[1] Univ Liege, Cyclotron Res Ctr, B-4000 Liege, Belgium
[2] CNRS, Inst Federatif Neurosci Lyon, Unite Mixte Rech 5167, F-69372 Lyon, France
[3] Inst Natl Sante & Rech Med, Inst Federatif Neurosci Lyon, Unite 821, F-65500 Lyon, France
[4] Univ Lyon 1, F-69622 Lyon, France