The Human Brain


The human being is considered to be the ultimate form of life on the
earth. This is not because the human body is strong and agile. Many other
animals posses skills much superior to humans and are able to perform feats
humans can only dream of. The one thing that distinguishes humans from all
of the other organisms on this planet is the brain. The brain is the site
that controls the human body. However, unlike in animals, in man, the brain
is also the site of the mind. The mind gives humans superiority over other
creatures. It provides humans with the ability to reason, to feel and to
adapt. Because of this, man has achieved so much, and has also realized
that much more is still ahead.

During the course of evolution, ever since early Homo sapiens and his
ancestors walked on the surface of the earth, man has wondered about
himself, and how he relates to the natural world. People learned and
adapted to new lifestyles. As time passed, humans learned to record
history. They analyzed past events and applied this knowledge to solve
problems. These processes improved as more and more people supplied their
experiences to the common pool of knowledge. Such co-operation created the
modern man with his superb ability to think.

Many sciences were born. Some of them centered around humans. They
included, among many others, psychology and neurology. While psychology
deals with the mind and human behavior, neurology is the study of the
nervous system.

The nervous system of the human being consists of several parts. The
main structures are the brain and the spinal chord. The system also
includes nerves which sense external and internal stimuli and then relate
all information to the central processing unit, i.e. the brain.

Because of man\'s rapid evolution in technology and medicine, humans now
know a great deal more about their own nervous system then they did even a
few years ago. This increase in knowledge is partly due to the recent
advances in nuclear medicine. Although X-ray machines have been the chief
mechanical tools for internal observations of the human body since Wilhelm
Roentgen discovered X-rays in 1901, the development of computers made it
possible for better and more accurate techniques to be applied to scan the
human body. These methods employ various scanners like the CAT, PET, MRI
and SPECT.

The CAT is an acronym for Computerized Axial Tomography. This method
of scanning generally involves X-rays and enables scientists to view the
inside of the head in a three dimensional format on a computer screen. PET
stands for Positron Emission Tomography and it is much more complicated
than the CAT scan. PET machines bombard the subject with doses of
positrons -- the anti-matter equivalents of the electrons. As the
positrons enter the body, they encounter electrons which are escaping from
radioactive elements which have been injected into the bloodstream. When
the positrons and the electrons collide, they give off energy which is
recorded by a computer. The result is a far more detailed 3-D picture of
the brain than the one obtained from the CAT machine. To obtain an even
better image, physicians use the MRI, which stands for Magnetic Resonance
Spectroscopy. With these three processes combined, every structure of the
body can be easily observed. The CAT and the MRI are c ently being used to
detect early signs of Multiple Sclerosis in patients who show MS symptoms.

The SPECT equipment is a brand new addition to the family of body
scanners. It is still in experimental mode at several United States
hospitals, but it has received much positive criticism. The SPECT, which
is the short form for Single Photon Emission Computed Tomography, is a
device which resembles the PET. However, it uses radiation which is less
harmful and the tracers which are injected into the patient are
non-radioactive isotopes of Lithium, Carbon and Phosphorus. The system is
also much faster which permits quicker diagnoses.

Modern technology is not the only method by which the human nervous
system can be studied. Traditional surgical procedures, along with fiber
optic cameras and sensors create an image of the brain that is fascinating.
It is known that the brain is made up of two hemispheres, left and right,
connected by a central "bridge" called the thalamus. In the back of the
human skull lies the cerebellum, an organ associated with the control of
muscles and maintaining equilibrium. Other structures of the brain include
the hypothalamus which governs the autonomic (non-voluntary) nervous
system. Below the hypothalamus lies the pituitary gland, which is
responsible for the production of various