University Post
University of Copenhagen
Independent of management


His biggest discovery came as an 80-year-old: A new part of the brain

Research breakthrough — Professor Kjeld Møllgård has a long career behind him, including as Rector of the University of Copenhagen. His biggest achievement, however, was when he recently found a new cerebral membrane.

Kjeld Møllgård lowered his head towards the microscope so he could get a closer look at the mouse’s brain.

Even before his current office at Panum was set in concrete in the 70s, he has looked at brains in microscopes. The stacks of black boxes on the shelves with slices of sheep and mouse brains attest to that.

But on this day, almost four years ago, he saw something that he had never seen before. A long brown line. This is surprising, he thought.

When he looks at the microscope, it is on slices of the brain. If he had cut exactly along a vein, this would explain the brown line. But his curiosity was aroused. So he examined slices cut from other joints and edges.

Here he saw the same thing, and this meant that it was not a line, but a plane. Nowadays it is clear to Kjeld Møllgård that he has found a new cerebral membrane. His life’s greatest discovery has recently been published in the prestigious scientific journal Science.

»Even a 80-year-old can be used for something or other. You are not just old and ready to be discarded with all your interest and experience,« he says.

Like expanding a house with a new storey

Kjeld Møllgård is at the microscope in the office at Panum and explains what he has found. He swivels the office chair 90 degrees and finds something on his computer.

You can see he likes communicating. He is employed by the University of Copenhagen as a professor and a part-time lecturer until 2026, when he will become professor emeritus. He conducted exams for medical students before Christmas 2022 and has done teaching right up until now, the last time.

»The young students need some young role models and not an older gentleman like me, shuffling into the auditorium,« he says.

I understand why they are jealous.
Kjeld Møllgård, hjerneforsker

On the computer he finds a drawing from one autumn day in 2019 when he was taking care of his three grandchildren. They find him good at drawing, so they often do it together. Everything from Star Wars to alpine landscapes. On this day, the oldest one thought that it should be a free drawing session. Pencils and paper were scattered across the table. Kjeld Møllgård reckoned that as he could now draw whatever he wanted, he would spend his time getting an overview of what he knew about the new cerebral membrane that he had seen for the first time in the microscope a few months earlier.

He drew the three, already familiar, brain membranes with blue, yellow and red. The new cerebral membrane he drew in with a green pencil in between two of the already known brain membranes within a space that was also already established.

»What is this supposed to be, granddad?« the children asked.

He compared it to a house. The new cerebral membrane is the separation between the storeys, set up in the high-ceiling living room, so there is now an extra floor. The blood vessels run down on the ground floor. But he could not yet explain what the newly discovered storey was used for.

He still can’t. But at night, when you sleep, the brain is flushed with brain fluid by means of vessels that run through this space. Waste products that you can see as an accumulation when the dementia disease Alzheimers is present, are flushed away. That is why his find may be important for the study of Alzheimer’s disease.

Grandchildren heard it first

When he drew the brain membrane with his children, it was the first time he had told anyone about what he had found.

After he got his article in Science, in threads of comments on the internat chat forums for the initiated, he met colleagues who believe that the fourth cerebral membrane is probably just a sub-section of the other membrane. But here the drawing that he made almost four years ago is important documentation.

»I understand why they are jealous. It was a real stroke of luck,« says Kjeld Møllgård.

»Well, there was probably a bit of understanding involved.«

Danish media released the news at the beginning of January with the headline:

»Textbooks to be rewritten after new find of extra brain membrane.«

But this will not happen immediately, according to Kjeld Møllgård.

»Nothing is true In science. Truth is just what most people believe in at a given point in time.«

It is not enough, in other words, for him to have found the cerebral membrane in his microscope. Those who are not yet convinced have to have see the membrane in theirs. Research takes time, so it may take a year before the textbooks are rewritten, according to Kjeld Møllgård.

Membrane was torn

One of the scientists who is not completely convinced is Carsten Bjarkam, a professor and chief physician at the Department of Clinical Medicine at Aalborg University Hospital.

»The discovery is interesting, but I do not believe that we yet have solid documentation for the fact that it is an independent cerebral membrane. The researchers have found that part of the brain that we normally perceive to be an independent structure is more complex, and that the innermost part has lymph vessel-properties. This is completely new and changes our understanding,« he says to

While his colleague in Aalborg will not reject the fourth cerebral membrane, Kjeld Møllgård is completely confident in the theory. He apologises, as he is »more humble usually,« he says.

»I understand that they are sceptical. I’ve been looking at brains for 50 years myself, and I haven’t seen the membrane.«

The reason no one else sees what Kjeld Møllgård sees is that neuroscientists usually cut their way in through the skull. When you do this, the most superficial brain membranes tend to follow. Then the newly found cerebral membrane follows, and it is torn apart because it is very thin – 12 μm to be exact, twelve times one thousandth of a millimetre.

Kjeld Møllgård was actually investigating the lymph vessels. To not cut through the outside membranes, he had started putting the whole skull into a decalcifying solution for a month. Then the softened skull could be removed without the outer cerebral membranes breaking. He could suddenly see the fourth one.

The method cannot be used on human brains. But he has demonstrated that there is also a fourth cerebral membrane in humans by finding the same substances that are found in the mouse’s fourth cerebral membrane.

Rector on a mission

You don’t get the impression from talking to Kjeld Møllgaard how big he actually thinks his find is.

»If you get an article in Science as a 80-year-old, it must be pretty good,« he just says. Shrugs and smiles.

Before the discovery of the cerebral membrane, he had a long career in both science and on the university senior management team. He has been dean and rector. »All this necessary administrative work,« he calls it.

»But doing research is the most fun,« he says.

He ran for the office of Rector on a campaign platform of more interdisciplinarity between the faculties.

»I always compared our university with a Greek temple with different pillars, or faculties. But the load-bearing element is the cross-disciplinary support above the pillars that carries the whole of the temple’s roof.«

You needed the support, he thought. And it was built under his leadership. It is a bit further down the Tagensvej main road: It is called the BRIC building or Biotech Research & Innovation Centre.

»It was very important for me to set up a place where both medical and natural science research, cancer research, but also legal and ethical aspects could meet,« says Kjeld Møllgård.


Kjeld Møllgård

Born 1942

Professor of neuroanatomy and external associate professor at the University of Copenhagen.

5 January 2023, he got an article in the prestigious scientific journal Science about his discovery of a new cerebral membrane.

Rector of the University of Copenhagen 1994-2002.

Story of a life

It is no coincidence that it was precisely BRIC that became the symbol of Kjeld Møllgård’s time as rector.

»Interdisciplinarity is my life story in a way,« he says.

As a child, when Kjeld Møllgård’s mates wanted to be firemen, he wanted to be a scientist. He was particularly interested in the brain.

»Because it is the brain that is you,« says Kjeld Møllgård.

»The big question is whether the human brain will ever be able to understand the human brain. In other words, can you understand something from the outside, if you only have what is in there?« he asks and points to his head.

He ended up as a neuroanatomist – someone who knows everything about the structure of the brain. As a young man, he was employed at Berkeley University in California. This was one of the first places where they carried out freeze fracturing. This means dividing the brain like when you open a sandwich to see its layers, as Kjeld Møllgård puts it.

»I was one of the first people in Europe to use this method. So I could contribute with something that no one else could,« he says.

One day, 50 years ago, he was at a large congress where a real hot shot was lecturing hundreds of leading neuroscientists. There was a long round of applause. But in the room, a young Kjeld Møllgård sat there with a question to what had just been said about the structure of the membranes. Or rather a correction. He put up his hand.

»If you could just go back to the slide number five, I can show you where the fracture that you are talking about actually is,« he said.

One thing you are good at

After the lecture, there was a coffee break, and many people wanted to talk to Kjeld Møllgård because of his correction.

»This turned into my approach. I know all your 540 muscles, 206 bones and the structure of your brain. To get access to the top of the pyramid and the best collaborating partners, you have to be able to do one thing very well.«

One of the people who wanted to talk to him was Norman Saunders who worked at University College in London. This is where interdisciplinarity comes into the picture. Unlike Kjeld Møllgård, he knew what all the small pieces that the brain consists of were actually used for. He was the world’s leading researcher into the function of the brain.

No one said to Picasso: Now you are 80 and so you had better stop painting.
Kjeld Møllgård, neuroscientist

He and Norman Saunders are still working together. Their research was published in the journal Nature in 1976. It was the biggest thing he had achieved until then.

Interdisciplinarity has become a cornerstone of his work. This was also the reason why he agreed to collaborate with brain researcher Maiken Nedergaard, who was doing research into the lymph vessels in the brain. And it was then that he, by chance, found the new cerebral membrane and got a scientific article in Science at the age of 80. It’s still fun to do research, he reckons.

»You can’t retire from a passion, and research is mine. No one said to Picasso: Now you are 80 and so you had better stop painting.«

READ ALSO: Younger scientist written out of cerebral membrane discovery