Why Does Exercise Improve Brain Health as You Age? Scientists Just Unlocked a Major Key To Finding Out

It’s a well-known fact that exercise and mental health are intertwined. When you get sweaty, you’re boosting your mood, increasing your self-esteem, and improving your memory and focus. Now, there’s a new reason to sweat: Research hailing from the Memory and Aging Center at the University of California, San Francisco, indicates that movement may also play a major role in guarding our brains against dementia as we age.

This article is a repost which originally appeared on Well + Good

Kells McPhillips - January 17, 2022
Edited for content and readability - Images sourced from Pexels
Source: https://doi.org/10.1002/alz.12530

Our Takeaways:

  • A healthy brain is one that transmits electrical signals effortlessly through the synapses in our brains.
  • The study examined the level of physical activity that the participants had before they passed away.
  • The more someone exercises, the more protective proteins develop in their brain—regardless of whether or not the person breaking a sweat already has markers for Alzheimer’s or dementia.

Published in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association, the study confirmed that exercise has a protective effect on the human brain—especially in later age. Scientists have long observed this benefit of exercise in mice test subjects before, but discovering the same relationship between movement and cognitive longevity in the human brain constitutes a major scientific milestone. The minds at UC-San Francisco uncovered this exercise-brain connection by studying people who donated their brains to scientific research as part of the Memory and Aging Project at Rush University in Chicago. The brains studied belonged to people who were between 70 and 80 years old at the time of their deaths.

Here’s how they figured it out. A healthy brain is one that transmits electrical signals effortlessly through the synapses in our brains. You can think of synapses as little doorways between neurons that let the signals squeeze through, and proteins are essential for the maintenance of these little doorways. “There are many proteins present at the synapse that help facilitate different aspects of the cell-to-cell communication. Those proteins need to be in balance with one another in order for the synapse to function optimally,” writes study author Kaitlin Casaletto, PhD.

As part of their research, Dr. Casaletto’s team looked at the level of physical activity that the study participants had before they passed away—and found that those who exercised more tended to have more of those protective proteins in their brains. “We found that higher levels of everyday physical activity in older adults relate to higher levels of these synaptic proteins in brain tissue at autopsy,” Dr. Casaletto tells Well+Good. “These are correlative so we do not know directionality, but it suggests that physical activity may promote maintenance of these protein levels even into the oldest ages.”

“These findings begin to support the dynamic nature of the brain in response to our activities, and the capacity of the elderly brain to mount healthy responses to activity—again, even into the oldest ages.” — Kaitlin Casaletto, PhD

In short, this means that the more someone exercises, the more protective proteins develop in their brain—regardless of whether or not the person breaking a sweat already has markers for Alzheimer’s or dementia. “These findings begin to support the dynamic nature of the brain in response to our activities, and the capacity of the elderly brain to mount healthy responses to activity—again, even into the oldest ages. We also found fairly linear relationships—meaning the more physical activity, the higher the synaptic protein levels in brain tissue,” says Dr. Casaletto, adding that she recommends aiming for about 150 minutes a week of physical activity.

So next time you’re working out, make sure to dedicate a mile, burpee, or crunch to those little proteins in your brain. They’re doing a whole lot for you.

Surprising New Information on How Salt Affects Blood Flow in the Brain

A first-of-its-kind study led by researchers at Georgia State reveals surprising new information about the relationship between neuron activity and blood flow deep in the brain, as well as how the brain is affected by salt consumption.

This article is a repost which originally appeared on SciTechDaily
GEORGIA STATE UNIVERSITY - NOVEMBER 21, 2021
Edited for content and readability - Images sourced from Pexels 
Study: DOI: 10.1016/j.celrep.2021.109925

When neurons are activated, it typically produces a rapid increase of blood flow to the area. This relationship is known as neurovascular coupling, or functional hyperemia, and it occurs via dilation of blood vessels in the brain called arterioles. Functional magnetic resource imaging (fMRI) is based on the concept of neurovascular coupling: experts look for areas of weak blood flow to diagnose brain disorders.

However, previous studies of neurovascular coupling have been limited to superficial areas of the brain (such as the cerebral cortex) and scientists have mostly examined how blood flow changes in response to sensory stimuli coming from the environment (such as visual or auditory stimuli). Little is known about whether the same principles apply to deeper brain regions attuned to stimuli produced by the body itself, known as interoceptive signals.

To study this relationship in deep brain regions, an interdisciplinary team of scientists led by Dr. Javier Stern, professor of neuroscience at Georgia State and director of the university’s Center for Neuroinflammation and Cardiometabolic Diseases, developed a novel approach that combines surgical techniques and state-of-the-art neuroimaging. The team focused on the hypothalamus, a deep brain region involved in critical body functions including drinking, eating, body temperature regulation and reproduction. The study, published in the journal Cell Reports, examined how blood flow to the hypothalamus changed in response to salt intake.

“We chose salt because the body needs to control sodium levels very precisely. We even have specific cells that detect how much salt is in your blood,” said Stern. “When you ingest salty food, the brain senses it and activates a series of compensatory mechanisms to bring sodium levels back down.”

The body does this in part by activating neurons that trigger the release of vasopressin, an antidiuretic hormone that plays a key role in maintaining the proper concentration of salt. In contrast to previous studies that have observed a positive link between neuron activity and increased blood flow, the researchers found a decrease in blood flow as the neurons became activated in the hypothalamus.

“The findings took us by surprise because we saw vasoconstriction, which is the opposite of what most people described in the cortex in response to a sensory stimulus,” said Stern. “Reduced blood flow is normally observed in the cortex in the case of diseases like Alzheimer’s or after a stroke or ischemia.”

The team dubbed the phenomenon “inverse neurovascular coupling,” or a decrease in blood flow that produces hypoxia. They also observed other differences: In the cortex, vascular responses to stimuli are very localized and the dilation occurs rapidly. In the hypothalamus, the response was diffuse and took place slowly, over a long period of time.

“When we eat a lot of salt, our sodium levels stay elevated for a long time,” said Stern. “We believe the hypoxia is a mechanism that strengthens the neurons’ ability to respond to the sustained salt stimulation, allowing them to remain active for a prolonged period.”

The findings raise interesting questions about how hypertension may affect the brain. Between 50 and 60 percent of hypertension is believed to be salt-dependent — triggered by excess salt consumption. The research team plans to study this inverse neurovascular coupling mechanism in animal models to determine whether it contributes to the pathology of salt-dependent hypertension. In addition, they hope to use their approach to study other brain regions and diseases, including depression, obesity and neurodegenerative conditions.

“If you chronically ingest a lot of salt, you’ll have hyperactivation of vasopressin neurons. This mechanism can then induce excessive hypoxia, which could lead to tissue damage in the brain,” said Stern. “If we can better understand this process, we can devise novel targets to stop this hypoxia-dependent activation and perhaps improve the outcomes of people with salt-dependent high blood pressure.”

The Strange Similarity of Neuron and Galaxy Networks

Your life’s memories could, in principle, be stored in the universe’s structure.

Nautilus | Franco Vazza and Alberto Feletti

Photo Collage by Francesco Izzo.

This article is a repost which originally appeared on pocket

Christof Koch, a leading researcher on consciousness and the human brain, has famously called the brain “the most complex object in the known universe.” It’s not hard to see why this might be true. With a hundred billion neurons and a hundred trillion connections, the brain is a dizzyingly complex object.

But there are plenty of other complicated objects in the universe. For example, galaxies can group into enormous structures (called clusters, superclusters, and filaments) that stretch for hundreds of millions of light-years. The boundary between these structures and neighboring stretches of empty space called cosmic voids can be extremely complex.1 Gravity accelerates matter at these boundaries to speeds of thousands of kilometers per second, creating shock waves and turbulence in intergalactic gases. We have predicted that the void-filament boundary is one of the most complex volumes of the universe, as measured by the number of bits of information it takes to describe it.

This got us to thinking: Is it more complex than the brain?

So we—an astrophysicist and a neuroscientist—joined forces to quantitatively compare the complexity of galaxy networks and neuronal networks. The first results from our comparison are truly surprising: Not only are the complexities of the brain and cosmic web actually similar, but so are their structures. The universe may be self-similar across scales that differ in size by a factor of a billion billion billion.

The task of comparing brains and clusters of galaxies is a difficult one. For one thing it requires dealing with data obtained in drastically different ways: telescopes and numerical simulations on the one hand, electron microscopy, immunohistochemistry, and functional magnetic resonance on the other.

It also requires us to consider enormously different scales: The entirety of the cosmic web—the large-scale structure traced out by all of the universe’s galaxies—extends over at least a few tens of billions of light-years. This is 27 orders of magnitude larger than the human brain. Plus, one of these galaxies is home to billions of actual brains. If the cosmic web is at least as complex as any of its constituent parts, we might naively conclude that it must be at least as complex as the brain.

The total number of neurons in the human brain falls in the same ballpark of the number of galaxies in the observable universe.

But the concept of emergence makes the comparison possible. Many natural phenomena are not equally complex at all scales. The majestic network of the cosmic web becomes evident only when the sky is surveyed over its largest extent. On smaller scales, with matter locked into stars, planets, and (probably) dark matter clouds, this structure is lost. An evolving galaxy does not care about the dance of electron orbitals within atoms, and electrons move around their nuclei without regard to the galactic system they reside in.

In this way, the universe contains many systems nested into systems, with little to no interaction across different scales. This scale segregation allows us to study physical phenomena as they emerge at their own natural scales.

The building blocks of the cosmic web are the self-gravitating halos of stars, gas, and dark matter (whose existence has yet to be definitively proved). In total, the number of galaxies within the observable universe should be on the order of 100 billion. The balance between the accelerating expansion of the fabric of spacetime and the pull of self-gravity gives this network its spider-web-like pattern. Ordinary and dark matter condense into string-like filaments, and clusters of galaxies form at filament intersections, leaving most of the remaining volume basically empty. The resulting structure looks vaguely biological.

A direct estimate of the number of cells or neurons in the human brain was not available in the literature until recently. Cortical gray matter (representing over 80 percent of brain mass) contains about 6 billions neurons (19 percent of brain neurons) and nearly 9 billion non-neuronal cells. The cerebellum has about 69 billion neurons (80.2 percent of brain neurons) and about 16 billion non-neuronal cells. Interestingly enough, the total number of neurons in the human brain falls in the same ballpark of the number of galaxies in the observable universe.

The eye immediately grasps some similarity between images of the cosmic web and the brain. In Figure 1 we show a simulated distribution of cosmic matter in a slice 1 billion light-years across, along with a real image of a 4 micrometers (µm)-thick slice through the human cerebellum.

Lookalikes (figure 1): A simulated matter distribution of the cosmic web (left) vs the observed distribution of neuronal bodies in the cerebellum (right). The neuronal bodies have been stained with clone 2F11 monoclonal antibody against neurofilaments. Credit: Automated Immunostainer Benchmark Xt, Ventana Medical System, Tucson, AZ, USA.

Is the apparent similarity just the human tendency to perceive meaningful patterns in random data (apophenia)? Remarkably enough, the answer seems to be no: Statistical analysis shows these systems do indeed present quantitative similarities. Researchers regularly use a technique called power spectrum analysis to study the large-scale distribution of galaxies. The power spectrum of an image measures the strength of structural fluctuations belonging to a specific spatial scale. In other words, it tells us how many high-frequency and low-frequency notes make the peculiar spatial melody of each image.

A stunning message emerges from the power spectrum graph in Figure 2 (below): The relative distribution of fluctuations in the two networks is remarkably similar, over several orders of magnitude.

An evolving galaxy does not care about the dance of electron orbitals within atoms.

The distribution of fluctuations in the cerebellum at 0.1-1 mm scales is reminiscent of the galaxy distribution on hundreds of billions of light-years. At the smallest scales available to microscopic observation (about 10 µm), it is the morphology of the cortex that more closely matches the one of galaxies, on scales of a few hundreds of thousands of light-years.

By comparison, the power spectra of other complex systems (including projected images of clouds, tree branches, and plasma and water turbulence) are quite dissimilar from that of the cosmic web. The power spectra of these other systems display a steeper dependence on scale, which may be a manifestation of their fractal nature. This is particularly striking for the distribution of branches in trees and in the pattern of clouds, both of which are well known for being fractal-like systems with self-similarity across a large variety of scales. For the complex networks of the cosmic web and of the human brain, on the other hand, the observed behavior is not fractal, which can be interpreted as evidence of the emergence of scale-dependent, self-organized structures.

As remarkable as the power spectrum comparison is, it doesn’t tell us whether the two systems are equally complex. A practical way of estimating the complexity of a network is to measure how difficult it is to predict its behavior. This can be quantified by counting how many bits of information are necessary for building the smallest possible computer program that can perform such a prediction.

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Fingerprints (figure 2): Distribution of fluctuations as a function of spatial scale for the same maps of Fig 1 (with the additional analysis of a thin slice through the human cortex, not shown in Fig 1). For comparison, the power spectral density of clouds, tree branches, and plasma and water turbulence are shown.

One of us has recently measured how difficult it is to predict how the cosmic network evolves, based on the digital evolution of a simulated universe.1 This estimate suggests that about 1 to 10 petabytes of data are needed to describe the evolution of the entire observable universe at the scale where its self-organization emerges (or at least of its simulated counterpart).

Estimating the complexity of the human brain is much more difficult, because global simulations of the brain remain an unmet challenge. However, we can argue that complexity is proportional to intelligence and cognition. Based on the latest analysis of the connectivity of the brain network, independent studies have concluded that the total memory capacity of the adult human brain should be around 2.5 petabytes, not far from the 1-10 petabyte range estimated for the cosmic web!

Roughly speaking, this similarity in memory capacity means that the entire body of information that is stored in a human brain (for instance, the entire life experience of a person) can also be encoded into the distribution of galaxies in our universe. Or, conversely, that a computing device with the memory capacity of the human brain can reproduce the complexity displayed by the universe at its largest scales.

It is truly a remarkable fact that the cosmic web is more similar to the human brain than it is to the interior of a galaxy; or that the neuronal network is more similar to the cosmic web than it is to the interior of a neuronal body. Despite extraordinary differences in substrate, physical mechanisms, and size, the human neuronal network and the cosmic web of galaxies, when considered with the tools of information theory, are strikingly similar.

Does this fact tell us something profound about the physics of emergent phenomena in the two systems? Maybe. But we must take these findings with a grain of salt. Our analysis has been limited to small samples taken with very different measurement techniques.

Also, our analysis doesn’t point to a dynamical similarity among these systems. A model of how information flows across spatial scales and time in the two systems will be the crucial test. This is already feasible for the cosmic web through numerical simulations. For the human brain we have to rely on more global estimates, usually derived from smaller portions that are then scaled upward. In the near future we aim at testing these concepts in more sophisticated numerical models of the human brain.

Programs like the Human Brain Project, designed to simulate an entire human neuronal network, and the Square Kilometer Array, the biggest enterprise ever in radio astronomy, will help us fill in some of these details and understand whether the universe is even more surprising than we thought.

Franco Vazza is a fellow of Marie Curie Slodowska Action of Horizon 2020, at the Radio Astronomy Institute, INAF, Bologna, Italy.

Alberto Feletti is a member of the department of neurosurgery at NOCSAE Hospital, Azienda Ospedaliero-Universitaria di Modena, Italy.

The authors gratefully acknowledge Dr. Elena Zunarelli (Department of Anatomic Pathology, University Hospital Policlinico di Modena, Modena, Italy) for producing the slices through the cortex and cerebellum of Figure 1.

Reference

  1. Vazza, F. On the complexity and the information content of cosmic structures. Monthly Notices of the Royal Astronomical Society 465, 4942-4955 (2017).

Pornography addiction leads to same brain activity as alcoholism or drug abuse, study shows

Cambridge University scientists reveal changes in brain for compulsive porn users which don’t occur in those with no such habit

Adam Withnall

This article is a repost which originally appeared on INDEPENDENT

Edited for content

People who are addicted to pornography show similar brain activity to alcoholics or drug addicts, a study has revealed.

MRI scans of test subjects who admitted to compulsive pornography use showed that the reward centres of the brain reacted to seeing explicit material in the same way as an alcoholic’s might on seeing a drinks advert.

The research by Cambridge University assessed the brain activity of 19 addictive pornography users against a control group of people who said they were not compulsive users.

Lead scientist Dr Valerie Voon, an honorary consultant neuropsychiatrist, told the Sunday Times: “We found greater activity in an area of the brain called the ventral striatum, which is a reward centre, involved in processing reward, motivation and pleasure.

“When an alcoholic sees an ad for a drink, their brain will light up in a certain way and they will be stimulated in a certain way. We are seeing this same kind of activity in users of pornography.”

The study is yet to be published, but will feature in a Channel 4 documentary called Porn on the Brain, which airs at 10pm on Monday 30 September.

The findings, which tally with recent but unconfirmed reports in the US that porn addiction is no different from chemical or substance addiction, will be seen as an argument in favour of David Cameron’s proposals to limit access to some pornographic websites.

They come as a three-day conference for adult website operators began in London today, with talks including “State of the Industry: The War on Porn”.

Women’s rights activists plan to protest outside the meet at the Radisson Edwardian Bloomsbury Hotel today, wearing overalls and masks in defiance of an industry which they describe as “toxic”.

Dr Julia Long from the London Feminist Network said: “At the very moment we are having a national debate on the harms of pornography, and not least the enormous amount of porn in teenagers’ and children’s lives, XBIZ is holding sessions specifically aimed at combating any attempts to curb access to internet pornography.

“Pornographers don’t care about the damage their industry does. Their only concern is profit.”

Conference organisers said the debate – featuring panellists from the adult industry – would look at the Government’s plans.

Industry lawyer Myles Jackman told the conference website: “Successive governments have mounted a sustained campaign against the UK porn industry and now’s the time to fight back.”