The patient called "Tan"
In a university collection in Paris, two brains float in glass jars of alcohol. These specimens belonged to two 19th-century men who changed our understanding of the brain. They were patients of the French physician and anatomist Paul Broca. The first, and most famous, was Louis Victor Leborgne, whom Broca met on April 11, 1861. Leborgne had been hospitalized for 21 years after losing the ability to speak. Though he could understand everything said to him, he could only produce a single syllable: "tan". Hospital staff and Broca himself referred to him as "Tan".
When Leborgne died on April 17, 1861, just days after their meeting, Broca performed an autopsy. He discovered a large, fluid-filled lesion in the posterior inferior frontal gyrus—a specific fold on the surface of the brain's left frontal lobe. Broca presented his findings the very next day, proposing that this specific area was the location of articulated language. This was the first time a specific cognitive function was convincingly linked to a precise anatomical location in the brain.
A second brain confirms the first
A few months later, Broca encountered another patient, an 84-year-old man named Lazare Lelong. Lelong's situation was remarkably similar. Following a stroke, he could understand language but was only able to speak five words: "oui" (yes), "non" (no), "toujours" (always), "tois" (a mispronunciation of three), and "Lelo" (a mispronunciation of his own name). When Lelong died, his autopsy revealed a lesion in the exact same area of the left frontal lobe as Leborgne's.
The two brains provided powerful evidence for the location of brain function, challenging the then-dominant idea that the brain worked as a whole. The condition is now known as Broca's aphasia, or expressive aphasia, and the critical speech-production region of the brain is universally called Broca's area. The specimens themselves, having been preserved by Broca, became important objects in the history of neuroscience. Modern high-resolution MRI scans performed on the preserved brains in 2007 confirmed the lesions and showed they were even more extensive than Broca could have known, reaching into deeper brain structures.