About the Authors
LSIS, UMR CNRS 6168, Université Aix-Marseille II, Marseille, France
LNAO, Neurospin, I2BM, CEA Saclay, Gif-sur-Yvette, France
The authors have declared that no competing interests exist.
Conceived and designed the experiments: JL JFM. Performed the experiments: JL. Analyzed the data: JL JFM. Contributed reagents/materials/analysis tools: JL. Wrote the paper: JL JFM.