Brain structure is changed in congenital anosmia.
Olfactory function in healthy people correlates with structural features of both the olfactory bulb and higher order olfactory processing areas, but we do not yet know how congenital anosmia affects these latter structures. In order to examine this question closer, we acquired T1 weighted magnetic resonance images from 17 subjects with congenital anosmia and from 17 age- and sex-matched controls. We compared white and gray matter volumes as well as cortical thickness between both groups. We found subjects with congenital anosmia to exhibit larger gray matter volumes in the left entorhinal and piriform cortices. Further, they had thicker orbitofrontal cortices bilaterally. Their left piriform cortex was also thicker than that of controls. These findings are in contrast to those observed in acquired anosmia, where reduced olfactory function is associated with reduced volumes and thickness. However, they fit well with observations from other sensory systems, e.g., vision, where congenital sensory loss is associated with a thicker primary cortex. This finding has been attributed to reduced or absent synaptic pruning as a result of missing peripheral sensory input. Our findings suggest that similar mechanisms take place in the olfactory system.
CERNEC, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada; Smell & Taste Clinic, Department of ENT, Technical University of Dresden Medical School, Dresden, Germany. Electronic address: frasnelli@yahoo.com.
Johannes
J
Frasnelli
Therese
T
Fark
Jacqueline
J
Lehmann
Johannes
J
Gerber
Thomas
T
Hummel
D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000151:congenital* / Q000473:pathology; D055815:Young Adult
Congenital; Cortical thickness; Smell; Voxel-based morphometry