For this CogBlog, I wanted to look into a case study about
an individual who suffered some kind of brain injury that altered their
cognition. There was one example of a case of someone’s cognition being changed
by some kind of brain damage mentioned in chapter two that interested me. The
man known in psychology textbooks as “Tan”. He was given and remembered through
history by this name because for a number of years it was the only sound he
could make to try and communicate. I had heard of Tan before but I didn’t know
much about why he was given his name besides that his condition lead to the
eventual discovery of the Broca’s area of the brain. I wanted to learn more
about this man’s case and how his impaired cognition occurred.
What I found when I did some research was that Tan, whose actual
name was Louis Victor Leborgne, was an epileptic. Apparently he had been living
with seizures for a long time in his life and until the development of his
speech loss at age 30 he had been dealing with the seizures rather well. Knowing
that he was epileptic could explain how Mr. Leborgne’s frontal lobe became
damaged. Seizures occur when something interrupts the normal signal processing
in the central nervous system. These interruptions, depending on where they
occur in the brain have different resulting side effects, the most commonly
known being the muscle spasms in generalized seizures. One type of seizure is
the complex focal seizure which occurs in the temporal lobe, the area in the
brain where Broca’s area is located.
Louis Victor Leborgne's brain. Damage can be clearly seen on the brain's frontal lobe. |
Considering the above, it would probably be a reasonable reaction
to say that the seizures must have done some damage to Mr. Leborgne’s Broca’s
area. However, while doing research, I found another interesting factor in the
state of Mr. Leborgne’s damaged brain. Many years after Mr. Leborgne’s death and
subsequent autopsy in 2007, it was discovered that the damage in Mr. Leborgne’s
brain was far more severe then was originally thought when Broca conducted his original
autopsy in 1861. A team of researchers at the University of California lead
by Nina Dronkers put the preserved brain through a high resolution volumetric
MRI scan and found that alongside the damage to the Broca’s area there was also
damage to the brain’s superior longitudinal fasciculus, which connects both the
anterior and posterior language regions of the brain.
The results of the 2007 high resolution MRI of Leborgne's brain |
This discovery would
imply that Mr. Leborgne’s brain damage that resulted in his loss of speech might
have been less extreme if only the Broca’s area had been affected. With this
new evidence bringing more language related areas of the brain into the picture,
it shows how extensive the damage to this man’s brain became over time and what
damage to the language areas of the brain can do to a person. It is unknown to
w
hether or not Mr. Leborgne’s many years of seizures were the sole cause of this brain damage, but with no recorded history of other serious trauma I would guess that in one way or another they were involved. Overall, the case of Mr. Leborgne is a fascinating case study to look at and serves as reminder of what can happen to even the most basic forms of cognition when the brain is damaged.