1. Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
2. Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
3. Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh, PA 15213, USA.
4. Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
5. Carnegie Mellon Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA.