Understanding how odors are encoded in the brain is of fundamental importance to neurobiology. The first two stages of olfactory information processing have been relatively well studied in both vertebrates and invertebrates. However, the organizational principles of higher order olfactory representations remain poorly understood. Neurons in the first relay of the olfactory system segregate into glomeruli, each corresponding to an odorant receptor. Higher-order neurons can receive input from multiple glomeruli, but it is not clear how they integrate their inputs and generate stimulus selectivity.
