Explosive powders propelled a three and a half foot long iron rod into
Phineas Gage's face. It pierced his left cheek, traveled behind his eye,
and flew out the top of his skull. He didn't die. In fact, almost immediately
after the accident, Gage could talk and walk.
Accounts of this bizarre accident along the railroad--Gage was a construction foreman--made the news bigtime in the spring of 1994 (1). That would not have been surprising considering the freakishness of the accident and its peculiar after-effects on Gage's personality, except for the fact that the accident occurred almost 150 years ago.
Gage had been tamping down dynamite on the roadbed. He and his crew were flattening the ground, preparing it for new train tracks. But he was working too fast: he pounded on the dynamite before his partner could cover it with a protective layer of sand. !!!POW!!! The rod became a rocket.
Gage's accident was newsworthy so long after the fact because brain
researchers had just gained fresh insights into the nature of his injuries.
They had carried out a detailed study of the pierced skull which, along
with the rod, had been preserved by Gage's foresightful doctor and family,
and they were able to tie together the structural damage to Gage's
brain--specifically his frontal lobes--with his altered behavior (2,3).
Before the accident, Gage had been a responsible, hard-working, fit and popular man. A report by his doctor that was published in 1868 (twenty years after the accident) described Gage as "a perfectly healthy, strong and active young man, twenty-five years of age, nervobilious temperament, five feet six inches in height, average weight one hundred and fifty pounds, possessing an iron will as well as an iron frame . . . having had scarcely a day's illness from his childhood to the date of this injury (4)."
After the accident, Gage became a nasty, vulgar, irresponsible vagrant.
His former employer, who regarded him as "the most efficient and capable
foreman in their employ previous to his injury," refused to rehire him
because he was so different. "The equilibrium or balance, so to speak,
between his intellectual faculties and animal propensities, seems to have
been destroyed. He is . . . irreverent, indulging at times in the grossest
profanity (which was not previously his custom), manifesting but little
deference for his fellows, impatient of restraint or advice when it
conflicts with his desires . . . obstinate, yet capricious and vacillating,
devising many plans of future operation, which are no sooner arranged than they are abandoned
in turn for others. . . "
But all had not been lost in Gage's brain. In fact, many of his intellectual skills were just fine, apparently untouched: "His mental operations being perfect in kind but not in degree or quantity (4)."
The researchers--Hanna and Antonio Damasio and their coworkers--combined
photographs and x-rays of Gage's skull with computer graphics and produced
on the computer screen a likeness of a brain that would have fit snuggly
inside Gage's skull. Then they plotted the probable path of the flying rod
through his head. From their analyses, it became clear that the rod had
damaged not one but both of Gage's frontal lobes. That provided an
explanation for the transformations to Gage's personality and behavior,
because, although Gage's experience had been one-of-a-kind, its effects
were not unique: other people with frontal lobe damage, including a number
of the Damasios' patients, exhibit personality changes that resemble Gage's.
Twelve patients with frontal lobe damage, either brought on by traumatic injury or disease, are able, for example, as Gage was, to remember facts and perform complicated calculations. But, when it comes to keeping commitments, being trustworthy, holding a job, or succeeding in a marriage, they fail miserably. They can't plan for the future, and they can't see how their behavior will affect their own lives or the lives of others (1).
In their large registry of "broken brains," the Damasios have compiled data on more than 1500 specific brain lesions and the learning, memory, and personality changes that accompany them (3). The registry includes information about the brains of people who can pull up old memories but can't form new ones, those who can recall nouns but not verbs and others who can recall verbs but not nouns, and those who are unable to remember the names of other people or recognize faces, including their own. The brain of each of these patients, like an enticing and unguarded pie, seems to be missing a (functional) slice or two.
Two powerful brain "imaging" technologies--positron emission tomography (PET) and magnetic resonance imaging (MRI)--have
provided pictures of intact and damaged brains for the brain registry. The
raw PET and MRI data are converted into high-resolution maps of brains and
brain lesions. These, in turn, provide fascinating and increasingly detailed
clues to how the different parts of the brain contribute to the success of
what seem like simple processes when they work properly--the recall of
words, perception of colors, the ability to speak, name and face recognition,
and so on.
Studies of broken brains open windows onto healthy brains, because, by showing what
can go wrong, such studies suggest what is going right in the brains of most people
most of the time.
This article was originally posted on the NIH electronic bulletin board EDNET on 3/15/94.
