The Whole-Brain Child is a must read by Drs. Dan Siegel and Tina Payne Bryson which clearly explains the inner workings of the emotional developing brain. Dr. Siegel calls this kind of human reaction as "Flipping your lid". Let's face it, toddlers aren't alone here. He uses the hand as a model of the brain and how the upstairs and downstairs brain connect. You can find out more about Dr. Siegel's work at www.drdansiegel.com.
Here is a video by Positive Discipline Coach and Educator, Casey O'Rourty of Joyful Courage, on how the brain functions in "flipping your lid".