Brain Mapping

 

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?

Activity

Neurologists continue to map the brain, even though they don't know exactly how it works. In this activity, you will map an area and then use your map as well as collected observational data to deduce the function of structures within the area.

Your name

Zotar from the planet GX-911, Galaxy Syymonia

Your mission

Map, identify, and explain one Earth block.

Your tools

• compass
• large measuring tape
• pencils
• large sheets of paper for map
• smaller sheets for observations
• a team of fellow Syymonians

Remember, this is your first visit to Earth from the galaxy Syymonia. Earth signs, symbols, and languages mean nothing to you. In all your observations, you must assume that you have no previous knowledge of the block and the humans you are studying.

Your orders

1. Select a fairly busy block. Make sure the block includes several types of buildings and lots of humans walking around.
2. Map the block and the streets adjacent to it. With the compass, find north and mark it with an arrow in an upper corner on your map. Using a scale of 1 cm = 2 meters, chart the buildings around the block, measuring accurately to represent sidewalks, vegetation, and structures.
3. Establish observation posts. For approximately a half hour (in Earth time), study and take notes that will help you answer the following questions:
4. Which buildings do humans enter and exit from most often?
5. Does only a particular type of human use a certain building? Identify them by characteristics such as age, sex, apparel, etc.
6. What items do the humans carry in and out of these buildings?
7. Observe individual human behavior. Does it differ depending on which buildings they enter?
8. Does the structure of the building itself seem be a factor in its function?
9. Formulate theories on the uses of the various buildings on your block.

   Questions

   1. What data was most helpful? What technology would have made this mission easier?
   2. Which were the easiest and hardest buildings to identify? Why?
   3. If you, as an alien, had to choose a single symbol to identify a building, what would it be? (And as a real-life human, did you catch yourself cheating? How?)

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Resources

• Asimov, I. (1987) How did we find out about the brain? New York: Walker
  and Company.
  
• Begley, S., et al. (1992, Apr 20) Mapping the brain. Newsweek, pp.
  66-70.
  
• Davidoff, J. (1993, Apr 10) Brain cells made for seeing. New Scientist,
  pp. 32-36.
  
• Goldsmith, J. (1994, May) This is your brain on Tetris. Wired, pp.
  72-73.
  
• Harding, G. (1993, Dec 11) How surgeons could navigate the brain. New Scientist,
  pp. 28-31.
  
• Posner, M.I. (1993, Oct 29) Seeing the mind. Science, pp. 673-674.

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  Additional sources of information

  
  

  American Academy of Neurology
  2221 University Ave. SE, Suite 335
  Minneapolis, MN  55414
  (612) 623-8115
  Brain Information Service
  BRI Publications Office
  43-367 CHS/UCLA School of Medicine
  Los Angeles, CA  90024-1746
  (310) 825-3417
  (information on general brain sciences)
  Society of Neurological Surgeons
  750 Washington St., Box 178
  Boston, MA  02111
  (617) 956-5858
  (call to find members in your city available for speaking)

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