[1] CSIC, IMSE, CNM, Natl Microelect Ctr, Seville 41012, Spain
[2] Johns Hopkins Univ, Whitaker Biomed Engn Inst, Baltimore, MD 21218 USA
[3] Univ Zurich, ETHZ, Inst Neuroinformat, Zurich, Switzerland
[4] Swiss Fed Inst, Zurich, Switzerland
[5] Univ Tokyo, Dept Frontier Informat, Tokyo, Japan