Ancient Arctic carbon is pouring into the sea, but the seabed captures most of it

 The Arctic's frozen ground contains enormous stores of organic carbon. As permafrost thaws and coastlines erode, some of that carbon is carried into the ocean. There, microorganisms can break it down and release greenhouse gases that contribute to climate change.

Until now, scientists have had limited information about how much of this carbon returns to the atmosphere and how much remains trapped in the ocean. Researchers from the Alfred Wegener Institute and MARUM - Centre for Marine Environmental Sciences at the University of Bremen have now examined this process along the permafrost coast of Qikiqtaruk (Herschel Island) in Canada.

By studying sediment cores, the team found that large amounts of carbon from land are preserved in the seafloor. They also discovered that marine microorganisms behave like selective eaters, favoring fresh carbon from the ocean over older carbon released from permafrost. The findings were published in Nature Geoscience.

Vast Carbon Stores Are Beginning to Thaw

Permafrost ecosystems on Arctic land contain about 1,300 gigatonnes of organic carbon, much of it from plant remains. Another 400 gigatonnes are stored in ocean sediments and river deltas.

As the planet warms, the Arctic is heating faster than any other region. This rapid temperature rise is causing frozen ground to thaw and coastlines to break apart. Carbon that was previously locked in the soil can then reach the Arctic Ocean through rivers and coastal erosion.

"Consequently, up to 0.02 gigatonnes are entering the sea each year, and according to forecasts, this outflow could rise by 70 to 150 percent by the year 2100," says Dr. Manuel Ruben, lead author of the study from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). "However, how much of this is released back into the atmosphere as a greenhouse gas and how much is stored in the seabed has, until now, been largely unknown."

Resolving that uncertainty is important because scientists need to know where the carbon ultimately ends up to estimate how thawing permafrost could affect the climate.

Sediment Cores Reveal Where the Carbon Goes

To investigate, the researchers collected sediment cores from several locations off the coast of Herschel Island. These cores contain layers of material deposited over roughly 50 years.

The results showed that only a relatively small share of the carbon swept into the ocean becomes part of the active carbon cycle.

"Although the sea here carries away huge quantities of organic carbon from the coast, surprisingly little of it ends up in the ocean's active carbon cycle," says Manuel Ruben. "Microorganisms convert around ten percent of the organic carbon from the sediments into gases, which rise into the water and can then enter our atmosphere."

Most of the remaining carbon stays buried in the seabed.

Chemical Clues Track Microbial Activity

The scientists analyzed the composition of the sediment cores and measured how quickly material from the permafrost accumulated on the ocean floor.

They also studied dissolved inorganic carbon found in tiny spaces between sediment particles, known as pore water. These measurements reveal how much CO2 microorganisms have released after consuming organic material.

The isotopic makeup of the pore water helped the team determine where that material came from.

"Carbon isotopes represent our atomic indicators that can identify the food source of the microorganisms," says Prof. Gesine Mollenhauer, a geochemist at the AWI and co-spokesperson for the 'The Ocean Floor - Earth's Unexplored Interface' cluster of Excellence. "The 13C isotope, for example, tells us whether they have consumed carbon from land or from the sea. By way of the 14C isotope, we were able to determine whether the single-celled organisms preferred old organic carbon from permafrost or fresh organic carbon from algae remains."

"Gourmet" Bacteria Prefer Fresh Carbon

The results suggest that the organisms living in the sediment are not equally interested in every type of carbon.

"The sediment is home to 'gourmet' bacteria that apparently prefer fresh carbon stemming from, for example, more recent algal remains over the 'old' carbon from permafrost deposits," explains Gesine Mollenhauer.

Because the microbes favor fresh marine material, older carbon from thawing permafrost may contribute less to atmospheric greenhouse gas levels than scientists once feared.

However, the researchers caution that the full picture is not yet clear.

"However, we do need further research here. This is because some of the organic carbon from the permafrost may already have been broken down before it reaches the seabed."

Coastal Carbon Could Reshape Arctic Ecosystems

The movement of carbon from land into the ocean may affect more than greenhouse gas emissions. It can also change the chemistry and biology of coastal waters that support food resources for local communities.

Sediment released by coastal erosion can reduce the amount of sunlight entering the water. Freshly eroded fragments make the coastal ocean cloudy, while dissolved organic carbon can darken the water.

That loss of light can affect single-celled organisms such as algae, which need sunlight to produce biomass and oxygen. This primary production supports a wider food web that includes fish, crustaceans and seals.

The researchers plan to explore these connections further during the international 'Arctic Pulse' campaign scheduled for 2027. Scientists will carry out coordinated observations from the Polarstern research icebreaker, aboard AWI research aircraft and at sites on land. Their goal is to understand how rapid environmental change is transforming Arctic ecosystems.

Improving Arctic Climate Models

"Our study shows, more precisely than ever before, how much carbon is safely stored in the seabed - and just how much of the decomposed material actually originates from the old permafrost," says Manuel Ruben. "This provides an important foundation for climate models that can predict the consequences of permafrost thawing for the global climate."

Source: ScienceDaily

The AMOC stayed strong even as a major ocean “lifeline” nearly shut down

 Scientists have long believed that warm, salty water flowing from the Indian Ocean around the southern tip of Africa and into the Atlantic helps support one of the planet's most important ocean circulation systems. This flow, known as Agulhas Leakage, has been considered a major contributor to the Atlantic Meridional Overturning Circulation (AMOC), which forms part of the global ocean conveyor system.

New findings from an international research team based in the Netherlands, USA, China and UK suggest that this relationship is more complicated than previously assumed. Their results indicate that changes in Agulhas Leakage do not always produce the expected response in deep water formation. The study offers a clearer picture of how the AMOC works and how its behavior may vary under different climate conditions.

Testing a Textbook Explanation of the AMOC

The Atlantic Meridional Overturning Circulation (AMOC) transports warm surface water toward the north while carrying colder, denser water back toward the south at greater depths. Through this exchange, it influences temperatures across the North Atlantic and much of Europe, making it a central part of the global climate system.

For decades, researchers have proposed that Agulhas Leakage helps maintain or strengthen the AMOC. This leakage carries warm, salty Indian Ocean water around South Africa and into the Atlantic. Its strength is influenced by shifts in the position of the subtropical front. According to the traditional explanation, the added salt encourages the formation of North Atlantic Deep Water, which helps sustain Atlantic overturning.

"This was basically the first textbook concept, that I learnt when I was a bachelor student. It was surprising to find geological evidence showing that it isn't universally true. The AMOC can remain strong even when Agulhas Leakage weakens," explains lead author Dr. Suning Hou from Utrecht University.

Hou and his colleagues examined conditions during the late Pliocene (3.6-2.6 million years ago). This period included a short but significant glacial event followed by the mid-Piacenzian Warm Period, when global conditions were warmer than they are today. The transition provided researchers with a useful opportunity to study how ocean circulation near South Africa and within the Atlantic responded as the climate shifted from cooler to warmer conditions.

Ancient Sediments Reveal Shifting Ocean Boundaries

The team studied a marine sediment core collected from International Ocean Discovery Program Site U1475 on the Agulhas Plateau, about 500 kilometers south of South Africa.

Within the core, researchers examined fossilized microplankton known as dinocysts, along with organic lipid biomarkers. These materials allowed them to estimate past ocean temperatures and track movements of the Southern Ocean subtropical front toward the north or south.

Hou: "If you find a change in the dinocyst assemblage in the sediment, this means that the front shifted. For instance, if you find more of the warmer species and less of the colder ones, the front has moved south. A more southerly front generally opens a wider pathway for Indian Ocean water to leak into the Atlantic, and vice versa."

Using these indicators, the researchers produced a detailed reconstruction of possible changes in Agulhas Leakage throughout the late Pliocene.

To determine how the Atlantic responded, they also developed temperature records from Ocean Drilling Program Site 625 in the northern Gulf of Mexico. They combined those findings with previously published evidence from the equatorial Atlantic, the North Atlantic and the Caribbean Sea.

The team then compared the geological records with numerical climate model simulations covering the late Pliocene glacial event and the warmer period that followed. Together, the evidence from several ocean basins connected movements of the Southern Ocean front with changes in Atlantic temperature layers and overturning circulation.

Agulhas Leakage Declined While Overturning Intensified

The reconstruction from waters south of Africa showed that the subtropical front began moving northward around 3.4 million years ago and continued doing so during the glacial event.

At the same time, temperatures in the Agulhas region fell by about 3 degrees Celsius. Site U1475 also developed subpolar conditions. These changes indicate that Agulhas Leakage weakened dramatically and may have come close to stopping.

According to the conventional theory, a reduction in the transport of salty water should have weakened the AMOC. Instead, both the geological evidence and the computer simulations revealed the opposite pattern in important parts of the circulation system.

During the glacial interval, the North Atlantic Current did not extend as far into the high northern latitudes. Even so, the formation of North Atlantic Deep Water became stronger, as did overturning at lower latitudes. This intensified circulation caused the thermocline, the boundary between warmer surface water and colder deep water, to become shallower across the Atlantic.

Source: ScienceDaily

Marine heatwaves are harming human health in surprising ways

 Marine heatwaves are increasingly being recognized as more than an environmental problem. New research warns that prolonged periods of unusually warm ocean temperatures can also threaten human physical and mental health.

Researchers from Adelaide University and the University of Hong Kong say marine heatwaves should be treated as an important public health concern. They argue that the effects on people have received relatively little attention, even as evidence continues to show how widely these events can affect communities.

The consequences can be severe. The rapid strengthening of Hurricane Otis in 2023 and the destruction it caused in Mexico (an estimated damage bill of more than US$15 billion) have been linked to marine heatwaves. Typhoon Doksuri in 2023, which had impacts across Asia (which affected more than two million people across Asia), has also been associated with unusually warm ocean conditions.

In South Australia, a devastating algal bloom linked to marine heat conditions has also been associated with numerous health problems in coastal communities.

How Marine Heatwaves Can Affect Human Health

A new paper published in Nature Sustainability describes how sustained periods of abnormally high ocean temperatures can set off a chain of consequences for people. These include more severe weather, reduced seafood availability, threats to food safety, disrupted livelihoods and greater mental health pressures in coastal areas.

Lead author Dr. Laura Falkenberg, from Adelaide University's School of Physics, Chemistry and Earth Sciences, said researchers have long recognized the ecological damage caused by marine heatwaves, but their effects on humans have attracted much less attention.

"Marine heatwaves are no longer just recognized as an environmental issue; they are increasingly also perceived as a human health issue," Dr. Falkenberg said.

"Our paper highlights that these events can influence people's health in many different ways, both directly and indirectly. They can intensify storms and atmospheric heatwaves, affect the availability and safety of seafood, disrupt livelihoods and contribute to anxiety, grief and other mental health impacts in communities that depend on healthy oceans."

Marine heatwaves are becoming more frequent, lasting longer and reaching greater intensity as the climate warms. Scientists have already connected them with widespread coral bleaching, large-scale deaths of marine organisms, harmful algal blooms and major disruptions to fisheries and aquaculture.

According to the researchers, those environmental disruptions can have serious consequences for people as well.

Stronger Storms, Unsafe Seafood and Food Security Risks

Extremely warm ocean water can help strengthen weather systems, raising the danger of injuries, deaths and displacement caused by storms and flooding.

Marine heatwaves can also make harmful algal blooms more likely. These blooms can contaminate seafood and create significant health hazards for people who consume or come into contact with affected marine environments.

The effects can continue long after an individual heatwave ends. Falling fish populations and reduced seafood production could undermine food security for billions of people around the world who depend on the ocean as an important source of nutrition.

The Mental Health Toll of a Changing Ocean

The researchers also draw attention to the psychological effects of marine ecosystem loss. People whose livelihoods, traditions and cultural identities are closely tied to the ocean can experience significant emotional stress as familiar environments deteriorate.

In 2025, the toxic algal bloom in South Australia was associated with high levels of 'eco-anxiety,' as well as grief, frustration and depression. The bloom was also linked to physical health problems including respiratory irritation and asthma.

"Many people rely on healthy oceans not only for food and income, but also for recreation, cultural identity and their overall sense of well-being," Dr. Falkenberg said.

"When marine ecosystems suffer, the impacts ripple through communities. We are seeing increasing evidence that these changes can contribute to eco-anxiety, grief and other mental health challenges, particularly for people who feel deeply connected to the marine environment."

Researchers Call for Public Health Planning

The authors say governments and public health agencies should prepare for marine heatwaves in ways similar to how they prepare for heatwaves on land.

That could include using marine heatwave forecasts in public health planning, accounting for human health consequences when making coastal and marine management decisions, and strengthening cooperation among ocean scientists, health agencies and resource managers.

Dr. Falkenberg said preparing before emergencies happen could make communities more resilient as marine heatwaves become increasingly severe.

"Recognizing these health impacts is the first step towards better protecting communities," she said.

"If we only respond after disasters occur, we will continue to experience greater impacts than if we had acted proactively. By understanding the links between ocean health and human health, we can develop better policies that protect both people and the marine ecosystems they depend on."

Source: ScienceDaily

Scientists turn Starlink into a giant scanner for Earth’s upper atmosphere

 The region surrounding Earth is getting more crowded as thousands of satellites and pieces of space debris move through low Earth orbit. Farther above, at altitudes of several hundred kilometers, traces of Earth's upper atmosphere can still exert enough drag to slow satellites. Accurately measuring atmospheric density at these heights is therefore important for forecasting satellite motion and reducing the risk of collisions.

More than 99 percent of the upper atmosphere consists of electrically neutral gas known as the thermosphere. The term thermospheric density refers to the density of this neutral atmosphere between about 100 and 1000 kilometers above Earth's surface. By comparison, the ionized gas of the ionosphere accounts for less than 1 percent of the atmosphere. Because ionized gas affects the way radio waves travel, the ionosphere is relatively straightforward to observe. Measuring conditions in the thermosphere is much more difficult.

A New Way to Observe the Thermosphere

Better measurements of thermospheric density could advance research into the upper atmosphere while also providing valuable information for space engineering. Motivated by both needs, researchers at Kyoto University developed a new technique for visualizing this difficult-to-observe region.

"This is a multidisciplinary study between space science and space engineering," says corresponding author Mamoru Yamamoto. "Reading papers from both research fields, we realized that deeper dialogue between researchers from both fields is necessary."

The researchers used publicly available orbital information from Starlink satellites and applied tomography, a technique commonly associated with medical imaging, to Earth's upper atmosphere. By examining atmospheric drag through the gradual decay of satellite orbits, the team estimated thermospheric density around approximately 1,200 satellites flying at an altitude of 482 kilometers.

Building a Two-Dimensional Atmospheric Map

Using those measurements, the researchers produced a two-dimensional latitude-longitude snapshot of thermospheric density at an altitude of roughly 500 kilometers. According to the team, this represents the first tomographic analysis of its kind.

The resulting density patterns also showed strong consistency with observations from the European Space Agency's SWARM satellites, which measure changes in atmospheric density along their orbital paths.

The work expands on an earlier study by the same team. In that research, scientists estimated how thermospheric density changed over time and altitude using general orbital information called Two-Line Element, or TLE, data from Starlink satellites. The new analysis adds another dimension by examining how density varies horizontally across latitude and longitude, revealing more of the thermosphere's geographic structure.

Making Crowded Orbits Safer

The findings could have practical benefits as the number of objects orbiting Earth continues to grow. More accurate information about atmospheric density can improve predictions of satellite motion, helping reduce the chance of collisions between satellites and between satellites and space debris.

The technique could also eventually support near-real-time measurements of atmospheric density around satellites. Such monitoring could improve space weather forecasting and contribute to safer, more dependable satellite operations in the future.

Source: ScienceDaily

The Atlantic Ocean can handle more warming than expected — with one big catch

 For years, climate scientists have warned that the Atlantic Meridional Overturning Circulation (AMOC) could eventually shut down if global temperatures rise too far. New findings from researchers at Utrecht University suggest that temperature alone does not determine the fate of this major ocean circulation system. The speed at which the planet warms also appears to play a critical role in whether the AMOC remains stable. The study was published in the scientific journal Nature Climate Change.

The Atlantic Meridional Overturning Circulation, or AMOC, is a vast network of ocean currents that carries warm water northward from the tropics. By moving heat around the planet, it strongly influences the global climate and helps maintain the relatively mild conditions found in Western Europe.

Scientists have long viewed this Atlantic 'heat engine' as a system that could cross a tipping point. If that happened, the AMOC could transition from its current strong circulation to a much weaker state within decades. Possible triggers include growing amounts of meltwater entering the ocean from polar regions as well as global warming itself.

Rethinking the AMOC Temperature Threshold

Researchers previously estimated that the AMOC could reach a tipping point and collapse at around +4°C of global warming. Scientists at the Institute for Marine and Atmospheric research Utrecht now say that this temperature threshold does not tell the whole story.

"Our results show there is not necessarily a fixed temperature beyond which the AMOC inevitably collapses," says lead author René van Westen. "The stability of the circulation depends on how fast the climate is changing."

The findings indicate that two worlds reaching the same eventual temperature could experience very different outcomes for the AMOC depending on how quickly the warming occurred.

Slow Warming Versus Fast Warming

To test the importance of warming speed, Van Westen and his colleagues ran two versions of a climate model. In both simulations, atmospheric CO2 increased gradually, but the rate of that increase differed substantially.

In one simulation, CO2 concentrations increased slowly (0.5 ppm per year). In the second, they climbed much more rapidly (2.5 ppm per year), which is comparable to today's rate.

The contrast produced dramatically different results. When warming occurred slowly, the AMOC remained stable well beyond +4°C and did not collapse even after warming reached +5°C. Under the faster warming scenario, however, the AMOC collapsed at around +2°C.

"We deliberately looked at a scenario that is much slower than what we're experiencing today," explains co-author Reyk Börner. "That allowed us to isolate the effect of the warming rate alone, independent of how warm it eventually gets."

Why the Ocean Needs Time to Adapt

The researchers say the difference comes down to the ocean's ability to respond to changing conditions.

"Under slow warming, the entire ocean, from the surface down to its deepest layers, has time to gradually reorganize and adapt to the changing conditions," says co-author Henk Dijkstra, professor of Dynamical Oceanography. "Under faster warming, the ocean simply can't keep up."

Slow climate change gives the ocean more time to adjust throughout its full depth. When temperatures rise more rapidly, those adjustments cannot happen quickly enough, leaving the circulation more vulnerable to instability.

A Critical Rate of Global Warming

According to the researchers, the critical warming rate is around 0.3°C per decade. The world is already approaching that pace.

Van Westen compares the situation to driving a car: "If you're driving toward a wall, it makes sense to steer around it. To do that, you need to brake, otherwise you fly off the road. When it comes to global warming, the world is still pressing extra hard on the accelerator right now."

The analogy highlights an important distinction. Avoiding dangerous climate changes may depend not only on limiting how warm the planet eventually becomes, but also on slowing how quickly it gets there.

Previous Research on AMOC Stability

The same research group has investigated AMOC stability from several different perspectives in recent years.

In 2024, the researchers found that increasing amounts of meltwater entering the North Atlantic make the AMOC less stable. Scientists had suspected this mechanism for years, but the research was the first to demonstrate it using a modern, complex climate model.

Those results showed that a critical meltwater threshold exists, beyond which the AMOC becomes unstable. However, the threshold was unrealistically high. This suggests that the present-day AMOC is unlikely to become unstable through this contribution alone. That study did not include the effects of global warming or the pace at which warming occurs.

A later study explored several global warming scenarios. It concluded that the AMOC could reach a tipping point around 2060 under both an intermediate- and high-emission scenario. In those simulations, the tipping point occurred at approximately 2.5°C of global warming.

The latest research helps explain why studies can produce different estimates for when the AMOC might reach a tipping point, as well as why temperature thresholds vary across climate models and emissions scenarios.

The AMOC does appear to have a critical threshold for meltwater, but the researchers find no universal temperature threshold for its collapse. Instead, its stability depends partly on how quickly the planet warms. Faster warming leaves the AMOC more vulnerable, while slower warming gives the ocean more time to adjust and allows the circulation to remain stable under substantially higher levels of global warming.

What the Findings Mean for Climate Policy

The findings suggest that slowing the pace of warming could reduce the near-term risk of an AMOC collapse by giving the Atlantic Ocean more time to adapt.

That could have important implications for climate policy. Much of current climate policy, including the Paris Agreement, focuses on limiting the eventual peak in global temperature.

Some strategies involve so-called overshoot pathways. Under these approaches, global temperatures would temporarily rise beyond a target limit, with the expectation that future technologies could later reduce temperatures again.

The new findings suggest that the path taken toward a given temperature may matter alongside the temperature itself. The faster global warming occurs, the less time the Atlantic Ocean has to adjust, potentially increasing the vulnerability of one of the planet's most important circulation systems.

Source: ScienceDaily

Scientists detect a surprising shift in human blood as atmospheric CO2 rises

 Rising levels of carbon dioxide in the atmosphere may already be influencing human biology. New research has identified long-term changes in blood chemistry that appear to track rising atmospheric CO2, raising concerns that an important blood marker could approach the upper end of its healthy range within the next several decades.

The findings may be particularly important for children and teenagers. Because their bodies are still developing, younger generations are expected to experience the greatest lifetime exposure to elevated atmospheric CO2.

Decades of Blood Data Reveal a Shift

In a study published in Air Quality, Atmosphere and Health, scientists from The Kids Research Institute Australia, Curtin University and The Australian National University (ANU) examined more than 20 years of U.S. population health data. They found persistent changes in several measures of blood chemistry that closely followed the upward trend in atmospheric CO2.

The researchers used information from the U.S. National Health and Nutrition Examination Survey (NHANES), analyzing blood test results from roughly 7,000 people at two-year intervals between 1999 and 2020.

Since 1999, average serum bicarbonate levels have increased by about 7 percent. Bicarbonate is a blood marker closely associated with carbon dioxide in the body. During the same period, average levels of calcium and phosphorus decreased.

Those biological trends occurred as atmospheric CO2 climbed from about 369 parts per million (ppm) in 2000 to more than 420 ppm today.

Study author Associate Professor Alexander Larcombe said the results indicate that the body may already be adjusting to changes in the composition of the atmosphere.

"What we're seeing is a gradual shift in blood chemistry that mirrors the rise in atmospheric carbon dioxide, which is driving climate change," A/Prof Larcombe said.

How the Body Responds to More CO2

Bicarbonate is essential for regulating the body's acid-base balance. As CO2 increases, the body can retain additional bicarbonate to help keep blood pH stable. Although this response helps preserve that balance, maintaining it over long periods could have physiological effects.

"If current trends continue, modeling indicates average bicarbonate levels could approach the upper limit of today's accepted healthy range within 50 years," A/Prof Larcombe said

"Calcium and phosphorus levels could also reach the lower end of their healthy ranges later this century."

Humans evolved when atmospheric CO2 concentrations were approximately 280 to 300 ppm. During the past decade, atmospheric levels have risen by an average of about 2.6 ppm each year, while 2024 alone saw an increase of 3.5 ppm.

Fellow Author Dr Phil Bierwirth, a retired environmental geoscientist affiliated with the ANU Emeritus Faculty, emphasized that the study does not establish a direct cause-and-effect relationship. However, he said the consistency of the changes across a large population warrants attention.

"I actually think that what we are seeing is because our bodies are not adapting," Dr Bierwirth said.

"It appears we are adapted to a range of CO2 in the air that may now have been surpassed.

"The normal range maintains a delicate balance between how much CO2 is in the air, our blood pH, our breathing rate and bicarbonate levels in the blood.

"As CO2 in the air is now higher than humans have ever experienced, it appears to be building up in our bodies. Maybe we can never adapt such that it is vitally important to limit atmospheric levels of CO2."

A Potential New Dimension of Climate Risk

The researchers say the results suggest that rising atmospheric CO2 could represent a form of climate-related risk that is different from more familiar threats such as heatwaves, extreme weather and sea-level rise.

According to A/Prof Larcombe, increasing CO2 may need to be considered not only as an environmental concern, but also as a long-term public health factor that should be monitored.

"We're not saying people are suddenly going to become unwell when we cross a certain threshold," he said.

"But this suggests there may be gradual physiological changes occurring at a population level, and that's something we should be monitoring as part of future climate change policy."

The researchers recommend monitoring the composition of the atmosphere together with biological markers across populations. Tracking both alongside established climate indicators could help scientists determine how slow environmental changes affect human biology over periods of decades.

Source: Science Daily

Scientists discover a hidden brain rhythm that could improve Parkinson’s treatment

 Deep brain stimulation (DBS) can reduce movement problems caused by Parkinson's disease, and new research is providing a clearer picture of why the treatment works. Scientists have found that its benefits appear to depend on stimulating a specific brain network that communicates primarily through a relatively fast beta rhythm (20 to 35 Hz).

The findings come from an interdisciplinary group of neuroscientists and clinicians at the University Hospitals of Cologne and Düsseldorf, Harvard Medical School and Charité Berlin. Published in the journal Brain, the study, 'The Deep Brain Stimulation Response Network in Parkinson's Disease Operates in the High Beta Band', is the first to bring together two approaches that have largely been studied separately: electrophysiology and brain imaging.

Pinpointing Where and How Brain Stimulation Works

"For the first time, we were able to characterize the DBS response network in Parkinson's disease in terms of space and time, simultaneously," says Professor Dr. Andreas Horn from the University of Cologne, who led the study and specializes in computational neurology. "We show that Parkinson's disease can best be treated if we stimulate a very precisely defined network. This network operates synchronized within a specific frequency band, and offers an explanation for how well patients respond to deep brain stimulation."

Deep brain stimulation of the subthalamic nucleus is already an established therapy for easing motor symptoms in people with Parkinson's disease. The treatment uses implanted electrodes to deliver small electrical pulses to areas located deep inside the brain.

Previous research has provided only part of the picture. Brain imaging studies have helped identify the locations where stimulation appears to work most effectively, while electrophysiological research has measured the frequencies of the electrical signals involved. Until now, researchers had not captured both the spatial location and timing of these signals at the same time.

Mapping a Parkinson's Brain Network

To investigate this connection, the team studied a large multicenter group consisting of fifty patients and one hundred brain hemispheres. The scientists simultaneously recorded brain activity through the implanted DBS electrodes and with magnetoencephalography (MEG).

Using these recordings, they mapped functional connections between regions deep within the brain and areas closer to its surface.

Their analysis revealed that the important network connecting the subthalamic nucleus with frontal areas of the brain communicates largely at a comparatively fast frequency (20-35 Hz). Importantly, the strength of this connection was associated with how much individual patients' motor symptoms improved following electrode implantation.

Source; ScienceDaily