The human nervous system consists of several parts. The main structures are the brain and the spinal cord. The system includes nerves that sense external and internal stimuli and then relay the information to the central processing unit -- the brain.

The brain is the portion of the vertebrate central nervous system that constitutes the organ of thought and neural coordination. It includes all the higher nervous centers, receiving stimuli from the sense organs and interpreting and correlating them to formulate the motor impulses. It is made up of neuronal cells, supporting and nutritive structures, and is enclosed within the skull. The brain is continuous with the spinal cord through the foramen magnum - the opening in the skull through which the spinal cord passes to become the medulla oblongata.

The knowledge we have of brain structure, function and interrelativity has been substantially accelerated over the last century. This is largely due to advances in nuclear medicine...technological advances in noninvasive methods of studying and viewing brain structure and the actual ability to visually measure live neural activity in relation to activity. The scope of this paper is to

Webster's Ninth New Collegiate Dictionary

PET stands for positron emission tomography, and it is much more complicated than the CT scan. A PET scans is a medical imaging technique that provides images of biochemical function over time. This enables researchers to map which areas of the brain become active to specific stimuli. 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 that are escaping from radioactive elements that have been injected into the bloodstream. When the positrons and the electrons collide, they give off energy that is recorded by a computer. The result of this scan is a detailed 3-D picture of the brain.

Some common words found in the essay are:
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Approximate Word count = 1710
Approximate Pages = 7 (250 words per page double spaced)