Scientists have found out the mechanism of fixing memories during sleep
The dorsal and ventral parts of the hippocampus coordinate their work during sleep to consolidate emotional memories of past events. This conclusion was reached by neuroscientists from Neuroscience NeuroSU and the Institute of Biology of Paris (IBPS) during experiments on rats. This was reported on April 26 in the journal Medical Xpress.
What is the hippocampus?
"We observed neural reactivation, a phenomenon that supports memory processing during sleep, which covers the entire hippocampal axis after an emotionally positive or negative experience," said Gabrielle Girardot, senior author of the study.
Previously, neuroscientists knew that the dorsal hippocampus is involved in memory consolidation during sleep and interacts with areas of the brain associated with emotion processing, in particular, the amygdala. However, anatomical data indicated that the dorsal hippocampus has no direct connections to these structures, which means that communication takes place through an intermediate area.
Girardot and her colleagues suggested that the role of mediator is performed by the ventral hippocampus, another segment of the hippocampus, which, unlike the dorsal, is directly connected to the emotional centers of the brain.
To test the hypothesis, the scientists conducted a series of experiments on free-roaming rats. Microelectrodes were implanted in the animals, which simultaneously recorded the activity of multiple neurons in both parts of the hippocampus. Some rats received a mild electric shock, while others received a reward. The researchers then recorded neural activity during subsequent sleep.
The analysis showed that during sleep, the rat brain actually reproduces the emotional experience experienced with the coordinated work of the dorsal and ventral hippocampus. At the same time, the reactivation of negative experiences turned out to be more accurate than positive ones.
Gabriel Girardot, senior author of the study
This may explain the tendency to remember negative events more strongly than positive ones. In a broader sense, we have identified a mechanism that allows us to form memories that combine context and emotions— both positive and negative.
If confirmed in humans, these findings could expand understanding of the neural processes underlying the consolidation of traumatic memories and their role in the development of post-traumatic stress disorder (PTSD) and other mental disorders.
On April 14, the journal Science Daily reported that loneliness in the elderly is associated with poorer memory, but it does not accelerate its decline over time. It was noted at the time that 10,217 adults aged 65 to 94 from 12 countries, including Germany, Spain, Sweden and Slovenia, participated in the large—scale European study. The surveillance lasted for seven years, from 2012 to 2019. The data was obtained as part of the long—term SHARE project, Surveys of Health, Aging and Retirement in Europe, launched back in 2002.
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