The interdisciplinary study of language processing in the brain, with an emphasis on the processing of spoken language when certain areas of the brain are damaged. It is also called neurological linguistics.
The journal Brain and Language offers this description of neurolinguistics: "human language or communication (speech, hearing, reading, writing, or nonverbal modalities) related to any aspect of the brain or brain function" -Elisabeth Ahlsén in Introduction to Neurolinguistics.
In a pioneering article published in Studies in Linguistics in 1961, Edith Trager characterized neurolinguistics as "a field of interdisciplinary study which does not have a formal existence. Its subject matter is the relationship between the human nervous system and language" ("The Field of Neurolinguistics"). Since then the field has evolved rapidly.
"The primary goal of the field of neurolinguistics is to understand and explicate the neurological bases of language and speech, and to characterize the mechanisms and processes involve in language use. The study of neuorolinguistics is broad-based; it includes language and speech impairments in the adult aphasias and in children, as well as reading disabilities and the lateralization of function as it relates to language and speech processing."
(Shari R. Baum and Sheila E. Blumstein, "Aphasia: Psycholinguistic Approaches." International Encyclopedia of Linguistics, 2nd ed., edited by William Frawley. Oxford University Press, 2003)
The Interdisciplinary Nature of Neurolinguistics
"Which disciplines have to be taken into account in neurolinguistics? Brain and Language states that its interdisciplinary focus includes the fields of linguistics, neuroanatomy, neurology, neurophysiology, philosophy, psychology, psychiatry, speech pathology, and computer science. These disciplines may be the ones most involved in neurolinguistics but several other disciplines are also highly relevant, having contributed to theories, methods, and findings in neurolinguistics. They include neurobiology, anthropology, chemistry, cognitive science, and artificial intelligence. Thus, the humanities, and medical, natural, and social sciences, as well as technology are all represented."
(Elisabeth Ahlsén, Introduction to Neurolinguistics. John Benjamins, 2006)
Co-evolution of Language and the Brain
"It is uncontroversial, in scientific circles at least, that the human brain has undergone very rapid growth in recent evolution. The brain has doubled in size in less than one million years. The cause of this 'runaway' growth (Wills, 1993) is a matter of conjecture and endless debate. A strong case can be made that the expansion of the brain was a consequence of the development of spoken language and the survival advantage that possessing a language confers. The areas of the brain that underwent greatest development appear to be specifically associated with language: the frontal lobes and the junction of the parietal, occipital and temporal lobes (the POT junction… )." (John C. L. Ingram, Neurolinguistics: An Introduction to Spoken Language Processing and Its Disorders. Cambridge University Press, 2007)
Neurolinguistics and Research in Speech Production
"The nature of neurolinguistic programs has attracted a great deal of research in recent years, especially in relation to speech production. It is evident, for example, that the brain does not issue motor commands one segment at a time… When we consider the whole range of factors that affect the timing of speech events (such as breathing rate, the movement and coordination of the articulators, the onset of vocal-fold vibration, the location of stress, and the placement and duration of pauses), it is evident that a highly sophisticated control system must be employed, otherwise speech would degenerate into an erratic, disorganized set of noises. It is now recognized that many areas of the brain are involved: in particular, the cerebellum and thalamus are known to assist the cortex in exercising this control. But it is not yet possible to construct a detailed model of neurolinguistic operation that takes all speech-production variables into account." (David Crystal, The Cambridge Encyclopedia of Language, 3rd ed. Cambridge University Press, 2010)