Beginning in the 1940s, Canadian brain surgeon Wilder Penfield mapped the brain's motor cortex -- the area that controls the movement of your body's muscles. He did this by applying mild electric currents to the exposed brains of patients while they were in surgery.

Now you can relive his exploration of the brain. In the following feature we give you an electric probe and an exposed brain. All you need to do is shock and observe.

For more information about the brain and the motor cortex, check out the following:

• Mapping the Motor Cortex: A History
• A Map of the Motor Cortex