functioning. on the left there with the normal control you can see there is a lot of good functioning in the very frontal region of the brain. see right at the top there -- >> the orange, yellow area. >> right at the top. that's good frontal lobe functioning. look on the right. the murderer, a distinct lack of activation in the very frontal region of the brain. >> that's an area of the brain often associated with judgment, but also inhibition. >> absolutely. it's part of the brain that regulates emotion, regulates impulsive action. a bit like the guardian angel on behavior or like the brakes on a car. if the brakes are open the car gets out of control. the same could be said of an individual with poor frontal lobe function. they can get out of control and become impulsively violent. >> you make these revelations about what's happening in the brain but also the physiology.