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Dissociated neural representations of intensity and valence in human olfaction

Abstract

Affective experience has been described in terms of two primary dimensions: intensity and valence. In the human brain, it is intrinsically difficult to dissociate the neural coding of these affective dimensions for visual and auditory stimuli, but such dissociation is more readily achieved in olfaction, where intensity and valence can be manipulated independently. Using event-related functional magnetic resonance imaging (fMRI), we found amygdala activation to be associated with intensity, and not valence, of odors. Activity in regions of orbitofrontal cortex, in contrast, were associated with valence independent of intensity. These findings show that distinct olfactory regions subserve the analysis of the degree and quality of olfactory stimulation, suggesting that the affective representations of intensity and valence draw upon dissociable neural substrates.

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Figure 1: Ideal and observed odor space.
Figure 2: Region of interest (ROI) analysis.
Figure 3: Time course of amygdala BOLD response.
Figure 4: Time course of orbitofrontal BOLD response.
Figure 5: Functional regions of interest (fROI) defined by their correlation with individual differences either in the evaluation of intensity, pleasantness or unpleasantness of the four odor conditions and clean air.

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Acknowledgements

This work was supported by grants from the Sense of Smell Institute (SOSI), NIH-NIDCD, the Searle Fellowship, an Army MURI, NIMH (MH12829-01) and the McDonnell-Pew Program in Cognitive Neuroscience (20002024). We thank Arak Elite.

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Correspondence to A.K. Anderson or N. Sobel.

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Anderson, A., Christoff, K., Stappen, I. et al. Dissociated neural representations of intensity and valence in human olfaction. Nat Neurosci 6, 196–202 (2003). https://doi.org/10.1038/nn1001

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