Phineas Gage and the Flying Tamping Iron

The strange story of Phineas Gage opens, like a spaghetti western, on a  furnace-hot
afternoon in the late 19th century, with  a gang of railroad  workers laying tracks across a
boulder-strewn desert in Vermont.

Gage’s job was to clear the
way for the track-layers by blowing away any boulders that were too big to
manhandle.  To do this he packed
explosive beneath the rock, then tamped it  down with a thick iron rod before
lighting the fuse.  Gage had been
chosen for this dangerous and important job because, of all the men, he was
judged to be the most careful, sober, and responsible.

On this afternoon, however, Gage
allowed himself to be distracted at a crucial moment. As he tamped down a
packet of explosive, something caused him to glance over his shoulder
, and in that second his rod struck the rock and created a spark. The
resulting explosion jettisoned the iron bar into Gage’s eye socket, then  through the
front of his head and out the top of his skull. As it exited it took with it a
clean core of brain tissue.

The force of the explosion knocked
Gage to the ground, but – astonishingly -  he was back on his feet and
talking lucidly within minutes.  He
was taken by cart to the nearest town, where, displaying the gaping hole in his
head, he greeted the doctor with a cheery: “See what business I have for
you here!”

As it turned out the business was
less disastrous, in one way, than anyone might have believed possible. Apart
from being blind in one eye, Gage made an almost complete recovery. Or so, at
first,  it
seemed. As the weeks went on, however, it became clear that the sober,
conscientious, polite and law-abiding man who led the railway gang had changed
into a foul-mouthed, reckless, heavy-drinking renegade. As a close friend
remarked, sadly, “Gage is simply no longer  Gage”.

The case of Phineas
Gage and the Tamping Iron has since become famous because the doctor who
initially treated him subsequently made a meticulous report of both the
personality changes and the precise damage to his brain. And so it was the
first case to show clearly that a particular area of brain tissue
“contained” the faculties that we would call human sensibility.
Gage’s tragic accident put the first major landmark on what, just over a
century later, has become a detailed map of the human mind.

Today we can tell which bits of
the brain do what by looking directly at the electrical
activity in it. Various imaging technologies show  exactly where  our sensations, emotions, thoughts and
behaviour are generated.

Apart from
furthering our understanding of the brain, brain imaging has proved invaluable
for neurosurgeons because it allows them to  identify precisely how to wield
the scalpel. If a patient suffers from severe  epilepsy, for example, surgeons
sometimes cut some of the fibres that connect different parts of the brain to
prevent the seizures from spreading uncontrollably. Brain scans now ensure that
the knife stays clear of areas which are crucial for faculties such as speech or
movement. They can also show the precise location of tumours and other forms of
damage or injury, allowing better diagnosis and treatment.

Until the
development of brain scanning  techniques surgeons and
neuroscientists were largely dependent on Gage-type “natural
experiments” to reveal the geography of the mind. One drawback to this
was that in order to match the location of an injury to a particular mental
function, it was usually necessary to wait for the subject to die. The two
major speech “modules” of the brain, for example, Broca’s and Wernicke’s
areas, were discovered by the two neurologists who gave their name to them by
dint of  first detailing the speech
deficiencies of  certain patients,
and then examining the patients’ brains at post mortem.  Broca, for
example, located the bit of brain that allows us to speak by keeping tabs, for
years, on a man who was called “Tan” on account of that being the
only syllable he was able to utter. When Tan died Broca
found a patch of damage in the  left frontal lobe of his
patient’s brain and concluded – rightly- that this was the part
responsible for language articulation.

Other pre-imaging
methods of brain-mapping included the famous experiments of Canadian
neurosurgeon Wilder Penfield.  The
brain has no pain receptors, so  Penfield (like other brain
surgeons) operated on his patients while they were conscious.  He found that many of his patients
reported what seemed like memory flashbacks when  certain parts of the cortex
were  touched by an electrode. Penfield  concluded
that memories were stored in clusters of nerve cells and he subsequently drew
up a “memory map” by stimulating various parts of his
patients’ brains and asking them what they experienced as a result.. We
now know that memories are distributed throughout the brain, but the areas
Penfield charted as the “storage depot” of experience –
mainly in  the
temporal lobe at the side of the brain – are  closely associated with memory recall.

Brain imaging is
improving today at a phenomenal rate. The latest technique – known as
Diffusion Tensor Imaging – can trace the connections between one neuron
and another through the entire breadth of the brain. And another technique,
using minute electrodes, can reveal exactly which neurons respond to, say , the raising of an eyebrow.

Scanning technology
has even shed more light on poor old Phineas Gage.
Hannah Damasio, a neuroscientist at the University of
………recently used computerised tomography to chart the precise
area of brain that was removed by the tamping iron.  They turned out to be precisely those
which modern
brain scans show to be active when people make moral or ethical
decisions, or inhibit self-satisfying impulses.  The “responsible” Gage it seems, was quite literally left behind in the desert sand.