TEHRAN (Iran News)  Researchers found that during sleep, the brain consolidates memories by repeating patterns of neuronal activity in the hippocampus, which are stored in the cortex.

The study, titled “A Hippocampal Circuit Mechanism to Balance Memory Reactivation During Sleep,” demonstrates that certain parts of the hippocampus go silent at specific times during deep sleep, allowing neurons to reset.

“This mechanism could allow the brain to reuse the same resources, the same neurons, for new learning the next day,” explained Azahara Oliva, assistant professor of neurobiology and behavior and the study’s corresponding author.

The hippocampus, divided into three regions—CA1, CA2, and CA3—has been well studied in areas CA1 and CA3, which are involved in encoding memories related to time and space. However, the study highlights the less understood CA2 region, which appears to generate the silencing and resetting of the hippocampus during sleep.

Using implanted electrodes in the hippocampi of mice, researchers observed neuronal activity during learning and sleep. They found that during sleep, neurons in the CA1 and CA3 regions reproduced the same patterns developed during learning. However, the researchers also noted periods when these regions became silent, allowing for memory reset.

“We realized there are other hippocampal states that happen during sleep where everything is silenced,” said Oliva. “The CA1 and CA3 regions that had been very active were suddenly quiet. It’s a reset of memory, and this state is generated by the middle region, CA2.”

The study also uncovered that the brain has parallel circuits regulated by two types of interneurons—one responsible for memory regulation and the other for memory resetting.

Researchers believe this understanding could lead to ways to enhance memory or even erase traumatic memories, which could benefit conditions like Alzheimer’s disease and post-traumatic stress disorder.

The findings provide insight into why sleep is essential for maintaining cognitive function and memory, with Oliva noting, “We show that memory is a dynamic process.”

The study was funded by the National Institutes of Health, a Sloan Fellowship, a Whitehall Research Grant, a Klingenstein-Simons Fellowship, and a New Frontiers Grant.

One in three New Zealand children is overweight or obese when they start school, research team co-leader Prof Rachael Taylor says.

The parents of half the 800 babies in the Otago study took part in a short prenatal discussion on sleep and received some further follow-up support.

The “striking” finding of the Otago study is that those infants who received sleep support were half as likely to be obese by the age of 2 than those who had not received it.

The “amazing thing” was that these weight-related benefits were just as strong at 5 years of age, “despite no intervention having had occurred for three years”, Prof Taylor said, Science Daily reported.

“I think sleep offers us a really exciting, different way to approach weight, that has benefits for so many,” she said.

Prof Taylor, who is director of the Edgar Diabetes and Obesity Research Centre, said every parent knew “getting enough good quality sleep keeps a child happy, behaving well and enjoying life”.

“It also helps them do well at school, their diets are better, and they tend to be more active – all factors that help us be healthy.”

It is understood that the Otago study provides some of the clearest international evidence of the value of a brief sleep-related intervention in reducing early childhood obesity.

The study was published in The American Journal of Clinical Nutrition, and funded by New Zealand’s Health Research Council.

Dunedin School of Medicine dean, and study co-lead Prof Barry Taylor said the long-term benefits shown in the study, despite no ongoing contact, were “almost unheard of” for obesity interventions.

Prof Taylor also runs a special clinic for very overweight children and says it is important for children to have a regular sleep routine.

Children should go to bed at a time that gave them enough sleep so they were not tired the next day, and screen-time should be avoided for at least 30 minutes before going to bed, as well as in bed.

Prof Rachael Taylor said those families receiving sleep support were also visited when the infants were about 3 weeks old, and researchers discussed with parents how to help their child with sleep.

If a sleep problem developed, expert support was available until infants were 2 years old, and about 100 parents took up this support, she said.

The study in the journal Molecular Psychiatry, which is published by Springer Nature, was led by Murray Stein of the University of California San Diego and the VA San Diego Healthcare System.

Up to 20 percent of Americans and up to 50 percent of US military veterans are said to have trouble sleeping. The effects insomnia has on a person’s health can be debilitating and place a strain on the healthcare system. Chronic insomnia goes hand in hand with various long-term health issues such as heart disease and type 2 diabetes, as well as mental illness such as post-traumatic stress disorder (PTSD) and suicide.

Twin studies have in the past shown that various sleep-related traits, including insomnia, are heritable. Based on these findings, researchers have started to look into the specific gene variants involved. Stein says such studies are important, given the vast range of reasons why people suffer from insomnia, and the different symptoms and varieties of sleeplessness that can be experienced.

“A better understanding of the molecular bases for insomnia will be critical for the development of new treatments,” he adds.

In this study, Stein’s research team conducted genome-wide association studies (GWAS). DNA samples obtained from more than 33,000 soldiers participating in the Army Study To Assess Risk and Resilience in Servicemembers (STARRS) were analyzed. Data from soldiers of European, African and Latino descent were grouped separately as part of efforts to identify the influence of specific ancestral lineages. Stein and his colleagues also compared their results with those of two recent studies that used data from the UK Biobank.

Overall, the study confirms that insomnia has a partially heritable basis. The researchers also found a strong genetic link between insomnia and type 2 diabetes. Among participants of European descent, there was additionally a genetic tie between sleeplessness and major depression, Science Daily reported.

“The genetic correlation between insomnia disorder and other psychiatric disorders, such as major depression, and physical disorders such as type 2 diabetes suggests a shared genetic diathesis for these commonly co-occurring phenotypes,” says Stein, who adds that the findings strengthen similar conclusions from prior twin and genome-wide association studies.

Insomnia was linked to the occurrence of specific variants on chromosome 7. In people of European descent, there were also differences on chromosome 9. The variant on chromosome 7, for instance, is close to AUTS2, a gene that has been linked to alcohol consumption, as well as others that relate to brain development and sleep-related electric signaling.

“Several of these variants rest comfortably among locations and pathways already known to be related to sleep and circadian rhythms,” Stein elaborates. “Such insomnia associated loci may contribute to the genetic risk underlying a range of health conditions including psychiatric disorders and metabolic disease.”

The study in the journal Molecular Psychiatry, which is published by Springer Nature, was led by Murray Stein of the University of California San Diego and the VA San Diego Healthcare System.

Up to 20 percent of Americans and up to 50 percent of US military veterans are said to have trouble sleeping. The effects insomnia has on a person’s health can be debilitating and place a strain on the healthcare system. Chronic insomnia goes hand in hand with various long-term health issues such as heart disease and type 2 diabetes, as well as mental illness such as post-traumatic stress disorder (PTSD) and suicide.

Twin studies have in the past shown that various sleep-related traits, including insomnia, are heritable. Based on these findings, researchers have started to look into the specific gene variants involved. Stein says such studies are important, given the vast range of reasons why people suffer from insomnia, and the different symptoms and varieties of sleeplessness that can be experienced.

“A better understanding of the molecular bases for insomnia will be critical for the development of new treatments,” he adds.

In this study, Stein’s research team conducted genome-wide association studies (GWAS). DNA samples obtained from more than 33,000 soldiers participating in the Army Study To Assess Risk and Resilience in Servicemembers (STARRS) were analyzed. Data from soldiers of European, African and Latino descent were grouped separately as part of efforts to identify the influence of specific ancestral lineages. Stein and his colleagues also compared their results with those of two recent studies that used data from the UK Biobank.

Overall, the study confirms that insomnia has a partially heritable basis. The researchers also found a strong genetic link between insomnia and type 2 diabetes. Among participants of European descent, there was additionally a genetic tie between sleeplessness and major depression, Science Daily reported.

“The genetic correlation between insomnia disorder and other psychiatric disorders, such as major depression, and physical disorders such as type 2 diabetes suggests a shared genetic diathesis for these commonly co-occurring phenotypes,” says Stein, who adds that the findings strengthen similar conclusions from prior twin and genome-wide association studies.

Insomnia was linked to the occurrence of specific variants on chromosome 7. In people of European descent, there were also differences on chromosome 9. The variant on chromosome 7, for instance, is close to AUTS2, a gene that has been linked to alcohol consumption, as well as others that relate to brain development and sleep-related electric signaling.

“Several of these variants rest comfortably among locations and pathways already known to be related to sleep and circadian rhythms,” Stein elaborates. “Such insomnia associated loci may contribute to the genetic risk underlying a range of health conditions including psychiatric disorders and metabolic disease.”