Posts Tagged ‘memory’

by ABBY OLENA

Animals learn by imitating behaviors, such as when a baby mimics her mother’s speaking voice or a young male zebra finch copies the mating song of an older male tutor, often his father. In a study published today in Science, researchers identified the neural circuit that a finch uses to learn the duration of the syllables of a song and then manipulated this pathway with optogenetics to create a false memory that juvenile birds used to develop their courtship song.

“In order to learn from observation, you have to create a memory of someone doing something right and then use this sensory information to guide your motor system to learn to perform the behavior. We really don’t know where and how these memories are formed,” says Dina Lipkind, a biologist at York College who did not participate in the study. The authors “addressed the first step of the process, which is how you form the memory that will later guide [you] towards performing this behavior.”

“Our original goals were actually much more modest,” says Todd Roberts, a neuroscientist at UT Southwestern Medical Center. Initially, Wenchan Zhao, a graduate student in his lab, set out to test whether or not disrupting neural activity while a young finch interacted with a tutor could block the bird’s ability to form a memory of the interchange. She used light to manipulate cells genetically engineered to be sensitive to illumination in a brain circuit previously implicated in song learning in juvenile birds.

Zhao turned the cells on by shining a light into the birds’ brains while they spent time with their tutors and, as a control experiment, when the birds were alone. Then she noticed that the songs that the so-called control birds developed were unusual—different from the songs of birds that had never met a tutor but also unlike the songs of those that interacted with an older bird.

Once Zhao and her colleagues picked up on the unusual songs, they decided to “test whether or not the activity in this circuit would be sufficient to implant memories,” says Roberts.

The researchers stimulated birds’ neural circuits with sessions of 50- or 300-millisecond optogenetic pulses over five days during the time at which they would typically be interacting with a tutor but without an adult male bird present. When these finches grew up, they sang adult courtship songs that corresponded to the duration of light they’d received. Those that got the short pulses sang songs with sounds that lasted about 50 milliseconds, while the ones that received the extended pulses held their notes longer. Some song features—including pitch and how noisy harmonic syllables were in the song—didn’t seem to be affected by optogenetic manipulation. Another measure, entropy, which approximates the amount of information carried in the communication, was not distinguishable in the songs of normally tutored birds and those that received 50-millisecond optogenetic pulses, but was higher in the songs of birds who’d received tutoring than in the songs of either isolated birds or those that received the 300-millisecond light pulses.

While the manipulation of the circuit affected the duration of the sounds in the finches’ songs, other elements of singing behavior—including the timeline of vocal development, how frequently the birds practiced, and in what social contexts they eventually used the songs—were similar to juveniles who’d learned from an adult bird.

The researchers then determined that when the birds received light stimulation at the same time as they interacted with a singing tutor, their adult songs were more like those of birds that had only received light stimulation, indicating that optogenetic stimulation can supplant tutoring.

When the team lesioned the circuit before young birds met their tutors, they didn’t make attempts to imitate the adult courtship songs. But if the juveniles were given a chance to interact with a tutor before the circuit was damaged, they had no problem learning the song. This finding points to an essential role for the pathway in forming the initial memory of the timing of vocalizations, but not in storing it long-term so that it can be referenced to guide song formation.

“What we were able to implant was information about the duration of syllables that the birds want to attempt to learn how to sing,” Roberts tells The Scientist. But there are many more characteristics birds have to attend to when they’re learning a song, including pitch and how to put the syllables in the correct order, he says. The next steps are to identify the circuits that are carrying other types of information and to investigate the mechanisms for encoding these memories and where in the brain they’re stored.

Sarah London, a neuroscientist at the University of Chicago who did not participate in the study, agrees that the strategies used here could serve as a template to tease apart where other characteristics of learned song come from. But more generally, this work in songbirds connects to the bigger picture of our understanding of learning and memory, she says.

Song learning “is a complicated behavior that requires multiple brain areas coordinating their functions over long stretches of development. The brain is changing anyway, and then on top of that the behavior’s changing in the brain,” she explains. Studying the development of songs in zebra finches can give insight into “how maturing neural circuits are influenced by the environment,” both the brain’s internal environment and the external, social environment, she adds. “This is a really unique opportunity, not just for song, not just for language, but for learning in a little larger context—of kids trying to understand and adopt behavioral patterns appropriate to their time and place.”

W. Zhao et al., “Inception of memories that guide vocal learning in the songbird,” Science, doi:10.1126/science.aaw4226, 2019.

https://www.the-scientist.com/news-opinion/researchers-implant-memories-in-zebra-finch-brains-66527?utm_campaign=TS_DAILY%20NEWSLETTER_2019&utm_source=hs_email&utm_medium=email&utm_content=77670023&_hsenc=p2ANqtz-87EBXf6eeNZge06b_5Aa8n7uTBGdQV0pm3iz03sqCnkbGRyfd6O5EXFMKR1hB7lhth1KN_lMxkB_08Kb9sVBXDAMT7gQ&_hsmi=77670023

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In a pilot study of 14 older adults with mild cognitive problems suggestive of early Alzheimer’s disease, Johns Hopkins Medicine researchers report that a high-fat, low-carbohydrate diet may improve brain function and memory.

Although the researchers say that finding participants willing to undertake restrictive diets for the three-month study—or partners willing to help them stick to those diets—was challenging, those who adhered to a modified Atkins diet (very low carbohydrates and extra fat) had small but measurable improvements on standardized tests of memory compared with those on a low-fat diet.

The short-term results, published in the April issue of the Journal of Alzheimer’s Disease, are far from proof that the modified Atkins diet has the potential to stave off progression from mild cognitive impairment to Alzheimer’s disease or other dementias. However, they are promising enough, the researchers say, to warrant larger, longer-term studies of dietary impact on brain function.

“Our early findings suggest that perhaps we don’t need to cut carbs as strictly as we initially tried. We may eventually see the same beneficial effects by adding a ketone supplement that would make the diet easier to follow,” says Jason Brandt, Ph.D., professor of psychiatry and behavioral sciences and neurology at the Johns Hopkins University School of Medicine. “Most of all, if we can confirm these preliminary findings, using dietary changes to mitigate cognitive loss in early-stage dementia would be a real game-changer. It’s something that 400-plus experimental drugs haven’t been able to do in clinical trials.”

Brandt explains that, typically, the brain uses the sugar glucose—a product of carbohydrate breakdown—as a primary fuel. However, research has shown that in the early stage of Alzheimer’s disease the brain isn’t able to efficiently use glucose as an energy source. Some experts, he says, even refer to Alzheimer’s as “type 3 diabetes.”

Using brain scans that show energy use, researchers have also found that ketones—chemicals formed during the breakdown of dietary fat—can be used as an alternative energy source in the brains of healthy people and those with mild cognitive impairment. For example, when a person is on a ketogenic diet, consisting of lots of fat and very few sugars and starches, the brain and body use ketones as an energy source instead of carbs.

For the current study, the researchers wanted to see if people with mild cognitive impairment, often an indicator of developing Alzheimer’s disease, would benefit from a diet that forced the brain to use ketones instead of carbohydrates for fuel.

After 2 1/2 years of recruitment efforts, the researchers were able to enroll 27 people in the 12-week diet study. There were a few dropouts, and so far, 14 participants have completed the study. The participants were an average age of 71. Half were women, and all but one were white.

To enroll, each participant required a study partner (typically a spouse) who was responsible for ensuring that the participant followed one of two diets for the full 12 weeks. Nine participants followed a modified Atkins diet meant to restrict carbs to 20 grams per day or less, with no restriction on calories. The typical American consumes between 200 and 300 grams of carbs a day. The other five participants followed a National Institute of Aging diet, similar to the Mediterranean diet, that doesn’t restrict carbohydrates, but favors fruits, vegetables, low- or fat-free dairy, whole grains and lean proteins such as seafood or chicken.

The participants and their partners were also asked to keep food diaries. Prior to starting the diets, those assigned to the modified Atkins diet were consuming about 158 grams of carbs per day. By week six of the diet, they had cut back to an average of 38.5 grams of carbs per day and continued dropping at nine weeks, but still short of the 20-gram target, before rising to an average of 53 grams of carbs by week 12. Participants on the National Institute of Aging diet continued to eat well over 100 grams of carbs per day.

Each participant also gave urine samples at the start of the dietary regimens and every three weeks up to the end of the study, which were used to track ketone levels. More than half of the participants on the modified Atkins diet had at least some ketones in their urine by six weeks into the diet until the end; as expected, none of the participants on the National Institute of Aging control diet had any detectable ketones.

Participants completed the Montreal Cognitive Assessment, the Mini-Mental State Examination and the Clinical Dementia Rating Scale at the start of the study. They were tested with a brief collection of neuropsychological memory tests before starting their diets and at six weeks and 12 weeks on the diet. At the six-week mark, the researchers found a significant improvement on memory tests, which coincided with the highest levels of ketones and lowest carb intakes.

When comparing the results of tests of delayed recall—the ability to recollect something they were told or shown a few minutes earlier—those who stuck to the modified Atkins diet improved by a couple of points on average (about 15% of the total score), whereas those who didn’t follow the diet on average dropped a couple of points.

The researchers say the biggest hurdle for researchers was finding people willing to make drastic changes to their eating habits and partners willing to enforce the diets. The increase in carbohydrate intake later in the study period, they said, suggests that the diet becomes unpalatable over long periods.

“Many people would rather take a pill that causes them all kinds of nasty side effects than change their diet,” says Brandt. “Older people often say that eating the foods they love is one of the few pleasures they still enjoy in life, and they aren’t willing to give that up.”

But, because Brandt’s team observed promising results even in those lax with the diet, they believe that a milder version of the high-fat/low-carb diet, perhaps in conjunction with ketone supplement drinks, is worth further study. As this study also depended on caregivers/partners to do most of the work preparing and implementing the diet, the group also wants to see if participants with less severe mild cognitive impairment can make their own dietary choices and be more apt to stick to a ketogenic diet.

A standardized modified Atkins diet was created and tested at Johns Hopkins Medicine in 2002, initially to treat some seizure disorders. It’s still used very successfully for this purpose.

According to the Alzheimer’s Association, about 5.8 million Americans have Alzheimer’s disease, and by 2050 the number is projected to increase to 14 million people.

Jason Brandt et al. Preliminary Report on the Feasibility and Efficacy of the Modified Atkins Diet for Treatment of Mild Cognitive Impairment and Early Alzheimer’s Disease, Journal of Alzheimer’s Disease (2019). DOI: 10.3233/JAD-180995

https://medicalxpress.com/news/2019-06-low-carb-keto-diet-atkins-style-modestly.html

by PETER DOCKRILL

When bad things happen, we don’t want to remember. We try to block, resist, ignore – but we should perhaps be doing the opposite, researchers say.

A new study led by scientists in Texas suggests the act of intentionally forgetting is linked to increased cerebral engagement with the unwanted information in question. In other words, to forget something, you actually need to focus on it.

“A moderate level of brain activity is critical to this forgetting mechanism,” explains psychologist Tracy Wang from the University of Texas at Austin.

“Too strong, and it will strengthen the memory; too weak, and you won’t modify it.”

Trying to actively forget unwanted memories doesn’t just help prevent your brain from getting overloaded.

It also lets people move on from painful experiences and emotions they’d rather not recall, which is part of the reason it’s an area of active interest to neuroscientists.

“We may want to discard memories that trigger maladaptive responses, such as traumatic memories, so that we can respond to new experiences in more adaptive ways,” says one of the researchers, Jarrod Lewis-Peacock.

“Decades of research has shown that we have the ability to voluntarily forget something, but how our brains do that is still being questioned.”

Much prior research on intentional forgetting has focussed on brain activity in the prefrontal cortex, and the brain’s memory centre, the hippocampus.

In the new study, the researchers monitored a different part of the brain called the ventral temporal cortex, which helps us process and categorise visual stimuli.

In an experiment with 24 healthy young adults, the participants were shown pictures of scenes and people’s faces, and were instructed to either remember or forget each image.

During the experiment, each of the participants had their brain activity monitored by functional magnetic resonance imaging (fMRI) machines.

When the researchers examined activity in the ventral temporal cortex, they found that the act of forgetting effectively uses more brain power than remembering.

“Pictures followed by a forget instruction elicited higher levels of processing in [the] ventral temporal cortex compared to those followed by a remember instruction,” the authors write in their paper.

“This boost in processing led to more forgetting, particularly for items that showed moderate (vs. weak or strong) activation.”

Of course, forgetting specific images on demand in a contrived laboratory experiment is very different to moving on from painful or traumatic memories of events experienced in the real world.

But the mechanisms at work could be the same, researchers say, and figuring out how to activate them could be a huge benefit to people around the world who need to forget things, but don’t know how.

Especially since this finding in particular challenges our natural intuition to suppress things; instead, we should involve more rather than less attention to unwanted information, in order to forget it.

“Importantly, it’s the intention to forget that increases the activation of the memory,” Wang says.

“When this activation hits the ‘moderate level’ sweet spot, that’s when it leads to later forgetting of that experience.”

The findings are reported in JNeurosci.

https://www.sciencealert.com/to-forget-something-you-need-to-think-about-it-neuroscientists-reveal

what-is-your-first-memory-and-did-it-ever-really-happen-309444

By Dr. Lucy Justice

I can remember being a baby. I recall being in a vast room inside a doctor’s surgery. I was passed to a nurse and then placed in cold metal scales to be weighed. I was always aware that this memory was unusual because it was from so early in my life, but I thought that perhaps I just had a really good memory, or that perhaps other people could remember being so young, too.

What is the earliest event that you can remember? How old do you think you are in this memory? How do you experience the memory? Is it vivid or vague? Positive or negative? Are you re-experiencing the memory as it originally happened, through your own eyes, or are you watching yourself “acting” in the memory?

In our recent study, we asked more than 6,000 people of all ages to do the same, to tell us what their first autobiographical memory was, how old they were when the event happened, to rate how emotional and vivid it was and to report what perspective the memory was “seen” from. We found that on average people reported their first memory occurring during the first half of the third year of their lives (3.24 years to be precise). This matches well with other studies that have investigated the age of early memories.

What does this mean for my memory of being a baby then? Perhaps I do just have a really good memory and can remember those early months of life. Indeed, in our study, we found that around 40% of participants reported remembering events from the age of two or below – and 14% of people recalled memories from age one and below. However, psychological research suggests that memories occurring below the age of three are highly unusual – and indeed, highly improbable.

The origin of memory

Researchers who have investigated memory development suggest that the neurological processes needed to form autobiographical memories are not fully developed until between the ages of three and four years. Other research has suggested that memories are linked to language development. Language allows children to share and discuss the past with others, enabling memories to be organised in a personal autobiography.

So how can I remember being a baby? And why did 2,487 people from our study remember events that they dated from the age of two years and younger?

One explanation is that people simply gave incorrect estimates of their age in the memory. After all, unless confirmatory evidence is present, guesswork is all we have when it comes to dating memories from across our lives, including the very earliest.

But if incorrect dating explained the presence of these memories, we would expect that they would be about similar events to those memories from ages three and above. But this was not the case – we found that very early reported memories were of events and objects from infancy (pram, cot, learning to walk) whereas older memories were of things typical of childhood (toys, school, holidays). This finding meant that these two groups of memories were qualitatively different and ruled out the misdating explanation.

If research tells us that these very early memories are highly unlikely, and we have ruled out a misdating explanation, then why do people, including me, have them?

Pure fiction?

We concluded that these memories are likely to be fictional – that is, that they never in fact occurred. Perhaps, rather than recalling an experienced event, we recall imagery derived from photographs, home movies, shared family stories or events and activities that frequently happen in infancy. These facts are then, we suggest, linked with some fragmentary visual imagery and are combined together to form the basis of these fictitious early memories. Over time, this combination of imagery and fact begins to be experienced as a memory.

Although 40% of participants in our study retrieved these fictitious memories, they are not altogether surprising. Contemporary theories of memory highlight the constructive nature of memory; memories are not “records” of events, but rather psychological representations of the self in the past.

In other words, all of our memories contain some degree of fiction – indeed, this is the sign of a healthy memory system in action. But perhaps, for reasons not yet known, we have a psychological need to fictionalise memories from times of our lives that we are unable to remember. For now, these “stories” remain a mystery.

https://theconversation.com/what-is-your-first-memory-and-did-it-ever-really-happen-95953

We may go to sleep at night, but our brains don’t. Instead, they spend those quiet hours tidying up, and one of their chores is to lug memories into long-term storage boxes.

Now, a group of scientists may have found a way to give that memory-storing process a boost, by delivering precisely timed electric zaps to the brain at the exact right moments of sleep. These zaps, the researchers found, can improve memory.

And to make matters even more interesting, the team of researchers was funded by the Defense Advanced Research Projects Agency (DARPA), the U.S. agency tasked with developing technology for the military. They reported their findings July 23 in The Journal of Neuroscience.

DARPA Wants to Zap Your Brain to Boost Your Memory
Credit: Shutterstock
We may go to sleep at night, but our brains don’t. Instead, they spend those quiet hours tidying up, and one of their chores is to lug memories into long-term storage boxes.

Now, a group of scientists may have found a way to give that memory-storing process a boost, by delivering precisely timed electric zaps to the brain at the exact right moments of sleep. These zaps, the researchers found, can improve memory.

And to make matters even more interesting, the team of researchers was funded by the Defense Advanced Research Projects Agency (DARPA), the U.S. agency tasked with developing technology for the military. They reported their findings July 23 in The Journal of Neuroscience.

If the findings are confirmed with additional research, the brain zaps could one day be used to help students study for a big exam, assist people at work or even treat patients with memory impairments, including those who experienced a traumatic brain injury in the military, said senior study author Praveen Pilly, a senior scientist at HRL Laboratories, a research facility focused on advancing technology.

The study involved 16 healthy adults from the Albuquerque, New Mexico, area. The first night, no experiments were run; instead, it was simply an opportunity for the participants to get accustomed to spending the night in the sleep lab while wearing the lumpy stimulation cap designed to deliver the tiny zaps to their brains. Indeed, when the researchers started the experiment, “our biggest worry [was] whether our subjects [could] sleep with all those wires,” Pilly told Live Science.

The next night, the experiment began: Before the participants fell asleep, they were shown war-like scenes and were asked to spot the location of certain targets, such as hidden bombs or snipers.

Then, the participants went to sleep, wearing the stimulation cap that not only delivered zaps but also measured brain activity using a device called an electroencephalogram (EEG). On the first night of the experiment, half of the participants received brain zaps, and half did not.

Using measurements from the EEG, the researchers aimed their electric zaps at a specific type of brain activity called “slow-wave oscillations.” These oscillations — which can be thought of as bursts of neuron activity that come and go with regularity — are known to be important for memory consolidation. They take place during two sleep stages: stage 2 (still a “light” sleep, when the heart rate slows down and body temperature drops) and stage 3 (deep sleep).

So, shortly after the participants in the zapping group fell into slow-wave oscillations, the stimulation cap would deliver slight zaps to the brain, in tune with the oscillations. The next morning, all of the participants were shown similar war-zone scenes, and the researchers measured how well they detected targets.

Five days later, the groups were switched for the second night of experiments.

The researchers found that, the mornings after, the participants who received the brain zaps weren’t any better at detecting targets in the same scene they saw the night before, compared with those who slept without zaps. But those who received the zapping were much better at detecting the same targets in novel scenes. For example, if the original scene showed a target under a rock, the “novel” scene might show the same target-rock image, but from a different angle, according to a press release from HRL Laboratories.

Researchers call this “generalization.” Pilly explained it as follows: “If you’re [studying] for a test, you learn a fact, and then, when you’re tested the following morning on the same fact … our intervention may not help you. On the other hand, if you’re tested on some questions related to that fact [but] which require you to generalize or integrate previous information,” the intervention would help you perform better.

This is because people rarely recall events exactly as they happen, Pilly said, referring to what’s known as episodic memory. Rather, people generalize what they learn and access that knowledge when faced with various situations. (For example, we know to stay away from a snake in the city, even if the first time we saw it, it was in the countryside.)

Previous studies have also investigated the effects of brain stimulation on memory. But although they delivered the zaps during the same sleep stage as the new study, the researchers in the previous studies didn’t attempt to match the zaps with the natural oscillations of the brain, Pilly said.

Jan Born, a professor of behavioral neuroscience at the University of Tübingen in Germany who was not part of the study, said the new research showed that, “at least in terms of behavior, [such a] procedure is effective.”

The approaches examined in the study have “huge potential, but we are still in the beginning [of this type of research], so we have to be cautious,” Born told Live Science.

One potential problem is that the stimulation typically hits the whole surface of the brain, Born said. Because the brain is wrinkled, and some neurons hide deep in the folds and others sit atop ridges, the stimulations aren’t very effective at targeting all of the neurons necessary, he said. This may make it difficult to reproduce the results every time, he added.

Pilly said that because the zaps aren’t specialized, they could also, in theory, lead to side effects. But he thinks, if anything, the side effect might simply be better-quality sleep.

https://www.livescience.com/63329-darpa-brain-zapping-memory.html

By Timothy Roberts

Being able to recall memories, whether short-term or long-term is something that we all need in life. It comes in handy when we are studying at school or when we are trying to remember where we left our keys. We also tend to use our memory at work and remembering somebody’s name is certainly a good thing.

Although many of us may consider ourselves to have a good memory, we are all going to forget things from time to time. When it happens, we might feel as if we are slipping but there may be more behind it than you realize.

Imagine this scenario; you go to the grocery store to pick up 3 items and suddenly, you forget why you were there. Even worse, you may walk from one room to another and forget why you got up in the first place!

If you often struggle with these types of problems, you will be happy to learn that there is probably nothing wrong with you. In fact, a study that was done by the Neuron Journal and it has some rather good news. It says that forgetting is part of the brain process that might actually make you smarter by the time the day is over.

Professors took part in a study at the University of Toronto and they discovered that the perfect memory actually doesn’t necessarily reflect your level of intelligence.

You might even be surprised to learn that when you forget details on occasion, it can make you smarter.

Most people would go by the general thought that remembering more means that you are smarter.

According to the study, however, when you forget a detail on occasion, it’s perfectly normal. It has to do with remembering the big picture compared to remembering little details. Remembering the big picture is better for the brain and for our safety.

Our brains are perhaps more of a computer than many of us think. The hippocampus, which is the part of the brain where memories are stored, tends to filter out the unnecessary details.

In other words, it helps us to “optimize intelligent decision making by holding onto what’s important and letting go of what’s not.”

Think about it this way; is it easier to remember somebody’s face or their name? Which is the most important?

In a social setting, it is typically better to remember both but if we were part of the animal kingdom, remembering somebody as being a threat would mean our very lives. Remembering their name would be inconsequential.

The brain doesn’t automatically decide what we should remember and what we shouldn’t. It holds new memories but it sometimes overwrites old memories.

When the brain becomes cluttered with memories, they tend to conflict with each other and that can make it difficult to make important decisions.

That is why the brain tends to hold on to those big picture memories but they are becoming less important with the advent of technology.

As an example, at one time, we would have learned how to spell words but now, we just use Google if we don’t know how to spell them. We also tend to look everything up online, from how to change a showerhead to how to cook meatloaf for dinner.

If you forget everything, you may want to consider having a checkup but if you forget things on occasion, it’s perfectly okay.

The moral of the story is, the next time you forget something, just think of it as your brain doing what it was designed to do.

http://wetpaintlife.com/scientists-say-that-being-forgetful-is-actually-a-sign-you-are-unusually-intelligent/?utm_source=vn&utm_tracking=11&utm_medium=Social

The majority of the cells in the brain are no neurons, but Glia (from “glue”) cells, that support the structure and function of the brain. Astrocytes (“start cells”) are star-shaped glial cells providing many supportive functions for the neurons surrounding them, such as the provision of nutrients and the regulation of their chemical environment. Newer studies showed that astrocytes also monitor and modulate neuronal activity. For example, these studies have shown that astrocytes are necessary for the ability of neurons to change the strength of the connections between them, the process underlying learning and memory, and indeed astrocytes are also necessary for normal cognitive function. However, it is still unknown whether astrocytic activity is only necessary, or is it may also be sufficient to induce synaptic potentiation and enhance cognitive performance.

In a new study published in Cell, two graduate students, Adar Adamsky and Adi Kol, from Inbal Goshen’s lab, employed chemogenetic and optogenetic tools that allow specific activation of astrocytes in behaving mice, to explore their role in synaptic activity and memory performance. They found that astrocytic activation in the hippocampus, a brain region that plays an important role in memory acquisition and consolidation, potentiated the synaptic connections in this region, measured in brain slices. Moreover, in the intact brain, astrocytic activation enhanced hippocampal neuronal activity in a task-dependent way: i.e. only during when it was combined with memory acquisition, but not when mice were at their home cage with no meaningful stimuli. The ability of astrocytes to increase neuronal activity during memory acquisition had a significant effect on cognitive function: Specifically, astrocytic activation during learning resulted in enhanced memory in two memory tests. In contrast, direct neuronal activation in the hippocampus induced a non-selective increase in activity (during learning or in the home cage), and thus resulted in drastic memory impairment.

The results suggest that the memory enhancement induced by astrocytic activation during learning is not simply a result of a general increase in hippocampal neuronal activity. Rather, the astrocytes, which sense and respond to changes in the surrounding neuronal activity, can detect and specifically enhance only the neuronal activity involved in learning, without affecting the general activity. This may explain why general astrocytic activation improves memory performance, whereas a similar activation of neurons impairs it.

Memory is not a binary process (remember/don’t remember); the strength of a memory can vary greatly, either for the same memory or between different memories. Here, we show that activating astrocytes in mice with intact cognition improves their memory performance. This finding has important clinical implications for cognitive augmentation treatments. Furthermore, the ability of astrocytes to strengthen neuronal communication and improve memory performance supports the claim that astrocytes are able to take an active part in the neuronal processes underlying cognitive function. This perspective expands the definition of the role of astrocytes, from passive support cells to active cells that can modulate neural activity and thus shape behavior.

Link: https://www.cell.com/cell/pdf/S0092-8674(18)30575-0.pdf

https://elsc.huji.ac.il/content/article-month-june-2018-goshens-lab