Hemispheres of the Brain

As I was reading the text I came upon a section that I thought to be
quite fascinating. It talked about people who have a brain that functions like
two different people inside of the brain. This is of course the Split-Brain
Personality. As I studied this topic in more detail I found it to be quite
broad and yet very detailed. I found that I needed a dictionary to be able to
read all of the medical journals and books that are out there, to be able to
understand what it was exactly, that I was reading. But with a little study and
research I found that this is a precise science that is still largely full of
The study of hemispheric asymmetry with in the cerebral cortex had long
been a fascination with the human race. The ancient Aztec cultures used to
perform a type of brain surgery on humans. This is evident from the human
remains that we find with incisions and piece\'s missing of the skull. Whether
or not these primitive surgeries were successful is unknown. The earliest way
for man to observe the brain was by noticing brain damage to a particular area
of the brain that was damaged. Such observations were first recorded some 5,000
years ago (Myers,1995). The most popular case is that of Phineas Gage a
railroad worker that had severe frontal lobe damage. This happened when a rail
road spike was shot through his head by a piece of dynamite. Miraculously he
lived through the experience, but with a severe change in his personality. From
this physiologists learned that personality was largely controlled from this
point namely by removing a persons inhibitions.
For the most part the brain has been a mystery that is waiting to be
opened. The last two decades have witnessed a period of research on the human
cerebral functions comparable to the great era of discovery initiated by Broca
in 1861(Young, G,. Segalowitz, S,. Corter, C,. Trehub, S,.1983). We have leaned
more in the past 20 years about the brain and it\'s hemispheric asymmetry than we
had learned in combined previous history.(Kosslyn, 1993). Most of this new work
has been devoted to the study of cerebral functions in adults, but recently
there has been a growing interest in infants and young children most especially
among the study of hand preference. About 10 percent of the human population in
left-handed(Myers,1995). By looking at ancient writings this right-hand
preference has seemed to develop right from the start of the human race. It
also is apparent that from ultrasound devises that about 9 in 10 fetuses suck
the right hand\'s thumb(Myers,1995). This would lead us to believe that
handedness was an inherited trait. Their was a man by the name of George
Michel, who in 1981 did a survey of new born babies and what side of their
bodies they liked to lay their heads. He found that about two-thirds of 150
babies preferred to have their heads turned to the right while about only one-
third laid their heads to the left. In a follow up survey Michel found that
almost all of the right-sided babies were starting to reach with their right
hand and again one-third of the left sided babies were reaching with their left
hand(Myers,1995). In contrary, it is also found that handedness is one of the
few genes that are not shared by genetically identical twins. So what is it
exactly that develops handedness? Some speculate that the handedness of a
person is evident in the brain and in its specialization concerning hemispheric
asymmetry. Tests reveal to us that about ninety-five percent of right-handers
process speech primarily in the left hemisphere(Myers,1995). While the study
has found that left handed people are more likely to be a little more diverse or
ambidextrous in their hemispheric asymmetry. But as we had learned in the first
chapter is this a correlation or a causation? I personally feel that it is a
correlation and not a causation. The brain is a very flexible and delicate
instrument. It has the ability to adapt and change with different stimuli. The
brain in left handed people I feel is just adapting to the use of a left hand
preference and that is why it is more likely to be ambidextrous
I would now like to talk about the asymmetry of the hemispheres. First,
I will talk about the left side of the brain and then I will talk about the
right. For well over a hundred years neuropsychologists have proposed that the
left hemisphere plays a special