Lasers create on/off switch for eating within mice

As the fight against obesity continues and companies work to find ways to help people lead healthier lifestyles, a new study reveals that overeating could be stopped through the use of lasers. Researchers from the University of North Carolina, US have led a successful test on mice to turn off the part of the brain that signals hunger.

In laboratory tests, scientists were able to identify the cells within the brains of mice that send hunger signals, resulting in the mice eating. Seth Blackshaw, neuroscientist from Johns Hopkins University, told Science News that the identification of these cells was the "missing piece of the puzzle" in the battle against obesity within humans.

The cells are located in the area of the brain called the bed nucleus stria terminalis (BNST), which contains neuronal fibres connected to the lateral hypothalamus - the area of the brain that is associated with hunger. Scientists genetically modified mice so that the cells would respond to a laser, effectively creating a on/off switch for mice's hunger.

In testing it was found that by activating the BNST neurons with a laser, it caused the mice to eat. Garret Stuber, one of the authors of the study, told Science News that once the laser is turned on the mice started to eat and would not stop until the laser had been turned off. According to Mr Stuber, the mice continued to eat with the laser turned on even when they were full. Another group of mice were modified to stop eating when the laser was turned on, which also showed positive results. 

The successful test highlight the fact that cells can be manipulated to affected the activity of some neurons, which could create modifications for other types of behaviour. It has also helped to understand how physiology can affect eating habits, as overeating in the mice was caused when neurons within the lateral hypothalamus were effectively shut down by the BNST stimulation. This suggests that this part of the brain usually works to restrict hunger.