Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
SAF Archives  search ask the scientists in the classroom cool science


Guide Index

Recycling the Trabant

Curing the Storm in the Head

Flight of the Dragonfly
in the classroom
TEACHING GUIDES


SCIENTIFIC BREAKTHROUGHS IN GERMANY:
Curing the Storm in the Head


Epilepsy -- the storm in the head -- can now be cured. The first step is to find the abnormal cells sending signals at the wrong time. Researchers at Siemens Corporation in Germany are working to perfect a diagnostic procedure that uses a biomagnetic scanner to locate the exact site of the epileptic focus. Once the site is found, neurosurgeons can safely remove the faulty tissue. Frontiers profiles two pioneers in the development of this remarkable advance.

Curriculum Links
Notes & Discussion
Activity: Electric Circus
Math Connection
For Further Thought
Science Fair Idea: Make a Human Battery!
In the Operating Room With Frontiers



CURRICULUM LINKS

BIOLOGY/
LIFE SCIENCE


nervous system,
regulation
CHEMISTRY


electrochemistry
HEALTH


diseases
PHYSICS

electric fields,
magnetism,
superconductivity



NOTES & DISCUSSION
  • Epilepsy is an ancient, much-misunderstood disease, and much of our common knowledge about it is likely based on myths. This Frontiers segment is an opportunity to launch discussions about what is true and untrue. If possible, invite an individual who suffers from epilepsy to share experiences. Or, contact the Epilepsy Foundation of America, 4351 Garden City Drive, Landover, MD 20785; phone 301-459-3700.

  • Compare other forms of imaging techniques -- the CT scan, PET scan, MRI. How does each procedure diagnose a problem? How is it different from the biomagnetic imaging seen on Frontiers? Find descriptions of various imaging processes in newspapers and magazines.

  • The electrical current in our brain generates a weak magnetic field, about a billion times weaker than the Earth's magnetic field. That's good news. Otherwise, we'd have to be careful when we walk past steel posts or get too close to a set of knives. What is a magnetic field? How is it created? Where can magnetic fields be found around us?




ACTIVITY: ELECTRIC CIRCUS

Does it surprise you that electrical activity is going on inside your brain right now? All materials on earth, including those that make up your body, are composed of positively and negatively charged particles. Discover how negative and positive particles behave in an electrically neutral environment. And see what happens when particles are organized so that negative ones are concentrated together, away from positive ones, creating "electrostatically charged" particles.

MATERIALS
  • handful of styrofoam "peanuts"
  • cardboard shoebox (no lid)
  • sheet of plastic wrap large enough to fit over the shoebox
  • large rubber band or masking tape


PROCEDURE
  1. Grab a handful of styrofoam peanuts, crumble them into tiny bits and put them inside the shoebox.

  2. Cover the shoebox with plastic wrap, making sure that the plastic is stretched tightly, like the skin of a drum. Keep the plastic wrap in place with either the rubber band or masking tape.

  3. Rub the plastic wrap rapidly in one direction with your fingertips or knuckles, repeating this action for about a minute.

  4. Sit back and watch your electric circus. You've just finished organizing a lot of charged particles and now they're going to perform for you. Can you explain the phenomenon?


LAB NOTES
  • Use this segment and activity to learn how electrical activity in the brain is related to the phenomena of electricity and magnetism. Just for fun, ask students if they know what the human body and a car battery have in common.

  • The "Electric Circus" activity lets you observe how negatively and positively charged particles behave. Because plastic wrap isn't a very good conductor, the negative charges transferred from your hand when you rub the plastic surface don't travel very far. In fact, most of them stay in clumps along the path your fingers or knuckles take. Concentrations of charge act like magnets.

  • The clumps of negative charges on the plastic sheet start to attract the positive charges and to repel the negative charges that are randomly arranged on the surfaces of the styrofoam bits. The positive charges are drawn to the top of each bit, and the negative charges get pushed to the bottom. The more concentrated the positive charges become at the top of a styrofoam bit, the more they are drawn toward the negative charges on the plastic. Eventually the concentrated positive charges are so attracted that the bit leaps into the air and sticks onto the plastic.




MATH CONNECTION
  • About 2.5 million Americans have epilepsy. What percentage of the U.S. population is that?




FOR FURTHER THOUGHT
  1. Why do negative charges get transferred from your hand to the plastic wrap?

  2. Why do the styrofoam bits eventually fall off the plastic?

  3. Are the styrofoam bits that leap up to the plastic wrap shaped differently from the ones that don't leap?

  4. Why do you see vertical formations of styrofoam bits, running from the bottom of the box up to the plastic?


ANSWERS
  1. Friction causes a charge to be transferred from one material to
    another.

  2. The negative charge from the plastic flows onto the styrofoam bits very slowly, neutralizing the top of the bit and making it fall to the bottom of the box. Eventually, the entire surface of the bit becomes random again, and the extra negative charges it carried down from the plastic wrap fall off.

  3. The more pointed the tip of the bit, the more concentrated the positive charge will get and the more likely it is that the bit will leap.

  4. Each bit becomes polarized and the bottom negative end attracts another bit's positive top.


CREDIT: Leslie Reinherz, who contributed this activity, is a freelance science education and museum consultant in Cleveland, Ohio.



SCIENCE FAIR IDEA: MAKE A HUMAN BATTERY!

MATERIALS
  • sheets of copper and aluminum (palm sized)
  • 200 microamp center zero meter
  • alligator clips
  • wire to connect sheets to meter


PROCEDURE
  • The human body conducts electricity fairly well, and it can also be used to create electrical current. How can you demonstrate this concept?

  • First, you'll need to connect the metal sheets to the meter. Then, moisten your hands slightly and put one hand on each metal sheet. Watch the meter and see how much current you've generated. Why does this work?

  • The salty sweat on a person's hand causes an electrochemical reaction to occur on each metal surface. On the copper surface, electrons are taken away; on the aluminum surface, electrons are added. The excess charge on the aluminum sheet flows through the wires to the copper sheet, passing through the meter and registering current along the way. Meanwhile, the extra charges created on one hand cause a current to flow through the body to the other hand. The current is so weak that it cannot be felt. As long as the salt on your palms keeps reacting chemically with the metal surfaces, the current will continue to flow. Usually, once the hands become dry, the current stops flowing. Compare this reaction to what goes on inside a commercial battery.


Note: The electrical current generated in this experiment is very low. Students should always use caution and good judgment when working with electricity.



IN THE OPERATING ROOM WITH Frontiers

To capture this segment, a Frontiers crew filmed open brain surgery -- a new experience for the producer and his cameraman, soundman and assistant. What was it like? To find out, we asked Producer David Huntley:

"I really didn't know personally how I would feel when I saw a person's head being opened up. It actually had the exact opposite effect on me than I thought it would. Once the surgeon opened up the skull and cut back the dura mater, exposing the actual brain underneath, I saw that it was very unbloody. It looks sort of like a globe or world unto itself -- like a map of some sort. It's very interesting. The crew and I felt no squeamishness. We were all intrigued with what was going on because we were getting a firsthand tour with this talented neurosurgeon. We quickly got completely absorbed in just watching this man work. It was really quite amazing. He has beautiful hands that look almost like he was sculpting something."








 

Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.