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Poster Session C: Friday, August 15, 2:00 – 5:00 pm, de Brug & E‑Hall

Probing compositional learning during spontaneous exploration of a reconfigurable 3D environment

Tzuhsuan Ma¹, Ann Hermundstad, Jakob Voigts; ¹HHMI Janelia Research Campus

Presenter: Tzuhsuan Ma

In natural settings, animals navigate richly-structured sensory surroundings and rapidly adapt to changes in these surroundings. While many studies have explored navigation in mazes and open arenas, relatively little is known about how animals navigate in terrain that lacks defined routes and is too complex to memorize. Here, we probe the structure of mouse behavior in a complex, reconfigurable 3D arena in darkness and without explicit reinforcement. Within the first several hours, mice quickly explore the whole arena and converge on a sparse set of running and jumping paths. Surprisingly, after this initial phase of exploration, mice continue to generate new long paths for several days. To capture this structure, we develop a hierarchical segmentation algorithm that compresses raw behavioral trajectories into a compact set of composable sub-paths, or ``motifs''. We find that the behavior is highly compressible, indicating that mice create long paths by combining reusable motifs, rather than through random exploration. To study the evolving dynamics of these behavioral compositions, we first show that mice combine motifs in a non-random manner, generating temporal structure that is not captured by a Markov-chain that preserves the average transition probabilities between motifs. Next, we examine different phases of behavior in generating novel compositions. We find diverse dynamics that involve the rapid creation and extinction of compositions, as well as slower and more subtle refinements such as morphing, short-cutting, streamlining, and reinforcing a composition. These results suggest that mice use diverse learning rules to configure compact behavioral trajectories through space.

Topic Area: Memory, Spatial Cognition & Skill Learning

Extended Abstract: Full Text PDF