Research
Research in the Veit lab is focused on information processing in cortical networks, using the visual system with its well-known circuitry, connectivity, and retinotopic maps as a foundation.
Our research is based on three interconnected interests
Circuits in the cortex are made up of different types of neurons. Most prominently, excitatory and inhibitory neurons can be distinguished, but each of these major groups is heterogeneous, containing many different subtypes. We are particularly interested in understanding the roles of the different inhibitory neurons, but also excitatory neurons with specific projection targets in neural coding and circuit dynamics.
Different projects focus on
- the role of SST, VIP, and PV neurons in visually induced gamma oscillations
- the role of these cell types in separating objects in a scene from the background, known as figure-ground perception
- the role of these cell types in encoding local and global visual motion.
Part of this research is funded by CRC-Transregio INCODE (https://sfb-trr384.de/, sfb-trr384.de/project/project-a05/ ) on inhibitory interneurons and how they shape the cortical code.
In this context, we also collaborate with the Allen Institute for Neural Dynamics (https://alleninstitute.org/) in Seattle, USA, in an Open Scope project (https://www.allenneuraldynamics.org/projects/openscope, alleninstitute.org/news/mapping-the-brains-visual-world-on-psychedelics-texture-and-time). Here, we aim to understand the encoding of local and global visual motion across cell types and visual areas.
While there was a lot of progress in understanding the circuits underlying the encoding of basic visual information in the last couple of decades, we still don’t understand how the “results” of these local computations are passed on and integrated in downstream areas, as well as fed back to upstream areas. When, how, and how much areas influence each other is still very poorly understood. Projects in the lab focus on
- how oscillations synchronize between different visual areas and how this synchronization depends on the activity of neurons in other areas, interneurons, and projection neurons between the areas
- the stimulus dependence of interareal influence
- the population activity patterns that are preferentially propagated between areas
All these local and distributed circuits are heavily influenced by neuromodulation. For example, when the animal starts moving, cholinergic and noradrenergic influences change firing rates, signal-to-noise ratios, and population correlations dramatically. We aim to gain a better understanding of how large, distributed populations of neurons are influenced by the moment-to-moment level of distinct neuromodulators to understand how they contribute to neuronal coding and interareal interactions.
Methods
We use an array of cutting-edge techniques in awake, behaving mice
These high-density probes can record the activity of hundreds of neurons simultaneously, across all layers of cortex, as well as the local field potential. This allows us to analyze how the encoding of distinct stimuli is implemented on the level of neuronal populations, rather than single cells. We often record with two or more probes simultaneously to understand how distributed populations work together.
We use cell-type-specific optogenetics to increase or decrease the level of activity of specific populations of neurons on a millisecond timescale with light. This allows us to not only observe, but also causally manipulate population activity patterns to test specific hypotheses about the roles of these neuronal types in the encoding and perception of specific stimuli.
This technique allows us to image the retinotopic maps of the primary and higher-order visual cortices to better target our optogenetic stimulation and electrophysiological recordings.
We use histological sections to verify the expression of the optogenetic constructs and the correct placement of our recording locations.