Our overarching goal is to crack the cognitive code. The fundamental question in cognitive neuroscience—what are the key coding principles of the brain enabling human thinking—still remains largely unanswered. In our long-term aim to tackle this question, we use two model systems: human memory and the neural population code for space, representing the summed activity of neurons while processing an individual’s position in its environment. This is based on one of the most fascinating discoveries in neuroscience, the Nobel Prize-awarded identification of spatially responsive cells in the rodent brain, in a region called the hippocampal formation. So-called hippocampal place cells, and grid cells in the nearby located entorhinal cortex, signal—in concert with other spatially tuned cells—position, direction, distance and speed. Thereby they provide an internal spatial map, the brain’s SatNav, the most intriguing coding scheme in the brain outside the sensory system.

Our framework is concerned with the key idea that this navigation system in the brain—potentially as a result of evolution—provides a fundamental neural metric for human cognition. Specifically, we propose that the brain represents experience in so-called ‘cognitive spaces’. For illustration, consider the simple example of describing cars, which you might do along two dimensions, their engine power and their weight. Depending on the two features, racing cars, for instance, would occupy a region characterized by high power and low weight, whereas campers by low power and high weight. We test the overarching model that—akin to representing places and paths in a spatial map—similar coding principles are involved in the formation of such cognitive spaces. Importantly, in our experimental framework we investigate if these domain-general principles support a broad range of our fundamental cognitive functions, ranging from spatial navigation, memory formation, learning, imagination, and perception to time processing, decision making, and knowledge acquisition.

Two translational research goals follow directly from this overarching mission: On the one hand we want to translate basic neuroscience to information technology to develop tools such as brain-computer interfaces to accelerate learning and to enhance cognition—with wider implications for real-world settings, such as school education. On the other hand, we want to transfer it to the clinic to identify novel biomarkers for the early detection of Alzheimer’s disease, which first affects entorhinal cortex. Our approach on neural coding in cognitive spaces can open an exciting new window into understanding this disease.

Discoveries are only made possible through innovative technologies. Our central, bread-and-butter research tools are space-resolved, functional magnetic resonance imaging (fMRI), including high-field scanning, to understand on a microarchitecture level how structure and function are associated to each other as well as time-resolved magnetoencephalography (MEG) to examine brain oscillations supporting cognition. We further combine neuroimaging with machine learning analysis techniques, informed by artificial intelligence, and innovative cognitive tasks, including virtual reality.

Space

How does the brain map space and help us to navigate the world? John O’Keefe, and May-Britt and Edvard Moser were recently awarded the Nobel Prize in Medicine for their groundbreaking discoveries of cells that constitute the brain’s SatNav. The striking quality of so-called place and grid cells in the hippocampal formation is that they signal the animal’s position in its environment, but how do they support memory and guide decision making?

By combining cutting-edge functional neuroimaging with virtual-reality techniques, we have demonstrated that similar spatial maps exist in the human brain. Our team uses proxy measures of cellular aspects of cognition in combination with the best high-resolution MRI scans. Our aim is to unravel the fine-grained, layer-specific neural mechanisms underlying successful wayfinding and its breakdown in neurodegenerative diseases and normal ageing. We are also excited by the question of how the specific structure of the brain (e.g. laminar organisation; entorhinal substructures) constrains its functional properties.

Memory

Memory is at the heart of our personality: the myriad of snapshots of our daily experiences have a pervasive and enduring influence on the self. Episodic memory permits us to live beyond the here and now by enabling us to recall events which we have experienced in the past. But how are these memories organised in the brain? What are the governing coding principles?

Our overarching model uniting our manifold experimental approaches posits that memories are not stored in isolation but are rather represented in highly dynamic, hierarchical mnemonic networks and possibly clustered in specialised hippocampal processing units. These mental maps allow us to dynamically integrate previously unrelated information and to continuously update stored representations.

Discoveries are only made possible through innovative technologies. In this ambitious research program, we leverage the best virtual reality technologies to generate life-simulating cognitive tasks to mimic everyday episodic experiences and decoding techniques for rapid readout of mental maps. In the long run, this approach will be transformed into a framework that potentially allows us to edit our memories.

Knowledge

In our everyday experience (e.g. witnessing an accident), we interpret incoming information against the backdrop of pre-existing knowledge, generalised across multiple encounters: We know what an accident is, which aspects it entails (i.e. ‘leading to traffic jam’, ‘subsequent media coverage’) and how we need to react (i.e. ‘provide first aid’, ‘call the police’). But how does the brain assemble our rich inventory of knowledge and how does it assign conceptual meaning to novel information?

We investigate knowledge acquisition by probing semantic networks in the brain and by tracking the emergence of factual information in neural systems. A detailed understanding of the fundamental coding principles of our mental maps for knowledge could in the future allow us to inform neural user models for brain-computer interfaces and help us to accelerate learning – with wider implications for real-world settings, such as the classroom and information technology.

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Our funding

Our research is funded by the Netherlands Organisation for Scientific Research (NWO-Vidi 452-12-009; NWO-Gravitation 024-001-006; NWO-MaGW 406-14-114; NWO-MaGW 406-15-291), the Kavli Foundation, the Centre of Excellence scheme of the Research Council of Norway – Centre for Biology of Memory and Centre for Neural Computation, The Egil and Pauline Braathen and Fred Kavli Centre for Cortical Microcircuits, the National Infrastructure scheme of the Research Council of Norway – NORBRAIN, and the European Research Council (ERC Starting Grant and ERC Consolidator Grant: ERC-StG RECONTEXT 261177; ERC-CoG GEOCOG 724836).