BLD- Bright light
DLD- Dim light
Credit: Michigan State University
The researchers studied the brains of
Nile grass rats (which, like humans, are diurnal and sleep at night) after
exposing them to dim and bright light for four weeks. The rodents exposed to
dim light lost about 30 percent of capacity in the hippocampus, a critical
brain region for learning and memory, and performed poorly on a spatial task
they had trained on previously.
The
rats exposed to bright light, on the other hand, showed significant improvement
on the spatial task. Further, when the rodents that had been exposed to dim
light were then exposed to bright light for four weeks (after a month-long
break), their brain capacity and performance on the task recovered fully.
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 the connections that allow neurons to
"talk" to one another.
This results in diminished learning and memory performance that
is dependent upon the hippocampus, dim lights are producing dimwits.
Ref: Joel et al., Light modulates hippocampal function and spatial learning in a diurnal
rodent species: A study using male nile grass rat (Arvicanthis niloticus). Hippocampus, 2017.
1. DOI: 10.1002/hipo.22822
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