1. Department of Human Anatomy and Physiology, University College Dublin, Earlsfort Terrace, Dublin 2, Ireland, UK
2. Autonomic Neuroscience Institute, Department of Physiology, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, UK and Dublin, Ireland
3. Department of Anaesthetics, Coombe Womens Hospital and St James Hospital, Dublin, Ireland