Bruno A. Olshausen received his doctorate in computation and neural systems in 1994 from the California Institute of Technology. In 1996, he joined the faculty of the Department of Psychology and the Center for Neuroscience of the University of California, Davis. Address: Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95616. Internet: baolshausen@ucdavis.edu