Lateralisation of nasal cycle is not reflected in the olfactory bulb volumes and cerebral activations

• Published in: The European journal of neuroscience 2024-05, Vol.59 (10), p.2850-2857
• Main Authors: Thaploo, Divesh, Joshi, Akshita, Thomas, Marie, Hummel, Thomas
• Format: Article
• Language: English
• Subjects: Adult; Benzaldehydes; Cerebral dominance; Female; Functional Laterality - physiology; functional magnetic resonance imaging (fMRI); Handedness; Humans; Information processing; laterality index (LI); laterality index wake; Magnetic Resonance Imaging - methods; Male; nasal cycle; nasal Holter; Nervous system; Odorants; Olfactory bulb; Olfactory Bulb - physiology; Olfactory perception; Olfactory Perception - physiology; Olfactory system; Structure-function relationships; Vanillin; Young Adult
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/ejn.16323

Nasal cycle (NC) is a rhythmic change of lateralised nasal airflow mediated by the autonomous nervous system. Previous studies reported the dependence of NC dominance or more patent side on handedness and hemispheric cerebral activity. We aimed to investigate firstly the possible lateralised effect of NC on olfactory bulb volume and secondly the association of NC with the lateralised cerebral dominance in terms of olfactory processing. Thirty‐five subjects (22 women and 13 men, mean age 26 ± 3 years) participated in the study. NC was ascertained using a portable rhino‐flowmeter. Structural and functional brain measurements were assessed using a 3T MR scanner. Vanillin odorant was presented during functional scans using a computer‐controlled olfactometer. NC was found to be independent of the olfactory bulb volumes. Also, cerebral activations were found independent of the NC during odorant perception. NC potency is not associated with lateralised structural or functional differences in the cerebral olfactory system. The study focuses on functional importance of nasal cycle. We hypothesised that fluctuating nasal cycle would affect processing of olfactory stimulus and volumes of olfactory bulb. Thirty‐five subjects participated in the study, and with the help of a Nasal Holter device, we measured their nasal cycle and patent side. Comparing both olfactory bulb volumes and processing of olfactory stimulus (vanilla), no differences were found. Although nasal cycle is quite important, in terms of filtering out molecules and conditioning of the nose, functional acuity to odors is not one of them.