Some like it, some do not: behavioral responses and central processing of olfactory–trigeminal mixture perception

Brain Structure and Function, vol. 226, pp. 247–261

Abstract

Exploring the potential of eucalyptol as a masking agent for aversive odors, we found that eucalyptol masks the olfactory but not the trigeminal sensation of ammonia in a previous study. Here, we further investigate the processing of a mixture consisting of eucalyptol and ammonia, two olfactory-trigeminal stimuli. We presented the two pure odors and a mixture thereof to 33 healthy participants. The nostrils were stimulated alternately (monorhinal application). We analyzed the behavioral ratings (intensity and pleasantness) and functional brain images. First, we replicated our previous finding that, within the mixture, the eucalyptol component suppressed the olfactory intensity of the ammonia component. Second, mixture pleasantness was rated differently by participants depending on which component dominated their mixture perception. Approximately half of the volunteers rated the eucalyptol component as more intense and evaluated the mixture as pleasant (pleasant group). The other half rated the ammonia component as more intense and evaluated the mixture as unpleasant (unpleasant group). Third, these individual differences were also found in functional imaging data. Contrasting the mixture either to eucalyptol or to both single odors, neural activation was found in the unpleasant group only. Activation in the anterior insula and SII was interpreted as evidence for an attentional shift towards the potentially threatening mixture component ammonia and for trigeminal enhancement. In addition to insula and SII, further regions of the pain matrix were involved when assessing all participant responses to the mixture. Both a painful sensation and an attentional shift towards the unpleasant mixture component complicates the development of an efficient mask because a pleasant perception is an important requirement for malodor coverage.

Authors 8

1. Franziska Sonja Müschenich corresponding Aachen Diagnostic and Interventional Neuroradiology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany. Franziska.mueschenich@web.de

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

2. Thorsten Sichtermann Aachen Diagnostic and Interventional Neuroradiology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

3. Maria Elisa Di Francesco Aachen Diagnostic and Interventional Neuroradiology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

4. Rea Rodriguez‐Raecke Aachen Diagnostic and Interventional Neuroradiology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

5. Lennart Heim Aachen Diagnostic and Interventional Neuroradiology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

6. Marco Singer

   Symrise (Germany)

   Affiliation as printed

   Scent and Care, Symrise AG, Holzminden, Germany

7. Martin Wiesmann Aachen Diagnostic and Interventional Neuroradiology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany

8. Jessica Freiherr Aachen Diagnostic and Interventional Neuroradiology

   Friedrich-Alexander-Universität Erlangen-Nürnberg · Fraunhofer Institute for Process Engineering and Packaging · Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany

   Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany

   Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany