Making the worms turn
To biophysicist Aravinthan Samuel, the roundworm Caenorhabditis elegans provides a pathway to understanding the brain and nervous system, first of the worm, then of higher animals, and even, perhaps, of humans. But to Samuel, working on anesthetized or immobilized worms can only tell you so much about how the brain and nervous system work. To truly understand the system, researchers need to see it in action. So Samuel and researchers in his lab set to work designing equipment that could measure nerve activity in living, wiggling worms. They first succeeded three or four years ago, becoming the first to record neural activity in freely moving worms. Then, last year, they topped that, using pulses of green and blue light on worms that had been genetically modified so that their nerves contained light-activated proteins. This allowed researchers to exert control over the worms by aiming pulses of light at specific nerves. To do this,...