1. Department of Bioengineering, University of Washington, Seattle, WA 98195-0005, USA
2. Department of Biology, University of Washington, Seattle, WA 98195-0005, USA
3. Graduate Program in Neuroscience, University of Washington, Seattle, WA 98195-0005, USA
4. Department of Biological Structure, University of Washington, Seattle, WA 98195-0005, USA
5. Department of Mechanical Engineering, University of Washington, Seattle, WA 98195-0005, USA