Dutch scientists find access to forgotten memories in brain

Dutch scientists have found access to memories that are forgotten due to lack of sleep. As the researchers write from the University of Groningen in an article in the journal Current Biology, lost information continues to be stored in the brain and remember it again, help medical intervention - for example, taking medication.

Sleep is essential for long-term memory formation, so preparing students for exams at night negatively affects the quality of information remembered. Scientists have tested whether sleep deprivation really causes information to be lost completely or whether it is just difficult to access it.

They used genetically modified rodents in which neurons that are activated during learning produce channel rhodopsin, a light-sensitive protein. This protein forms membrane channels involved in the formation of the action potential, or nerve impulse, so when exposed to light directly, brain neurons are selectively activated, causing the trained mice to behave accordingly. The scientists targeted hippocampal neurons, the area responsible for the consolidation of long-term memory.

First, the mice were trained in a spatial task in which they had to remember the location of some objects. A few days later, during the second session of the experiment, the animals tried to perform the same task, but one of the objects moved to a different location. In the group of rodents with sleep deprivation (several hours before the first session), the rodents did not detect this change, that is, they could not remember the original location of the object. However, after reactivation of hippocampal neurons by light, the mice detected that the object had been moved.

The scientists concluded that sleep deprivation promotes suboptimal storage of information that was previously thought to be permanently lost. It can be accessed using optogenetic stimulation even days after "forgetting."

The drug roflumilast, used in the fight against asthma or chronic obstructive pulmonary disease, affects the molecular mechanism behind neuronal reactivation. Scientists gave it to mice before the second session, which promoted recall of information. According to the scientists, roflumilast could be tested in future studies involving people with memory problems - for example, patients with the initial stages of Alzheimer's disease.

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