Our skin contains millions of nerve endings and touch sensors that collect information about different sensations like temperature, pressure, vibration, pain and send it to the brain for processing and reaction. But it’s when our sensory system goes wrong that we learn most about how our senses help us understand the world around us. Neurologist Dr Guy Leschziner talks to Alison, whose delicious seafood dinner sends her nervous system haywire. Poisoned by fish contaminated with ciguatera toxin, her sense of temperature is turned upside down – so hot feels cold and the cold floor tiles burn the soles of her feet. We hear from Dawn, whose damaged nerve triggers excruciating pain down the side of her face – illustrating how our senses can trick us about the source of our agony. We meet Paul, who has broken every bone in his body, yet never feels a jot of pain. His rare genetic condition, congenital insensitivity to pain, means his brain never receives signals warning of damage to his flesh and bones. And whilst a pain-free life might sound appealing, we find out it has serious physical and psychological consequences. And through Rahel we learn about a lesser-known touch sensation, called proprioception. When it is not working, it affects our co-ordination. And for Rahel, that means she struggles to stay upright when it is dark. Photo: Vicki and Paul Waters Courtesy of the Waters family