The consequence is, according to researchers from Michigan State University, is that spending too long a period in dimly lit rooms and offices can change the brain’s structure. In turn this affects one’s ability to remember and learn. This should ideally lead to owners of homes and offices seeking improved lighting, according to the neuroscientists.
The findings do not directly relate to human subjects, however. For the research the scientists studied Nile grass rats exposed to dim lights for a period of four weeks. Studies of the rodent showed they experienced, on average, a 30 percent decrease in the number of ‘dendritic spine’ connections in their brains. A dendritic spine is a small membranous protrusion from a neuron’s dendrite. It functions to receive an input from a single axon at the synapse. Dendritic spines work as a storage site for synaptic strength and help transmit electrical signals to the neuron’s cell body.
The test rats were found to perform poorly on a maze-like task. In contrast, a control group of rats exposed to bright light were found to possess many more of the dendritic connections. When the bright light rats undertook the same challenge, they showed superior performance on the task.
Further study found that exposure to dim light led to largereductions in a brain derived neurotrophic factor, which is a peptide that helps maintain healthy connections and neurons in the hippocampus.
According to lead research Professor Antonio Nunez: “When we exposed the rats to dim light, mimicking the cloudy days of Midwestern winters or typical indoor lighting, the animals showed impairments in spatial learning. 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 in a shopping mall or movie theater.”
The research not only has implications in terms of seasonality; it could affect how homes and offices are lit. Moreover, the study could have implications for the elderly and those with glaucoma, retinal degeneration or cognitive impairments. In each case this is about maximizing exposure to bright or natural light.
The finding have been published in the journal Hippocampus. The research paper is titled “Light modulates hippocampal function and spatial learning in a diurnal rodent species: A study using male nile grass rat (Arvicanthis niloticus).”
