Classical Descriptions A Brocas Cases

Broca's area is named for Pierre Paul Broca, the French surgeon and anthropologist who identified the area and defined it as the seat of the faculty of articulate language in 1861. In his capacity as a general surgeon, Broca was called upon to treat a case of advanced gangrene of the leg. As Broca treated the patient, Leborgne, he learned that Leborgne was unable to speak due to a chronic brain lesion. Leborgne, who had experienced epileptic attacks since youth, lost his ability to speak at the age of 31. Ten years later he developed paralysis on his right side. Broca, examining him at the age of 51 determined that Leborgne could produce virtually no speech. He often said "tan" (and later became known as "Tan") and occasionally uttered the phrase "Sacre nom de Deiu.'' Tan's mouth, tongue, and larynx were intact, indicating a central cause for the lack of speech. Tan could hear and comprehend speech because he responded correctly to questions that he could answer with motions of his left hand, such as indicating the number of years he had been without speech. Because of his loss of speech, Leborgne had been living in the Hospice of Bicetre, where he had been known for his vindictiveness and sometimes objectionable character. He thus seemed to have retained his intelligence despite his lack of articulation, until the paralysis and gangrene confined him to his bed.

One week after Broca's initial examination, Tan died of gangrene. Broca performed an autopsy and found that most of the left hemisphere of the brain was softened from the disease process. The anterior part of the hemisphere contained a large lesion, centered over the posterior aspect of the middle and inferior frontal gyri. The lesion also encompassed part of the anterior insula, the inferior marginal gyrus, and the striate body. Based on an examination of the surrounding, less damaged tissue, and the knowledge that the clinical course was progressive, Broca postulated that the lesion had begun in the third frontal gyrus and extended to surrounding tissue as the disease progressed.

Broca presented Leborgne's brain at a meeting of the Societe d'Anthropologie one day after the patient's death and then deposited the brain in the Musee

Dupuytren. Figure 1 shows Leborgne's brain viewed from the left, with a lesion clearly visible in the third frontal convolution. Broca coined the term "aphemia" to describe the condition of loss of articulate speech coupled with the retention of hearing, comprehension, and intelligence. He inferred a correspondence between the anatomical and symptomatological periods of Leborgne's condition: The 10-year period of aphasia occurred while the lesion was confined to the frontal lobe, and as it progressed into the corpus striatum, the symptoms of paralysis of the right extremities developed. Broca concluded that the origin of the lesion, the second or third frontal gyrus, must be responsible for the loss of articulate language.

Even as he described this area and its importance to the study of language in the brain, Broca emphasized that the linguistic aspect of his discovery was less significant than its implications for the general theory of localization of function in the brain. Broca (as quoted in Von Bonin, 1960, p. 55) was well aware that this was the first strong evidence that specific mental functions were specifically localized:

The point is cerebral localization, not this or that school of phrenology... . If all cerebral faculties were as distinct and as clearly circumscribed as this one, one would finally have a definite point from which to attack the controversial question of

Leborgne Brain

Figure 1 Photograph of Leborgne's brain, the first patient Paul Broca diagnosed with aphemia (later to be known as Broca's aphasia) in 1861. This is a view of the left hemisphere, in which a lesion is visible in the area of the third frontal gyrus, now known as Broca's area (reproduced with permission from Signoret et al. (1989), Brain Language 22, 303-319).

Figure 1 Photograph of Leborgne's brain, the first patient Paul Broca diagnosed with aphemia (later to be known as Broca's aphasia) in 1861. This is a view of the left hemisphere, in which a lesion is visible in the area of the third frontal gyrus, now known as Broca's area (reproduced with permission from Signoret et al. (1989), Brain Language 22, 303-319).

cerebral localization. Unfortunately, this is not the case, and the greatest obstacle in this part of physiology comes from the insufficiency and the uncertainty of the functional analysis which necessarily has to precede the search of the organs which are coordinated to each function.

Broca's second case was a man named Lelong, who also had lost his ability to use articulate speech but whose aphemia was not complicated by other symptoms. At autopsy, Lelong's lesion proved much more circumscribed than Leborgne's but was also located in the posterior portion of the third frontal convolution. Broca subsequently chronicled 20 more cases in which patients with aphemia had lesions of the third frontal convolution, lending strong support to his hyopthesis originally based on a single case. Collectively, these cases paved the way for the systematic investigation of the functional organization of the human brain based on the analysis of clinical cases. For decades, lesion-deficit analysis was based on postmortem lesion localization. With the advent of X-ray computed tomography (CT) and magnetic resonance imaging (MRI), lesion localization has become premorbid and quantitative (e.g., describing lesion volume as well as location). This work, summarized in Section II, largely confirms Broca's original observations.

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