Help mazes the brain

About thinking in spaceThe ancient, navigating brain

"Excuse me, may I ask you something? How do I get here to Deutschlandfunk?" - "So there is a roundabout in front, just turn right, 90 degrees to the right. And when you have walked straight ahead, you will see a large car dealership and to the right of it is the Deutschlandfunk tower."

Our living space is the city, the forest, the steppe. Somehow we have to find our way around it and special nerve cells help us with it: Specialists, exclusively responsible for orientation in space - it was previously thought.

"Little by little, actually, over the last few years there has been increasing evidence that these cells are also relevant for the coding of non-spatial information."

"We say a tone is higher or lower, someone is superior or subordinate, even with parties we say that they are left and right parties."

Navigation with olfactory waypoints in the experiment by Markus Knauff (Markus Knauff)

Smells and sounds as waypoints

The way to Markus Knauff is not difficult to find. Up one flight of stairs in the Institute of Psychology at the University of Giessen, once on the left and once on the right, and you've reached the office. No comparison to the confusing virtual rooms into which the professor kidnaps his test subjects.

A barren labyrinth with gray walls through which lonely paths run. Wherever paths cross, fragrances exist as waypoints. At one intersection it stinks of rotten fish, at the next like fresh coffee, at the third like aftershave. The test subjects should memorize their route through the labyrinth and find it again after a while.

"And the surprising finding was that the test subjects were very good, simply because they noticed the smells at the respective intersections. And remembered that I had to turn left for the smell of fish, I had to turn right for the smell of coffee, and so on What is very interesting about that is that it also worked when those were smells that people couldn't name. "

Markus Knauff found similar results in experiments in which the routes were marked acoustically; with barking dogs, playing the piano or a bell. Knauff not only concludes from this that spatial representation can be built up with the help of the most varied of sensual impressions. His central thesis goes much further. He believes that space is a basic system of orientation for our thinking.

Spatial representation as the basic structure of our thinking

"In the development of Homo Sapiens, we imagine, the members of the group met in the evening and, for example, reported on their hunt. And when you talk about the hunt, you report a lot of spatial issues: where did the animal fled to , how did we cut him off and so on. And so - that's at least one hypothesis - this is how the special prominence of the room and the special role played by ideas may have arisen. "

Where is a safe place? Where can I find something to eat? Which is the quickest path to get there? The ability to find one's way around in the environment was fundamental to survival, especially in the earliest history of mankind. It therefore decisively influenced how inner spiritual representations were formed, ideas of what the world is like.

"I believe that people have become more and more experts in space in the evolution of Homo Sapiens. And what is special then is that areas of the brain that were originally only responsible for spatial perception and spatial orientation were increasingly used for others, much more complex skills like thinking, problem solving, and so on. "

An evolutionary hypothesis, emphasizes Markus Knauff, that is difficult to prove. But the origins of the mind are still largely in the dark to this day. And the evidence is growing.

The three 2014 Nobel Prize for Medicine; John O'Keefe, May-Britt Moser and Edward Moser (AFP / Jonathan Nackstrand)

Breakthrough research by the 2014 Nobel Prize winners

A maze with rats that have to find a way. First right, then left, then right again twice. In 1971, neuroscientist John O’Keefe made the animals walk through various routes of the maze at University College London. In doing so, he registers what is happening in her brain. In the hippocampus, a memory area that looks like a seahorse, he finds cells that he baptizes place cells. Christian F. Doeller from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig:

"These place cells or place cells are cells in the hippocampus that always fire when the animal is at a certain position in space. And these cells only fire in this one place; if the animal goes somewhere else, the cell no longer fires In principle, however, the cells also have a memory, ie when the animal comes back to that position or one day later in the same place, the cell fires there again.

The second big discovery followed in 2005. May-Britt and Edvard Moser came across cells at the Technical and Natural Sciences University in Trondheim, which they call grid cells. They collect right next to the hippocampus, in what is known as the entorhinal cortex. Doeller:

"And in contrast to the location cell, where the individual cell only fires in one place, a single grid cell fires at very different locations, in principle in a grid-like, grid-like pattern Imagine the ground, so to speak, and they help with the so-called path integration. That is, if you want to measure how long the path from A to B is, then you go through a certain number of fields of a specific grid cell. So it is a relatively rigid, but very precise system to code directions and distances in principle. "

A brain navigation system for which the discoverers jointly received the Nobel Prize in 2014. It also exists in the human brain.

Information is stored in "cognitive maps"

The Leipzig Max Planck Institute for Cognitive and Neurosciences. If you want to meet one of the scientists here who wants to take research on the brain's navigation system to a new level, take the elevator right behind the entrance. Christian Doeller welcomes you in a spacious conference room on the third floor. There is a sign on the front door: "O‘Keefe-Raum". Did the Nobel Prize winner work in Leipzig? Doeller laughs: "No, no, that's my role model."

John O’Keefe scientifically justified the 1940s thesis of the fundamental importance of spatial orientation. Christian Doeller now wants to see how far cognitive research can get with it. And gives an example that some football fans will have to nibble on.

"For example, in my lexicon of sports, Borussia Dortmund and FC Bayern Munich are of course represented very close to each other, although the two clubs are very different. But they are represented close together in my map of sports, with other aspects, a tennis club X, very much far away is represented by a soccer club Y. "

In strict scientific terms, it sounds like this: "We assume that information is represented in so-called cognitive maps, cognitive spaces."

Location and grid cells map acoustic pitches

Christian Doeller has been researching in Trondheim, the place where the grid cells were discovered, since 2016. For two years now as director of the psychology department at the Max Planck Institute in Leipzig. Navigation cells not only create spatial orientation, he says. You can structure different areas of experience by arranging information in maps according to geometrical principles. Any information. The position in a social group, political views, ups and downs in music. A groundbreaking experiment at Princeton University provided the first evidence.Pitch pitches are also evidently mapped as a spatial dimension (illustration Julia Kuhl)

Rats could produce an ascending tone by themselves. They were trained to hold down a lever, which raised a tone higher and higher. If a rat released the lever at a certain target sound, it received a reward. Amazingly, her hippocampus and the adjacent entorhinal cortex were active. Location and grid cells evidently mapped the sequence of tones that led to the food. Doeller:

"If you imagine this pitch or the series of tones, individual place cells would represent the high tones, the others the low tones. And with the grid cells, individual cells would represent a specific tone and then tones in the pitch space at different regular intervals, but not the ones in between lie."

Experiments by other researchers showed the same for other sensory impressions. "When animals look at pictures, pictures of surroundings, of pieces of furniture, and at the same time, in addition to brain activity, you also record the eye movement, i.e. where the animal is looking at a specific point in time, you can also see even though the animal is stationary and not navigating through space , one sees activity in the grid cells and in the place cell system. So in principle the visual space is mapped in the firing behavior of the cells. "

Christian Doeller also placed human test subjects in front of a monitor. You should pursue a point there. "And there we see in our fMRI signals exactly the evidence for an activity in the grid cell and place cell system in the human brain."

In Jacob Bellmund's experiment, the test subjects have to navigate through a virtual city (MPI CBS / Bellmund)

Experiments in a virtual city on the monitor

Jacob Bellmund is also present in the conference room of the Max Planck Institute in Leipzig.

"I'm interested in how our brain forms quasi cognitive maps and how we map temporal relationships between different events in our memory."

Bellmund opens his laptop. After a few key clicks, a virtual city appears on the monitor. A city with skyscrapers and small houses, parks, lanterns and many intersections. As in a computer game, the test subject makes his or her way along grayish cobbled streets. Again and again she discovers wooden treasure chests in which she finds various objects, sometimes a hat, sometimes a ball, sometimes a wheel. She should memorize the location of these objects.

"And the highlight of this experiment was that we wanted to separate the temporal distance, i.e. the time intervals between the objects, from the spatial distances between the objects. And we did that by positioning various teleporters in the city."

Every now and then the test person encounters mysterious-looking dark boxes. If you open one of them, you will be beamed to a completely different place in town. Then the search for treasure chests with new objects continues. When the walk through the virtual city is over, the test person should remember the objects they found. Your brain activity is scanned.

"What we have seen is that precisely these relationships between the positions have been mapped, as it were, in the hippocampus and in the entorhinal cortex."

Spatial and temporal location forms memory

Separately for the spatial and temporal position of the objects. The activity patterns of the two brain regions responsible for navigation were all the more similar the closer the remembered objects of the virtual city were spatially to one another. But they were also similar when the objects were discovered in quick succession.

"It was actually the case that the test subjects' brains took the time intervals in order to ultimately order the memory."

Christian Doeller is convinced that this is a far-reaching discovery. It shows how the brain manages to keep memories of events in the correct order.

"Interestingly, in the very same system, both the hippocampus and the entorhinal cortex, we find cells that encode time, so-called time cells, which only fire at a very specific point in time of an event. You could say that there will - just like rather the spatial structure of the grid cells - rather the temporal structure, the temporal context of events. "

We remember episodes of our life by locating them in time and space. There was the birthday party at my uncle's in Munich. The birthday cake in the garden. Then later a walk through the park. When did what happened where? Memory researchers speak of "episodic memory" when individual episodes of life are vividly remembered. The neural mechanisms are not yet fully understood. For Christian Doeller, the discoveries about the brain's navigation system can help.

"So these two systems, which represent these main components of the navigation system, also encode time. This is of course incredibly exciting from the point of view of a memory researcher, because these are very precisely the two components, space and time, that define an episode and thus an episodic one Contribute to memory entry. "

The navigation system in the brain may be the basis for cognitive processes (Ella Maru Studio & MPI CBS / Doellerlab)

Navigation system as a basis for generalizations?

Our mind aims to recognize structure, and the navigation cells that organize space apparently also help to sort out perceptions and memories. But we are also creative, establish logical connections, generalize and think new. Does the brain's navigation system provide the basis for this too?

"What is amazing is that we can use it so flexibly when we interpret new situations or develop connections that we have never experienced directly."

Stephanie Theves is a postdoc with Christian Doeller. When we see an unknown bird, how do we know whether it can fly or not? Theves conducted two experiments to find out what role the brain's navigational system plays in such generalizations.

Test subjects see abstract symbols on a screen: squares of differently permeable colors on which there are sometimes larger and sometimes smaller circles. Over time, the subjects learn to systematically differentiate the symbols based on these two characteristics. In the brain scanner, they should then remember the symbols again.

"What we found was that objects are represented all the more similarly in the hippocampus when they are close in conceptual space."

This means that the activity patterns in the hippocampus were more similar if the objects were objects with a similar circle size and color transparency. The navigation area had apparently rated the objects according to their essential characteristics. Something similar is represented in a similar way, that is, they move closer together in cognitive spaces.

Reduce complex information to the essentials

In a second study, Stephanie Theves examined what happens in the brain when the test subjects also had to remember other features of the figures, for example the number of points on the circular discs. Again, the activity patterns in the navigational areas of the brain were more similar when objects were remembered that were similar in terms of the relevant features alone. Apparently the areas had differentiated the regular from the non-regular, they reduced the many dimensions of the objects to the two essential ones: to size and color.

Christian Doeller leads this to the following hypothesis: "What we are assuming is that the hippocampus, the entorhinal cortex, may also make higher-dimensional information accessible, in that information is then represented in two, possibly three dimensions, as in such a section, so that it is actually in the to be able to deal with daily life. "

Abstract spatial ideas reduce the sensual variety to the essentials. Birds have different beaks, tails, feathers, or weights. For the question "Can this unknown bird fly?" but only the wingspan and weight are relevant. We apparently start from these characteristics and relate them to previous knowledge: what weight and what wingspan do birds normally have when they can fly? From this we generalize: looks like a robin, should be able to fly.

Spatial categories describe social structures

The theory of cortical maps or spaces offers an explanatory model of how geometric order patterns help to reduce the complex world to the essentials. This even extends into interpersonal relationships, as a study by New York scientists shows. Doeller:

"Test subjects were presented with social stimuli, that is, various virtual people who were in a dependency relationship. So there was one dimension of space, in principle, the power structure within a company, and it has also shown that the hippocampus also represents these very abstract social spaces.

Climb the corporate ladder. Looking down on someone. To be on top. Negotiating with someone on an equal footing ... When we describe social relationships, we often use spatial categories. This is no coincidence, says Doeller.However, it would be premature to conclude that the navigation system is only interested in hierarchies. In the New York study, the test subjects were also able to establish bonds and social closeness with virtual people. The navigation cells also reflected how strongly or weakly they were socially connected.

"Social mobility. Social advancement. The right. The left. The broad center of society. The center of political attention."

Can vivid, pictorial ideas hinder thinking?

To this day, the view exists that thinking works particularly well when it is clear and pictorial. That is why scientific textbooks are packed full of illustrations.

Markus Knauff, the psychologist and cognitive researcher from Giessen, is now skeptical: "In any case, we have shown in many experiments that thinking works better when we do it on the basis of spatial models."

One of these experiments looks like this: "The dog has a dirtier coat than the cat. The cat has a dirtier coat than the monkey. Which animal is the cleanest?"

Test subjects should answer such questions in the first part of the experiment. The second part of the experiment was about the same logical task, but the questions were less specific. "Person A is smarter than person B, person B is smarter than person C: who is the stupidest?"

Knauff: "You can't visualize that very clearly because the people remain abstract, intelligence is not something you look at people straight away. Now you could guess which tasks have led to more errors and which are better solved? - I'll tell you right away, against your intuition: people thought better with the abstract people A and B. They made fewer mistakes and were also able to think faster. "

For Markus Knauff, this means that vivid, pictorial ideas can hinder thinking. They cover the logical core of a task with too many minor details. A problem better grasp who works with abstract relationships in space and time. And cognition is also designed towards this.

Are people with strong visual imaginations worse at reasoning? (dpa / picture-alliance)

The cognitive system has limited resources

Knauff's test subjects keep telling him that when they think they imagine arrows, angles or planes that they layer next to, on top of or on top of one another. According to Markus Knauff, detailed pictures help little in logical thinking, whereas spatial connections do.

"Which animal is the cleanest?" And: "Is person A, B or C the stupidest?"

The test subjects should again solve these two tasks. This time, however, they are in a brain scanner and have to work on other tasks at the same time.

"The fact is that our cognitive system has limited resources in many areas, which means we have to deal with them efficiently. And we were able to show that it actually only bothers us when we do additional spatial tasks, while other tasks are not so much This again indicates that this thought process has a spatial character that is less concrete than pictorial ideas. "

A view that Knauff was further strengthened when his team asked test subjects how they solve their tasks. At first most of them said: visually. When the scientists inquired, a different picture emerged.

"If you ask, for example, what color the object was, they say, oh yes, I didn't even think about the color. Or how big was that exactly? We did a lot of things, for example the classification of cars in a parking lot and where they are, how they relate to each other. And then we asked what kind of car is that, is it a Mercedes or a BMW or a Porsche? And then they said, ah yes, that is irrelevant for the task, my visual imagination did not go that far. "

Abstract concepts help with logical tasks

How far can spatial thinking be trained? The results of an English study provide the first clues, says Markus Knauff. Because they show "that people who are not that good at logical thinking are often the ones who think very visually and those who are better think more abstractly. And the interesting thing is that the people who are bad are better become if you stop them from thinking too visually. "

The subjects had a choice. They were allowed to solve logical tasks by working either with abstract symbols or with descriptive graphics. The performance of many who used the graphics increased when the vivid images were taken away from them.

So does the human mind rest on an ancient system with which humans began to find their way around in their environment? When structuring a wide variety of mental functions, the brain relies on the brain's navigation system, which evolved early on. And it seems to be worthwhile to fall back on abstract spatial patterns, at least when thinking logically. These are the fundamental findings that research on the spatial foundations of cognition has provided so far. In the meantime, however, they are already the starting point for further questions: For example, whether the navigation system is a stable bastion for life - or has it changed over the years?

In old age, the navigation system in the entorhinal cortex appears to be less clear (Current Biology / DZNE)

The brain's navigation system becomes fuzzy with age

Test subjects wear glasses through which they cannot see anything while they are guided through a room by helpers. Some of them are young, the oldest is over eighty years old. Every now and then you will be asked in the middle of the way to estimate the distance between your current position and the starting point. Do the older test subjects do worse than the younger ones?

Thomas Wolbers from the German Center for Neurodegenerative Diseases in Magdeburg carried out this experiment together with American scientists. Wolbers sums up the result that not everyone aged around 50 or 55 did worse:

"Nonetheless, we see that, overall, these calculations actually get noisy with age. So it really looks like these grid cells, that the signal becomes increasingly blurred with age, that the position is coded more and more unclearly, and then the people become more and more uncertain where exactly they are in the room. "

The brain's navigation system ages and loses its precision in the process. The extent to which this also has a direct impact on cognitive abilities has yet to be investigated. But there is already evidence that it plays a role in Alzheimer's disease, which is associated with severe mental disabilities. Especially with amnesia and increasing mental confusion. Nikolai Axmacher from the Ruhr University Bochum:

"When symptoms occur, it is the case that the brain has already been largely destroyed and it will not be possible to improve the cognitive impairments with the therapy options that are conceivable in the near future."

Subjects with a genetic risk of Alzheimer's have difficulties navigating if no orientation marks are visible (RUB, Anne Bierbrauer)

A connection with Alzheimer's is conceivable

Researchers have therefore been looking for early markers for a long time. In this context, the neuropsychologist Axmacher examined people who carry a risk gene for Alzheimer's disease. It is called APOE for short and increases the risk of Alzheimer's disease three to four times. Axmacher had these carriers of the risk gene navigate virtually through a room while they were lying in a brain scanner. If the risk takers could orient themselves to clearly perceptible markings in the room, for example a lighthouse, they found the route just as well as control persons without risk genes. When such markings were absent, however, their sense of navigation worked far less well. That could be read in the brain.

"The change was massive and we hadn't expected that in the form. But it was so that the typical grid cell activity could only be found in the control subjects and not at all in the subjects with the risk factor - it actually failed completely."

So could it be that Alzheimer's disease is associated with early breakdown in the brain's navigational system? An interesting finding, but one should not jump to conclusions from this first study.

May-Britt and Edvard Moser will also devote themselves to research into Alzheimer's (Rita Elmkvist Nilsen / Kavli Institute for Systems Neuroscience)

Cognitive maps do not provide a total explanation of the mind

This also applies to research on cognitive maps as a whole, says Thomas Wolbers from the Magdeburg Center for Neurodegenerative Diseases. The brain consists of many closely interwoven subsystems. So you shouldn't overload the navigation system with expectations.

"It's just a building block, certainly an important building block, definitely, but it will certainly not explain everything."

Christian Doeller also does not claim the total explanation of the spirit for the square and grid cells. But he is convinced that looking at the navigation system will deliver lasting results and deepen our understanding of the processes in our brain:

"Simpler information is represented in other regions in the brain system. But when it comes to more complex information that also involves the combination, integration of different features, we think that these maps are very, very important."