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A Free-breathing fMRI Method to Study Human Olfactory Function
Published on: July 30, 2017
The human brain representation of odor identification
Grete Kjelvik1, Hallvard R Evensmoen, Veronika Brezova
1Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
Journal of Neurophysiology
|April 28, 2012
Summary
Identifying odors involves the entorhinal cortex and hippocampus, crucial for Alzheimer's disease and schizophrenia biomarkers. Successfully identifying odors activates these areas more than non-identified smells.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Odor identification (OI) is a clinical biomarker for neurodegenerative and psychiatric conditions like Alzheimer's disease and schizophrenia.
- Understanding the neural basis of OI is crucial for developing and refining these diagnostic tools.
Purpose of the Study:
- To directly compare the brain activity associated with identified versus non-identified odors.
- To investigate the role of medial temporal lobe (MTL) structures in odor identification.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to study brain activity in 17 females with normal olfactory function during an OI task.
- An event-related analysis compared brain responses to spontaneously identified and non-identified odors at the whole-brain and region-of-interest (ROI) levels.
- Blood oxygenated level-dependent (BOLD) signals were analyzed in key olfactory and memory-related regions, including the entorhinal cortex and hippocampus.
Main Results:
- Correct odor identification (OI) correlated with increased activity in the left entorhinal cortex, orbitofrontal cortex, and other secondary olfactory areas.
- The hippocampus and entorhinal cortex showed BOLD signal increases for identified odors and decreases for non-identified odors.
- Piriform and orbitofrontal cortices were active for both identified and non-identified odors, but showed a significantly greater response to identified odors.
Conclusions:
- The entorhinal cortex and hippocampus play a specific role in odor identification.
- Piriform and orbitofrontal cortices are involved in both olfactory processing and odor identification.
- Episodic and semantic memory systems appear to support the process of odor identification.
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