Aphasia and the Relationship of Language and Brain
Eleanor M. Saffran, Ph.D.
This article provides a brief history of the study of aphasia, along with current data on aphasic syndromes and their localization in the brain as well as information on testing procedures. A brief examination of language from a functional perspective is alsoprovided, as it is difficult to understand the breakdown patterns without an appreciation for the complexities of language processing per se. Keywords: Aphasia, language disorders, brain damage
A HISTORICAL PERSPECTIVE Interest in the relationship of language and brain began with the emergence of a scientific mind set in the 19th century. The question was first posed byphrenologists—practitioners of the pseudoscience that associated bony protrusions in the skull with the enlargement of brain tissue below and hence the development of particular capacities. Although most of the traits that interested phrenologists would strike us as fanciful today (e.g., parental love, conjugality), they did attempt to localize language. They assigned this function to the frontal poles of both hemispheresand assessed it by measuring the size of the bony protrusion below the eye. The young French physician and anthropologist Paul Broca was skeptical of this approach. He believed
that capacities were associated with particular convolutions of the cerebral hemispheres that were not linked in any direct way to bumps on the skull. Broca had the opportunity to examine the brain of a language-impairedpatient, M. Leborgne, when it came to autopsy. The patient had been capable of very little speech although his comprehension appeared well preserved. Broca observed an area of damage in the left cerebral hemisphere, surrounding the third frontal convolution. After seeing a number of similar cases, Broca1 postulated that this area of the brain was the locus for articulate speech. He also suggestedthat left hemisphere control of language production was associated with its control of the dominant right hand, and he proposed mirror image organization—right hemisphere dominance—in left-handers. Although Broca was correct in his first assumption, we
Objectives On completion of this article the reader will be able to summarize the seminal observations regarding localization of languagedisturbance in the brain. Accreditation The Indiana University School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. Credit The Indiana University School of Medicine designates this educational activity for a maximum of 1.0 hours in category one credit toward the AMA Physicians Recognition Award. Eachphysician should claim only those hours of credit that he/she actually spent in the educational activity.
Disclosure Statements have been obtained regarding the author’s relationships with financial supporters of this activity. There is no apparent conflict of interest related to the context of participation of the author of this article.
Center for Cognitive Neuroscience, Department of Neurology,Temple University School of Medicine, Philadelphia, Pennsylvania. Reprint requests: Dr. Saffran, Center for Cognitive Neuroscience, Department of Neurology, Temple University School of Medicine, 3400 North Broad Street, Philadelphia, PA 19140. Copyright © 2000 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. +1(212) 584-4662.0271-8235,p;2000,20,04,409,418,ftx,en;sin00095x.
SEMINARS IN NEUROLOGY VOLUME 20, NUMBER 4 2000
now know that the left hemisphere is dominant for language in most left-handers (approximately 70%) as well as nearly all right-handers (on the order of 96%).2 Several years later, Carl Wernicke3 made other important observations. He saw a patient whose comprehension was severely impaired; when the patient came to...