, making them difficult to interpret. Consequently, EEG and MEG are used primarily to inform theories of the cognitive/computational architecture of language, without regard to their precise neurobiological implementation. For example, one might suspect that out of three categories of words that could end a sentence, two are actually tapping into the same mechanism, but the third is represented differently. Showing that these two categories elicit an identical electrophysiological response different from that of the third would support such a hypothesis. An example of an important topic in Neurolinguistics is the N400– effect.

New developments
Among newer noninvasive techniques to study the workings of the brain, including how language works, transcranial magnetic stimulation is also worthy of mention.

Psycholinguistics
Closely related to such research is the field of psycholinguistics, which seeks to elucidate the cognitive mechanisms of language by employing the traditional techniques of experimental psychology, including analyses of such indicators as reaction time, error rates and eye movements.

Computational modeling
One other important methodology in the cognitive neuroscience of language is computational modeling, which can demonstrate the (im)plausibility of specific hypotheses about the neural organization of language while generating novel predictions for further empirical research. Currently, computational modelers are collaborating increasingly with brain imagers and psychologists in coordinated, interdisciplinary programs of research. Such programs have yielded important new insights into the nature of language, as well as major language disorders affecting millions, such as stuttering and dyslexia.