[1] Northwestern Univ, Dept Biomed Engn, Evanston, IL USA
[2] Northwestern Univ, Dept Neurobiol & Physiol, Evanston, IL USA
[3] Northwestern Univ, Inst Neurosci, Evanston, IL 60208 USA
[4] Swedish Univ Agr Sci, Fac Vet Med, Dept Med & Surg, S-75007 Uppsala, Sweden