1. The worm is 1 mm long and few hundred microns across.
2. It has a fully characterized nervous system - 302 well defined neurons that have been mapped and named in exquisite detail. We even know which neurons connect to which! Have for decades. Still can’t tell how they function though.
3. The authors are expressing optogenetics proteins in various sets of neurons. Line 1 expresses them for example in 8 neurons known to play a role in chemotaxis (moves towards food).
4. They just shine a flash of light on the worm which would activate all these neurons together. This is probably still as blunt as putting an electrode into a mouse or monkey brain in some rough area and zapping them. I was hoping for slightly precise control.
I’ve been waiting for optogenetics to enter worms - mainly because they’re like the cheapest and easiest to work with creatures and I always believed understanding the simplest organism first is the right way to understanding any complex system.