Paul Broca’s research in Aphasia

Paul Broca

Paul Broca

On July 9, 1880, French physician, anatomist and anthropologist Paul Broca passed away. He is best known for his research on Broca’s area, a region of the frontal lobe that has been named after him. Broca’s Area is involved with language. His work revealed that the brains of patients suffering from aphasia contained lesions in a particular part of the cortex, in the left frontal region. This was the first anatomical proof of the localization of brain function.

In his early research, Paul Broca investigated the histology of cartilage and bone, cancer pathology, the treatment of aneurysms, and infant mortality. He also researched the the comparative anatomy of the brain. As a neuroanatomist he made important contributions to the understanding of the limbic system and rhinencephalon. In his mind, olfaction was a sign of animality and Broca wrote extensively on biological evolution, then known as transformism in France. Paul Broca became active for health care for the poor and became an important figure in the Assistance Publique. Broca was also known to advocated secular education for women and famously opposed Félix-Antoine-Philibert Dupanloup.

Paul Broca is widely celebrated for his  discovery of the speech production center of the brain located in the ventroposterior region of the frontal lobes. He arrived at this discovery by studying the brains of aphasic patients. Broca’s starting point was the dispute between the proponents of cerebral localization. Their views derived from the phrenology of Franz Joseph Gall and their opponents led by Pierre Flourens. Gall’s student Jean-Baptiste Bouillaud kept the localization of function hypothesis, especially with regards to the language center, alive and probably rejected much of the rest of phrenological thinking. Bouillaud challenged professionals of the time to disprove him by finding a case of frontal lobe damage unaccompanied by a disorder of speech. His son-in-law rnest Aubertin, began seeking out cases to either support or disprove the theory, and he found several in support of it.

Aubertin joined Broca’s Society of Anthropology of Paris which became a platform for the localization of function controversy. Even though Aubertin was persistent in presenting new patients to counter their views, it was Broca, who finally put the localization of function existence issue to rest.

In 1861, Paul Broca heard of a patient in the Bicêtre Hospital. The 21-year old had a progressive loss of speech and paralysis but not a loss of comprehension nor mental function. After the patient’s death, Broca determined that as predicted, the patient did in fact have a lesion in the frontal lobe of the left cerebral hemisphere. From a comparative progression of his loss of speech and motor movement, the area of the brain important for speech production was determined to lie within the third convolution of the left frontal lobe, next to the lateral sulcus. For the next two years, Broca went on to find autopsy evidence from 12 more cases in support of the localization of articulated language.

Patients with damage to Broca’s area and/or to neighboring regions of the left inferior frontal lobe are often categorized clinically as having Expressive aphasia. The discovery of Broca’s area revolutionized the understanding of language processing, speech production, and comprehension, as well as what effects damage to this area may cause.

At yovisto you can learn more about Language Pathways and Disorderd by Richard Ivry at Berkeley.

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