Oscillations and Sparsening of Odor Representations in the Mushroom Body

TLDR

In insects, the antennal lobe relays olfactory signals with oscillatory output, while the mushroom body stores memories using sparse, selective representations, highlighting a contrast between dense, dynamic coding in the antennal lobe and sparse coding in the mushroom body. The study investigates how oscillatory synchronization facilitates information transfer between the antennal lobe and mushroom body. Odor representations are transformed by combining oscillatory dynamics with intrinsic and circuit properties that selectively filter and synthesize antennal lobe output. The findings confirm that oscillatory synchronization is functionally relevant, supporting correlation codes in sensory networks.

Abstract

In the insect olfactory system, oscillatory synchronization is functionally relevant and reflects the coherent activation of dynamic neural assemblies. We examined the role of such oscillatory synchronization in information transfer between networks in this system. The antennal lobe is the obligatory relay for olfactory afferent signals and generates oscillatory output. The mushroom body is responsible for formation and retrieval of olfactory and other memories. The format of odor representations differs significantly across these structures. Whereas representations are dense, dynamic, and seemingly redundant in the antennal lobe, they are sparse and carried by more selective neurons in the mushroom body. This transformation relies on a combination of oscillatory dynamics and intrinsic and circuit properties that act together to selectively filter and synthesize the output from the antennal lobe. These results provide direct support for the functional relevance of correlation codes and shed some light on the role of oscillatory synchronization in sensory networks.