Neuroscience: Click and Learn

These biology mini-lessons are illustrated with interactive Web animation. The Adobe Flash plug-in is required for these click and learn features. Download it free from Adobe.com.
	Neural Control of Walking and Running Different gaits employed by animals and how the nervous system is able to switch between them. Also featured on the HHMI DVD, Making Your Mind: Molecules, Motion, and Memory, available free from HHMI. Order DVDs here.
	Electrical Activity of Neurons Measuring neuronal activity, generating action potentials, and recording the firing of individual neurons. Also featured on the HHMI DVD, Making Your Mind: Molecules, Motion, and Memory, available free from HHMI. Order DVDs here.
	The Proteasome and Protein Regulation The proteasome is a large molecular machine that plays an important role in recycling and regulating cellular proteins. Learn about the structure and function of this fascinating cellular machine. Also featured on the HHMI DVD, Learning from Patients: The Science of Medicine, available free from HHMI. Order DVDs here.

Experiment with the Electric Field of
Gymnarchus niloticus

Electric Fish! You're probably thinking of an electric eel, sending out 800 volts of electricity—enough to stun or kill a person, even a horse.

But most species of electric fish live in fresh water and are actually harmless. They generate from only a fraction of a volt up to a few volts of electricity with their electric organs located in the tail, which is made up of specialized muscle or nerve tissue.

Go ahead and move your cursor over the upper button on the left. You'll see a color-contour representation of the electric field generated by Gymnarchus niloticus, an African electric fish.

Move your cursor over the middle button on the left. You have now put a virtual aluminum rod near the fish. Because aluminum is a better conductor than fresh water, the electric field bends toward it, causing a distortion in the field. The fish detects the changes in the electric field using sensors located all over the body. These sensors are called electroreceptors.

Now, move your cursor over the lower button. You have put a virtual plastic rod near the fish. Because plastic is a poor conductor of electricity, the electric field bends away from it, just the opposite of the distortion caused by the aluminum.

In nature, materials conduct electricity differently. By monitoring how the electric field changes as the fish moves around its environment, Gymnarchus can navigate through a maze of materials even if the water is muddy or during the night when vision is restricted.

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