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Elife. 2018 Mar 29;7. pii: e34831. doi: 10.7554/eLife.34831.

A transformation from temporal to ensemble coding in a model of piriform cortex.

Author information

1
Edmond and Lily Safra Center for Brain Sciences, Hebrew University, Jerusalem, Israel.
2
Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States.
3
Department of Neurobiology, Duke University School of Medicine, Durham, United States.

Abstract

Different coding strategies are used to represent odor information at various stages of the mammalian olfactory system. A temporal latency code represents odor identity in olfactory bulb (OB), but this temporal information is discarded in piriform cortex (PCx) where odor identity is instead encoded through ensemble membership. We developed a spiking PCx network model to understand how this transformation is implemented. In the model, the impact of OB inputs activated earliest after inhalation is amplified within PCx by diffuse recurrent collateral excitation, which then recruits strong, sustained feedback inhibition that suppresses the impact of later-responding glomeruli. We model increasing odor concentrations by decreasing glomerulus onset latencies while preserving their activation sequences. This produces a multiplexed cortical odor code in which activated ensembles are robust to concentration changes while concentration information is encoded through population synchrony. Our model demonstrates how PCx circuitry can implement multiplexed ensemble-identity/temporal-concentration odor coding.

KEYWORDS:

concentration invariance; neuroscience; none; normalization; olfaction; piriform cortex; sensory coding; spiking network model

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