1 Neuropathology Unit, Division of Brain Sciences, Department of Medicine, Imperial College London, Burlington Danes Building, Hammersmith Hospital Campus, London, W12 0NN, UK.
2 Neuropathology Unit, Division of Brain Sciences, Department of Medicine, Imperial College London, Burlington Danes Building, Hammersmith Hospital Campus, London, W12 0NN, UK. s.gentleman@imperial.ac.uk.