1. Neurology Research Group, UCT Neuroscience Institute, University of Cape Town (UCT), Cape Town, South Africa
2. Department of Statistical Sciences, Statistical Consulting Service, University of Cape Town, Cape Town, South Africa
3. Department of Neurology, Brain Centre Rudolf Magnus, University Medical Centre Utrecht, Utrecht, The Netherlands
4. Department of Psychology, and UCT Neuroscience Institute, University of Cape Town, Cape Town, South Africa