Funding for this research was provided by:
Wellcome Trust (WT089893MA)
National Institute for Health Research (ACLNEUR03)
Received: 2 September 2018
Revised: 1 January 2019
Accepted: 3 January 2019
First Online: 10 January 2019
Compliance with ethical standards
: On behalf of all authors, the corresponding author states that there is no conflict of interest.
: Most investigations were carried out as part of routine clinical care. Studies of motor cortical evoked potentials (MEP) and coherence were approved by the local NHS research ethics committee (approval number 08/H0908/3) and conformed to the Declaration of Helsinki.