Broca's aphasia General term for a group of speech disorders caused by injury or disease in Broca's area of the left hemisphere; selective loss of the ability to produce articulate speech despite preserved speech comprehension and not due to motor impairment.

Broca's area Area of the cerebral cortex responsible for motor speech planning usually located in the frontal lobe of the left hemisphere. The area is named for Pierre Paul Broca, who deemed the left inferior frontal gyrus to be the "seat of articulate language'' in 1861. It is the first brain area for which a specific function was identified, "thus the existence of the first localization once admitted, the principle of localization by convolutions would be established."

functional magnetic resonance imaging Use of magnetic resonance imaging to detect physiological events; technique for mapping task-induced changes in regional neural activity by detecting changes in local blood flow, blood volume, and tissue oxygen content triggered by neuronal activity.

positron emission tomography Technique for scanning the brain in which radionuclides are used to determine oxygen utilization, glucose metabolism, and blood flow in the cerebral cortex; used for mapping brain functional organization and for detecting brain disorders.

Broca's area—the posterior, inferior portion of the human left frontal lobe—has the impressive distinction of being the first area of the human brain for which a specific function was proposed: articulatory control of speech. Since its original description in the mid-19th century, Broca's area has been the subject of thousands of scientific articles. Remarkably, present-day conceptualizations of the function of Broca's area are fundamentally similar to those originally proposed more than a century ago. During the past century, the technologies applied to the study of the human brain have steadily advanced. Early clinical and anatomical investigations have been bolstered by cortical electrical stimulation and, recently, by functional brain imaging. Although improvements in technology have provided finer functional descriptions and fractionations, the region of the brain called Broca's area is still firmly rooted in the classical descriptions of the 19th century.

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