A Science Odyssey Probe The Brain

Mapping the Motor Cortex: Part II

Wilder Penfield

Photograph of exposed brain

Wilder Penfield, a pioneering brain surgeon, mapped the motor cortex using mild electric current.

Wilder Penfield took the next exploratory voyage into the brain starting in the 1940s. While operating on epileptic patients, Penfield applied electric currents to the surface of patients' brains in order to find problem areas. Since the patients were awake during the operations, they could tell Penfield what they were experiencing. Probing some areas triggered whole memory sequences. For one patient, Penfield triggered a familiar song that sounded so clear, the patient thought it was being played in the operating room.

During these operations, Penfield watched for any movement of the patients' bodies. From this information, he was able to map the motor cortex, the very part of the brain you can map in this feature's activity.

To see a more detailed drawing of this map, go to A Map of the Motor Cortex.

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