Intro | Broca's Area | Wernicke's Area
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
Broca's Area was described in 1861 by a French surgeon, Paul Broca. Broca had treated a man who had been unable to speak for much of his life. Upon autopsy, he noted that his patient had a lesion that was located on the outside surface of the left frontal lobe.
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In numerous papers and textbooks, Paul Broca has received credit for contributing four important concepts to the study of cortical function: 1) the description of the behavioral syndrome characterized by the inability to speak in the presence of preserved language comprehension and vocalization, 2) introduction of the term aphemia to describe this syndrome, 3) identification of the cortical region responsible for this syndrome, and 4) initiation of the concept of left hemispheric dominance for language. Careful consideration of early research on the localization of cerebral function, however, indicates that Broca's involvement was less inceptive than this. For example, the clinical symptoms that Broca reported were described earlier by Gall (late 1700's), Jean Baptiste Bouillaud (1825), Marc Dax (1836), and Ernest Auburtin (1861). Auburtin presented a paper on this phenomenon to the Anthropological Society of Paris in 1861. Five days later Broca, founder of this society who attended Auburtin's lecture, coincidentally received a patient with the same symptoms and lesion site. He conferred with Auburtin about this case and shortly after submitted his own report to the society. In the aftermath of this report, one of Broca's colleagues (Trousseau) criticized his use of the term aphemia. Trousseau argued that its meaning, infamy, carried an inappropriate connotation for a clinical diagnosis. He suggested that the term aphasia be used in its place, which Broca criticized for its meaning, "the state of a man who has run out of arguments". In spite of this objection, aphasia is the term that is still in use. Finally, records show that Marc Dax was the first to argue for the concept of cerebral dominance. Broca himself acknowledged the contributions of his colleagues, but nonetheless has often received the credit for their accomplishments. This situation demonstrates the effects of optimal timing and status on professional influence! Regardless, Broca should be acknowledged for his ability to stimulate the excitement of scientists and the public over the theory of localization of cerebral function.
Broca's aphasia is often referred to as non-fluent aphasia because fluent speech is abolished. Damage limited to Broca's area normally produces only a transient disruption of speech. For chronic and severe speech loss, more extensive damage to surrounding cortex in frontal lobe and deeper structures is necessary. Indeed, normal speech increases cerebral blood flow in Broca's area, primary motor cortex and surrounding areas, and deeper structures such as thalamus and basal ganglia; indicating the multiple areas involved in speech production. When speech is present in non-fluent aphasia it takes on a telegraphic quality with pronouns, prepositions, conjunctions, quantifiers often omitted. The control of simple mouth movements is disturbed. In addition, language production via the use of gestures (e.g., sign language) and writing are disrupted by damage to Broca's area. Thus, this region plays a role in language production that extends beyond mere speech.