ESI News

Exploring how the brain predicts the future

Experience changes the way we behave. This is also true for the neurons in our brain. Scientific evidence shows that our brain uses past experience to infer what is to be expected for the immediate future. Now, ESI scientist Martin Vinck has been awarded with an ERC starting grant to research how this is implemented by brain cells.

3 Sep 2019

Crystal balls, tarot cards, tea leafs – fortune telling methods that are most evidently ineffective. If there’s one thing that might be able to predict the future, it is the brain. “The ability to predict is critical, because actions do not take place in the immediate present, but in the future.” says Martin Vinck, principal investigator at the Ernst Strüngmann Institute in Frankfurt am Main. “For example, a tennis player needs to prepare a racket swing while the ball is still in the other side of the tennis court, and thus needs to predict the future trajectory of the ball.” The ability to infer future situations based on prior experience very likely is an important key to how we perceive the world. To better understand how this strategy is implemented in the brain Martin Vinck now receives one of the prestigious ERC starting grants offered by the European Commission to support excellent research by young scientists.

Looking forward to first results: Martin Vinck is excited about the opportunities the ERC grant is offering. (picture credit: Martin Vinck)

Looking forward to first results: Martin Vinck is excited about the opportunities the ERC grant is offering. (picture credit: Martin Vinck)

The world as perceived by the brain

In a traditional view the brain works in a highly hierarchical manner. Sensory cells are specialized to detect certain properties of a stimulus, let’s say the image of a chair. Some cells will register its outline, others its colour. Higher order cells in the next level of processing bring these information together and pass it on again until eventually a coherent image is constructed, attached with a name tag and meaning – based on which a behavioural decision can follow, such as sitting down. While this systematic approach explains well how perceptions of objects are constructed, there are reasons to suspect this might not be the default working mode of the brain: We recognize a chair as a chair also when its defining characteristics are skewed, such as standing upside down or when partly hidden by another object. Moreover computing an image bottom up from its smallest details every time you encounter it takes a lot of time. Time that can be precious in an environment where survival depends on quick actions.

Perceiving our environment gets a lot quicker, more efficient, and flexible when the brain makes use of the experience it has about the world. Much like listening to the first tune of a song and already knowing what will follow, the brain has the ability to infer from a minimum amount of sensory evidence what it has to expect for the larger picture. This way standard templates can be filled in without effort and time: Brown object in known location – chair in front of office desk – sit down. Capacity then is freed up to process relevant information, namely aspects of the world that are not as expected. Brown object in known location making roaring noises – grizzly in front of office desk – run away.

Unraveling the secrets of neural communication

Over the past twenty years scientists have found more and more evidence for the predictive abilities of the brain. However very little is known about how this strategy is implemented by the neuronal cells. In his ERC funded project Martin Vinck hopes to change exactly that: “In any given situation, some sensory inputs could be predicted from prior experience, while others could be unpredicted. We are testing exactly how the responses of neurons and their coordinated activity is modulated by this predictability.” He expects the timing of neuronal responses and particularly the rhythm that is produced by the simultaneous activity of multiple neurons will be critical to separate predictable from unpredictable inputs. To test these ideas he and his co-workers will use computer algorithms to detect response rules of neurons and predict patterns of brain activity.

The idea for the project has been on Martin Vinck’s mind for quite some time. The ERC grant now puts him in the position to finally pursue his idea. Needless to say he is thrilled: “The project is challenging but I am very much looking forward. I can’t wait for the first results to come in.” What these results will look like no brain can predict. But irrespective of its exact findings, the project surely will increase our understanding of the way the brain works.

Prospective PhD Students and Postdocs who are interested in working with Martin Vinck on this project are welcome to get in touch with him via email. Further information about him and his projects can be found on his homepage.

Look again: Brain rhythms show what humans see.

Do rhythms in the brain serve a function or not? This question has been much debated by scientists. Now, a new study co-authored by ESI scientists shows how gamma-band oscillations in the visual system reflect what humans see. The results refute conclusions of a previous study and support the theory that gamma-oscillations do serve a function in information processing by the brain.

18 Jul 2019

The brain is full of rhythms that show quite something about what the brain’s owner is up to: Simple EEG recordings are enough to recognize readily if somebody is sleeping, daydreaming, or concentrating on a task. So the connection between these swinging brain rhythms and cognitive states is well established. However, the nature of this connection has remained cryptic: Are oscillations in the brain a mere by-product of neural activity? Or do they have a function in information processing within the cerebral cortex?

“If we look at brain oscillations, particularly in what we call the gamma-band between 30 and 80 Hertz, we have seen over and over that the firing thresholds for neurons change in correspondence with them – I can’t imagine that this doesn’t have a function.” explains Nicolas Brunet, Assistant Professor at Millsaps College in Jackson Mississippi and lead-author of a new study that shows, for the first time, a correlation between visual perception under natural stimulation and gamma-band activity in the human brain. The study puts a basic assumption to the test: Oscillations serve a function in how we perceive things. If they are important for example for seeing things, they should be present whenever there is something to see.

Oscillations: Always present when there's something to see?

As simple as that sounds, until recently we didn’t know if that’s actually the case. Whatever there is to see during an experiment usually doesn’t have much in common with things to see in real life. Research participants, humans as well as animals, usually get to look at checkerboards or gratings, in which contrast and colour are perfectly controlled. Many studies have shown that those simple laboratory stimuli are very potent in evoking strong gamma-band activity. But what happens when people look at more realistic images? This is something Nicolas Brunet explored a couple of years back in a study with macaque monkeys, as ESI Director Pascal Fries remembers: “Initially I was sceptical. I expected the natural and thus uncontrolled stimuli would produce ambiguous results. However, the data proved to have a very clear message: Every single of the 65 natural images we presented, elicited notable gamma-oscillations.”

Because of this, both Pascal Fries and Nicolas Brunet were very surprised to hear a team of scientists at Stanford, probing the phenomenon in a human subject, hadn’t been able to reproduce the findings. Due to severe epilepsy, the study’s subject was implanted with intracranial electrodes touching the surface of the visual cortex. The US scientists had the patient view black and white photographs of everyday snapshots like houses, cars or faces. In their report, only half of these images were accompanied by a significant increase gamma-band activity. As oscillations were absent for pictures that could be seen well, the authors concluded that the brain-rhythms do not play a functional role in perception.

Disagreements over theories is part of science, thinks Nicolas Brunet and explains: “It’s like a game of ping pong. You keep passing the ball until someone puts forward a match-winning, empirical argument.” For now Brunet is not ready to put the bat aside. He and Pascal Fries repeated the analysis of the human data themselves.

Revelation at second sight

Taking a closer look at the data they found gamma oscillations did in fact increase with every stimulus. This increase was easy to miss as it depended on the image structure. Images with little structure and larger areas of uniform grey resulted in weaker gamma-responses. Images with strong structures also produced strong gamma-band responses. Using an algorithm from computer vision Nicolas Brunet and Pascal Fries managed to quantify the correlation between image structure and rhythmic brain activity. It turned out that the amount of information contained in the gamma-band spectra was large enough to allow the scientists to tell from the oscillations alone, with 70% accuracy, which of two randomly drawn images had been presented.

More to see, more to swing – measuring image structure is a way to quantify how much information a picture contains. Cloudy grey sky like the one surrounding the “Founders Tower” on Millsaps College Campus (left) results in a low structure image (0.03 using DCT Energy measure operator). The image of the girl waving the college flag (right) is rich in details and thus has high image structure (0.31). (photographs: Nicolas Brunet)

More to see, more to swing – measuring image structure is a way to quantify how much information a picture contains. Cloudy grey sky like the one surrounding the “Founders Tower” on Millsaps College Campus (left) results in a low structure image (0.03 using DCT Energy measure operator). The image of the girl waving the college flag (right) is rich in details and thus has high image structure (0.31). (photographs: Nicolas Brunet)

Compelling results, but they come with a limitation: The data derives from a single subject. Surgery is a last resort of hope that is offered only to patients with severe epilepsy. Of those few patients who undergo surgery, even fewer require electrodes to be placed over the visual areas of the brain. Despite the single case report nature of the study, the significance of the results is not to be underestimated, believes Nicholas Brunet: “Most of our observations are made studying monkeys. And sure, humans are close to monkeys, but in the end monkeys will be monkeys.” Albeit limited to one subject, the human data does imply that observations made in macaque monkeys are transferable to people at least in this case. Whether monkey or human: The more there is to see, the more there is in swing. This shows that gamma-band oscillations are not limited to animals and artificial stimuli but do indeed play a role in how humans see the real world.

Eröffnungsfeier des Neubaus

25 Sep 2018

Nach dem Abschluss des Neubaus des Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, feiert das ESI am 20.09.2018 ab 15:00 seine Einweihung. Boris Rhein, der hessische Staatsminister für Wissenschaft und Kunst, Dr. Ina Hartwig, die Dezernentin für Kultur und Wissenschaft der Stadt Frankfurt, Dr. Andreas Strüngmann, einer der beiden Stifter (Dr. Thomas und Dr. Andreas Strüngmann) und Prof. Dr. Martin Stratmann, der Präsident der Max-Planck-Gesellschaft werden Grußworte sprechen. Prof. Dr.Wolf Singer, der Gründungsdirektor des ESI schildert die Vorgeschichte des ESI, und Prof. Dr. Pascal Fries, der Direktor des ESI, die Geschichte des ESI seit der Gründung. Abgerundet wird das Programm durch einen Festvortrag zu dem Thema “The mirror mechanism: a mechanism for understanding others” von Prof. Dr. Giacomo Rizzolatti, einem der Mitentdecker der Spiegelneuronen. Das ESI leistet Grundlagenforschung im Bereich der Neurowissenschaften und der Hirnforschung. Das Entstehen des ESI geht auf die Gründer des Pharma-Unternehmens Hexal zurück. Dr. Andreas und Dr. Thomas Strüngmann haben die Gründung durch die nach ihrem Vater benannte Dr. Ernst-Strüngmann Foundation ermöglicht. Diese finanziert aus den Erträgen des Stiftungskapitals den dauerhaften Betrieb des Institutes. Um die wissenschaftliche Exzellenz der Forschung zu garantieren, besteht ein Kooperationsvertrag zwischen dem ESI und der Max-Planck-Gesellschaft. Die Direktoren werden als Max-Planck Direktoren berufen. Das Land Hessen hat für den Neubau des ESI 30 Millionen in einer Projektförderung zur Verfügung gestellt, damit das alte Gebäude abgerissen und das neue Gebäude gebaut werden konnte. „Ich freue mich, diesen eindrucksvollen Neubau an die Mitarbeiterinnen und Mitarbeiter des Ernst-Strüngmann-Instituts übergeben zu können“, betonte Wissenschaftsminister Boris Rhein. „Er enthält alle notwendigen Räumlichkeiten sowohl für die Forschung als auch für die Verwaltung des Instituts, so dass es auch für alle zukünftigen Weiterentwicklungen räumlich gut aufgestellt ist. Das Gebäude bildet also die Basis für eine erfolgreiche Fortführung der bisherigen Arbeit und die dauerhafte Etablierung des Instituts an diesem Standort.“

„Ich bin überzeugt, dass diese Investitionen beste Voraussetzung schaffen, um auch künftig im Wettbewerb exzellenter Forschung vorne mitspielen zu können. Damit setzt das Land für die Wissenschaft ein zukunftsweisendes Signal. Die Investitionen in die Spitzenforschung in Hessen sind ein wichtiger Beitrag zur langfristigen Sicherung des Wissenschafts- und Wirtschaftsstandortes Hessen“, so Wissenschaftsminister Boris Rhein abschließend.

Auch die Stadt Frankfurt freut sich mit dem ESI über den Neubau: „Dass wir heute den imposanten Neubau des Ernst Strüngmann Institutes eröffnen dürfen, ist einer Reihe äußerst glücklicher Fügungen zu verdanken. Vorausschauend und unbürokratisch hat das Land Hessen 30 Millionen Euro bereitgestellt, um das alte, in die Jahre gekommene Hirnforschungsbäude von 1962 am Niederräder Mainufer ersetzen zu können. Auch das restliche Risikokapital wurde von den beiden Institutsgründern Andreas und Thomas Strüngmann ohne Zögern in die Hand genommen. Ein Beispiel vorbildlichen Mäzenatentums, über das wir uns als Stadt Frankfurt außerordentlich freuen.“, so Dr. Ina Hartwig, Dezernentin für Kultur und Wissenschaft der Stadt Frankfurt am Main. „Die Verbundenheit des Ernst Strüngmann Institute mit Frankfurt werten wir als ein wichtiges Signal für unseren Wissenschaftsstandort. Auch deshalb möchte ich allen Beteiligten im Namen der Stadt Frankfurt am Main meinen herzlichen Dank aussprechen.“