The idea was simple. Recruit hundreds of people in their 80s and 90s, equip them with fitness trackers, and monitor their physical activity. Then, when the participants died, collect their brains and examine the tissue. Is there evidence, lurking in the tissue, that exercise benefits the brain?
The results, from a 2022 collaboration between the University of California in San Francisco and the University of British Columbia, were striking. Physical exercise, late in life, seemed to protect the ageing connections between brain cells – the synapses where memories are made. The work, if backed up by further studies, could see exercise, and potentially drugs that mimic biochemical aspects of activity – prescribed to help slow the onset of dementia.
We know there is a 30%-80% reduced risk of dementia in people who exercise
“We know there is a 30%-80% reduced risk of dementia in people who exercise,” says Kaitlin Casaletto, the lead author on the study and an assistant professor in neurology at UCSF. “My question was, wouldn’t it be cool if we could figure out exactly how this is happening? If we could identify some of the mechanisms of exercise for brain health? These are potential therapeutic targets we can bottle.”
A small mountain of work has linked physical exercise to better brain health and lower risk of dementia in older age. One recent study of nearly 80,000 people in the UK found that the risk of dementia was halved in people who reached the goal of 10,000 steps a day. But much is still unclear. Part of the observed benefit could be down to people with healthier brains simply exercising more.
While there are definite benefits to be had from exercise – greater blood flow to the brain, better cardiovascular health, lower blood pressure, less obesity and diabetes – there is still plenty to nail down.
Dementia is the number one killer in the UK, with the disorder affecting about 900,000 people. Most cases, about two-thirds, are driven by Alzheimer’s disease, but it is far from the only cause. Other forms, namely vascular dementia, dementia with Lewy bodies, and frontotemporal dementia, arise from other processes.
Whatever the cause, the steady destruction of brain cells erodes memory, thinking, movement and personality. In old age, dementia can be several of these conditions at once.
Some of the highest rates of dementia are found in developed countries with older populations. In Germany, Italy and Japan, more than 20 in every 1,000 people have dementia compared with fewer than nine per 1,000 in proportionally younger countries including Mexico, Turkey and South Africa.
The UK sits in the middle. Indigenous groups in the Amazon have some of the lowest rates. In one recent study, researchers confirmed only six cases among 604 Bolivian Tsimane and Moseten people aged 60 and over, suggesting that lifelong physical activity and healthier preindustrial diets substantially reduce the risk.
Over the next three decades, global dementia is due to rise substantially, particularly in north Africa, the Middle East and eastern sub-Saharan Africa, where population growth and ageing will be among the driving forces.
But dementia is not inevitable, nor is it the reward for dodging other fatal conditions. Take all of the risk factors that we as individuals, or nations through their policies, might improve, and potentially 40% of cases could be prevented or delayed. We would not eradicate dementia, and many people who did everything to keep their brains healthy would still succumb to the disease…
The neural representations of a perceived image and the memory of it are almost the same. New work shows how and why they are different. Memory and perception seem like entirely distinct experiences, and neuroscientists used to be confident that the brain produced them differently, too. But in the 1990s neuroimaging studies revealed that parts of the brain that were thought to be active only during sensory perception are also active during the recall of memories.
“It started to raise the question of whether a memory representation is actually different from a perceptual representation at all,” said Sam Ling, an associate professor of neuroscience and director of the Visual Neuroscience Lab at Boston University. Could our memory of a beautiful forest glade, for example, be just a re-creation of the neural activity that previously enabled us to see it?
“The argument has swung from being this debate over whether there’s even any involvement of sensory cortices to saying ‘Oh, wait a minute, is there any difference?’” said Christopher Baker, an investigator at the National Institute of Mental Health who runs the learning and plasticity unit. “The pendulum has swung from one side to the other, but it’s swung too far.”
Even if there is a very strong neurological similarity between memories and experiences, we know that they can’t be exactly the same. “People don’t get confused between them,” said Serra Favila, a postdoctoral scientist at Columbia University and the lead author of a recent Nature Communications study. Her team’s work has identified at least one of the ways in which memories and perceptions of images are assembled differently at the neurological level.
When we look at the world, visual information about it streams through the photoreceptors of the retina and into the visual cortex, where it is processed sequentially in different groups of neurons. Each group adds new levels of complexity to the image: Simple dots of light turn into lines and edges, then contours, then shapes, then complete scenes that embody what we’re seeing.
In the new study, the researchers focused on a feature of vision processing that’s very important in the early groups of neurons: where things are located in space. The pixels and contours making up an image need to be in the correct places or else the brain will create a shuffled, unrecognizable distortion of what we’re seeing.
The researchers trained participants to memorize the positions of four different patterns on a backdrop that resembled a dartboard. Each pattern was placed in a very specific location on the board and associated with a color at the center of the board. Each participant was tested to make sure that they had memorized this information correctly — that if they saw a green dot, for example, they knew the star shape was at the far left position.
Then, as the participants perceived and remembered the locations of the patterns, the researchers recorded their brain activity. The brain scans allowed the researchers to map out how neurons recorded where something was as well as how they later remembered it. Each neuron attends to one space, or “receptive field,” in the expanse of your vision, such as the lower left corner.
A neuron is “only going to fire when you put something in that little spot,” Favila said. Neurons that are tuned to a certain spot in space tend to cluster together, making their activity easy to detect in brain scans. Previous studies of visual perception established that neurons in the early, lower levels of processing have small receptive fields, and neurons in later, higher levels have larger ones.
This makes sense because the higher-tier neurons are compiling signals from many lower-tier neurons, drawing in information across a wider patch of the visual field. But the bigger receptive field also means lower spatial precision, producing an effect like putting a large blob of ink over North America on a map to indicate New Jersey. In effect, visual processing during perception is a matter of small crisp dots evolving into larger, blurrier but more meaningful blobs.
But when Favila and her colleagues looked at how perceptions and memories were represented in the various areas of the visual cortex, they discovered major differences. As participants recalled the images, the receptive fields in the highest level of visual processing were the same size they had been during perception — but the receptive fields stayed that size down through all the other levels painting the mental image. The remembered image was a large, blurry blob at every stage.
This suggests that when the memory of the image was stored, only the highest-level representation of it was kept. When the memory was experienced again, all the areas of the visual cortex were activated — but their activity was based on the less precise version as an input. So depending on whether information is coming from the retina or from wherever memories are stored, the brain handles and processes it very differently.
Some of the precision of the original perception gets lost on its way into memory, and “you can’t magically get it back,” Favila said. A “really beautiful” aspect of this study was that the researchers could read out the information about a memory directly from the brain rather than rely on the human subject to report what they were seeing, said Adam Steel, a postdoctoral researcher at Dartmouth College. “The empirical work that they did, I think, is really outstanding.”
A Feature or a Bug?
But why are memories recalled in this “blurrier” way? To find out, the researchers created a model of the visual cortex that had different levels of neurons with receptive fields of increasing size. They then simulated an evoked memory by sending a signal through the levels in reverse order. As in the brain scans, the spatial blurriness seen in the level with the largest receptive field persisted through all the rest. That suggests that the remembered image forms in this way due to the hierarchical nature of the visual system, Favila said.
One theory about why the visual system is arranged hierarchically is that it helps with object recognition. If receptive fields were tiny, the brain would need to integrate more information to make sense of what was in view; that could make it hard to recognize something big like the Eiffel Tower, Favila said. The “blurrier” memory image might be the “consequence of having a system that’s been optimized for things like object recognition.”
If you’re looking for ways to increase your lifespan, incorporating intense exercise into a workout routine is something to consider. Vigorous exercise can help improve a range of essential biomarkers, including resting heart rate, blood pressure, body composition, blood flow to muscles, and muscle strength, all of which are important indicators of health and disease.
Before we dive into the relationship between exercise intensity and longevity, let’s first examine what counts as high-intensity exercise.
What counts as vigorous exercise?
Measuring your heart rate before, during, and after your workout is one of the most effective ways to gauge exercise intensity. By tracking your heart rate, you can determine how much effort you’re putting into each workout, as well as what these numbers mean for overall heart health.
Track your heart rate
There are three different ranges of exercise intensity—low, moderate, and intense—and each one has a different set of heart rate zones attached to them. Low- and moderate-intensity exercises are completed with less physical strain, while vigorous exercise is a form of activity that is done with a large amount of effort which results in reaching 70 to 85 percent of your maximum heart rate.
To calculate your maximum heart rate, subtract your age from 220, and this will result in the average maximum number of times your heart should beat per minute during exercise.
Examples of vigorous activity
Generally speaking, high-intensity exercise can be any activity that requires 7/10 effort or higher and is difficult to sustain. You should be short of breath but may still be able to speak in choppy sentences. Examples of vigorous activity include swimming, playing soccer, jumping rope, or running over 5 MPH.
Correlation between exercise and longevity
Increase the intensity to prolong your life
Regular exercise is one of the most beneficial things you can do for your body (other than paying attention to nutrition, of course!). From improved mental health to better sleeping patterns to weight management, there are so many ways that exercise benefits the body. But what about increasing your lifespan?
A recent study showed that women with poor exercise capacity (less than 10 METs) had an annual rate of death from cardiovascular disease of four times greater than women with good exercise capacity of 10 METs or more .
Another study showed people who had a higher ratio of vigorous to moderate activity ratio (at least 150 minutes of intense exercise per week) had a lower risk of all-cause mortality, which is commonly used to gauge lifespan .
Why does intense exercise reign supreme?
Vigorous activity improves VO2peak, resting heart rate, blood pressure, blood flow to muscles, and muscle strength, all of which are important biomarkers for overall health [4, 5, 6]. These biomarkers have a strong correlation with cardiovascular disease, type 2 diabetes, insulin sensitivity, and even death – and improving these numbers can be helpful for extending your life and healthy years. . Intense exercise also helps with weight management and improves body composition, such as increasing lean muscle mass and boosting metabolism for several hours post-workout.
Athlete’s heart: a natural adaptation
Participating in intense exercise for more than five hours per week may result in a phenomenon deemed “athlete’s heart”. Essentially, vigorous activity causes the heart to remodel over time. The chamber size of the left ventricle, and the muscle mass and wall thickness of the heart increase to pump more blood through the body and meet the oxygen demands of working muscles [8, 11].
When the size of the left ventricle increases, heart rate decreases while still maintaining the right amount of cardiac output. As the heart continually endures this type of physical stress, it may lead to remodeling of the heart or thicker heart walls . It’s important to keep in mind that this is a natural occurrence and can happen as the heart adapts to intense athletic training.An athlete’s heart only becomes an issue if you have a pre-existing heart condition, so consult your doctor before starting (or continuing) to increase your training levels.
Can you do too much intense exercise?
The more you exercise, the better, right? Not necessarily true! There is such a thing as overdoing it, and by pushing yourself too hard, you risk injury, negating your results, reaching burnout, or damaging your heart . In fact, large exercise volumes and vigorous-intensity exercises have both been associated with accelerated coronary artery calcification, myocardial fibrosis, and other potential cardiac maladaptations [9,10].
For those with an underlying cardiac disease, high-intensity exercise can increase the risk of heart rhythm disorders, atrial fibrillation, cardiac arrest, or sudden cardiac death [10,11].
Consult your healthcare provider about identifying any underlying cardiac issues! This will help you understand your physical limits and how best to tailor your training sessions to achieve maximum performance.
To avoid over-training and to achieve maximum cardiovascular results, consider doing moderate-intensity cardio with some vigorous activity sprinkled in a few days per week. This will help to supplement your workouts and take your intensity to the next level without overdoing it. Plus, it will keep things new and exciting. If you find that you’re extra sore and tired after a workout or series of workouts, listen to your body. Sometimes extra rest is exactly what your body needs.
Tips for athletes
If you want to incorporate more vigorous exercises into your routine, here are some ways to (safely) spice things up and get your heart rate pumping:
Introduce interval training. Add in some high-intensity exercises to training sessions a few times per week for additional heart health benefits. This will help improve overall performance as well as longevity.
Find your target heart rate zone. Take your training to the next level by finding your maximum heart rate and catering your activity levels to those zones. Be cautious to not exceed your maximum heart rate and be sure to pay attention to how you feel during any workout.
Recover properly. High-intensity training sessions can be exhausting, so don’t skip the recovery phase! Be sure to drink enough water, eat a nutritious post-workout snack, cool down properly, and take it easy on rest days to avoid injury.
There is no denying the health benefits of physical activity, especially when it comes to high intensity workouts. Incorporating vigorous exercises into your routine can improve your longevity by reducing the risk of CVD, and improving blood pressure, insulin sensitivity, muscle mass, and body composition. Moreover, incorporating high intensity activity throughout the week can help you take your fitness and athletic performance to the next level.
As you continue to work in high intensity exercises into your routine, don’t forget about the importance of adequate recovery, as well as to watch for signs of overtraining, excess fatigue, or changes in your physical or mental health. By listening to your body, you will be able to gauge what it needs the most, which can help prevent injury, improve happiness, and increase lifespan.
We’ve all had those moments of pure attention, when it seems everyone in the room is attracted to your energy. Yet for many of us, that place is difficult to tap into. Your mind races with nervousness about something previously said and you worry about what to say next, each distraction lessening the power of your interaction.
The key to success in these moments is empathy. This ability to understand and relate to others is a powerful skill that takes work, but in mastering it, you can better both your personal and professional interactions.
Empathy is about establishing trust by outwardly recognizing what someone else is experiencing. It’s difficult for people to fully engage in any interaction if they don’t feel that they are being heard and understood.
Think about how free and open your interactions are with close friends and family. Your conversations are super productive because you have each freed yourself to fully engage.
However, at work or in our other day-to-day interactions, we are naturally cautious. We withhold information, we don’t ask the tough questions, and it’s much harder to make decisions or resolve issues. That generally leads to subpar outcomes.
Four Steps for Practicing Empathy
1. Observe: Pay attention to voice, tone, body language, and the situation.
2. Listen: What feelings and emotions are being conveyed?
3. Interpret: What needs are behind those feelings and emotions?
4. Share: Openly state what you think you understand about the other person and ask for feedback to make sure you’re right.
Straightforward, right? Not exactly.
Why Listening is Scientifically a Struggle
Being a good empathizer is largely connected with being a good listener.
Chris Voss, former FBI negotiator and author of Never Split the Difference: Negotiating As If Your Life Depended On It, explains that it’s a struggle to focus in attentive moments because listening is far from a passive activity. It is the most active thing you can do, and empathetic listening can power some of the most fundamental functions of your workplace.
If you struggle with listening, you are not alone. Renowned author and journalist Michael Pollan examined this difficulty in his recent book, How to Change Your Mind: What the New Science of Psychedelics Teaches Us About Consciousness, Dying, Addiction, Depression and Transcendence.
Pollan found that a major area of the brain known as the default mode network (DMN), which acts as an overseer keeping brain operations in check, is most likely the very operator that makes active listening so difficult.
How the DMN Works
The DMN is what kicks in when you have nothing to do. And it seems to be responsible for the construction of what we call the self or ego. It’s all that noise that comes pouring in when you’re in idle; the flood of thoughts about the past and future and myriad distractions that we often feel powerless to overcome. It can become who we are. It also leads to rumination and self-referential thinking, which is not conducive to empathy.
The DMN is powerful, but you are not powerless to resist it. Attention, focus, and active listening help quiet the ego, allowing you more effective listening.
Try this: Consistent meditation, even just 10 minutes a day, has been shown to decrease activity in the DMN, which then leads to better empathy.
Practicing Empathy in the Workplace
Empathy in the workplace is something I encourage the team at D Custom to actively practice. Here are some of the things it can power.
Empathy and Negotiating
While Voss’ FBI negotiations might not be the first place your mind goes in wondering where and how empathy might be better understood and applied, it is paramount in their field. As he notes, when preparing for a negotiation, it’s more important to concentrate on demeanor and state of mind rather than what you will say or do. This is empathy in all its glory.
Empathy and Trust
Empathy establishes trust, and establishing trust enables more productive working relationships. By practicing empathy in the workplace, you will expose goals and concerns more readily. And you cannot resolve issues until that comes from both sides.
Implementing empathy to build trust starts with recognizing people’s fears and validating them without passing judgment or offering a solution. If you do that in a consistent way as a team member or leader, you will get all manner of engagement from your team.
Empathy and Creativity
Empathy is about a genuine connection, and active listening is a gateway to thoughtful collaboration. Ideas come to light in a creative environment, and an attentive approach helps increase input so much that possibilities expand in a way they would not have otherwise.
Empathy can be a force for powerful relationships. From persuading groups to negotiating with terrorists to growing a fruitful community of coworkers, empathy emerges as an imminent provider of success. It’s wired into our psychology to the point that we can’t resist it. So be present and empathy will follow. From that, the possibilities are boundless.
Neuroscientists have begun to uncover how breathing is coordinated with other behaviors and how its rhythm may influence a variety of regions in the brain....CREDIT: ESTHER AARTS
If you’re lucky enough to live to 80, you’ll take up to a billion breaths in the course of your life, inhaling and exhaling enough air to fill about 50 Goodyear blimps or more. We take about 20,000 breaths a day, sucking in oxygen to fuel our cells and tissues, and ridding the body of carbon dioxide that builds up as a result of cellular metabolism. Breathing is so essential to life that people generally die within minutes if it stops.
It’s a behavior so automatic that we tend to take it for granted. But breathing is a physiological marvel — both extremely reliable and incredibly flexible. Our breathing rate can change almost instantaneously in response to stress or arousal and even before an increase in physical activity. And breathing is so seamlessly coordinated with other behaviors like eating, talking, laughing and sighing that you may have never even noticed how your breathing changes to accommodate them. Breathing can also influence your state of mind, as evidenced by the controlled breathing practices of yoga and other ancient meditative traditions.
In recent years, researchers have begun to unravel some of the underlying neural mechanisms of breathing and its many influences on body and mind. In the late 1980s, neuroscientists identified a network of neurons in the brainstem that sets the rhythm for respiration. That discovery has been a springboard for investigations into how the brain integrates breathing with other behaviors. At the same time, researchers have been finding evidence that breathing may influence activity across wide swaths of the brain, including ones with important roles in emotion and cognition.
“Breathing has a lot of jobs,” says Jack L. Feldman, a neuroscientist at the University of California, Los Angeles, and coauthor of a recent article on the interplay of breathing and emotion in the Annual Review of Neuroscience. “It’s very complicated because we’re constantly changing our posture and our metabolism, and it has to be coordinated with all these other behaviors.”
Each breath a symphony of lung, muscle, brain
Every time you inhale, your lungs fill with oxygen-rich air that then diffuses into your bloodstream to be distributed throughout your body. A typical pair of human lungs contains about 500 million tiny sacs called alveoli, the walls of which are where gases pass between the airway and bloodstream. The total surface area of this interface is about 750 square feet — a bit more than the square footage of a typical one-bedroom apartment in San Francisco, and a bit less than that of a racquetball court.
“The remarkable thing about mammals, including humans, is that we pack an enormous amount of surface area into our chests,” says Feldman. More surface area means more gas is exchanged per second.
But the lungs can’t do it alone. They’re essentially limp sacks of tissue. “In order for this to work, the lungs have to be pumped like a bellows,” Feldman says. And they are — with each inhalation, the diaphragm muscle at the bottom of the chest cavity contracts, moving downward about half an inch. At the same time, the intercostal muscles between the ribs move the rib cage up and out — all of which expands the lungs and draws in air. (If you’ve ever had the wind knocked out of you by a blow to the stomach, you know all about the diaphragm; and if you’ve eaten barbecued ribs, you have encountered intercostal muscles.)
At rest, these muscles contract only during inhalation. Exhalation occurs passively when the muscles relax and the lungs deflate. During exercise, different sets of muscles contract to actively force out air and speed up respiration.
Breathing requires coordinated movements of the diaphragm and intercostal muscles. When these muscles contract, air is drawn into the lungs, where hundreds of millions of tiny alveoli provide a surface where oxygen can diffuse into the blood and carbon dioxide can diffuse out. With each exhalation, these muscles relax, and air is forced back out.
Unlike the heart muscle, which has pacemaker cells that set its rhythm, the muscles that control breathing take their orders from the brain. Given the life-enabling importance of those brain signals, it took a surprisingly long time to track them down. One of the first to ponder their source was Galen, the Greek physician who noticed that gladiators whose necks were broken above a certain level were unable to breathe normally. Later experiments pointed to the brainstem, and in the 1930s, the British physiologist Edgar Adrian demonstrated that the dissected brainstem of a goldfish continues to produce rhythmic electrical activity, which he believed to be the pattern-generating signal underlying respiration.
But the exact location of the brainstem respiratory-pattern generator remained unknown until the late 1980s, when Feldman and colleagues narrowed it down to a network of about 3,000 neurons in the rodent brainstem (in humans it contains about 10,000 neurons). It’s now called the preBötzinger Complex (preBötC). Neurons there spontaneously exhibit rhythmic bursts of electrical activity that, relayed through intermediate neurons, direct the muscles that control breathing.
Over the years, some people have assumed Bötzinger must have been a famous anatomist, Feldman says, perhaps a German or Austrian. But in fact the name came to him in a flash during a dinner at a scientific conference where he suspected a colleague was inappropriately about to claim the discovery for himself. Feldman clinked his glass to propose a toast and suggested naming the brain region after the wine being served, which came from the area around Bötzingen, Germany. Perhaps lubricated by said wine, the others agreed, and the name stuck. “Scientists are just as weird as anyone else,” Feldman says. “We have fun doing things like this.”
A long, deep breath can express many things: sadness, relief, resignation, yearning, exhaustion. But we humans aren’t the only ones who sigh — it’s thought that all mammals do — and it may be because sighing has an important biological function in addition to its expressive qualities.
Pinpointing breath’s rhythm setters
Much of Feldman’s subsequent research has focused on understanding exactly how neurons in the preBötC generate the breathing rhythm. This work has also laid a foundation for his lab and others to investigate how the brain orchestrates the interplay between breathing and other behaviors that require alterations in breathing.
Sighing is one interesting example. A long, deep breath can express many things: sadness, relief, resignation, yearning, exhaustion. But we humans aren’t the only ones who sigh — it’s thought that all mammals do — and it may be because sighing has an important biological function in addition to its expressive qualities. Humans sigh every few minutes, and each sigh begins with an inhale that takes in about twice as much air as a normal breath. Scientists suspect this helps pop open collapsed alveoli, the tiny chambers in the lung where gas exchange occurs, much as blowing into a latex glove pops open the fingers. Several lines of evidence support this idea: Hospital ventilators programmed to incorporate periodic sighing, for example, have been shown to improve lung function and maintain patients’ blood oxygen levels.
In a study published in 2016 in Nature, Feldman and colleagues identified four small populations of neurons that appear to be responsible for generating sighs in rodents. Two of these groups of neurons reside in a brainstem region near the preBötC, and they send signals to the other two groups, which reside inside the preBötC. When the researchers killed these preBötC neurons with a highly selective toxin, the rats ceased to sigh, but their breathing remained robust. On the other hand, when scientists injected neuropeptides that activate the neurons, the rats sighed 10 times more frequently. In essence, the researchers conclude, these four groups of neurons form a circuit that tells preBötC to interrupt its regular program of normal-sized breaths and order up a deeper breath.
The preBötC also has a role in coordinating other behaviors with breathing. One of Feldman’s collaborators on the sighing paper, neuroscientist Kevin Yackle, and colleagues recently used mice to investigate interactions between breathing and vocalizations. When separated from their nest, newborn mice make ultrasonic cries, too high-pitched for humans to hear. There are typically several cries at regular intervals within a single breath, not unlike the syllables in human speech, says Yackle, who’s now at the University of California, San Francisco. “You have this slower breathing rhythm and then nested within it you have this faster vocalization rhythm,” he says.
To figure out how this works, the researchers worked their way backwards from the larynx, the part of the throat involved in producing sound. They used anatomical tracers to identify the neurons that control the larynx and follow their connections back to a cluster of cells in the brainstem, in an area they named the intermediate reticular oscillator (iRO). Using a variety of techniques, the researchers found that killing or inhibiting iRO neurons removes the ability to vocalize a cry, and stimulating them increases the number of cries per breath.
When the researchers dissected out slices of brain tissue with iRO neurons, the cells kept firing in a regular pattern. “These neurons produce a rhythm that’s exactly like the cries in the animal, where it’s faster than but nested within the preBötC breathing rhythm,” Yackle says.
Breathing appears to have far-reaching influences on the brain, including on regions with roles in cognition and emotion, such as the hippocampus, amygdala and prefrontal cortex. These effects may originate from signals generated by the brainstem breathing center, preBötC; from sensory inputs via the vagus nerve or olfactory system; or in response to levels of oxygen (O2) and carbon dioxide (CO2) in the blood.
Additional experiments suggested that iRO neurons help integrate vocalizations with breathing by telling the preBötC to make tiny inhalations that interrupt exhalation — enabling a series of brief cries to fit neatly within a single exhaled breath. That is, rhythmic crying isn’t produced by a series of exhalations, but rather from one long exhalation with several interruptions.
The findings, reported earlier this year in Neuron, may have implications for understanding human language. The number of syllables per second falls within a relatively narrow range across all human languages, Yackle says. Perhaps, he suggests, that’s due to constraints imposed by the need to coordinate vocalizations with breathing.
Setting the pace in the brain
Recent studies have suggested that breathing can influence people’s performance on a surprisingly wide range of lab tests. Where someone is in the cycle of inhalation and exhalation can influence abilities as diverse as detecting a faint touch and distinguishing three-dimensional objects. One study found that people tend to inhale just before a cognitive task — and that doing so tends to improve performance. Several have found that it is only breathing through the nose that has these effects; breathing through the mouth does not.
One emerging idea about how this might work focuses on well-documented rhythmic oscillations of electrical activity in the brain. These waves, often measured with electrodes on the scalp, capture the cumulative activity of thousands of neurons, and for decades some neuroscientists have argued that they reflect communication between far-flung brain regions that could underlie important aspects of cognition. They could be, for example, how the brain integrates sensory information processed separately in auditory and visual parts of the brain to produce what we experience as a seamless perception of a scene’s sounds and sights. Some scientists have even proposed that such synchronized activity could be the basis of consciousness itself (needless to say, this has been hard to prove).
Growing evidence suggests breathing may set the pace for some of these oscillations. In experiments with rodents, several research teams have found that the breathing rhythm influences waves of activity in the hippocampus, a region critical for learning and memory. During wakefulness, the collective electrical activity of neurons in the hippocampus rises and falls at a consistent rate — typically between six and 10 times per second. This theta rhythm, as it’s called, occurs in all animals that have been studied, including humans.
Not only does the respiration rhythm synchronize activity in brain regions involved in emotion and memory, it can also affect people’s performance on tasks involving emotion and memory.
In a 2016 study, neuroscientist Adriano Tort at the Federal University of Rio Grande do Norte in Brazil and colleagues set out to study theta oscillations but noticed that their electrodes were also picking up another rhythm, a slower one with about three peaks per second, roughly the same as a resting mouse’s respiration rate. At first they worried it was an artifact, Tort says, perhaps caused by an unstable electrode or the animal’s movements. But additional experiments convinced them that not only was the rhythmic activity real and synched with respiration, but also that it acted like a metronome to set the pace for the faster theta oscillations in the hippocampus.
Around the same time, neuroscientist Christina Zelano and colleagues reported similar findings in humans. Using data from electrodes placed by surgeons on the brains of epilepsy patients to monitor their seizures, the researchers found that natural breathing synchronizes oscillations within several brain regions, including the hippocampus and the amygdala, an important player in emotional processing. This synchronizing effect diminished when the researchers asked subjects to breathe through their mouth, suggesting that sensory feedback from nasal airflow plays a key role.
Not only does the respiration rhythm synchronize activity in brain regions involved in emotion and memory, it can also affect people’s performance on tasks involving emotion and memory, Zelano and colleagues found. In one experiment they monitored subjects’ respiration and asked them to identify the emotion expressed by people in a set of photos developed by psychologists to test emotion recognition. Subjects were quicker to identify fearful faces when the photo appeared as they were taking a breath compared to during exhalation. In a different test, subjects more accurately remembered whether they’d seen a photo previously when it was presented as they inhaled. Again, the effects were strongest when subjects breathed through the nose.
More recent work suggests the respiratory rhythm could synchronize activity not just within but also between brain regions. In one study, neuroscientists Nikolaos Karalis and Anton Sirota found that the respiration rate synchronizes activity between the hippocampus and the prefrontal cortex in sleeping mice. This synchronization could play a role in making long-term memories, Karalis and Sirota suggest in a paper published earlier this year in Nature Communications. Many neuroscientists think memories initially form in the hippocampus before being transferred during sleep to the cortex for long-term storage — a process thought to require synchronized activity between the hippocampus and cortex.
For Tort, such findings suggest there may be important links between respiration and brain function, but he says more work is needed to connect the dots. The evidence that breathing influences brain oscillations is strong, he says. The challenge now is figuring out what that means for behavior, cognition and emotion.
Controlled breath, calm mind?
For millennia, practitioners of yoga and other ancient meditation traditions have practiced controlled breathing as a means of influencing their state of mind. In recent years, researchers have become increasingly interested in the biological mechanisms of these effects and how they might be applied to help people with anxiety and mood disorders.
One challenge has been separating the effects of breathing from other aspects of these practices, says Helen Lavretsky, a psychiatrist at UCLA. “It’s really hard to distinguish what’s most effective when you’re doing this multicomponent intervention where there’s stretching and movement and visualization and chanting,” she says. Not to mention the cultural and spiritual components many people attach to the practice.
For many years, Lavretsky has collaborated with neuroscientists and others to investigate how different types of meditation affect the brain and biological markers of stress and immune function. She has found, among other things, that meditation can improve performance on lab tests of memory and alter brain connectivity in older people with mild cognitive impairment, a potential precursor to Alzheimer’s disease and other types of dementia. In more recent studies, which have yet to be published, she’s moved toward investigating whether the breath control methods alone can help.
“Even though I’m a psychiatrist, my research is on how to avoid [prescribing] drugs,” says Lavretsky, who is also a certified yoga instructor. She thinks breathing exercises might be a good alternative for many people, especially with more research on which breathing techniques work best for which conditions and how they might be tailored to individuals. “We all have this tool, we just have to learn how to use it,” she says.
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