Researchers long believed that the cerebellum did little more than process our senses and control our muscles. New techniques to study the most densely packed neurons in our brains reveal that it may do much more. Pity the cerebellum, tucked in the back of the brain mostly just keeping our muscles running smoothly. Its larger neighbor, the cerebrum, gets all the attention. It's the seat of intelligence, the home of thinking and planning. It's what separates humans from our less quick-witted ancestors. The cerebellum - which literally means "little brain" - is thought to just sit there helping us balance and breathe, like some kind of wee heating and ventilation system. But maybe not for long. In a series of experiments published March 20 in Nature, Stanford researchers show that neurons within the cerebellum respond to and learn to anticipate rewards, a first step toward a much more exciting future for the cerebrum's largely overlooked little brother and one that could open up new