Animals must learn through experience which foods are nutritious and should be consumed, and which are toxic and should be avoided. This learning process is critical for survival in the wild and contributes to the motivational pull of energy dense foods in modern society. However, our understanding of the underlying cells, signals and pathways remains rudimentary. I will describe our work developing genetic tools to monitor and manipulate GI sensory pathways in the mouse, and the application of these tools to investigate mechanisms of post-ingestive learning.