In the mushroom body of insects, odors are represented by very few spikes in a small number of neurons, a highly efficient strategy known as sparse coding. Physiological studies of these neurons have shown that sparseness is maintained across thousand-fold changes in odor concentration. Using a realistic computational model, we propose that sparseness in the olfactory system is regulated by adaptive feedforward inhibition. When odor concentration changes, feedforward inhibition modulates the duration of the temporal window over which the mushroom body neurons may integrate excitatory presynaptic input. This simple adaptive mechanism could maintain the sparseness of sensory representations across wide ranges of stimulus conditions.
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This work was supported by grants from the US National Institute of Deafness and other Communication Disorders (C.A., G.L. and M.B.), the National Science Foundation (G.L.) and a US National Institute of Child Health and Human Development intramural award (M.S.).
The authors declare no competing financial interests.
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Assisi, C., Stopfer, M., Laurent, G. et al. Adaptive regulation of sparseness by feedforward inhibition. Nat Neurosci 10, 1176–1184 (2007). https://doi.org/10.1038/nn1947
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