We've been learning in class that although the brain and the rest of the nervous system function as a whole, different areas of the brain also serve different primary functions. Among these areas is a strip of cortext parallel to the face and about midline along the top of the brain that is called the sensory-motor cortex.

Along these strips of cortex is a kind of "map" of the body. This "map" was first charted by the Canadian neurosurgeon Wilder Penfield in the 1930's. Similar to the story line of your text, Conversations with Neil's Brain, Penfield operated on many patients who had intractable epilepsy, in an attempt to reduce the frequency and severity of their seizures.

Just as it is important for Dr. Calvin and Dr. Ojemann to know what parts of Neil's brain perform what functions, it was important for Dr. Penfield to know this about his patients, too. Although in general the same areas of each person's brain do the same kinds of things, each individual brain is slightly different. Thus, neurosurgeons take time to map each individual's brain before they remove any tissue, in order to preserve as much functionality as they can for the patient.

Based on his stimulation of the brains of many, many patients, Dr. Penfield developed a generic chart of the areas of the brain responsible for motor control of various parts of the body. A similar map was made for parts of the brain that receive sensory information from different parts of the body. Penfield represented the brain's generic "body map" using a little figure he called "the homunculus" ("little man").

In this exercise, you will explore the motor cortex and try to map what areas of this brain region are responsible for voluntary motion of what body parts. As you simulate the work of Penfield and others, take note of what body areas move when a given brain area is stimulated. Then, using the diagram given in class (you can also download that handout here), make your own "motor homunculus" or motor map of the cortex. Submit this completed map in class to complete your assignment.

Stimulate the Brain!

Go to this website to try your hand at mapping the motor cortex. Be sure to note what areas of the brain, when stimulated, result in what movement, and where. Then transcribe your results onto your brain stimulation handout, and turn it in to your instructor.