From synchrony to sparseness.

The neurons in the antennal lobe of the locust had been shown to encode the identity of odorants using spatially distributed synchronized patterns of neural activity. Recent work describes how such neural patterns are detected. By using non-linear membrane properties, one set of target neurons, the Kenyon cells of the mushroom bodies, are able to act as coincidence detectors, sensitive to synchronized activity. In addition, the specific circuitry between the antennal lobe and the mushroom body refines the spatial-temporal selectivity of the Kenyon cells. In this process, the neural representation of odor identity is transformed from a dense spatial-temporal code into a sparse code.