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Brain hemispheres swap memories to help you see the big picture
Scientists observe how the halves of the brain keep us informed about everything everywhere.
Imagine you're about to cross a busy street. You look right and see a car coming towards you two short blocks away. You look the other way, and no cars are coming. Should you cross? No. Why not? Because your brain retains the memory of that approaching car even when you look the other way.
The ability to remember things we're not currently looking at allows us to construct and maintain a cohesive picture in our working memory of the physical context in which we find ourselves.
"You need to know where things are in the real world, regardless of where you happen to be looking or how you are oriented at a given moment," says Scott Brincat, senior author of a new study from researchers at The Picower Institute for Learning and Memory at MIT in Cambridge, Massachusetts. "But the representation that your brain gets from the outside world changes every time you move your eyes around."
The study, published in Neuron, describes what a fancy bit of brainwork this is.
Two sides of the big picture
Credit: Jake Schumacher/Unsplash
In our working memories, the left and right hemispheres work independently when it comes to memory storage — what we see on our left is immediately stored in the right hemisphere and vice versa.
The Picower researchers have found, however, that things get substantially more interesting when we shift our gaze in the opposite direction, or if an object we're looking at moves from one side to the other.
Using our street-crossing example, when you look to the right and spot the approaching vehicle, a memory of the car is stored in our brain's left hemisphere. When you look left, a copy of that memory is quickly sent to the right hemisphere, but the copy is somehow marked in such a way that the brain understands it's not actually located on your left but is just a memory of something that's currently out of view on your right. The net result is that your working memory remains aware of traffic on both sides even when it's just looking in one direction.
"If you didn't have that," says Earl Miller, senior author of the study and in whose lab the research was conducted, "we would just be simple creatures who could only react to whatever is coming right at us in the environment, that's all. But because we can hold things in mind, we can have volitional control over what we do. We don't have to react to something now, we can save it for later."
Games animals play
Credit: Eric Isselée/Adobe Stock
For the study's experiments, monkeys were taught to identify onscreen objects that didn't match something they had viewed moments earlier, such as an image of a banana. To do this, they had to hold a memory of the original object in memory to make the comparison.
As this happened, researchers monitored the electrical activity of hundreds of neurons in the prefrontal cortices of both hemispheres. The researchers observed memory transfers as they happened thanks to characteristic patterns in the synchronization of brainwave frequencies that occurred each time a memory was stored, an action that takes mere milliseconds. A software decoder identified the telltale patterns.
The trials began with the monkeys staring at one side of the screen as an object appeared in the screen's center. As the monkeys perceived the object as belonging primarily to one side or the other, the researchers saw the original memory being stored in the corresponding hemisphere and a copy being made in the other.
Monkeys were also instructed at times to look from one side to the other, reassigning the central object to a new primary side as the researchers observed the memories being re-written. The speed with which monkeys could spot non-matching objects slowed down during these shifts, giving some hint of the complicated memory gymnastics going on. "It feels trivial to us, but it apparently isn't," says Miller.
An ensemble surprise and mystery
The memory is transferred from a group, or ensemble, of neurons in one hemisphere to another ensemble on the other side. One of the surprises in the study is that even though the original memory and its copy describe the same object in the same location, they use completely different neuron ensembles on each side to represent it.
Miller notes that it used to be believed that individual neurons stored memories but that over time it became clear that groups, or ensembles, of neurons were the actual memory receptacles. Now however, if the same memory is stored in two different types of ensembles due to a difference in their role within a particular hemisphere, maybe things are even more complex than that. "Perhaps even ensembles aren't the functional units of the brain," he surmises. "So what is the functional unit of the brain? It's the computational space that brain network activity creates."
- Adult language-learning changes how the brain's hemispheres ... ›
- Right-Brain/Left-Brain is a Myth, Creativity Exists in Both Hemispheres ›
A new study finds that dogs fed fresh human-grade food don't need to eat—or do their business—as much.
- Most dogs eat a diet that's primarily kibble.
- When fed a fresh-food diet, however, they don't need to consume as much.
- Dogs on fresh-food diets have healthier gut biomes.
Four diets were tested<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NjY0NjIxMn0._w0k-qFOC86AqmtPHJBK_i-9F5oVyVYsYtUrdvfUxWQ/img.jpg?width=980" id="1b1e4" class="rm-shortcode" data-rm-shortcode-id="87937436a81c700a8ab3b1d763354843" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: AntonioDiaz/Adobe Stock<p>The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The <a href="https://frontierpets.com.au/blogs/news/how-kibble-or-dry-dog-food-is-made" target="_blank">ingredients</a> of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a <a href="https://en.wikipedia.org/wiki/Food_extrusion" target="_blank">pasta maker</a>. The resulting pellets are sprayed with additional flavor and color.</p><p>For four weeks, researchers fed 12 beagles one of four diets:</p><ol><li>a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe</li><li>a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe</li><li>a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe</li><li>another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.</li></ol><p>The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts. </p><p>(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)</p><p>Senior author <a href="https://ansc.illinois.edu/directory/ksswanso" target="_blank" rel="noopener noreferrer">Kelly S. Swanson</a> of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he <a href="https://aces.illinois.edu/news/feed-fido-fresh-human-grade-dog-food-scoop-less-poop" target="_blank">says</a>, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."</p>
Tracking the effect of each diet<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NjY1NTgyOX0.AdyMb8OEcjCD6iWYnXjToDmcnjfTSn-0-dfG96SIpUA/img.jpg?width=980" id="da892" class="rm-shortcode" data-rm-shortcode-id="880d952420679aeccd1eaf32b5339810" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: Patryk Kosmider/Adobe Stock<p>The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.</p><p>It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.</p><p>Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."</p><p>Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.</p><p>"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in <a href="https://academic.oup.com/jas/article/92/9/3781/4702209#110855647" target="_blank">previous studies</a>, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."</p>
How did kibble take over canine diets?<p>Historically, dogs ate scraps left over by humans. It has only been <a href="https://www.thefarmersdog.com/digest/the-history-of-commercial-pet-food-a-great-american-marketing-story/" target="_blank">since 1870</a>, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn <a href="https://www.dogfoodadvisor.com/choosing-dog-food/animal-by-products/" target="_blank">human-food waste</a> into profit.</p><p>Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are <a href="https://www.nytimes.com/2014/08/03/magazine/who-made-that-dog-biscuit.html" target="_blank">overweight or obese</a>, and certainly their diet is a factor.<span></span></p><p>We're not so special among animals after all. If something's healthy for us to eat—we're <em>not</em> looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.</p>
New study suggests the placebo effect can be as powerful as microdosing LSD.
- New research from Imperial College London investigated the psychological effects of microdosing LSD in 191 volunteers.
- While microdosers experienced beneficial mental health effects, the placebo group performed statistically similar to those who took LSD.
- Researchers believe the expectation of a trip could produce some of the same sensations as actually ingesting psychedelics.
Psychedelics: The scientific renaissance of mind-altering drugs<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="92360c805fe66c11de38a75b0967f417"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/5T0LmbWROKY?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>For the study published in eLife, the team recruited 191 citizen cosmonauts to microdose either LSD or a placebo over the course of several weeks and note the psychological effects. Volunteers were already microdosing LSD, so there was no true control. Each volunteer was given instructions on creating their own low-dose gel capsules, some containing LSD, others not. Then they mixed the capsules in envelopes so they didn't know if they were taking the real thing or not.</p><p>The trial design was ingenious: each capsule featured a QR code that was scanned after the addition of ingredients but before they were placed in the envelope so that researchers knew what they were ingesting.</p><p>The problem: volunteers sourced their own LSD. Lack of quality control could have had a profound effect on the results. </p><p>The results: LSD microdosers reported feeling more mindful, satisfied with life, and better overall; they also noticed a reduction in feelings of paranoia. </p><p>The catch: the control group felt the same thing, with no statistical difference between the groups. </p><p>Lead author Balázs Szigeti comments on the findings: "This suggests that the improvements may not be due to the pharmacological action of the drug but can instead be explained by the placebo effect." </p>
Credit: Alexander / Adobe Stock<p>Psychedelics are notoriously difficult to control for given the intensity of the experience. Yet there is precedent for the above findings. A <a href="https://link.springer.com/article/10.1007/s00213-020-05464-5" target="_blank">2019 study</a> found that 61 percent of volunteers that took a placebo instead of psilocybin felt some psychedelic effects, with a few volunteers experiencing full-on trips.</p><p style="margin-left: 20px;">"Several stated that they saw the paintings on the walls 'move' or 'reshape' themselves, others felt 'heavy. . . as if gravity [had] a stronger hold', and one had a 'come down' before another 'wave' hit her."</p><p>The Imperial team believes the expectation of a trip might have been enough to produce similar results. Senior author David Erritzoe is excited for future studies on the topic, believing they tapped into a new wave of citizen science that could push forward our knowledge of psychedelic substances.</p><p style="margin-left: 20px;">"Accounting for the placebo effect is important when assessing trends such as the use of cannabidiol oils, fad diets or supplements where social pressure or users' expectations can lead to a strong placebo response. Self-blinding citizen science initiatives could be used as an inexpensive, initial screening tool before launching expensive clinical studies."</p><p>As investments into the psychedelics market explode, with one company <a href="https://www.bloomberg.com/news/articles/2021-03-03/thiel-backed-magic-mushroom-firm-atai-hits-2-billion-valuation" target="_blank">reaching a $2 billion valuation</a>, a recurring irony appears in the long arc of psychedelics and research: the power of our minds might be enough to feel greater life satisfaction and a deeper sense of mindfulness. If that's possible with a placebo, we have to question why the rush to create more pharmacology is necessary. </p><p>This is, mind you, a separate conversation over the role of psychedelics and rituals for group bonding. The function of group cohesion around consciousness-altering substances will continue to play an important role in many communities. </p><p>Of course, we should continue to explore the efficacy of psychedelics on anxiety, depression, suicidal ideation, PTSD, and addiction. <a href="https://bigthink.com/surprising-science/antidepressant-effects" target="_self">Pharmacological dependence</a> is a stain on the psychiatry industry. Whether or not psychedelics can be prescribed for daily use remains to be seen, but we know a moneyed interest is expecting a return on investment—the above company, ATAI Life Sciences, raised $157 million in its Series D round. </p><p>When it comes to wellbeing, some things money just can't buy. How we navigate the tricky terrain of mainstreaming psychedelics remains to be seen. </p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a> and <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank" rel="noopener noreferrer">Facebook</a>. His most recent book is</em> "<em><a href="https://www.amazon.com/gp/product/B08KRVMP2M?pf_rd_r=MDJW43337675SZ0X00FH&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee" target="_blank" rel="noopener noreferrer">Hero's Dose: The Case For Psychedelics in Ritual and Therapy</a>."</em></p>
What makes some people more likely to shiver than others?
Some people just aren't bothered by the cold, no matter how low the temperature dips. And the reason for this may be in a person's genes.