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Brain Mapping

 

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Overview
When Lewis and Clark set out to map America, they had to find ways to observe and chart the land around them. Today's surveyors also depend on creative ways of studying and mapping what many consider the final frontier--the human brain. While anatomical blueprints have existed for centuries, the new challenge lies in creating a functional map--a chart which shows where in our brain we hear music, get a joke, or even think about our brain. Early scientists would secretly dissect cadavers to ponder over the three-pound mass of gelatinous tissue that forms our brain. A better way to understand the brain is positron emission tomography (PET). This technique relies on X-ray photography to track cerebral blood flow. Before the test, the patient is given an injection of a radioactive glucose analogue. Since the brain uses glucose as fuel, neurologists can identify neuralhot spots by seeing which areas of the brain use more glucose and are therefore more active than other areas. Some early functional maps were made by exposing a large area of the brain during surgery, stimulating its surface, and simply watching what happened. A technique using that same principle, called magnetoencephalography (you can call it MEG, unless you're really into tongue-twisters), gives neuroscientists a less-invasive look. Small sensors are placed all over the patient's head to detect electromagnetic changes caused by neurons. By monitoring this energy, scientists can measure levels of brain activity. This information is updated every millisecond, matching a patient's active thinking speed. Scientists sometimes collect data on a subject in a roundabout manner. For instance,the brain uses one-quarter of all the oxygen you breathe. Neurologists can identify the active sections of the brain by tracking oxygen-rich blood. Magnetic resonance imaging, or MRI, is the first noninvasive, nonradioactive way to observe brain activity. An MRI machine relies on very large magnets to track the flow of blood cells in the brain and identify where the brain processes our thoughts, motor activities, and sensations. This system has such good terminal resolution that it can record changes in the brain which occur even just 50 milliseconds apart. No single mapping technique provides complete information. Scientists combine a number of technologies to create more comprehensive maps of the human brain. These maps provide critical information to help neurosurgeons perform safer robotic microneurosurgery or even help scientists identify the brain sections that hear different musical tones. As technology advances, it's just a matter of time before a map of the human mind will be as detailed and comprehensive as a road map. Why do scientists need a functional as well as an anatomical map of the brain? How would a functional map aid in brain surgery, psychology, or sports? How are traditional mapping techniques used in brain mapping?

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