About the Authors
Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kindgom
The authors have declared that no competing interests exist.
Conceived and designed the experiments: JMK WDP. Performed the experiments: JMK WDP. Analyzed the data: MJR WDP. Contributed reagents/materials/analysis tools: MJR JMK WDP. Wrote the paper: MJR JMK WDP.