Behavioral determination of odor preference is coded by the oscillation frequency in a collective oscillating network of a terrestrial mollusk.

The brain receives sensory inputs, processes them and finally produces outputs in the form of behavior. In olfaction, many excellent studies have clarified the initial step of neural processing. However, the next step, i.e. how the meaning of the odor is added to the recognized quality of the chemical odor, is poorly understood. This is a critical problem in brain science, because the meaning of a stimulus finally determines the behavior of the animal. In this paper, we first review the characteristics of the olfactory CNS of the land slug Limax marginatus and related species, focusing on the synchronized network oscillation of membrane potentials of the neurons and then report our recent study on a neural mechanism for determining the aversive meaning of odors in the mollusk.