Received: 22 October 2019
Accepted: 24 July 2020
First Online: 15 September 2020
: N.J. and P.M.T. are joint principal investigators for a research grant from Biogen, Inc. (Boston, USA) for processing of imaging data, some of which was used in this paper. Biogen, Inc had no role in the conceptualization, design, data collection, analysis, decision to publish, or preparation of the manuscript. The remaining authors declare no competing financial or non-financial interests.