Rethinking the "Lesser Brain"; August 2003; Scientific American Magazine; by James M. Bower and Lawrence M. Parsons; 8 Page(s)
"In the back of our skulls, perched upon the brain stem under the overarching mantle of the great hemispheres of the cerebrum, is a baseball-sized, bean-shaped lump of gray and white brain tissue. This is the cerebellum, the 'lesser brain.'" So began, somewhat modestly, the article that in 1958 introduced the cerebellum to the readers of Scientific American. Written by Ray S. Snider of Northwestern University, the introduction continued, "In contrast to the cerebrum, where men have sought and found the centers of so many vital mental activities, the cerebellum remains a region of subtle and tantalizing mystery, its function hidden from investigators." But by the time the second Scientific American article on the cerebellum appeared 17 years later, author Rodolfo R. Llinas (currently at New York University Medical Center) confidently stated, "There is no longer any doubt that the cerebellum is a central control point for the organization of movement."
Recently, however, the cerebellum's function has again become a subject of debate. In particular, cognitive neuroscientists using powerful new tools of brain imaging have found that the human cerebellum is active during a wide range of activities that are not directly related to movement. Sophisticated cognitive studies have also revealed that damage to specific areas of the cerebellum can cause unanticipated impairments in nonmotor processes, especially in how quickly and accurately people perceive sensory information. Other findings indicate that the cerebellum may play important roles in shortterm memory, attention, impulse control, emotion, higher cognition, the ability to schedule and plan tasks, and possibly even in conditions such as schizophrenia and autism. Additional neurobiological experiments-both on the pattern of sensory inputs to the cerebellum and on the ways in which the cerebellum processes that information-also suggest a need to substantially revise current thinking about the function of this organ. The cerebellum has once again become an area of "tantalizing mystery."