Pioneering research by a team of neuroscientists at Michigan State University (USA) has concluded that spending a lot of time in dimly lit rooms and offices can change the structure of the brain and damage our ability to learn and remember.
The researchers studied the brains of African grass rats ( Arvicanthis niloticus ) (which, like humans, are diurnal and sleep at night) after exposure to dim, bright light for four weeks. The rodents exposed to dim light lost about 30% of the capacity in the hippocampus, a critical region of the brain for learning and memory, and performed poorly on a spatial task with prior training, compared to the group of control.
Rats exposed to bright light (second group) showed significant improvement in spatial task. Additionally, when rodents that had been exposed to dim light were exposed to bright light for four weeks (after a month-long break), their brain power and task performance fully recovered.
The study, funded by the National Institutes of Health , is the first to show that changes in ambient light, in a range normally experienced by humans, lead to structural changes in the brain.
“When we exposed the rats to dim light, mimicking the cloudy days of Midwestern winters or typical indoor lighting, the animals showed deficits in spatial learning,” said Antonio “Tony” Núñez, co-author of the study that publishes the Hippocampus magazine. “This is similar to when people can’t find their way back to their cars in a busy parking lot after spending a few hours at a mall or movie theater.”
According to experts, sustained exposure to dim light led to significant reductions in a substance called brain-derived neurotrophic factor, a peptide that helps maintain healthy connections and neurons in the hippocampus, and in dendritic spines, or connections. that allow neurons to communicate with each other.
“Since fewer connections are made, this reduces learning and memory performance that depends on the hippocampus,” said Joel Soler, a co-author of the work.
Interestingly, light does not directly affect the hippocampus, which means it first acts on other locations within the brain after passing through the eyes. This research could have implications for the elderly and people with glaucoma, retinal degeneration, or cognitive disabilities.
“For people with eye diseases who don’t get a lot of light, can we directly manipulate this group of neurons in the brain, bypass the eye, and provide them with the same benefits of exposure to bright light?” Asks Lily Yan, study leader.
“Another possibility is to improve cognitive function in the aging population and those with neurological disorders. Can we help them recover from disability or prevent further decline?”
We will soon know. The investigation continues.
Reference: Joel E. Soler, Alfred J. Robison, Antonio A. Núñez, Lily Yan. Light modulates hippocampal function and spatial learning in a diurnal rodent species: A study using male nile grass rat (Arvicanthis niloticus) . Hippocampus , 2017; DOI: 10.1002 / hipo.22822
