memory formation Archives - Amazing Health Advances

Pupil Size in Sleep Reveals How Memories are Sorted, Preserved

The AHA! Team — Fri, 28 Feb 2025 06:29:41 +0000

Cornell University via EurekAlert! – Cornell University researchers have found the pupil is key to understanding how, and when, the brain forms strong, long-lasting memories. By studying mice equipped with brain electrodes and tiny eye-tracking cameras, the researchers determined that new memories are being replayed and consolidated when the pupil is contracted during a substage of non-REM sleep. When the pupil is dilated, the process repeats for older memories. The brain’s ability to separate these two substages of sleep with a previously unknown micro-structure is what prevents “catastrophic forgetting” in which the consolidation of one memory wipes out another one. The findings could lead to better memory enhancement techniques for humans and may help computer scientists train artificial neural networks to be more efficient. The study, under embargo until 11am ET on Jan. 1 in Nature, was led by assistant professors Azahara Oliva and Antonio Fernandez-Ruiz. Over the course of a month, a group of mice was taught a variety of tasks, such as collecting water or cookie rewards in a maze. Then the mice were outfitted with brain electrodes and tiny spy cameras that hung in front of their eyes to track their pupil dynamics. One day, the mice learned a new task and when they fell asleep, the electrodes captured their neural activity, and the cameras recorded the changes to their pupils. “Non-REM sleep is when the actual memory consolidation happens, and these moments are very, very short periods of time undetectable by humans, like 100 milliseconds,” Oliva said. Non-REM sleep is when the actual memory consolidation happens “How does the brain distribute these screenings of memory that are very fast and very short throughout the overall night? And how does that separate the new knowledge coming in, in a way that it doesn’t interfere with old knowledge that we already have in our minds?” The recordings showed that the temporal structure of sleeping mice is more varied, and more akin to the sleep stages in humans, than previously thought. By interrupting the mice’s sleep at different moments and later testing how well they recalled their learned tasks, the researchers were able to parse the processes. When a mouse enters a substage of non-REM sleep, its pupil shrinks, and it’s here the recently learned tasks – i.e., the new memories – are being reactivated and consolidated while previous knowledge is not. Conversely, older memories are replayed and integrated when the pupil is dilated. “It’s like new learning, old knowledge, new learning, old knowledge, and that is fluctuating slowly throughout the sleep,” Oliva said. “We are proposing that the brain has this intermediate timescale that separates the new learning from the old knowledge.” The research was supported by the National Institutes of Health, the Sloan Foundation, the Whitehall Foundation, the Klingenstein-Simons Fellowship Program, and the Klarman Fellowships Program. Journal Nature Article Title Sleep micro-structure organizes memory replay To read the original article click here.

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Memory Formation Influenced By How Brain Networks Develop During Youth

AHA Publisher — Wed, 16 Feb 2022 08:00:49 +0000

Northwestern University via Newswise – CHICAGO — In a new, rare study of direct brain recordings in children and adolescents, a Northwestern Medicine scientist and colleagues from Wayne State University have discovered as brains mature, the precise ways by which two key memory regions in the brain communicate make us better at forming lasting memories. The findings also suggest how brains learn to multitask with age. The study will be published Feb. 15 in Current Biology. Historically, a lack of high-resolution data from children’s brains have led to gaps in our understanding of how the developing brain forms memories. The study innovated the use of intracranial electroencephalogram (iEEG) on pediatric patients to examine how brain development supports memory development. The scientists found a link between how the brains of people aged 5 to 21 were developing and how well they were able to form memories throughout that 16-year period. For example, younger children, whose brains were not as developed as the adolescent participants, weren’t able to form as many memories as some adolescents. “Our study helps us actually explain how memory develops, not just that it develops,” said corresponding author Lisa Johnson, assistant professor of medical social sciences and pediatrics at Northwestern University Feinberg School of Medicine. “By understanding how something comes to be — memory, in this instance — it gives us windows into why it eventually falls apart. “Human memory develops throughout childhood, peaks in your 20s and, for most people, declines with age, even in those who don’t develop dementia.” To address this, her work focuses on the lifespan of memory to provide a holistic approach to understanding brain development and memory, which is why this study focused on pediatric patients. Rhythms of Key Memory Regions of the Brain The study focused on communication between two regions of the brain that play a key role in supporting memory formation: the medial temporal lobe (MTL) and prefrontal cortex (PFC). To learn how these regions talk to one another, the scientists analyzed two brain signals — a slowly oscillating brain wave and a faster oscillating one — that enable communication between regions. The rhythms dictated whether a memory was successfully formed and differentiated top-performing adolescents from lower-performing adolescents and children. Pioneering Intracranial EEG in Pediatric Patients The participants in the study were already undergoing brain surgery for another reason (usually to treat their epilepsy), and the scientists capitalized on this rare opportunity to examine data from electrodes placed directly on the exposed surface of the brain. Following brain surgery, patients spent a week in the hospital for monitoring. This is when Johnson’s team conducted its studies, having the participants look at pictures of scenes to see how well they remembered them. The research team presented them with the same images again and new scenes they hadn’t yet seen (e.g., a different image of an outdoor area) to observe age-related differences in how well study participants remembered what they’d seen. Our Brains Learn to Multitask With Age Another novel finding in the study is that there appear to be age differences in fast and slow theta oscillations—rhythms in the brain that help with cognition, behavior, learning and memory. The slow theta frequency slows down with age, and the fast gets faster. “These rhythms seemed to diverge with age so that they were similar in 5-year-olds and different in 20-year-olds,” Johnson said. “The fact that key memory regions are interacting at both frequencies suggests how your brain is learning to multitask as you get older.” To read the original article click here.

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Saturated Fatty Acid Levels Increase When Making Memories

AHA Publisher — Tue, 06 Jul 2021 07:00:02 +0000

University of Queensland via EurekAlert – Saturated fatty acid levels unexpectedly rise in the brain during memory formation, according to research, opening a new avenue of investigation into how memories are made. Dr Tristan Wallis, from Professor Frederic Meunier’s laboratory at UQ’s Queensland Brain Institute (QBI), said traditionally, polyunsaturated fatty acids were considered important to health and memory, but this study highlighted the unexpected role of saturated fatty acids. “We tested the most common fatty acids to see how their levels changed as new memories were formed in the brain,” Dr Wallis said. “Unexpectedly, the changes of saturated fat levels in the brain cells were the most marked, especially that of myristic acid, which is found in coconut oil and butter. “In the kitchen, saturated fats are those which are solid at room temperature while unsaturated fats are normally liquid. “The brain is the fattiest organ in the body, being 60 per cent fat, which provides energy, structure and assists in passing messages between brain cells. “Fatty acids are the building blocks of lipids or fats and are vital for communication between nerve cells, because they help synaptic vesicles — microscopic sacs containing neurotransmitters–to fuse with the cell membrane and pass messages between the cells. “We have previously shown that when brain cells communicate with each other in a dish, the levels of saturated fatty acids increase.” Researchers have found that fatty acid levels in the rat brain, particularly saturated fatty acids, increase as memories are formed, but when they used a drug to block learning and memory formation in rats, the fatty acid levels did not change. The highest concentration of saturated fatty acids was found in the amygdala — the part of the brain involved in forming new memories specifically related to fear and strong emotions. Study contributor and QBI Director Professor Pankaj Sah said the work opened a new avenue on how memory was formed. “This research has huge implications on our understanding of synaptic plasticity — the change that occurs at the junctions between neurons that allow them to communicate, learn and build memories,” Professor Sah said. To read the original article click here.

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