FOR 12 years, the man in front of me lived with Parkinson’s: he had a stammer; he dragged his left foot. At 79, his mental faculties were slowing - but strangely, he didn’t have the tremors we normally associate with the disease.

When I say he is in front of me, what I mean to say is that his central nervous system - his brain and spinal column - is laid out before me. I am in a dissection room at the Division of Brain Sciences, Imperial College London.

Life savings: Inside London’s brain bank