RESEARCH ARTICLE Correlation between olfactory bulb volume and olfactory function in children and adolescents T. Hummel • M. Smitka • S. Puschmann • J. C. Gerber • B. Schaal • D. Buschhu ¨ter Received: 27 June 2011 / Accepted: 1 August 2011 / Published online: 13 August 2011 Ó Springer-Verlag 2011 Abstract 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 inves- tigate a possible correlation between OB volume and spe- cific 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. Keywords Brain Á Olfaction Á Smell Á Olfactory bulb Á Children Á MRI Á Volumetry Á Plasticity Á Development Introduction The olfactory bulb (OB) is the first relay station in the olfactory pathway without any prior thalamic connection. Its anatomy is well known in adults (Parent and Carpenter 1996). From the paired OBs, the signal is transmitted along the lateral olfactory tract to structures in the paleocortex including the entorhinal cortex and the amygdala. Despite the importance of chemosensation in the regulation of ingestive behavior including the response of infants to a wide range of odors, there is only limited knowledge on the development of the human OBs from birth to adolescence. Acquisition of odor preferences has been shown to exist already prenatally, because newborns show that they rec- ognize specific fragrances introduced into the mother’s diet during the last 3 months of pregnancy (Marlier et al. 1997). Furthermore, recent studies have shown that olfactory information processing abilities of children undergo chan- ges during early stages of life (Hummel et al. 2007). Due to the continuous improvement, magnetic reso- nance imaging (MRI)-based volumetric analyses offer an ideal instrument to reliably evaluate children’s OB vol- umes, which seem to be connected to the functional state of the olfactory system. Therefore, the size of the OB has been previously studied in patients with post-traumatic chemosensory deficits (Yousem et al. 1996b, 1999), post- infectious olfactory deficits (Mueller et al. 2005b; Rom- baux et al. 2006), congenital anosmia (Abolmaali et al. T. Hummel (&) Á S. Puschmann Á D. Buschhu ¨ter Department of Otorhinolaryngology, University of Dresden Medical School, Fetscherstrasse 74, 01307 Dresden, Germany e-mail: thummel@mail.zih.tu-dresden.de M. Smitka Department of Pediatrics, University of Dresden Medical School, Fetscherstrasse 74, 01307 Dresden, Germany J. C. Gerber Department of Neuroradiology, University of Dresden Medical School, Fetscherstrasse 74, 01307 Dresden, Germany B. Schaal Centre de Gout, Dijon, France 123 Exp Brain Res (2011) 214:285–291 DOI 10.1007/s00221-011-2832-7