Pulsed infrared laser light, which can stimulate neural cells, does so by changing cell membrane electrical properties reports a study published in Nature Communications this week. The work provides insight into how infrared light can stimulate cells without any chemical or genetic pre-treatment and may facilitate its use in biomedical research. Animal studies have shown that pulses of infrared light can stimulate nerves but how this occurs has been a mystery. Francisco Bezanilla and colleagues stimulated frog oocytes and mammalian cells and show that infrared light induces electrical currents and that this process requires water. The team tested the effects of the infrared light in solution and note that that the light raised the temperature of the solution therefore they suggest that it is likely water that is heated in the living cell. Using artificial membrane they further show that stimulating with infrared light can alter the amount of electric potential energy that is stored in the membranes. Their findings provide a mechanism for explaining how infrared light can electrically stimulate nerve cells and this may promote further study of the use of infrared light in stimulating brain function and heart cells.