Olfactory function and dysfunction in humans

Compared to other sensory modalities, the physiology and pathophysiology of olfaction remains poorly explored in humans. Yet, olfactory disorders are common in the general population, affecting up to 20% of the population. Over the recent years, the recording of ERPs triggered by the transient presentation of odorants has been receiving strong and increasing interest. The approach is not only of interest for basic researchers aiming to characterize the cortical representation of odors in humans. Indeed, it is also of great interest for clinicians currently needing objective and robust tools to diagnose disorders of olfaction. In addition, the recording of chemosensory ERPs could contribute to the early diagnosis of neurodegenerative disorders in which olfactory dysfunction is thought to constitute an early and specific sign, in particular, Alzheimer’s disease. Unfortunately, olfactory chemosensory ERPs exhibit a very low signal-to-noise ratio. Hence, although the technique is recognized as having great potential, its current usefulness remains very limited, particularly in the context of clinical diagnosis.

In a first project, we hypothesize that the low signal-to-noise ratio of chemosensory ERPs could at least in part be due to an important amount of temporal jitter affecting the brain responses to chemosensory stimulation, itself due to the number of steps required for transduction of the chemosensory stimulus into a neural impulse. For this reason, we develop an approach to reveal olfactory EEG responses that are not strictly phase-locked to the onset of the stimulus, using a method based on the continuous wavelet transform. We found that this approach significantly enhances the signal-to-noise ratio of the elicited responses, and discloses an important fraction of the cortical activity to chemosensory stimulation that is lost by conventional time-domain averaging. By providing a more complete view of how odors are represented in the human brain, we believe that our approach could constitute the basis for a robust clinical tool to assess olfaction in humans.

Researchers involved


European Annals of Oto-rhino-laryngology, Head and Neck diseases

Adaptation of the Sniffin Sticks Test in South-Kivu


Balungwe P, Huart C, Matanda R, Bisimwa G, Mouraux A, Rombaux P.


Frontiers in Neuroscience

Mechanisms linking olfactory impairment and risk of mortality


Van Regemorter V , Hummel T, Rosenzweig F, Mouraux A, Rombaux P, Huart C.



Development of a new psychophysical method to assess intranasal trigeminal chemosensory function


Huart C, Hummel T, Kaehling C, Konstantinidis I, Hox V, Mouraux A, Rombaux P.

57(5): 375-384

Journal of Bioenergetics and Biomembranes

Neural plasticity in developing and adult olfactory pathways - focus on the human olfactory bulb


Huart C, Rombaux P, Hummel T.



Parkinson disease in eldery patients: lessons from odour detection thresholds on olfacto-trigeminal interaction


Foguem C, Lemdani M, Huart C.


Neuroimage Clinical

Brain lesion-pattern analysis in patients with olfactory dysfunctions following head trauma


Lötsch J, Ultsch A, Eckhardt M, Huart C, Rombaux P, Hummel T.



Post-injury smell disorders


Rombaux P, Huart C, Balungwe P, de Toeuf C, Collet S, Duprez T.

Suppl 26(2):39-46

Current Allergy and Asthma Reports

Olfaction in Chronic Rhinosinusitis


Rombaux P, Huart C, Levie P, Cingi C, Hummel T.


Journal of Alzheimer's Disease

Unirhinal olfactory testing for the diagnostic workup of mild cognitive impairment


Huart C, Rombaux P, Gérard T, Hanseeuw B, Lhommel R, Quenon L, Ivanoiu A, Mouraux A.

47(1): 253-270

Journal of Neurology

Volume of olfactory bulb and depth of olfactory sulcus in 378 consecutive patients with olfactory loss


Hummel T, Urbig A, Huart C, Duprez T, Rombaux P.


The Journal of Pediatrics

Olfactory event-related potentials in infants


Schriever VA, Gois-Eanes M, Schuster B, Huart C, Hummel T.

165(2): 372-375


Plasticity of the human olfactory system : the olfactory bulb


Huart C, Rombaux P, Hummel T.

18(9): 11586-600

Institute of Neuroscience (IONS) - Université catholique de Louvain (UCL)