Sung Soo Kim
Neural Circuit Mechanisms Underlying Dynamic Stimulus Selection
In every moment, we are bombarded by an enormous amount of diverse sensory input––riotous combinations of colors, shapes and patterns, sounds, smells, and more. Yet, our brain can extract essential and salient information that allows us to plan appropriate behaviors. My lab pursues a mechanistic understanding of how populations and networks of neurons represent information about the surrounding world and how such representations are leveraged during navigation behavior to determine the next action.
My lab studies these questions in the fruit fly Drosophila melanogaster. This powerful model organism features robust navigation behaviors as part of its rich behavioral repertoire, a numerically simple brain small enough to allow whole populations of neurons to be visualized simultaneously, and genetic tractability that makes individual neuron types experimentally accessible.
Flies use visual information and path integration to navigate the world. A key brain function that supports this behavior is the sense of direction, which is encoded by a small population of neurons called compass neurons. Tethered flies navigating in a virtual reality arena actively orient to landmarks and show other direction-sensitive behaviors, even when we remove the cuticle on the top of their head to directly observe neurons involved in these behaviors. This enables us to use multi-color two-photon calcium imaging and optogenetics to record and manipulate the activity of the entire population of compass neurons and their upstream and downstream partners. We also use electron microscopy (EM) data to reconstruct neural circuit structures. By combining anatomic results with computational models, we derive explanations for the physiologically observed neural activity during navigation.
This way, we aim to learn how the sensory information of the world is transformed into abstract representations. Ultimately, we hope to reveal the computational principles of how these representations of real-world phenomena, such as the sense of direction, interact with the activity of other brain areas to influence orienting decisions.