Twilight leads to stupidity
Neuroscientists at Michigan State University suspect that prolonged exposure to poorly lit rooms alters brain structure. The ability to learn and remember falls by the wayside.
The researchers of the Michigan State University experimented with Kusurrats, also called grass rats in their native Africa. Like humans, they are diurnal and sleep at night.
Effect can be reversed
Research leader Antonio Nunez and his team exposed some of the animals to twilight for four weeks. The others lived in normal lighting. The researchers then examined the brains of the rats, which were more like mice. Result: the capacity of the hippocampus of the animals that came out of dim light had decreased by 30 percent. In addition, their ability to solve tasks requiring spatial reasoning had decreased. Before the experiment, they could solve the tasks with ease. The animals that had lived in normal lighting were still able to improve in solving the spatial tasks.
However, the supposed stultification could be reversed. When the animals lived in the light again for four weeks after the dark phase, they were able to perform their trained tasks as well as before. "For lighting, we mimicked winter days with lots of clouds in the Midwest," Nunez said. The partial loss of the ability to think spatially, he said, resembles the situation of people who have lost their ability to think spatially after a trip to the movies or a Stroll through a shopping mall not find their car again, which may be an isolated problem.
Growth factor is to blame
Joel Soler from Nunez's team describes what happens in the animals' brains. Dim light, he says, leads to a significant decrease in the growth factor BDNF. That's a peptide essential to maintaining communication pathways in the brain and neurons in the hippocampus. "In other words, dim light produces dimwits," Soler says. While people with normal vision can easily protect themselves against this kind of dumbing down, it's a different story for those with eye problems. In the medium term, however, they can be helped, the researchers believe. It would be possible to directly stimulate the neurons that are affected, thus bypassing the eye. Whether the results of the experiments with rats can actually be transferred to humans has not yet been proven.
Text: pressetext.editorial office, Wolfgang Kempkens
