Neuropsychology, Part I: Broca's aphasia

Neuropsychology is the study of the structure and functioning of brains, and makes use of both cognitive psychology and neuroscience, as well as brain lesion studies. This post is the first in a series looking at some of the most interesting neurological disorders.

Paul Broca was a French physician, who happened to come across a very unusual patient: despite being able to comprehend language, all he could say in response was the single syllable "tan".

Patient Tan, as he was later known as, was admitted to the hospital at the age of 21, able-bodied and intelligent, but only replying to questions "tan, tan", accompanied by a series of gestures. However, his condition began to deteriorate, and after about 10 years, he began to lose the movement of his right arm. The paralysis spread to his right leg, rendering him bedridden for the next few years. It was also thought that his sight worsened, and his intelligence was markedly decreasing.

In 1861, Tan underwent surgery for gangrene on his paralysed right leg, and it was during this time that he met Paul Broca. Broca observed the man, unsurprisingly, with a great deal of interest. How could it be that he deteriorated in this way, with his intelligence, motor skills, and language so severely affected? That he could comprehend language, use his fingers to indicate what time it was without error, and certainly wanted to communicate, but could only utter one syllable?

Unfortunately, Tan died April 17, 1861, with very little known about the causes of his condition. However, the autopsy revealed the cause: the frontal lobe of the left hemisphere was strangely soft, and whilst the orbital region although atrophied had maintained its shape, many of the other frontal structures, were entirely destroyed. The result of this destruction of the cerebral substance was a large cavity filled with fluid.

The middle frontal lobe of the left hemisphere was the most extensive lesion, and the damage to the inferior frontal gyrus in an area now known as Broca's area, was concluded to be the cause of Tan's loss of speech. His condition is now known as Broca's aphasia, the inability to produce speech.

Not only was Tan a remarkable case study for Broca, but the case study was one of the earliest to suggest that language processing occurred in different parts of the brain, and that damage to one area did not mean that all language abilities would be impaired. Thus, it's opened up a field of research into the areas that appear to be involved in language production, a field which is still developing today.