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Updated: Jul 10, 2026

An Objective and Reproducible Test of Olfactory Learning and Discrimination in Mice
Published on: March 22, 2018
Can we smell without an olfactory bulb?
Philippe Rombaux1, André Mouraux, Bernard Bertrand
1Department of Otorhinolaryngology, Cliniques Universitaires Saint Luc, Brussels, Belgium. philippe.rombaux@orlo.ucl.ac.be
Background:
Lack of an olfactory bulb (OB) is typically associated with anosmia.
Methods:
We present a patient with subnormal olfactory function in whom the OB could not be detected with magnetic resonance imaging (MRI).
Results:
Olfactory function was evaluated on two occasions. Orthonasal olfactory function was assessed with the "Sniffin' Sticks" test providing a score equivalent to hyposmia. Retronasal olfactory function was studied with "smell powders" indicating a decreased, but not absence of, olfactory function. Importantly, chemosensory event-related potentials were clearly present in response to olfactory and trigeminal stimuli.
Conclusion:
This indicates that olfactory function may be present in some subjects even when an OB can not be detected with MRI.
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