Christiaan Levelt poseert voor een foto.

NWO ENW-KLEIN grant for the groups of Levelt and Roelfsema

The research groups of Christiaan Levelt and Pieter Roelfsema have jointly obtained an NWO Open Competition ENW-KLEIN grant (€700.000) for their research in understanding the underlying mechanisms of visual perception and awareness.

We are aware of what we see, because our visual system almost instantaneously integrates information it receives from our eyes with the behavioral context. This process requires ongoing recurrent interactions between lower- and higher-order brain regions and is a hallmark of conscious perception. A well-established example of the essential contribution of recurrent activity in perceiving visual information is figure-ground segregation: the grouping of image elements that are behaviorally relevant and their separation from the background. While the interactions of excitatory neurons (i.e. those that activate other neurons) in the visual system have been well-studied in this process, the contribution of inhibitory neurons is still unknown.

The proposed research aims to identify the specific types of inhibitory neurons in the thalamus and cortex that are responsible for these processes and to understand how they contribute to separating behaviorally relevant visual information from the background. Our results will unveil novel biological principles that contribute to visual perception and will also have important implications for understanding awareness.


KLEIN grants are intended to realize high-quality, fundamental research driven by curiosity and/or scientific urgency. The KLEIN grant offers researchers the opportunity to develop creative and challenging ideas and to realize scientific innovations that can form the basis for the research themes of the future.

Christiaan Levelt poseert voor een foto.

Levelt Group

Plasticity of the neocortex is crucial for us to learn and adapt to our environment. Once tasks or functions are learned, the brain can carry them out very efficiently, in a routine-like fashion. However, learning and carrying out routine functions do not go hand in hand. During development the brain is highly malleable, but processes information rather slowly and erratically. Vice versa, when we perform routine tasks, little learning occurs and we ignore many inputs. This situation can suddenly change when a routine procedure results in an unexpected outcome. We rapidly become aware of additional circumstances and learn what caused the unexpected result.

Recent evidence, also from our laboratory, suggests that these increases in plasticity levels during critical periods of development or in response to reinforcement signals are achieved by a temporary reduction in cortical inhibition. Possibly, high levels of inhibition increase performance of neuronal networks by suppressing inputs that are irrelevant for the execution of routine tasks. Reduced inhibition may support learning by allowing such inputs to be taken into consideration to solve a novel challenge.

Using the mouse visual cortex as a model, the Levelt lab studies how inhibition regulates cortical plasticity levels at the right time. To achieve this goal the lab employs a combination of state-of-the art two-photon microscopy, electrophysiology, optogenetics and gene manipulation.

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Roelfsema Group

The Vision and Cognition group is led by Dr. Pieter Roelfsema, also director of the Netherlands Institute for Neuroscience. Research of this group is directed at understanding cortical mechanisms of visual perception, memory and plasticity. One of our goals is to create a visual cortical prosthesis to restore vision in blind people.


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