Observing stroke recovery in mice may provide guide for humans
- Scientists have observed genes responsible for helping mice recover from strokes.
- This could provide guidance for humans.
- Drugs could be developed to target these specific genes.
Scientists at Stanford Medicine recently observed that some mice recovered from strokes better than others, leading them to wonder whether or not they could find evidence that specific genes played a role in recovery. They did.
The results of the study — which can be read here — describes thirty-three male mice with strokes and seven mice without strokes being charged with balancing on a "horizontal rotating beam" — running out across and back. After the stroke, the mice couldn't do this. Two weeks after the stroke, 25% of the mice were able to recover well enough to run across the length of the beam and back.
Previous research into stroke recovery in mice has noted that sensory deprivation has pushed its brain in a more healthy direction if its whiskers were trimmed; blocking an immune response aids stroke recovery; Ambien can aid in recovery; there's research that talks about a rich, playful environment aiding in a mouse's recovery, which is featured in the video below; and even a grape-rich diet can help improve stroke recovery in mice.
Why look at genetic recovery in mice? "Understanding the genes regulated post-stroke could help us design novel ways to treat patients in the days and weeks after the initial event," Michelle Y. Cheng is quoted as saying.
What was found? "Distinct biological pathways" in the portion of the motor cortex opposite the lesion wrought by the stroke as well as pathways on the same side of lesion-affected cortex. There were 38 genes on the side of the brain impacted by the lesion associated with recovery and 74 genes opposite the lesion that were associated with recovery.
A majority of these genes are involved with something called cAMP signaling. cAMP signaling detects molecules outside already existing cells and has a role in determining a response.
'cAMP signalling' activates a protein called a protein kinase that modifies other proteins in the body that send signals off somewhere else. Broadly speaking, cAMP signalling also has a role in memory, water absorbed in the kidney, whether or not the heart is relaxed, breaking down fats, and more.
The particular genes involved in cAMP signalling that played a role in stroke recovery for the mice are called adenosine receptor A2A, dopamine receptor D2, and phosphodiesterase 10A. Receptors are protein molecules embedded in cell membranes that respond to external stimuli to transmit information somewhere else. The A2A is often a target of caffeine. It is a protein that is abundant in platelets, lymphocytes, and more. The D2 receptor is typically the target of most antipsychotic drugs. Current research suggests that there might be a link between phosphodiesterase 10A and obesity.
In the case of post-stroke recovery, however, the study notes that activating A2A "signaling within a few hours poststroke can reduce inflammatory cell infiltration after stroke"; that "activation of Drd2 on astrocytes in acute stroke can reduce neuroinflammation"; and that "inhibition of Pde10a may be a promising therapeutic strategy for psychiatric and neurodegenerative diseases."
There are complications — blocking A2A signaling can help against a lesion-induced toxicity; and not only does Drd2 inhibit cAMP communicating with the rest of the body, but "the role of Drd2 in brain repair is also unclear."
Nevertheless, this is research that makes the figurative target of our interest a little clearer and a little sharper, illustrating where medicine can take aim next.
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The idea of 'absolute time' is an illusion. Physics and subjective experience reveal why.
- Since Einstein posited his theory of general relativity, we've understood that gravity has the power to warp space and time.
- This "time dilation" effect occurs even at small levels.
- Outside of physics, we experience distortions in how we perceive time — sometimes to a startling extent.
Physics without time<p>In his book "The Order of Time," Italian theoretical physicist Carlo Rovelli suggests that our perception of time — our sense that time is forever flowing forward — could be a highly subjective projection. After all, when you look at reality on the smallest scale (using equations of quantum gravity, at least), time vanishes.</p><p style="margin-left: 20px;">"If I observe the microscopic state of things," writes Rovelli, "then the difference between past and future vanishes … in the elementary grammar of things, there is no distinction between 'cause' and 'effect.'"</p><p>So, why do we perceive time as flowing <em>forward</em>? Rovelli notes that, although time disappears on extremely small scales, we still obviously perceive events occur sequentially in reality. In other words, we observe entropy: Order changing into disorder; an egg cracking and getting scrambled.</p><p>Rovelli says key aspects of time are described by the second law of thermodynamics, which states that heat always passes from hot to cold. This is a one-way street. For example, an ice cube melts into a hot cup of tea, never the reverse. Rovelli suggests a similar phenomenon might explain why we're only able to perceive the past and not the future.</p><p style="margin-left: 20px;">"Any time the future is definitely distinguishable from the past, there is something like heat involved," Rovelli wrote for the <a href="https://www.ft.com/content/ce6ef7b8-429a-11e8-93cf-67ac3a6482fd" target="_blank"><em>Financial Times</em></a>. "Thermodynamics traces the direction of time to something called the 'low entropy of the past', a still mysterious phenomenon on which discussions rage."</p>
The strange subjectivity of time<p>Time moves differently atop a mountain than it does on a beach. But you don't need to travel any distance at all to experience strange distortions in your perception of time. In moments of life-or-death fear, for example, your brain would release large amounts of adrenaline, which would speed up your internal clock, causing you to perceive the outside world as moving slowly.<br></p><p>Another common distortion occurs when we focus our attention in particular ways.</p><p style="margin-left: 20px;">"If you're thinking about how time is <em>currently</em> passing by, the biggest factor influencing your time perception is attention," Aaron Sackett, associate professor of marketing at the University of St. Thomas, told <em><a href="https://gizmodo.com/why-does-time-slow-down-and-speed-up-1840133782" target="_blank">Gizmodo</a></em>.<em> "</em>The more attention you give to the passage of time, the slower it tends to go. As you become distracted from time's passing—perhaps by something interesting happening nearby, or a good daydreaming session—you're more likely to lose track of time, giving you the feeling that it's slipping by more quickly than before. "Time flies when you're having fun," they say, but really, it's more like "time flies when you're thinking about other things." That's why time will also often fly by when you're definitely <em>not</em> having fun—like when you're having a heated argument or are terrified about an upcoming presentation."</p><p>One of the most mysterious ways people experience time-perception distortions is through psychedelic drugs. In an interview with <a href="https://www.theguardian.com/books/2018/apr/14/carlo-rovelli-exploding-commonsense-notions-order-of-time-interview" target="_blank"><em>The Guardian</em></a>, Rovelli described a time he experimented with LSD.</p><p style="margin-left: 20px;">"It was an extraordinarily strong experience that touched me also intellectually," he said. "Among the strange phenomena was the sense of time stopping. Things were happening in my mind but the clock was not going ahead; the flow of time was not passing any more. It was a total subversion of the structure of reality."<br></p><p>It seems few scientists or philosophers believe time is completely an illusion.</p><p style="margin-left: 20px;">"What we call <em>time</em> is a rich, stratified concept; it has many layers," Rovelli told <em><a href="https://physicstoday.scitation.org/do/10.1063/PT.6.4.20190219a/full/" target="_blank">Physics Today</a>.</em> "Some of time's layers apply only at limited scales within limited domains. This does not make them illusions."</p>What <em>is</em> an illusion is the idea that time flows at an absolute rate. The river of time might be flowing forever forward, but it moves at different speeds, between people, and even within your own mind.
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Controversial physics theory says reality around us behaves like a computer neural network.
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Vanchurin interview:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="539759cbfd8fcd5b6ebf14a3b597b3f9"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/bmyRy2-UhEE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Vanchurin on “Hidden Phenomena”:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="18886ffd5e5840bb19d4494212f88d82"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/2NDVdNwsHCo?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>Vitaly Vanchurin speaking at the 6th International FQXi Conference, "Mind Matters: Intelligence and Agency in the Physical World." The Foundational Questions...
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