Bioengineers at the Johns Hopkins Medical Institutions, taking Plato's concept of reality and illusion into the world of robots, have uncovered some of the algorithms of learning, the "primitives" the brain uses to comprehend the world. In particular, they have described the mathematical shapes used to control movements of the arms.
The primitives demonstrate why certain tasks are hard for us to learn, and that there may be fundamental limitations to what is learnable by the human brain.
In an article in the October 12 issue of Nature, Kurt Thoroughman, a graduate student in biomedical engineering, and Reza Shadmehr, Ph.D., assistant professor of biomedical engineering and neuroscience, report mathematically deconstructing the learning process.
Subjects in the experiment learn to control the motion of a robotic arm. Shadmehr and Thoroughman have mathematically described how they do it by constructing an internal model of reality in the brain. The report finds the specific shape and size of the primitives with which the brain builds internal models of physical dynamics.
"By programming the robot, we can produce the dynamics of things that either exist naturally or don't make sense. We simulate the dynamics of systems and we look at how people learn to control those systems," he says.
Behind the experiments is a concept called "primitives," the abstract elements by which the brain deals with the physics of objects and how the arm interacts with them. One way to think of primitives is to think of a Lego set, which contains a finite number of blocks, in particular shapes and sizes. To perceive reality, the brain arranges the blocks in order and eventually builds an internal model of the physical dynamics being produced by the robot, just like one builds a castle with Lagos. The smaller the size of the Lagos, and the more movements the Lagos make, the more intricate the internal model the brain can build and the more precisely the brain can contr
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Contact: Gary Stephenson
gstephenson@jhmi.edu
410-955-5384
Johns Hopkins Medical Institutions
11-Oct-2000