Inside the Human Brian
How do scientists find out how the brain works? They use a number of different procedures that map out parts of the brain.
A relatively new technique called a PET scan (positron emission tomography) shows which parts of the brain are active while a person performs certain tasks. Doctors first inject a harmless radioactive glucose (sugar) solution into the patient's arm The glucose soon enters the brain, which absorbs the solution. As the patient performs a particular task (for example, looks at a picture), the part of the brain that's involved in the task consumes large amounts of glucose. Sensors detect the consumption rate and display the active region on a computer screen.
Surgeons sometimes use a more invasive method of brain mapping, electrically stimulating different sections of the brain during surgery. The brain is not sensitive to pain, so a patient can be awake during this procedure. As a surgeon stimulates one part, the patient could say what he or she is experiencing.
Regardless of the procedure used, scientists have gained tremendous insight as to how the brain works.