Clinical NeuroscienceAn extension of olfactometry methods: An expandable, fully automated, mobile, MRI-compatible olfactometer

â¿¢Presentation of an olfactometer design to overcome the challenges in fMRI experiments.â¿¢Challenges due to the magnetic environment, space and experimental designs are addressed.â¿¢Functional efficiency is confirmed by results of an fMRI study and a massspectrometer.â¿¢Activation in piriform cortex, OFC, amygdala, insula and hippocampus.â¿¢Stable odor concentration over time measured with CIMS.

BackgroundfMRI experiments on olfaction offer new insights into the complex, but in contrast to other sensory systems, less studied cognition of odors. To perform these experiments is still a challenge.New methodTo address the challenge posed by MR settings, an olfactometer design is presented including specific improvements to the limited number of already existing olfactometers. Innovative features such as pneumatically controlled pinch valves, useable in the scanner and providing exact stimulus timing as well as a 3D-printed nasal mask inlet for common sleep laboratory masks that can be used for lateral divided stimulus presentation are introduced. To ensure a fully automated and mobile system, the use of a flexible and easily-adapted Matlab-Code and a portable adaptable container system are presented.ResultsThe functional efficiency of these features are proven by results of an fMRI study as well as testing temporal resolution and concentration stability with a mass spectrometer.Comparison with existing methodsThe 24-channel olfactometer design presented here provides an inexpensive alternative to the currently available olfactometers including the achievement of fast onset times, lateral divided stimulus presentation and high flexibility and adaptability to different scientific questions.ConclusionThe olfactometer design presented in this paper can be seen as a realistic and feasible solution to overcome the challenges of presenting olfactory stimuli within the MR setting.