Photons play an important role in the basic functioning of cells. In fact, it looks very much as if many cells use light to communicate. There's ... evidence that bacteria, plants and even kidney cells communicate in this way. Various groups have even shown that rats brains are literally alight thanks to the photons produced by neurons as they work, [and] evidence is beginning to emerge that light may well play an important role in neuronal function. For example, earlier this year, one group showed that spinal neurons in rats can actually conduct light. Today, Majid Rahnama at Shahid Bahonar University of Kerman in Iran and a group of pals, suggest how this might work. Rhanama and co hypothesise that microtubules can act as wave guides, channeling light from one part of a cell to another. Microtubules are the internal scaffolding inside cells, providing structural support but also creating highways along which molecular machines transport freight around the cell. They're extraordinary things. Could it be that they also work like optical fibres? Maybe. They go on to suggest that the light channelled by microtubules can help to co-ordinate activities in different parts of the brain. Electrical activity in the brain is synchronised over distances that cannot be easily explained. Electrical signals travel too slowly to do this job, so something else must be at work. It's a big jump to assume that photons do this job. But science is built on leaps of imagination like this.