A groundbreaking discovery by Attila Losonczy and his research group could open new horizons in the treatment of ageing-associated and neurological diseases. The collaborative research conducted by the Zuckerman Institute at Columbia University in New York, the BrainVisionCenter Research Institute and Competence Centre led by Balázs Rózsa, and the HUN-REN Institute of Experimental Medicine has achieved revolutionary results. Using a 3D laser scanning microscope developed by a Hungarian team, researchers succeeded for the first time in observing the formation of memories within living animals in mere fractions of a second, in structures a hundred times thinner than a human hair. The study was published in the prestigious journal Nature.

The recall of memories is based on changes in the strength of connections between brain cells, known as synapses. Although this theory has been around for nearly fifty years, scientists have not been able to directly observe such synaptic changes in living rodent models. Only in recent years have advances in microscopic technologies allowed researchers to study the real-time activity of brain cells in living, behaving animals.“A deeper understanding of the mechanisms underlying memory formation and consolidation is essential for identifying precise genetic and molecular targets for future therapies,” said Attila Losonczy, Principal Investigator at the Zuckerman Institute at Columbia University, emphasizing the societal benefits of the work. The exploration of these mechanisms is key to the mission of the BrainVisionCenter, founded by Botond Roska and Balázs Rózsa, and the therapeutic and diagnostic mission will be partly carried out at the institute.

The hippocampus, a key region involved in memory, is one of the most studied areas of the brain, but research in recent decades has relied primarily on EEG scans and brain slices. While they are valuable, the inability to study brain processes in real time with high spatial and temporal resolution in living animals limits the capabilities of these methods. Observing neural networks in action is essetnial for a more profound knowledge of brain function, which requires technologies capable of rapidly and accurately scanning cells and synapses within large volumes of tissue.

“Current models of learning and memory are based on the idea that the strength of synapses, or connections between cells in the brain, changes during learning and memory consolidation. Although previous insights into the functioning of synaptic plasticity came from experiments with relatively simple animals, such as sea slugs, or from research conducted under artificial conditions, such as from brain cells grown in laboratories, this model of memory has become extremely successful over the past 50 years and has also served as the basis for the rapid development of artificial intelligence. It is not surprising, however, that studies in live animals have not been done until now, as this has been a huge technical challenge for researchers,” explained Attila Losonczy.

The team’s research, published in Nature, marks a significant breakthrough in overcoming this obstacle. Their goal was to develop a method to measure long-term synaptic plasticity—the changes in synapse strength that can last for hours or days—in the neurons responsible for learning and memory in real-time, using living rodent models. Achieving this required the specialized two-photon laser scanning microscope developed by the group led by Balázs Rózsa at the HUN-REN Institute of Experimental Medicine and utilized at the BrainVisionCenter. Equipped with 3D real-time motion correction, the system compensates for the brain’s constant movement, enabling the study of minuscule brain structures such as cells and their extensions.

“In in-vivo measurements, involuntary movements such as heartbeat and breathing, as well as voluntary movements, can cause displacements of tens of micrometers, much larger than the structures being measured. This, in turn, makes measurements with high spatial and temporal resolution impossible because the biological structures of interest (cell bodies, cell processes, dendrites, dendritic spines) constantly evade the laser scan. The femtosecond [one millionth of a thousand billionth of a second, the time it takes light to travel 0.3 micrometers, roughly the size of a bacterium] laser scanning technique that we use compensates for movement in real time and in 3D,” explained Balázs Rózsa, Director of BrainVisionCenter, Principal Investigator at HUN-REN KOKI and co-author of the publication, explaining the usefulness of the new method.

The system can image activity in structures as small as one-hundredth the thickness of a human hair and is fast enough to capture the changes in synaptic strength that occur on a millisecond scale. By combining this microscope with voltage sensors, the team achieved what had seemed impossible: measuring voltage signals at the level of a single synapse in the brain of a live, behaving animal.

One of the most surprising discoveries was that the synapses of the observed hippocampal neurons [located in the temporal lobe of the brain, key to learning, memory and spatial orientation] did not behave uniformly along their branched extensions, the so-called dendrites. Throughout the measurements, synaptic activity and strength varied along the dendritic branches near the apex of pyramidal cells but not near their base. “It’s still unclear why this happens or why this mechanism is important,” noted Losonczy. “We know that memories are organized at multiple levels, from synapses to individual neurons and neural circuits. Now we see that even within a single cell, there may be a level of organization.”
These findings pave the way for further studies aimed at understanding the molecular, biochemical, and genetic changes responsible for preserving the altered synaptic strength and stabilizing it at the cellular level.

This is not the first major scientific breakthrough by Losonczy’s team, achieved with the help of Hungarian developments. In 2020, their research on inhibitory neurons in the brain’s memory center was published in Neuron. This was followed in 2022 by another Nature publication demonstrating that neurons in an important memory center work together in small, coordinated networks.

The BrainVisionCenter Research Institute and Competence Center (BVC), in collaboration with the HUN-REN Institute of Experimental Medicine, has developed a unique virtual reality (VR) headset optimized for mice. This innovation opens new horizons in the study of brain function and the development of vision-restoring brain-computer interfaces. The device, named Moculus, is the first to enable the realistic simulation of natural vision in experimental animals. While previously it took experimental animals 5–9 days to learn to differentiate between two images, with the new device, this learning process can now be 100 times faster. This means that studying the mechanisms of vision is now possible within an hour.

Their newly developed virtual reality system, combined with rapid 3D imaging, has enabled rodents to perform fast visual learning tasks in as little as one day. Moculus provides a more realistic virtual presence for mice in the VR world through a lifelike, stereoscopic display, significantly accelerating the learning process.

Over the past 20–30 years, neuroscientists, pharmaceutical companies, and corporations have developed numerous virtual reality tools to study the vision of experimental animals. However, these tools all relied on two-dimensional projections to represent virtual spaces, assuming that experimental animals, like humans, could understand and reconstruct the surrounding 3D reality from two-dimensional projections, such as the flat image of a television screen. Recent research, however, has revealed that this assumption is incorrect. For rodents, two-dimensional projections do not provide a realistic experience, which distorts the results.

This was illustrated with a simple yet convincing example: mice ran across a virtual abyss displayed on traditional VR screens without hesitation. In contrast, they almost immediately stopped and even retreated backward when the abyss was presented using the newly developed Moculus system, as they perceived it to be realistic.

In other words, the Moculus project demonstrated that mice can only perceive the world in three dimensions if the virtual reality is precisely calculated and projected in a way tailored to their vision, replicating how they see reality. This is because, unlike humans, mice lack sufficient capacity for abstract visual thinking.

The Moculus VR system includes a specialized treadmill that records and transmits data on the mouse’s movements, two screens, and an optical imaging system designed to match them. This system provides a field of view wider than 180 degrees, which is essential for mice, allowing them to interact naturally with the virtual environment. Meanwhile, researchers can use two-photon microscopy to precisely map the brain activity patterns of the mice. Mapping these patterns offers insights into how animals learn and the neural mechanisms that regulate decision-making. These studies not only enhance our understanding of fundamental brain functions but also contribute to the development of therapeutic solutions for neurological disorders, such as vision impairments.

The essence of learning lies in the fact that these rich neuronal representations compete with one another. During learning, a kind of “competitive process” takes place in the brain among spatiotemporal neuronal representations. The goal of this competition is to encode behaviorally relevant information, such as rewards or punishments. Researchers have demonstrated that feedback derived from rewards and punishments serves as the critical information that continuously teaches and reprograms the functioning of the entire neural network at the cellular level. This process ultimately determines the “winning” representation, which dominates the encoding, while the coding of other previously competing information decreases and returns to baseline activity.

According to the current state of the literature, neuronal activity in the visual cortex increases by only about 10% as a result of learning. However, the most recent studies report even more surprising findings, including cases of 0% change in activity or even decreases in activity. It is important to note that in these earlier studies, training mice took at least 5–9 days, providing ample time for various processes to reorganize brain activity patterns.

The ultra-fast learning capability provided by Moculus has, for the first time, enabled the capture of a snapshot of brain activity before reorganization processes have begun. The results revealed that the functioning of vision differs significantly from previously established textbook data. The brain can temporarily activate nearly all neurons in the visual cortex to perform visual tasks, thereby maximizing its computational capacity to ensure the richest possible representation of the specific visual components.

The study of mice using VR headsets opens new possibilities in neurobiological research and can contribute to a more comprehensive understanding of the human brain’s functioning. The project’s most significant achievement is that the new tool generates spatiotemporal brain activity patterns that encode specific visual elements of the environment with unparalleled precision and depth. This capability allows vision restoration devices based on 3D acousto-optical microscopy to reactivate neuronal activity more accurately than ever before, enabling the creation of much more precise artificial vision.

The mouse VR system has generated significant interest in the market for neuroscience research tools, as no similar device is currently available. One of its major advantages is its compact, modular design, which allows it to be easily integrated with various electrophysiological or imaging equipment, such as two-photon microscopes.

The project is the result of a collaboration between the BrainVisionCenter, founded in 2021 by Botond Roska, Balázs Rózsa (Director), and the Ministry of Innovation and Technology, and the HUN-REN Institute of Experimental Medicine. The research was supported by grants ERC-682426 (VISIONby3DSTIM), GINOP-2016, NKP-2017, VKE-2018, GINOP-2021-00061, PM/20453-15/2020, KFI-2018-097, AMPLITUDE, GYORSÍTÓSÁV-2021-04, GINOP_PLUSZ-00143, GYORSÍTÓSÁV-2022-064, NL-2022-012, KK-2022-05, ED-2021-00190, ED-2022-00208, and Gergely Szalay’s NKFIH/143650 research fellowship.

Gergely Dobos, Balázs Rózsa, and Gergely Szalay are the inventors of the PCT/HU2020/050029 patent.

Publication: Moculus: an immersive virtual reality system for mice incorporating stereo vision

DOI: 10.1038/s41592-024-02554-6

The BrainVisionCenter Research Institute and Competence Center (BVC), in collaboration with the HUN-REN Institute of Experimental Medicine (HUN-REN KOKI), has developed a virtual reality (VR) headset optimized for mice. This groundbreaking device creates new avenues for studying brain function and advancing brain-computer interfaces aimed at restoring vision. The device, named “Moculus,” provides experimental animals with a highly realistic simulation of natural vision, enabling up to 100 times faster learning. The innovation aligns with the mission of the BVC, founded by Botond Roska and Balázs Rózsa, which focuses on developing vision-restoring therapies and treatments for central nervous system diseases. The development is the work of Linda Judák, Gergely Szalay, Gergely Dobos, and Balázs Rózsa, who examined the plasticity of the mouse visual cortex during rapid learning. The significance of their research is underscored by its publication in one of the world’s most prestigious scientific journals, Nature Methods.

The cortical representation of behavior and perception is one of the key areas of scientific research, as it forms the foundation for a deeper understanding of brain mechanisms and the discovery and development of related therapeutic strategies. To understand these phenomena at the level of individual cells, the most appropriate method is to study the brain activity of mice using real-time 3D imaging. However, during such studies, it is particularly important to keep the mouse’s head completely stable, as movement can compromise the accuracy of the results. Researchers typically achieve this by fixing the mouse’s head and employing virtual reality systems.

Over the past 20–30 years, neuroscientists, pharmaceutical companies, and corporations have developed numerous virtual reality tools to study the vision of experimental animals. However, these tools typically used two-dimensional projections to represent virtual spaces, assuming that experimental animals, like humans, are capable of reconstructing the surrounding 3D reality from two-dimensional images, such as humans do for the flat image of a television screen. Researchers from HUN-REN KOKI, BVC, the Institute of Molecular and Clinical Ophthalmology Basel, and Pázmány Péter University, however, have demonstrated that this assumption is incorrect. For rodents, two-dimensional projections do not provide a realistic experience, which can distort behavior results. This was illustrated by Gergely Dobos and his colleagues with a simple yet striking example: mice crossed a virtual abyss displayed on traditional VR screens without hesitation. In contrast, they immediately stopped and even retreated backward when the abyss was presented using the Moculus system.

“The project has proven that mice can only perceive the world in three dimensions if virtual reality is projected in a realistic way tailored to their vision. Unlike humans, mice lack sufficient capacity for abstract visual thinking, making it essential for what they see to faithfully reflect reality,” explained dr. Gergely Szalay, lead researcher at HUN-REN KOKI and BVC.

The Moculus VR system includes a specialized treadmill that records and transmits data on the mouse’s movements, two screens, and a matching optical imaging system. The latter provides the mice with a field of vision wider than 180 degrees, enabling them to interact naturally with the virtual environment. Meanwhile, researchers can map the mouse’s brain activity patterns using two-photon microscopy, which allows them to gain deeper insights into how animals learn and the neural mechanisms that govern decision-making. These studies not only advance our understanding of fundamental brain functions but also contribute to the development of therapeutic solutions for neurological disorders, such as vision impairment.

“Rodents’ visual learning abilities are surprisingly advanced. Contrary to previous assumptions, they can acquire new visual information in as little as one day, or sometimes just 30 minutes. This means rodents learn over 100 times faster with Moculus than with earlier virtual reality systems, which required 5–9 days of training. By reducing the difficulties and artifacts associated with lengthy training sessions, Moculus is revolutionizing the study of visual learning mechanisms, enabling discoveries even during a single short training session,” explained Dr. Linda Judák, lead researcher at HUN-REN KOKI and BVC. One of the device’s greatest advantage is its ability to identify complex brain activity patterns associated with learning, including so-called anticipatory neuronal signals that appear even before the presentation of visual stimuli. Dr. Linda Judák also added that during their research, they observed that neurons gradually become engaged in the learning process, with their activity intensifying particularly during the critical period preceding behavioral decisions. Using the device, they discovered new, previously unknown neural network mechanisms that emerge during visual learning.

According to current scientific literature, the activity of neurons in the visual cortex increases by approximately 10% as a result of learning. Moreover, the latest research has produced surprising findings: in some cases, a 0% change in activity or even a decrease in activity has been observed. It is important to note that in these earlier studies, training mice took 5–9 days, providing sufficient time for memory consolidation processes to reorganize brain activity patterns. Thanks to the ultra-fast learning opportunity provided by Moculus, researchers were able, for the first time, to capture a snapshot of brain activity before these reorganization processes began, directly observing the effects of learning. The results indicate that the functioning of the visual cortex differs significantly from the previously accepted textbook data. The brain is capable of activating nearly all neurons in the visual cortex for a short time to perform visual tasks, thereby maximizing its computational capacity to achieve a richer representation of visual components.

The essence of learning lies in the competition between these rich neuronal representations. During the learning process, a kind of “competitive process” occurs in the brain among spatiotemporal neuronal representations, aiming to encode behaviorally relevant information, such as positive or negative reinforcement. It has been demonstrated that the feedback derived from these signals is the critical information that teaches and reprograms the functioning of neural networks at the cellular level. This process determines the “winning” representation that dominates the encoding, while the coding of other information returns to baseline activity,” explained Dr. Balázs Rózsa, Director of BVC and Group Leader at HUN-REN KOKI and Pázmány Péter Catholic University.
He emphasized that the most significant achievement of the project is the new tool, which generates spatiotemporal brain activity patterns that encode specific visual elements of our environment with orders of magnitude greater precision and depth. This enables vision restoration devices based on 3D acousto-optical microscopy to reactivate neuronal activity with unprecedented accuracy, thereby creating much more precise artificial vision than ever before.

“Three years ago, at the end of 2021, during the establishment of the BrainVisionCenter, Botond Roska and I identified as our main mission, the basic research in vision restoration, the development of specialized research tools necessary for this, and cortical vision restoration related research. Moculus represents an important milestone in these efforts, as it allows the cortical role of the genetic engineering methods developed by Botond and his team to be tested more effectively than with previous methods,” emphasized the director.

The device has generated significant interest in the field of neuroscience research tools, as no similar solution is currently available on the market. One of its major advantages is its compact, modular design, which makes it easily adaptable to any electrophysiological or imaging equipment, such as two-photon microscopey system.

In June, we had the incredible opportunity to participate in the Kosztolányi Dezső High School Career Orientation Day. Our goal was to show that there are many paths to success in research. Whether you plan each step meticulously, take spontaneous opportunities, or explore multiple interests until you find your true passion, every approach is valid. The journey might include failures and dead ends, but each step is a learning experience.

We emphasized the crucial role that biology and chemistry play in our everyday lives. With deep knowledge and practice in natural sciences, we can shape the future of humanity. Here are some inspiring examples:

• Chemistry for Clean Water: Chemists can contribute to providing drinking water in areas where it is scarce, ensuring minimal carbon dioxide emissions and environmental impact.
• Fluorescent Sensors in Medicine: Developing efficient fluorescent sensor molecules aids neuroscientific discoveries and therapies.
• Gene Editing in Biology: Research biologists can help cure or alleviate symptoms of life-threatening diseases through gene editing.

We hope to have sparked some thoughtful career considerations.

We proudly announce that BrainVisionCenter co-founder, Botond Roska, has been awarded the 2024 Wolf Prize in Medicine. The Hungarian neurobiologist, professor, and director of the Institute of Molecular and Clinical Ophthalmology Basel (IOB) in Switzerland, received the medical prize jointly with French scientist José-Alain Sahel, who works in France and the United States. This award recognizes their efforts aimed at restoring vision to blind individuals using optogenetic therapy.

The Wolf Prize in Medicine, established in 1978, is one of the six Wolf Prizes and is considered the third most prestigious award in medicine, following the Nobel Prize and the Lasker Award.

Learn more about their pioneering research here.

 

 

The scientific event features presentations by leading researchers, collaborators and partners of the BrainVisionCenter Research Institute and Competence Centre in the following topics, which forms the basis for future medical diagnostic and therapeutic tools and procedures:
– new molecular biology and neurochemistry methodologies,
– new developments and measurements in 3D acousto-optical laser microscopy,
– a completely new principle of brain function,
– the use of AAV measurement vectors and related innovation breakthroughs
– the diagnosis, inheritance and state-of-the-art therapeutic possibilities of ophthalmic disease.

Scientific Presentations

Prof. Dr. Balázs Rózsa – Senior Researcher

Functional clusters of cells in the brain: 3D laser scanning microscopy has challenged decades of dogma about brain function

Fundamental to the BrainVisionCenter’s mission, we have developed new methods for in vivo measurements that have been awaited by science for more than 20 years: fast, 3D direct optical measurement of neuronal electrical activity; 3D fast image stabilization that allows the real-time elimination of motion artefacts caused by breathing, physical movement and heartbeat; and the activation of neuronal networks with 3D spatiotemporal patterns. Our fast spatial measurements have shown that neurons in the memory centre of the brain and in the visual cortex learn together by organising into small clusters. Learning appears as a kind of competition in the brain, where the more successful group of cells with stronger representations gradually overcomes the weaker one and takes over. A major breakthrough has been achieved with the laser microscope, which allows the cells responsible for spatial orientation and visual representation and their functional neighbours – which are relatively dispersed in the deeper layers of the brain – to be measured simultaneously in 3D with a precision and high speed that no other method can achieve.

Dr. Zoltán Mucsi – Department of Biological Chemistry

New opportunities in neurobiology: rewiring voltage sensors and new neural networks using chemistry – Research goals of the Department of Biology-Chemistry of BrainVisionCenter

The enormous temporal and spatial resolution of 3D acousto-optical systems allows us to study biological processes in neurons at very small microsecond time intervals using specific sensor molecules. Special fluorescent, voltage-sensing molecules are needed to visualise and study these processes, and their research and development is a priority. An important aspect in neuroscience is the ability to trigger stimuli under controlled conditions, confined in space and time, for which we are developing so-called photosensitive uncaging triggering molecules. We are developing novel reagent systems for the laser-guided generation of precision neural networks, whose future application could open up revolutionary perspectives in medicine.

Dr. Arnold Szabó – Head of Human Retina Laboratory

The importance of human biological model systems in neuroscience research

In the absence of suitable human model systems, complex neural networks are typically studied using live experimental animals or animal tissue samples. The insights gained form the basis of our biological knowledge, but a major obstacle is that results from animal studies cannot be directly applied to humans. A survival human retina model developed at Semmelweis University allows complex experiments previously thought impossible to be performed on human retinal tissue, thus bridging the gap between animal studies and clinical trials.

Dr. Gergely Szalay – Head of Department of Biology

Development of a high-resolution acousto-optic stimulation technology for the targeted elicitation of specific cortical activity patterns

In contrast to the retina, the cortical representation of visual information shows no spatial organisation; individual sensations are encoded in the activity patterns of neurons that may be quite distant from each other. In order to artificially induce this type of sensations, we are developing a stimulation technique to control the activity of individual neurons individually according to a predefined pattern without affecting neighbouring cells. To achieve this, we exploit the fast switching capability of a 3D acousto-optical microscope, which allows us to control the location of stimulation, amplitude and wavelength at arbitrary intervals of 30 microseconds, thus creating the precise patterns required.

Dr. Zsolt Zoltán Nagy – Professor, ophthalmologist, clinical director

Genetic testing and therapeutic options in the treatment of hereditary retinal lesions

Today, the genetic background of many retinal diseases has been partially or completely elucidated. This lecture will review the most important hereditary diseases of the fundus, their diagnosis, inheritance and state-of-the-art therapeutic options. One way forward, in addition to the usual forms of ophthalmic therapy and surgery, is genetic treatments (optogenetics) to restore the independence of affected patients previously condemned to blindness.

Prof. Dr. Botond Roska – Senior Researcher

The Human Retina

Throughout history, scientists have studied animal bodies as a surrogate tool to understand human biology. However, this approach has proved insufficient to develop methods for curing many diseases, especially brain diseases. So recently, new methods have been developed to study a human organ, the eyes. These human-centred methods are in the focus of my presentation.