The cerebellum, once thought to be simply a motor coordination center, is now understood to participate in both cognitive and emotional processing. Somewhat resembling the cerebrum (with lobes and a highly folded cortex), but far smaller, it was given the name cerebellum meaning “little brain”. After early studies showed its obvious role in motor coordination, the cerebellum was type-cast as a dedicated motor processor.
Even on a purely anatomical level, the cerebellum is an amazing structure. While making up only 11% of the brain’s mass, it contains about half of all neurons in the brain. It achieves this phenomenal density with vast numbers of tiny neurons called granule cells. Indeed, their small size and density has slowed progress by making it difficult to record the activity of individual cells. On the tissue level, the cerebellum has an impressively regular organization that’s suggestive of a printed circuit board.
So perhaps it’s no surprise that new research implicates the cerebellum as a “calculator”, not just for motor coordination, but in other roles. A study last year (summarized here) showed greater involvement between the cerebellum and cognitive centers, lending credence to the notion that it plays a general role in “quality control”, not just in movement but in thinking. And a paper earlier this year (summarized here) showed powerful control by the cerebellum over an emotional reward center in the brain, thus controlling behavior. Other studies have suggested roles for the cerebellum in autism and schizophrenia. With this recent “sprint” in research, the cerebellum has begun to earn new respect.