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From diagnosing brain disorders to cognitive enhancement, 100 years of EEG have transformed neuroscience

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theconversation.com – Erika Nyhus, Associate Professor of Psychology and Neuroscience, Bowdoin College – 2024-07-02 07:28:40

The electroencephalogram scientists to record and read brain activity.
Kateryna Kon/Science Photo Library via Getty Images

Erika Nyhus, Bowdoin College

Electroencephalography, or EEG, was invented 100 years ago. In the years since the invention of this device to monitor brain electricity, it has had an incredible impact on how scientists study the human brain.

Since its first use, the EEG has shaped researchers’ understanding of cognition, from perception to memory. It has also been important for diagnosing and guiding treatment of multiple brain disorders, epilepsy.

I am a cognitive neuroscientist who uses EEG to study how people remember from their past. The EEG’s 100-year anniversary is an to reflect on this discovery’s significance in neuroscience and medicine.

Discovery of EEG

On July 6, 1924, psychiatrist Hans Berger performed the first EEG recording on a human, a 17-year-old boy undergoing neurosurgery. At the time, Berger and other researchers were performing electrical recordings on the brains of animals.

What set Berger apart was his obsession with finding the physical basis of what he called psychic energy, or mental effort, in people. Through a series of experiments spanning his early career, Berger measured brain volume and temperature to study changes in mental processes such as intellectual work, attention and desire.

He then turned to recording electrical activity. Though he recorded the first traces of EEG in the human brain in 1924, he did not publish the results until 1929. Those five intervening years were a tortuous phase of self-doubt about the source of the EEG signal in the brain and refining the experimental setup. Berger recorded hundreds of EEGs on multiple subjects, including his own , with both experimental successes and setbacks.

From diagnosing brain disorders to cognitive enhancement, 100 years of EEG have transformed neuroscience
Two EEG traces, the top more irregular in rhythm than the bottom.
Hans Berger/รœber das Elektrenkephalogramm des Menchen. Archives fรผr Psychiatrie. 1929; 87:527-70 via Wikimedia Commons

Finally convinced of his results, he published a series of papers in the journal Archiv fรผr Psychiatrie and had hopes of winning a Nobel Prize. Unfortunately, the research community doubted his results, and years passed before anyone else started using EEG in their own research.

Berger was eventually nominated for a Nobel Prize in 1940. But Nobels were not awarded that year in any category due to World War II and Germany’s occupation of Norway.

Neural oscillations

When many neurons are active at the same time, they produce an electrical signal strong enough to spread instantaneously through the conductive tissue of the brain, skull and scalp. EEG electrodes placed on the head can record these electrical signals.

Since the discovery of EEG, researchers have shown that neural activity oscillates at specific frequencies. In his initial EEG recordings in 1924, Berger noted the predominance of oscillatory activity that cycled eight to 12 times per second, or 8 to 12 hertz, named alpha oscillations. Since the discovery of alpha rhythms, there have been many attempts to understand how and why neurons oscillate.

Neural oscillations are thought to be important for effective communication between specialized brain regions. For example, theta oscillations that cycle at 4 to 8 hertz are important for communication between brain regions involved in memory encoding and retrieval in animals and humans.

Finger pointing at EEG reading
Different frequencies of neural oscillations indicate different types of brain activity.
undefined undefined/iStock via Getty Images Plus

Researchers then examined whether they could alter neural oscillations and therefore affect how neurons to each other. Studies have shown that many behavioral and noninvasive methods can alter neural oscillations and to changes in cognitive performance. Engaging in specific mental activities can induce neural oscillations in the frequencies those mental activities use. For example, my team’s research found that mindfulness meditation can increase theta frequency oscillations and improve memory retrieval.

Noninvasive brain stimulation methods can target frequencies of interest. For example, my team’s ongoing research found that brain stimulation at theta frequency can lead to improved memory retrieval.

EEG has also led to major discoveries about how the brain processes information in many other cognitive domains, including how people perceive the world around them, how they focus their attention, how they communicate through language and how they emotions.

Diagnosing and treating brain disorders

EEG is commonly used to diagnose sleep disorders and epilepsy and to guide brain disorder treatments.

Scientists are using EEG to see whether memory can be improved with noninvasive brain stimulation. Although the research is still in its infancy, there have been some promising results. For example, one study found that noninvasive brain stimulation at gamma frequency โ€“ 25 hertz โ€“ improved memory and neurotransmitter transmission in Alzheimer’s disease.

Back of person's head enveloped by the many, small round electrodes of an EEG cap
Researchers and clinicians use EEG to diagnose conditions like epilepsy.
BSIP/Collection Mix: Subjects via Getty Images

A new type of noninvasive brain stimulation called temporal interference uses two high frequencies to cause neural activity equal to the difference between the stimulation frequencies. The high frequencies can better penetrate the brain and reach the targeted area. Researchers recently tested this method in people using 2,000 hertz and 2,005 hertz to send 5 hertz theta frequency at a key brain region for memory, the hippocampus. This led to improvements in remembering the name associated with a face.

Although these results are promising, more research is needed to understand the exact role neural oscillations play in cognition and whether altering them can lead to long-lasting cognitive enhancement.

The future of EEG

The 100-year anniversary of the EEG provides an opportunity to consider what it has taught us about brain function and what this technique can do in the future.

In a survey commissioned by the journal Nature Human Behaviour, over 500 researchers who use EEG in their work were asked to make predictions on the future of the technique. What will be possible in the next 100 years of EEG?

Some researchers, including myself, predict that we’ll use EEG to diagnose and create targeted treatments for brain disorders. Others anticipate that an affordable, wearable EEG will be widely used to enhance cognitive function at home or will be seamlessly integrated into virtual reality applications. The possibilities are vast.The Conversation

Erika Nyhus, Associate Professor of Psychology and Neuroscience, Bowdoin College

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Halloween candy binges can overload your gut microbiome โ€“ a gut doctor explains how to minimize spooking your helpful bacteria

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theconversation.com – Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of Washington – 2024-10-23 07:41:00

It’s probably best to enjoy your Halloween spoils in moderation.

Jupiterimages/The Image Bank via Getty Images

Christopher Damman, University of Washington

Each October, as the days shorten and the grows crisp, millions of Americans prepare for the beloved โ€“ and often sugar-fueled โ€“ tradition of Halloween. From jack-o’-lanterns glowing on porches to costumes ranging from the whimsical to the gory, Halloween is a time of playful scares, childhood memories and, of course, candy.

But as the wrappers pile up and the sugar rush hits, there’s something far more sinister beneath the surface: the negative effects of candy on your gut .

Sugar and other ingredients in Halloween treats can cast a sickly spell on the trillions of microorganisms that reside in your gut, collectively known as the gut microbiome. As a gastroenterologist and gut microbiome researcher at the University of Washington School of Medicine, I have dedicated my career to decoding the cipher of how food affects this microbial community within your gut.

While no candy is truly healthy, some options are better for your gut than others. And there are ways you can wake your gut from its sugar โ€œspellโ€ after indulgence.

Gut-busting treats

What does all this candy do to your gut?

In a healthy state, your gut microbiome acts like a microbial factory. It digests nutrients your body can’t โ€“ such as fiber and colorful, health-conferring plant compounds called polyphenols โ€“ and produces important molecules called metabolites that protect against infection and support brain health. It also regulates metabolism, or the transformation of food into useful components that power and grow cells.

A balanced diet keeps your gut’s microbial cauldron churning smoothly. But the concentrated sugar, saturated fat and additives in candy can throw things into disarray by feeding inflammatory microbes that weaken your gut barrier โ€“ the protective lining that separates your microbiome from the rest of the body.

Once the gut barrier is breached, even friendly microbes can stir up inflammation, causing health issues ranging from overweight to obesity, infections to autoimmune disease, and mild cognitive impairment to Alzheimer’s.

The food you eat shapes your gut microbes, which in turn shape your overall health.

Sugar and inflammation impair your microbiome’s ability to digest food and regulate metabolism. Instead of producing healthy byproducts โ€“ such as butyrate from fiber and urolithin A from polyphenols โ€“ candy lacking these nutrients may trick your system into storing more fat, providing less energy for your muscles and brain.

Too much candy can also affect your immune system. A healthy gut microbiome helps your immune system distinguish between friend and foe, reducing the risk of infections and autoimmune disorders. Sugar and inflammation undermine the microbiome’s role in training the immune system to distinguish between harmful invaders and harmless substances. Without a carefully calibrated immune system, your body may not effectively clear infections or may strongly react to its own cells.

Neurologically, excess sweets can also affect the gut-brain axis, the two-way communication between the gut and brain. A healthy microbiome normally produces neurotransmitters and metabolites, such as serotonin and butyrate, that influence mood and cognitive performance. Sugar and inflammation adversely affects the microbiome’s role in mental health and cognitive function, contributing to depression, anxiety and memory troubles.

The candy conundrum

Not all Halloween treats are created equal, especially when it to their nutritional value and effects on gut health. Sugar-coated nuts and fruit such as honey-roasted almonds and candy apples rank among the top, offering whole food just beneath the sugary coating. Packed with fiber and polyphenols, they help support gut health and healthy metabolism.

On the opposite end of the spectrum are chewy treats such as candy corn, Skittles, Starbursts and Twizzlers. These sugar-laden confections are mostly made of high fructose corn syrup, saturated fat and additives. They can increase the unsavory bacterial species in your gut and to inflammation, making them one of the least healthy Halloween choices.

Chocolate-based candies, however, stand out as a more microbiome-friendly option. While varieties such as Twix, Three Musketeers and Milky Way contain only a small amount of chocolate, pure chocolate bars โ€“ especially dark chocolate โ€“ are rich in fiber and polyphenols. In moderation, dark chocolate with at least 80% to 85% cacao may even benefit your gut microbiome and mood by encouraging beneficial bacterial species to grow.

Two green apples on a stick, coated in caramel and dusted with pecans.

Candy apples usually a serving of fruit and nuts.

Ryan Benyi Photography/Connect Images via Getty Images

Chocolates with whole nuts, such as almonds or peanuts, offer a boost of fiber, protein and omega-3 fats, making them a healthier choice. Dark chocolate with nuts is best. But when sorting through Halloween treats, Peanut M&Ms, 100 Grands and Almond Joys may be better options over Rolos, Krackels and Crunches. Even candies with processed nuts, such as Reese’s Peanut Butter Cups and Butterfingers, retain small amounts of fiber and protein, making them preferable to nut-free options.

At the bottom of the list, along with chewy sugar candies, are pure sugar candies such as lollipops, Jolly Ranchers, gummies and Smarties. These sweets lack nutritional value, and their high sugar content can contribute to the growth of unhealthy bacteria in your gut microbiome.

In the end, all candies are high in sugar, which can be harmful when consumed in large quantities. Moderation and an otherwise balanced diet is key to enjoying Halloween treats.

Rebalancing after indulgence

If the microbiome is critical for health, and candy can disrupt its balance, how can you restore gut health after Halloween?

One simple strategy is focusing on the four F’s of food: fiber, phytochemicals, unsaturated fats and fermented foods. These food components can help support gut health.

Fiber-rich foods such as whole grains, nuts, seeds, beans, fruits and vegetables regulate digestion and nourish beneficial gut bacteria.

Partially unwrapped chocolate bar

Dark chocolate is a treat that may offer some health benefits.

Wachiwit/iStock via Getty Images Plus

Polyphenol-rich foods such as dark chocolate, berries, red grapes, green tea and extra virgin olive oil help reduce inflammation and encourage the growth of healthy gut bacteria.

Unsaturated fats such as omega-3 fats, walnuts, chia seeds, flaxseed, avocados and fatty fish such as salmon can also support a healthy microbiome.

Fermented foods such as sauerkraut, kimchi, yogurt, kefir and miso help replenish beneficial bacteria and restore gut balance.

To make tracking your diet easier, consider using a food calculator to measure how well your meals align with the four F’s and microbiome friendly options. Like a virtual โ€œspellbook,โ€ an online tool can help ensure your food choices support your gut health and ward off the effects of sugar overload.

As my daughters often remind me, it’s perfectly fine to indulge every now and then in a few tricks and treats. But remember, moderation is key. With a balanced diet, you’ll keep your gut healthy and strong long after the Halloween season ends.The Conversation

Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of Washington

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Both Harris and Trump have records on space policy โˆ’ an international affairs expert examines where they differ when it comes to the final frontier

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theconversation.com G. Roberts, Postdoctoral Fellow in International Affiars, Georgia Institute of Technology – 2024-10-23 07:43:00

Neither candidate has talked much about policy on the campaign trail, but both have records to consider.

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Thomas G. Roberts, Georgia Institute of Technology

The next president of the United States could be the first in that office to accept a phone call from the Moon and hear a woman’s voice on the line. To do so, they’ll first need to make a of strategic space policy decisions. They’ll also need a little luck.

Enormous government investment supports outer space activities, so the U.S. president has an outsize role in shaping space policy during their time in office.

Past presidents have leveraged this power to accelerate U.S. leadership in space and boost their presidential brand along the way. Presidential advocacy has helped the U.S. astronauts on the surface of the Moon, establish lasting international partnerships with civil space agencies abroad and led to many other important space milestones.

But most presidential candidates refrain from discussing space policy on the campaign trail in meaningful detail, leaving voters in the dark on their visions for the final frontier.

For many candidates, getting into the weeds of their space policy plans may be more trouble than it’s worth. For one, not every president even gets the for meaningful and memorable space policy decision-making, since space missions can operate on decades-long timelines. And in past elections, those who do show for space initiatives often face criticism from their opponents for their high price tags.

But the 2024 election is different. Both candidates have executive records in space policy, a rare treat for space enthusiasts casting their votes this November.

As a researcher who studies international affairs in outer space, I am interested in how those records interface with the strategic and sustainable use of that domain. A closer look shows that former and Vice President Kamala Harris have used their positions to consistently prioritize U.S. leadership in space, but they have done so with noticeably different styles and results.

Trump’s space policy record

As president, Trump established a record of meaningful and lasting space policy decisions, but did so while attracting more attention to his administration’s space activities than his predecessors. He regularly took personal credit for ideas and accomplishments that predated his time in office.

The former president oversaw the establishment of the U.S. Space Force and the reestablishment of the U.S. Space Command, as well as the National Space Council. These support the and operation of military space technologies, defend national security satellites in future conflicts and coordinate between federal agencies working in the space domain.

A commander in military uniform waves a black flag with the emblem of the US Space Force (an arrow pointing up in front of a sphere representing the Earth).

While president, Donald Trump oversaw the creation of the U.S. Space Force.

AP Photo/Alex Brandon

He also had the most productive record of space policy directives in recent history. These policy directives clarify the U.S. government’s goals in space, including how it should both support and rely on the commercial space sector, track objects in Earth’s orbit and protect satellites from cyber threats.

He has called his advocacy for the creation of the Space Force one of his proudest achievements of his term. However, this advocacy contributed to polarized support for the new branch. This polarization broke the more common pattern of bipartisan public support for space programming.

Like many presidents, not all of Trump’s visions for space were realized. He successfully redirected NASA’s key human spaceflight destination from Mars back to the Moon. But his explicit goal of astronauts reaching the lunar surface by 2024 was not realistic, given his budget proposal for the agency.

Should he be elected again, the former president may wish to accelerate NASA’s Moon plans by furthering investment in the agency’s Artemis program, which houses its lunar initiatives.

He may frame the initiative as a new space race against China.

Harris’ space policy record

The Biden administration has continued to support Trump-era initiatives, resisting the temptation to undo or cancel past proposals. Its legacy in space is noticeably smaller.

As the chair of the National Space Council, Harris has set U.S. space policy priorities and represented the United States on the global stage.

A group of people gathered around a large table, with Kamala Harris standing at a podium at the front next to a screen that says 'National Space Council.'

As vice president, Harris has chaired the National Space Council.

NASA/Joel Kowsky, CC BY-NC-ND

Notably, the Trump administration kept this position that the president can alter at will assigned to the vice president, a precedent the Biden administration upheld.

In this role, Harris led the United States’ commitment to refrain from testing weapons in space that produce dangerous, long-lasting space debris. This decision marks an achievement for the U.S. in keeping space operations sustainable and setting an example for others in the international space community.

Like some Trump administration space policy priorities, not all of Harris’ proposals found footing in Washington.

The council’s plan to establish a framework for comprehensively regulating commercial space activities in the U.S., for example, stalled in Congress.

If enacted, these new regulations would have ensured that future space activities, such as private companies operating on the Moon or transporting tourists to orbit and back, pass critical safety checks.

Should she be elected, Harris may choose to continue her efforts to shape responsible norms of behavior in space and organize oversight over the space industry.

Alternatively, she could cede the portfolio to her own vice president, Minnesota Gov. Tim Walz, who has virtually no track record on space policy issues.

Stability in major space policy decisions

Despite the two candidates’ vastly different platforms, voters can expect stability in U.S. space policy as a result of this year’s election.

Given their past leadership, it is unlikely that either candidate will seek to dramatically alter the long-term missions the largest government space organizations have underway during the upcoming presidential term. And neither is likely to undercut their predecessors’ accomplishments.The Conversation

Thomas G. Roberts, Postdoctoral Fellow in International Affiars, Georgia Institute of Technology

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Women are at a higher risk of dying from heart disease โˆ’ in part because doctors donโ€™t take major sex and gender differences into account

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theconversation.com – Amy Huebschmann, Professor of Medicine, University of Colorado Anschutz Medical Campus – 2024-10-22 07:45:00

Rates of heart disease and cardiac events in women are often underestimated.

eternalcreative/iStock via Getty Images

Amy Huebschmann, University of Colorado Anschutz Medical Campus and Judith Regensteiner, University of Colorado Anschutz Medical Campus

A simple difference in the genetic code โ€“ two X chromosomes versus one X chromosome and one Y chromosome โ€“ can to major differences in heart disease. It turns out that these genetic differences influence more than just sex organs and sex assigned at birth โ€“ they fundamentally alter the way cardiovascular disease develops and .

While sex influences the mechanisms behind how cardiovascular disease develops, gender plays a role in how providers recognize and manage it. Sex refers to biological characteristics such as genetics, hormones, anatomy and physiology, while gender refers to social, psychological and cultural constructs. Women are more likely to die after a first heart attack or stroke than . Women are also more likely to have additional or different heart attack symptoms that go beyond chest pain, such as nausea, jaw pain, dizziness and fatigue. It is often difficult to fully disentangle the influences of sex on cardiovascular disease outcomes versus the influences of gender.

While women who haven’t entered menopause have a lower risk of cardiovascular disease than men, their cardiovascular risk accelerates dramatically after menopause. In addition, if a woman has Type 2 diabetes, her risk of heart attack accelerates to be equivalent to that of men, even if the woman with diabetes has not yet gone through menopause. Further data is needed to better understand differences in cardiovascular disease risk among nonbinary and transgender patients.

Despite these differences, one key thing is the same: Heart attack, stroke and other forms of cardiovascular disease are the leading cause of death for all people, regardless of sex or gender.

We are researchers who study women’s health and the way cardiovascular disease develops and presents differently in women and men. Our work has identified a crucial need to update medical guidelines with more sex-specific approaches to diagnosis and treatment in order to improve health outcomes for all.

Gender differences in heart disease

The reasons behind sex and gender differences in cardiovascular disease are not completely known. Nor are the distinct biological effects of sex, such as hormonal and genetic factors, versus gender, such as social, cultural and psychological factors, clearly differentiated.

What researchers do know is that the accumulated evidence of what good heart care should look like for women compared with men has as many holes in it as Swiss cheese. Medical evidence for treating cardiovascular disease often comes from trials that excluded women, since women for the most part weren’t included in scientific research until the NIH Revitalization Act of 1993. For example, current guidelines to treat cardiovascular risk factors such as high blood pressure are based primarily on data from men. This is despite evidence that differences in the way that cardiovascular disease develops leads women to experience cardiovascular disease differently.

Clinician holding stethoscope against a patient's chest

Gender biases in health care influence the kind of tests and attention that women receive.

FG Trade Latin/E+ via Getty Images

In addition to sex differences, implicit gender biases among providers and gendered social norms among patients lead clinicians to underestimate the risk of cardiac events in women with men. These biases play a role in why women are more likely than men to die from cardiac events. For example, for with symptoms that are borderline for cardiovascular disease, clinicians tend to be more aggressive in ordering artery imaging for men than for women. One study linked this tendency to order less aggressive tests for women partly to a gender bias that men are more open than women to taking risks.

In a study of about 3,000 patients with a recent heart attack, women were less likely than men to think that their heart attack symptoms were due to a heart . Additionally, most women do not know that cardiovascular disease is the No. 1 cause of death among women. Overall, women’s misperceptions of their own risk may hold them back from getting a doctor to check out possible symptoms of a heart attack or stroke.

These issues are further exacerbated for women of color. Lack of access to health care and additional challenges drive health disparities among underrepresented racial and ethnic minority populations.

Sex difference in heart disease

Cardiovascular disease physically looks different for women and men, specifically in the plaque buildup on artery walls that contributes to illness.

Women have fewer cholesterol crystals and fewer calcium deposits in their artery plaque than men do. Physiological differences in the smallest blood vessels feeding the heart also play a role in cardiovascular outcomes.

Women are more likely than men to have cardiovascular disease that presents as multiple narrowed arteries that are not fully โ€œclogged,โ€ resulting in chest pain because blood flow can’t ratchet up enough to meet higher oxygen demands with exercise, much like a low-flow showerhead. When chest pain presents in this way, doctors call this condition ischemia and no obstructive coronary arteries. In comparison, men are more likely to have a โ€œcloggedโ€ artery in a concentrated area that can be opened up with a stent or with cardiac bypass surgery. Options for multiple narrowed arteries have lagged behind treatment options for typical โ€œcloggedโ€ arteries, which puts women at a disadvantage.

In addition, in the early stages of a heart attack, the levels of blood markers that indicate to the heart are lower in women than in men. This can lead to more missed diagnoses of coronary artery disease in women compared with men.

The reasons for these differences are not fully clear. Some potential factors include differences in artery plaque composition that make men’s plaque more likely to rupture or burst and women’s plaque more likely to erode. Women also have lower heart mass and smaller arteries than men even after taking body size into consideration.

Reducing sex disparities

Too often, women with symptoms of cardiovascular disease are sent away from doctor’s offices because of gender biases that โ€œwomen don’t get heart disease.โ€

Considering how symptoms of cardiovascular disease vary by sex and gender could doctors better care for all patients.

One way that the rubber is meeting the road is with regard to better approaches to diagnosing heart attacks for women and men. Specifically, when diagnosing heart attacks, using sex-specific cutoffs for blood tests that measure heart damage โ€“ called high-sensitivity troponin tests โ€“ can improve their accuracy, decreasing missed diagnoses, or false negatives, in women while also decreasing overdiagnoses, or false positives, in men.

Our research laboratory’s leaders,collaborators and other internationally recognized research colleagues โ€“ some of whom partner with our Ludeman Family Center for Women’s Health Research on the University of Colorado Anschutz Medical Campus โ€“ will continue this important work to close this gap between the sexes in health care. Research in this field is critical to shine a light on ways clinicians can better address sex-specific symptoms and to bring forward more tailored treatments.

The Biden administration’s recent executive order to advance women’s health research is paving the way for research to go beyond just understanding what causes sex differences in cardiovascular disease. Developing and testing right-sized approaches to care for each patient can help achieve better health for all.The Conversation

Amy Huebschmann, Professor of Medicine, University of Colorado Anschutz Medical Campus and Judith Regensteiner, Professor of Medicine, University of Colorado Anschutz Medical Campus

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