Abstract
Sensory systems create neural representations of sensory world, which can be reformatted from one brain region to another depending on the computational tasks such as classification, discrimination, and associative memory. Insect olfactory systems offer numerous advantages to study sensory information processing in a network of multiple layers, such as the relatively simple olfactory circuit with common design features across phyla (including mammals), the easily accessible brains to electrophysiology in intact animals, the variety of odor-induced behaviors, and the powerful genetic tools available. At the first stage of olfactory processing, each odor is represented by a unique combination of olfactory receptor neurons. This activated neural population remains relatively fixed during odor response. Although neurons in the antennal lobe receive static odor inputs from olfactory receptor neurons, lateral inhibitions in the antennal lobe produce dynamic spatio-temporal representations of odors that rapidly reduce the similarity of spatial patterns between odors over time. This decorrelation process may provide foundations for both odor classification and discrimination. Kenyon cells in the mushroom body, the important neural population for associative memory, receive odor inputs from the antennal lobe and use a sparse coding scheme to represent odors. Here, I summarize recent progresses in insects and other animals.
