We expose how electricity powers the nervous system. Chris Smith and Hannah Critchlow speak to a panel of experts about why chillis taste hot and mint feels cool, how ion channels could tackle diabetes and the new technique that uses algae could shed light on the brain. In the news, re-programming stem cells in situ, the TV programme that's changing accents 400 miles away, the insects that use natural gears to propel themselves and how you can tell whether a panda is pregnant.