Health Science Reviews

By Kestrel Williamson

You’ve probably been told many times to get a full night’s sleep before an exam, and it’s generally explained to be important because sleep is important for memory consolidation. Neuroscientists agree that there is in fact a well-supported connection between sleep and memory, however, the mechanism explaining how sleep contributes to memory consolidation remains unclear. This is the question which these researchers set out to answer.

So how does a researcher study a mechanistic connection between sleep and memory? These researchers used a fly model (consisting of transgenic Drosophila flies) and measured the activity of a specific group of neurons (dopaminergic neurons) which regulate forgetting of olfactory memories. These neurons promote the fly to forget a particular olfactory experience. The researchers studied the activity of these neurons in different conditions – awake and asleep – to determine whether these neurons act as a physiological link between sleep and memory.

After performing these experiments, what did they find? Their results supported the consensus that sleep improves memory consolidation, firstly by indicating that sleeping after learning impairs forgetting, as well as by indicating that increased wakefulness after learning increases forgetting. This is, of course, unfortunate news for all students who engage in all-nighters before exams.

Their findings may provide the link between sleep and memory, as their data indicates that the studied dopaminergic neurons have reduced activity during sleep, which may be the mechanism by which memory is promoted during sleep, as these forgetting-promoting neurons are less active.

Adapted from: Berry, J., Cervantes-Sandoval, I., Chakraborty, M. & Davis, R., 2015. Sleep Facilitates Memory by Blocking Dopamine Neuron-Mediated Forgetting. Cell, 161(7), pp. 1656-1667. http://dx.doi.org/10.1016/j.cell.2015.05.027