Correlation between olfactory bulb volume and olfactory function in children and adolescents.

The olfactory bulb (OB) is considered to be the most important relay station in odor processing. The present study aimed to investigate the volumetric development of the human bulb and the olfactory function during childhood and youth. Furthermore, the present study aimed to investigate a possible correlation between OB volume and specific olfactory functions including odor threshold, odor discrimination and odor identification. A total of 87 subjects (46 boys, 41 girls), aged 1-17 years (mean age 8 years), participated in this study. None of them reported olfactory dysfunction or had signs of a dysfunctional sense of smell. Whenever possible, participants received a volumetric scan of the brain and lateralized olfactory tests. Volumetric measurements of the right and left OB were taken by manual segmentation of the coronal slices through the OB. Significant correlations between OB volumes and olfactory function were observed. Both, OB volumes and olfactory function increased with age, although the correlation between structure and function was not mediated by the subjects' age. In conclusion, for the first time, the present study showed a correlation between OB volume and olfactory functions in children.

Increasing olfactory bulb volume due to treatment of chronic rhinosinusitis--a longitudinal study.

Differentiation of progenitor cells into neurons in the olfactory bulb depends on olfactory stimulation that can lead to an increase in olfactory bulb volume. In this study, we investigated whether the human olfactory bulb volume increases with increasing olfactory function due to treatment of chronic rhinosinusitis. Nineteen patients with chronic rhinosinusitis were investigated before and after treatment. For comparison, additional measurements were performed in 18 healthy volunteers. Volumetric measurements of the olfactory bulb were based on planimetric manual contouring of magnetic resonance scans. Olfactory function was evaluated separately for each nostril using tests for odour threshold, odour discrimination and odour identification. Measurements were performed on two occasions, 3 months apart. In healthy controls, the olfactory bulb volume did not change significantly between the two measurements. In contrast, the olfactory bulb volume in patients increased significantly from the initial 64.5 +/- 3.2 to 70.0 +/- 3.5 mm(3) on the left side (P = 0.02) and from 60.9 +/- 3.5 to 72.4 +/- 2.8 mm(3) on the right side (P < 0.001). The increase in olfactory bulb volume correlated significantly with an increase in odour thresholds (r = 0.60, P = 0.006, left side; r = 0.49, P = 0.03, right side), but not with changes in odour discrimination or odour identification. Results of this study support the idea that stimulation of olfactory receptor neurons impacts on the cell death in the olfactory bulb, not only in rodents but also in humans. To our knowledge, this is the first longitudinal study that describes an enlargement of the human olfactory bulb due to improvement of peripheral olfactory function.

Correlation between olfactory bulb volume and olfactory function.

The olfactory bulb (OB) is considered to be the most important relay station in odor processing. Involving 125 randomly selected subjects (58 men, 67 women; age range: 19 to 79 years), the present study aimed to investigate a possible correlation between OB volume and specific olfactory functions including odor threshold, odor discrimination, and odor identification. The history of all participants was taken in great detail to exclude possible causes of smell dysfunction. All participants received an otolaryngological investigation including a volumetric scan of the brain (MRI), lateralized olfactory tests and a screen for cognitive impairment. Volumetric measurements of the right and left OB were performed by manual segmentation of the coronal slices through the OB. Significant correlations between OB volumes in relation to olfactory function were observed, independent of the subjects' age. Additionally, OB volumes decreased with age. In agreement with previous research the present study confirmed the correlation between OB volume and specific olfactory functions. Furthermore, the correlation between OB volume and olfactory function was not mediated by the subjects' age. In conclusion, the present data obtained from a relatively large group of subjects forms the basis for age-related normative values of OB volumes.

Contextual influences on the relationship between familiarity and hedonicity of odors.

The aim of the present study was to investigate how the presence or absence of a verbal label of an odor affects its familiarity or hedonicity. In addition, we wanted to examine how the participants' age or sex influences the effect of odor-label presentation on familiarity and hedonicity. A total of 12 odorants from the "Sniffin' Sticks" odor identification test were presented to 133 participants (50 men and 83 women) with an age range from 5 to 74 y. Familiarity and hedonicity of the odorants were assessed by using a 6-point scoring scale both before and after participants received the odor label. In 5 and 8 odorants, respectively, odor familiarity and hedonicity were significantly different between before and after participants had received the label. Moreover, the relationship between the odor familiarity and hedonicity was different between the situation when participants had an odor label or not. Specifically, in odors that had been perceived as relatively pleasant without a label (orange, cinnamon, lemon, and banana) the correlation between hedonicity and familiarity decreased after the label had been presented. This was the other way around for odors that had been rated as relatively unpleasant when presented without a label (shoe leather, coffee, clove, and fish). Moreover, the odor label effects on the relationship between odor familiarity and hedonicity seemed to be influenced by the participants' age and sex. In conclusion, our results indicate that the relationship between odor familiarity and hedonicity is not always positive, and is influenced by the presence of an odor label and other variables, including the participants' sex, age, and expectations.