1. Computation and Neural Systems, California Institute of Technology, Pasadena, CA 91125, USA.
2. Bioengineering, California Institute of Technology, Pasadena, CA 91125, USA.
3. Department of Electrical Engineering and Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, WA 98195, USA.
4. Computer Science, California Institute of Technology, Pasadena, CA 91125, USA.
5. Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX 78701, USA.