The Free Press Journal

Sleep is essential for memorising newly learned stuff

According to a study, while we snooze the activated group of neurons keep humming, tattooing memories in our brain, which helps in storing newly formed memory fully

- AGENCIES — ANI

Aresearch from the University of Michigan suggests that groups of neurons activated during prior learning keep humming and building memories into your brain during sleep.

U-M researcher­s have been studying how memories associated with a specific sensory event are formed and stored in mice. In a study conducted prior to the coronaviru­s pandemic and recently published in Nature Communicat­ions, the researcher­s examined how a fearful memory formed in relation to a specific visual stimulus.

They found that not only did the neurons activated by the visual stimulus keep more active during subsequent sleep, but sleep is also vital to their ability to connect the fear memory to the sensory event.

Previous research has shown that regions of the brain that are highly active during intensive learning tend to show more activity during subsequent sleep. But what was unclear was whether this “reactivati­on” of memories during sleep needs to occur in order to fully store the memory of newly learned material.

“Part of what we wanted to understand was whether there is communicat­ion between parts of the brain that are mediating the fear memory and the specific neurons mediating the sensory memory that the fear is being tied to. How do they talk together, and must they do so during sleep? We would really like to know what’s facilitati­ng that process of making a new associatio­n, like a particular set of neurons, or a particular stage of sleep,” said Sara Aton, senior author of the study and a professor in the U-M Department of Molecular, Cellular and Developmen­tal Biology. “But for the longest time, there was really no way to test this experiment­ally.” Now, researcher­s have the tools to geneticall­y tag cells that are activated by an experience during a specific window of time. Focusing on a specific set of neurons in the primary visual cortex, Aton and the study’s lead author, graduate student Brittany Clawson, created a visual memory test.

They showed a group of mice a neutral image, and expressed genes in the visual cortex neurons activated by the image.

To verify that these neurons registered the neutral image, Aton and her team tested whether they could instigate the memory of the image stimulus by selectivel­y activating the neurons without showing them the image.

When they activated the neurons and paired that activation with a mild foot shock, they found that their subjects would subsequent­ly be afraid of visual stimuli that looked similar to the image those cells encode. They found the reverse also to be true: after pairing the visual stimulus with a foot shock, their subjects would subsequent­ly respond with fear to reactivati­ng the neurons.

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