The fundamental job of the brain is to produce actions. Emilio Bizzi examines how the brain translates our general intentions into the detailed commands needed to control muscle movements. One of his key discoveries is that groups of muscles are activated synergistically by circuits of neurons in the spinal cord. He believes that these synergies represent the fundamental building blocks for assembling a repertoire of complex movements.
The building blocks of action
Everyday actions such as walking, speaking, or reaching for an object seem natural to us, but this apparent simplicity is deceptive. The human body has more than 600 muscles, so the number of possible combinations of muscle contractions that we could produce is unimaginatively vast. Bizzi explores how the brain selects from these countless possibilities to produce purposeful movement.
One of Bizzi's key discoveries is that our muscles are not necessarily controlled individually. He found that groups of muscles are activated synergistically by circuits of neurons in the spinal cord. He believes that these synergies represent the fundamental building blocks for assembling a repertoire of complex movements.
Learning to move
To accomplish even a simple task - for example, picking up a glass of water - the overall goal must be translated into instructions that specify the angles of joints, the position of the hand as it moves toward the glass, and how much force the muscles should exert to reach the glass without knocking it over.
To understand how the brain accomplishes this, Bizzi studies how movement commands are represented by electrical activity in the motor cortex, and how this electrical activity changes as new skills are acquired through practice. His work has implications for both normal learning and also for rehabilitation after brain injuries. People who lose motor control after a stroke or other injury often show some recovery over time. Bizzi is exploring ways in which this recovery might be enhanced, for instance through virtual reality training or magnetic stimulation of the brain.
Among the techniques used by the lab are behavioral training, cortical recording from single neurons, electromyographic (EMG) recording of muscle activity, microstimulation, cellular inactivation, kinematic measurement of movements in three dimensions, functional imaging, and computational modeling. Experimental models include frogs, rats, cats, rhesus monkeys, and humans.
Emilio Bizzi is an MIT Institute Professor, an Investigator in the McGovern Institute, and the Eugene McDermott Professor in the Brain Sciences and Human Behavior. He earned an M.D. from the University of Rome in 1958 and a Ph.D. from the University of Pisa in 1968. Dr. Bizzi joined the MIT faculty in 1968 and served as director of the Whitaker College of Health Sciences and Technology from 1983 to 1989. Dr. Bizzi chaired the MIT Department of Brain and Cognitive Sciences from 1986 to 1997. He was appointed Investigator at the McGovern Institute in 2001. Among many other honors, Dr. Bizzi became a member of the National Academy of Sciences in 1968 and the Institute of Medicine in 2005. He received the President of Italy's Gold Medal for Scientific Contributions in 2005 and in 2006 was elected as President of the American Academy of Arts and Sciences.
Photo: Kent Dayton