title: Effects of chronic peripheral olfactory loss on functional brain networks.
abstract: The effects of sensory loss on central processing in various sensory systems have already been described. The olfactory system holds the special ability to be activated by a sensorimotor act, without the presentation of an odor. In this study, we investigated brain changes related to chronic peripheral smell loss. We included 11 anosmic patients (eight female, three male; mean age, 43.5 years) with smell loss after an infection of the upper respiratory tract (mean disease duration, 4.64 years) and 14 healthy controls (seven female, seven male; mean age, 30.1 years) in a functional magnetic resonance imaging experiment with a sniffing paradigm. Data were analyzed using group-independent component analysis and functional connectivity analysis. Our results revealed a spatially intact olfactory network in patients, whereas major aberrations due to peripheral loss were observed in functional connectivity through a variety of distributed brain areas. This is the first study to show the re-organization caused by the lack of peripheral input. The results of this study indicate that anosmic patients hold the ability to activate an olfaction-related functional network through the sensorimotor component of odor-perception (sniffing). The areas involved were not different from those that emerged in healthy controls. However, functional connectivity appears to be different between the two groups, with a decrease in functional connectivity in the brain in patients with chronic peripheral sensory loss. We can further conclude that the loss of the sense of smell may induce far-reaching effects in the whole brain, which lead to compensatory mechanisms from other sensory systems due to the close interconnectivity of the olfactory system with other functional networks.
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Austria; Department of Pediatric and Adolescent Medicine, Medical University of Vienna, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Kollndorfer
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Jakab
authors.affiliation: Department of Otorhinolaryngology, Medical University of Vienna, Austria.
authors.forename: C A
authors.initials: CA
authors.lastname: Mueller
authors.affiliation: High-Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Trattnig
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Austria; Institute of Psychology, University of Graz, Austria; BioTechMed, Graz, Austria. Electronic address: veronika.schoepf@uni-graz.at.
authors.forename: V
authors.initials: V
authors.lastname: Schöpf
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009812:Odorants; D000857:Olfaction Disorders / Q000209:etiology / Q000503:physiopathology*; D009833:Olfactory Pathways / Q000503:physiopathology*; D055696:Olfactory Perception / Q000502:physiology*; D012141:Respiratory Tract Infections / Q000150:complications
keywords: anosmia; functional connectivity; olfaction; piriform cortex; sniffing