{"id":10370,"date":"2025-06-24T09:26:12","date_gmt":"2025-06-24T09:26:12","guid":{"rendered":"https:\/\/www.europesays.com\/us\/10370\/"},"modified":"2025-06-24T09:26:12","modified_gmt":"2025-06-24T09:26:12","slug":"sleeps-secret-sequence-may-sculpt-our-memories-like-a-garden","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/10370\/","title":{"rendered":"Sleep\u2019s Secret Sequence May Sculpt Our Memories Like a Garden"},"content":{"rendered":"<p><strong>Summary: <\/strong>A new theory suggests that the order of sleep phases\u2014non-REM followed by REM\u2014is essential for strengthening and organizing memories. In mouse studies and computational models, researchers found that non-REM sleep reinforces new memories, while REM sleep prunes overlapping or irrelevant ones, keeping them distinct.<\/p>\n<p>Reversing this cycle causes memory degradation, highlighting why the natural progression of sleep stages is so evolutionarily conserved. While more research is needed, the findings offer a compelling explanation for how sleep architecture supports learning and memory.<\/p>\n<p><strong>Key Facts:<\/strong><\/p>\n<ul class=\"wp-block-list\">\n<li><strong>Memory Gardening:<\/strong> Non-REM sleep grows and stabilizes memories; REM trims overlapping ones to keep them distinct.<\/li>\n<li><strong>Order Matters:<\/strong> Reversing the non-REM to REM sequence causes loss of memory rather than refinement.<\/li>\n<li><strong>Model-Driven Insight:<\/strong> Combining mouse data with circuit-based simulations revealed how acetylcholine dynamics shape memory during sleep.<\/li>\n<\/ul>\n<p><strong>Source: <\/strong>University of Michigan<\/p>\n<p><strong>Although we know sleep is essential to our physical and mental well-being, it remains an incredibly enigmatic behavior, scientifically speaking.\u00a0<\/strong><\/p>\n<p>Researchers at the University of Michigan, however, may have developed a new theory to account for one of sleep\u2019s looming mysteries.<\/p>\n<p>Every living thing that sleeps appears to follow the same basic pattern. From wakefulness, organisms transition to a repeating cycle of sleep with low brain activity followed by a stage where our brains are harder at work, among other things, generating vivid dreams.<\/p>\n<p>  <img fetchpriority=\"high\" decoding=\"async\" width=\"1200\" height=\"801\" src=\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/06\/memory-sleep-sculpting-neuroscience.jpg\" alt=\"This shows a brain as a tree.\"  \/> But researchers can\u2019t yet zero in on all the individual neurons encoding specific memories with available techniques, so this is where the team\u2019s modeling stepped in to help complete the picture. Credit: Neuroscience News<\/p>\n<p>Humans\u2019 eyes also dance around behind our eyelids during that high-activity stage, which is why it\u2019s referred to as rapid eye movement, or REM, sleep.<\/p>\n<p>Although there are a few notable exceptions\u2014including people with narcolepsy and people who haven\u2019t slept in days\u2014this repeating non-REM to REM sleep cycle is remarkably prevalent across the animal kingdom.\u00a0<\/p>\n<p>\u201cEvolutionarily, it\u2019s so preserved and so ubiquitous across species,\u201d said\u00a0Sara Aton, U-M professor of molecular, cellular and developmental biology.<\/p>\n<p>\u201cThat means there\u2019s probably something really important about that particular order of sleep. And it never goes in reverse, unless something has really screwed up the system.\u201d<\/p>\n<p>Yet, scientists have lacked a satisfying explanation for the biological function of this virtually universal phenomenon.<\/p>\n<p>Now, U-M researchers led by Aton and\u00a0Michal Zochowski\u00a0have put together a theory built on experimental observations in mice and computer modeling of the brain\u2019s neural circuitry.<\/p>\n<p>That theory posits that, if memories were shrubs, the non-REM phase of sleep helps them grow taller and stronger. The REM stage then prunes, keeping them shapely and distinct, and preventing them from overlapping and growing into each other.<\/p>\n<p>\u201cIt only works if you have this sequence. If you go in reverse and have REM first, it prunes everything away. Then no memory is left,\u201d Aton said.<\/p>\n<p>\u201cIn the proper sequence, you reinforce things that need to be reinforced. Then REM comes in to prune back the overlapping portions of unrelated memories.\u201d<\/p>\n<p>In mice, the researchers could observe the effect of sleep on remembering simple conditioning experiments. In humans, Zochowski said, this could have familiar implications in our everyday business.<\/p>\n<p>\u201cLet\u2019s say you have three meetings in a day. We know that you\u2019ll remember these meetings better after a good night\u2019s sleep,\u201d Zochowski said.<\/p>\n<p>\u201cNow, it appears that during non-REM sleep, you\u2019re strengthening your memory of each meeting. But you also need to remember who said what and during which meeting. What REM does is keep that separate.\u201d<\/p>\n<p>The work is published in the journal\u00a0PLoS Computational Biology\u00a0and was supported by the National Science Foundation, a Chan Zuckerberg Initiative and the National Institutes of Health.<\/p>\n<p>The project was made possible, in part, by advances made by the broader community over the last dozen years, fostered by the NIH\u2019s Brain Research Through Advancing Innovative Neurotechnologies, or BRAIN, Initiative.<\/p>\n<p><strong>Cycles and circuits<\/strong><\/p>\n<p>Led by Aton\u2019s team, the researchers\u2019 latest experiments monitored mice brains to see which parts of the hippocampus were active during different phases of sleep following a simple conditioning scenario.\u00a0<\/p>\n<p>Mice were moved from their home enclosures to a new environment and, after exploring a couple minutes, would receive a small shock to their feet. There was also a control group of mice who experienced no such unpleasantries.<\/p>\n<p>This enabled the researchers to compare brain activity of sleeping mice during REM and non-REM cycles that had and hadn\u2019t forged an association between the new space and a shock.<\/p>\n<p>But researchers can\u2019t yet zero in on all the individual neurons encoding specific memories with available techniques, so this is where the team\u2019s modeling stepped in to help complete the picture.<\/p>\n<p>The model was developed by Zochowski\u2019s group and treats newly encoded memories as changes in the activity of neurons in circuits, subject to the brain\u2019s environment where a biochemical called acetylcholine modulates their activity.\u00a0<\/p>\n<p>\u201cWe can actually simulate and pinpoint which neurons are being activated by a learning event,\u201d Aton said.<\/p>\n<p>\u201cWe can model that and we can model changes that happen with respect to acetylcholine as an animal goes through the different stages of sleep.\u201d<\/p>\n<p>There are also two types of neurons: excitatory ones that tend to stimulate their neighbors and inhibitory ones that tamp down the activity of others.<\/p>\n<p>By combining these dynamics with real world data on brain activity and acetylcholine levels during different phases of sleep, the model helped reveal conclusions that were previously inaccessible.<\/p>\n<p>Although the researchers are excited by the result, they stressed that this is not the final word on the matter. Their circuit model is a simplified representation of the brain and the team\u2019s experiments tested relatively straightforward memory scenarios.<\/p>\n<p>Thus, the theory could change or evolve as researchers subject it to more complex test cases and provide it with new and different types of data.<\/p>\n<p>\u201cWhat we have now is a study that says, \u2018Look, this is what could be happening,&#8217;\u201d Zochowski said. \u201cNow we have to prove that the model is associated with reality.\u201d<\/p>\n<p>About this sleep and memory research news<\/p>\n<p class=\"has-background\" style=\"background-color:#ffffe8\"><strong>Author: <\/strong><a href=\"http:\/\/neurosciencenews.com\/cdn-cgi\/l\/email-protection#c9a4a8bdbdb9a6bbbd89bca4a0aaa1e7acadbc\" target=\"_blank\" rel=\"noreferrer noopener\">Matt Davenport<\/a><br \/><strong>Source: <\/strong><a href=\"https:\/\/umich.edu\" target=\"_blank\" rel=\"noreferrer noopener\">University of Michigan<\/a><br \/><strong>Contact: <\/strong>Matt Davenport \u2013 University of Michigan<br \/><strong>Image: <\/strong>The image is credited to Neuroscience News<\/p>\n<p class=\"has-background\" style=\"background-color:#ffffe8\"><strong>Original Research: <\/strong>Open access.<br \/>\u201c<a href=\"https:\/\/dx.doi.org\/10.1371\/journal.pcbi.1013097\" target=\"_blank\" rel=\"noreferrer noopener\">Cholinergic modulation of neural networks supports sequential and complementary roles for NREM and REM states in memory consolidation<\/a>\u201d by Sara Aton et al. PLOS Computational Biology<\/p>\n<p><strong>Abstract<\/strong><\/p>\n<p><strong>Cholinergic modulation of neural networks supports sequential and complementary roles for NREM and REM states in memory consolidation<\/strong><\/p>\n<p>Across vertebrate species, sleep consists of repeating cycles of NREM followed by REM. However, their respective functions, and their stereotypic cycling pattern are not well understood.<\/p>\n<p>Using a simplified biophysical network model, we investigate the potential role of cholinergic modulation, acting via the muscarinic receptors, on network dynamics and memory consolidation.<\/p>\n<p>We show that low and high cholinergic levels associated with NREM and REM sleep, respectively, may play critical, sequential roles in memory consolidation.<\/p>\n<p>The network dynamics that facilitate these roles arise through alteration of neural excitability and changes to network-wide excitatory\/inhibitory balance.<\/p>\n<p>At low acetylcholine (ACh) levels, reduced activation of inhibitory neurons leads to network-wide disinhibition and bursts of synchronized activity led by engram neurons, driving recruitment of additional excitatory neurons into the engram.<\/p>\n<p>In contrast, at high ACh levels, increased network inhibition suppresses firing in all but the most strongly recruited excitatory neurons, pruning the expanded engram population.<\/p>\n<p>Together, these results provide a testable hypothesis regarding the role of sleep state-specific cholinergic modulation in the process of memory consolidation.<\/p>\n","protected":false},"excerpt":{"rendered":"Summary: A new theory suggests that the order of sleep phases\u2014non-REM followed by REM\u2014is essential for strengthening and&hellip;\n","protected":false},"author":3,"featured_media":10371,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[11284,827,210,3810,829,831,1079,67,132,11285,68],"class_list":{"0":"post-10370","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-health","8":"tag-acetylcholine","9":"tag-brain-research","10":"tag-health","11":"tag-memory","12":"tag-neurobiology","13":"tag-neuroscience","14":"tag-sleep","15":"tag-united-states","16":"tag-unitedstates","17":"tag-university-of-michigan","18":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/114737629353127768","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/10370","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=10370"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/10370\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/10371"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=10370"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=10370"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=10370"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}