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How does the brain turn experiences into memories? Scientists reveal how two neuron types control learning.
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00:05Whether we're thinking, eating, talking, laughing, riding a bike or just having a snooze, our
00:14brain is always hard at work.
00:16The brain has about 86 billion neurons, nerve cells that form an enormous network.
00:22They constantly pass information to one another as tiny electrical signals.
00:26But how exactly does that work?
00:32All that and more coming up on DW's Science Show.
00:36Welcome to Tomorrow Today.
00:41The Institute of Physiology at the University of Freiburg in Germany.
00:47This is where neuroscientist Marlene Bartos is investigating one of the brain's biggest
00:52mysteries – how we learn.
00:56How does the brain store information and bring it back when we need it?
01:04The brain is one of the least understood organs in our body.
01:10We don't really know why we remember some things extremely well, while other memories
01:15seem to disappear completely.
01:22Almost as if they've been wiped away.
01:29Brain research has long been shaped by two big ideas.
01:33The first is localization theory.
01:36It dates back to the physician Franz Josef Gall and the idea that specific brain regions handle
01:43specific functions.
01:44But as scientists mapped the brain, more and more specialized areas appeared.
01:50And the boundaries between them weren't always clear.
01:54The second is the neuron doctrine.
01:58Formulated by Spanish neuroscientist Santiago Ramón y Cajal, it showed that the brain is
02:03built from individual nerve cells or neurons.
02:07Rather than specialized areas, the activity of vast neural networks gives rise to thought
02:13and consciousness.
02:15There's strong evidence for both ideas.
02:18Most researchers see the brain as a combination of specialized regions working together through
02:24distributed networks.
02:28We now know that different brain areas are so strongly interconnected that these regions
02:34can perform far more diverse functions than we once thought.
02:39So today, we no longer think in terms of two opposing doctrines.
02:48So if there isn't a single memory center, how can we actually decode how memory works?
02:57Studying individual neurons might sound impossible, but is it?
03:03Today, researchers can watch individual neurons in action in real time using advanced laser
03:10microscopy.
03:13Scientists direct a laser into the brain through a tiny window in the skull.
03:18The neurons are genetically engineered to fluoresce when they become active.
03:23That faint glow can be recorded and turned into moving images of the brain at work.
03:28But can this technology really reveal how memories form?
03:35An experiment with mice navigating a virtual obstacle course may offer some answers.
03:43It's like a virtual game.
03:45The mice run on a styrofoam ball.
03:47When they find a specific spot, they get a reward.
03:50A drop of sweet soy milk.
03:55Using the laser microscope, Batos can watch what happens inside the mouse's brain as it reaches
04:02a target location.
04:04She begins with a key group of neurons known as principal cells.
04:10Principal cells make up about 80 to 85 percent of neurons in the cerebral cortex.
04:16They help encode information, from visual features like color and shape, to spatial details and
04:24sensory details, such as whether something feels soft, hard, sharp or rough.
04:33When we walk from here to the train station, the special principal cells called place cells
04:39become active.
04:42And they help encode the route to the station.
04:45You can think of them as workhorses carrying the code.
04:52Sensory information, the experiences we have, are carried, in a sense, by groups of these
04:59excitatory principal cells.
05:06Batos lets the mouse run the course again and again, even weeks later.
05:12And when the animal returns to the same virtual location, the very same network of principal
05:18cells lights up again.
05:20The mouse remembers.
05:24This suggests that learning involves forming specific neural networks tied to particular
05:31experiences.
05:32But one big question remains, what controls when the principal cells join these memory circuits?
05:42To find out, Batos is studying a second major class of neurons, inhibitory neurons.
05:53They make up roughly 15 percent of cortical neurons.
05:59Their role is to regulate principal cells, shaping when and how strongly those cells are allowed
06:06to fire.
06:09You can think of them like traffic lights, deciding who gets to go where and when.
06:19Using targeted drugs, Batos can temporarily suppress these inhibitory neurons.
06:25When their activity is reduced, something striking happens.
06:29The brain's representations become fuzzy, and clear memory traces are much harder to form.
06:35When we inhibit them, suppress their activity, everything starts to overlap and blur.
06:43So inhibitory neurons don't store memories themselves.
06:47They help keep the brain's activity organized, making sure each memory gets its own distinct
06:53neural pattern.
06:54But how does that work?
07:01That's exactly what we're working on now, understanding how inhibitory neurons determine which cells
07:09become active in a circuit and when.
07:13You can think of them as team leaders in a work group.
07:16They decide who does what and what role each principal cell takes on.
07:25Batos's research is helping explain how memories form and why they sometimes break down.
07:32So inhibitory neurons, these tiny cellular traffic controllers, might one day help explain
07:38Alzheimer's disease and schizophrenia.
07:40The mysteries of the brain are far from solved.
07:47Our brain never stands still.
07:49It's always active, taking in new information, asking questions.
07:54It's constantly devouring new ideas.
07:57But how do you measure something like intelligence?
08:00A viewer from Peru wants to know more.
08:06How is IQ measured?
08:09IQ stands for intelligence quotient.
08:12But an IQ test doesn't actually measure how smart or educated someone is.
08:17The first IQ test was developed in the early 20th century by psychologist Alfred Binet.
08:23His goal was simple.
08:24He wanted to identify children who might need extra support in school.
08:28Today, an IQ score mainly reflects how well someone can solve complex problems, recognize patterns, and process information quickly.
08:38There are many different kinds of IQ tests.
08:42A common task involves completing a sequence of words or numbers.
08:47Here, the goal is to spot the pattern and think analytically.
08:52Another task uses geometric shapes that must be arranged or completed.
08:57These tasks measure abstract thinking.
09:00The faster and more accurately someone solves them, the more points they earn.
09:05The final number at the end is their IQ score.
09:10Most people score somewhere around 100.
09:13But a score of 130 doesn't automatically make someone a genius, and 70 doesn't mean someone's unintelligent.
09:21The result may point to learning difficulties, or simply show that a person is especially strong at solving logic problems.
09:29Today, IQ tests are used in job applications and in scientific research.
09:34They can show how well someone recognizes patterns, navigates spatial problems, or works with language.
09:45But there's a lot they don't measure.
09:48Creativity.
09:50Social and emotional intelligence.
09:53Or hands-on practical skills.
09:57That's why IQ tests face ongoing criticism, especially since many of them are based on Western academic norms.
10:05And a single number can never capture who a person truly is.
10:13What are stars made of?
10:16How many colors can butterflies see?
10:19Could robots have babies one day?
10:22Do you have a science question?
10:24Then send it to us as a video, text or voice message.
10:28If we answer it in the show, then we'll send you a little gift as a thank you.
10:32So, just ask.
10:38Lynx aren't big travelers.
10:40Europe's largest wildcat prefers to stay close to home.
10:44By the 19th century, they'd almost vanished from much of Europe.
10:48Today, they live in small, isolated pockets.
10:51When populations don't mix, their gene pool shrinks, which can make them more vulnerable.
10:57So, conservationists are helping out with a little family planning.
11:06July 2024, at the Langenberg Wildlife Park in Zurich, Switzerland.
11:12It's the first checkup for the lynx kittens born in the breeding enclosure.
11:16They're eight weeks old, and today we learn both are females.
11:21They're being vaccinated, and blood and saliva samples are taken.
11:26A genetic test will confirm their family line is exactly as expected.
11:35I'm not in any doubt.
11:36We've already had several young animals from this pair and tested them.
11:40They've always been the right subspecies, the carpathian lynx we want to reintroduce into the wild.
11:47So, I'm optimistic.
11:50Now, it's time to return them to their mother in the enclosure.
11:59January 2025.
12:01During the day, it's mostly the lynx mother who appears.
12:05Her daughters rarely leave their hiding places, something Martin Kilchenmann is glad to see.
12:13When they're released, we want them to behave like truly wild lynx, staying to themselves.
12:20A lynx should never seek out humans, and that's how it should be.
12:24It keeps people from feeling threatened and helps prevent conflicts.
12:31A decision has been made.
12:33One of the young females will be released in eastern Germany.
12:37The other will move to another wildlife park.
12:41The placements are coordinated at the animal park in Bayern.
12:47Curator Dina Gephat oversees the lynx here.
12:50She also manages the stud book for European zoos and wildlife parks that breed lynx for release programs.
12:58Our goal is to keep genetic diversity in the European breeding program as high as possible.
13:03We want to avoid inbreeding, so I pair the males with the females they're least related to.
13:13The detailed family trees of all breeding lynx are stored in the electronic stud book.
13:21Mid-February.
13:22It's time for the young female in Zurich to travel to Germany.
13:28She and her sister spent a few days without their mother in the enclosure.
13:33And eventually she entered the transport crate.
13:46The transport team arrives from Bahn, bringing a male lynx who will also be released in Germany.
13:52The female from Zurich, secured and ready for the journey, is loaded as well.
13:57It's time to say goodbye.
14:03She has a bright future in the wild.
14:08The journey begins.
14:10600 kilometers north from Zurich to eastern Germany and the village of Hücheroda.
14:16The village is home to a special wildlife facility, the Wildcat Village.
14:22It includes a secluded enclosure designed to prepare zoo-born lynx for life in the wild.
14:32This is where the two Swiss lynx will stay.
14:35It's empty at the moment.
14:37They'll remain here until they're ready to be released.
14:42The idea is to let them grow up.
14:44But most importantly, to keep them as separate from humans as possible until they're adults.
14:49We want them to stay shy.
14:51We don't want a lynx wandering through a shopping center because it's hungry.
14:54They belong in the forest, so the shy-er the better.
15:01That evening, the transport arrives.
15:04The female from Langenberg is carefully unloaded.
15:08After the long trip, the team want to release her as quickly as possible.
15:13It takes some gentle persuasion, but eventually the young lynx steps out.
15:23For the next few months, this enclosure will be her home.
15:29Half a year later, she's ready for the wild.
15:32And she now has a name, Freya.
15:36A tranquilizer is prepared.
15:39Freya's journey into freedom begins with a stressful moment.
15:43She's been captured and will be given a medical check before transport.
15:48Great.
15:55Great.
15:57Good night.
16:05Great.
16:16Outside, Freya receives her final check.
16:27She's then fitted with a GPS collar so conservationists can track her first months in the wild.
16:37And then it's time, off toward freedom.
16:43The drive continues 200 kilometers east of the Wildcat Village, not far from the Czech border.
16:49Near the town of Eibnstok lies Freya's new home.
17:09This time, she doesn't hesitate. Moments later, she's out in the wild.
17:18Freya is now part of a Europe-wide effort to reconnect isolated lynx populations
17:24and ensure healthy genetic exchange for the future of the species.
17:32For wild animals, winter is just part of daily life.
17:36They know which slopes are safe and which to avoid.
17:42But when humans enter this landscape, the snow itself can become dangerous.
17:49So how can we predict when an avalanche might break loose?
17:57We're heading out with avalanche researcher Georg Kronthaler.
18:02Today's official forecast rates the avalanche danger as fairly high.
18:06But that warning covers a large area.
18:09On any single slope, the risk can vary widely.
18:15The bulletin can't tell us much about a specific slope, so I need to be able to judge it myself.
18:23That's where SkiTouren Guru comes in.
18:25The new online tool combines the official forecast with data on slope angle and the surrounding terrain.
18:33It then estimates the risk for the route.
18:36On our route, two sections light up in red.
18:42It shows the dangerous spots and their risk level really clearly.
18:46It's fantastic.
18:48But how dangerous are these spots really?
18:51To find out, Kronthaler uses what he calls a small block test.
18:56He cuts out a compact snow block about 30 to 40 centimeters across.
19:03The avalanche bulletin mentions weak, old snow.
19:06And yes, this snow is made up of angular crystals.
19:10This faceted or sugar snow pours through your fingers like sand.
19:15But I can't tell whether the layers are well bonded, so I'll test that.
19:22To check whether a slab could slide on the sand-like layer, he taps the block from the side.
19:29A slab does break loose, but only after a hard hit, and the fracture is stepped rather than smooth.
19:41According to our research, it would take a large additional load to cause a fracture here.
19:50For example, if skiers don't maintain enough distance from each other.
19:54His test is straightforward, and a short course is enough to learn the basics.
19:59To interpret the results, Kronthaler created the LARA app.
20:03It asks what the tests showed, then uses color codes to assess the risk and recommend next steps.
20:11LARA says I'm in the green zone, so an avalanche is unlikely.
20:17LARA recommends keeping generous spacing on both the ascent and descent.
20:23Skiers can learn the method in a one-day course, and when applied correctly, use it to enjoy a safer
20:30day on the slopes.
20:35Geologists believe a hidden resource may lie deep inside mountain rock, natural white hydrogen.
20:42But how do we find it, and get it out of the rock?
20:46If we succeed, it could power a new generation of clean energy.
20:54The Italian Alps, just a stone's throw from Lake Maggiore.
20:59This is where geologist Otmar Muntiner is searching for what he calls the gold of the future.
21:07He's hoping to find geologic hydrogen, also called white hydrogen.
21:12The rocks nearby Mucha are packed with iron, an important clue.
21:17When these rocks turn magnetic, it can be a hint that hydrogen is being created deep underground.
21:23Could a powerful, renewable, zero-carbon fuel really be forming right beneath our feet?
21:30A fuel that could power humanity for thousands of years?
21:34Researchers still know surprisingly little about how white hydrogen forms.
21:39This spot in Balmuccia is where we'll drill a deep borehole to understand how exactly hydrogen is produced there.
21:51Muntiner's search began three years ago, almost by accident.
21:55He was carrying out geological research, drilling hundreds of meters into the ground.
22:01Suddenly, the borehole filled with gas bubbles, hydrogen.
22:07He was struck by an idea.
22:10Could he have stumbled upon a natural hydrogen factory?
22:13Muntiner brought rock samples back to his home base at the University of Lausanne in Switzerland.
22:20Small amounts of hydrogen can form during shallow drilling when reactive rock encounters water.
22:27But Muntiner and his team realized they tapped into a deep, large reservoir of naturally occurring white hydrogen,
22:36formed by a unique geological and chemical process.
22:41When ground water encounters olivine, an iron-rich mineral in the Earth's mantle,
22:47it sparks a chemical reaction, releasing naturally produced white hydrogen.
22:53At the same time, the rock becomes more magnetic, a tell-tale fingerprint of the reaction.
23:02Lab experiments at the University of Grenoble in France back this up.
23:07When grains of olivine are crushed or react with fluids under high pressure,
23:12it releases hydrogen trapped inside the rock, visible here as a peak in the data.
23:21So the secret to how hydrogen forms is hidden inside the minerals, meaning whether they turn magnetic.
23:28To test the samples from Balmucha, Muntiner uses something surprisingly simple, a magnet.
23:36This old piece of olivine is magnetic, meaning the reaction that can generate hydrogen has already happened.
23:44Now he'll hold the magnet up to the Balmucha sample.
23:50It's not magnetic, so its hydrogen-producing potential is still untapped.
23:56If I had to bet on where to find hydrogen, it would be the spot we're going to drill next.
24:03White hydrogen can be renewed by geological processes.
24:08If we can reach it, it would be far cheaper than producing hydrogen through electrolysis.
24:12My hope is that the next deep drilling, down through the crust-mantel boundary,
24:18will reach mantle rocks that actively produce hydrogen.
24:22If we're lucky, one day we might be able to tap it as a source of clean energy.
24:29Across the border at the University of Lausanne, geologist Frank Zwan is also chasing white hydrogen from a different angle.
24:38He studies how entire mountain ranges rise and collide, the same process that created the Alps.
24:46The best places to look for hydrogen are where the Earth's crust was torn open millions of years ago
24:53and later crushed back together.
24:56When mantle rocks are pushed upward and exposed to circulating water,
25:00the minerals can start producing hydrogen gas.
25:06So the big question is, where are the large, accessible pockets of hydrogen that didn't escape?
25:15We know the Earth produces enormous amounts of hydrogen,
25:20that hydrogen would be fantastic for the energy transition.
25:24It's clean energy and non-polluting, it's basically problem-free.
25:28The challenge is finding hydrogen reservoirs that we can actually reach by drilling.
25:35Science is now caught in a kind of modern-day gold rush.
25:39The race to find white hydrogen has begun.
25:48And that's all from us this time around.
25:51Thanks for watching.
25:52We'll be back soon with more exciting stories on Tomorrow Today.
25:57See you then. Take care.
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