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Odor quality coding and categorization in human posterior piriform cortex

Abstract

Efficient recognition of odorous objects universally shapes animal behavior and is crucial for survival. To distinguish kin from nonkin, mate from nonmate and food from nonfood, organisms must be able to create meaningful perceptual representations of odor qualities and categories. It is currently unknown where and in what form the brain encodes information about odor quality. By combining functional magnetic resonance imaging (fMRI) with multivariate (pattern-based) techniques, we found that spatially distributed ensemble activity in human posterior piriform cortex (PPC) coincides with perceptual ratings of odor quality, such that odorants with more (or less) similar fMRI patterns were perceived as more (or less) alike. We did not observe these effects in anterior piriform cortex, amygdala or orbitofrontal cortex, indicating that ensemble coding of odor categorical perception is regionally specific for PPC. These findings substantiate theoretical models emphasizing the importance of distributed piriform templates for the perceptual reconstruction of odor object quality.

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Figure 1: Schematic diagram of the correlation analysis.
Figure 2: Behavioral data and univariate imaging analysis for Experiment 1.
Figure 3: Pattern discrimination of odor quality in human PPC and OFC.
Figure 4: Odorant-specific spatial maps in PPC.
Figure 5: Odor stimuli and psychophysical ratings for Experiment 2.
Figure 6: fMRI pattern discrimination of odor categorical perception in PPC.
Figure 7: Alignment of fMRI spatial patterns and perceived odor quality.

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Acknowledgements

We would like to thank T. Egner, W. Li, J.-P. Magué and T. Parrish for helpful suggestions. This work was supported by grants from the National Institute on Deafness and Other Communication Disorders to J.A.G. (K08-DC007653 and R01-DC010014).

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Authors and Affiliations

Authors

Contributions

J.A.G. conceived the experiment, with contributions and methodological suggestions from J.-D. Haynes. J.D. Howard and J.P. collected the imaging and behavioral data. J.D. Howard, J.P. and J.A.G. analyzed the data. M.G., J.-D. Haynes and J.D. Howard implemented the flat map analysis. J.A.G., J.D. Howard and J.P. wrote the manuscript.

Corresponding author

Correspondence to Jay A Gottfried.

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Supplementary Figures 1–6, Supplementary Table 1, Supplementary Data and Supplementary Discussion (PDF 404 kb)

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Howard, J., Plailly, J., Grueschow, M. et al. Odor quality coding and categorization in human posterior piriform cortex. Nat Neurosci 12, 932–938 (2009). https://doi.org/10.1038/nn.2324

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