Roland Piquepaille writes "A Stanford University team has developed a microscope weighing only 1.1 grams. It is so small that it can be mounted to the head of a freely moving mouse to watch its brain cell activity. According to what the lead researcher told New Scientist, 'A lot of work has been done using brain slices, or anaesthetised animals — even using animals that are awake but restrained. But so far it has been impossible to image cellular-level activity in a freely moving mouse.' Not any more. And as mice are the 'preferred' animals in medical labs, this new kind of microscope could lead to new ways to study human diseases."