Normal Olfactory Functional Connectivity Despite Lifelong Absence of Olfactory Experiences

• Published in: Cerebral cortex (New York, N.Y. 1991) N.Y. 1991), 2021-01, Vol.31 (1), p.159-168
• Main Authors: Peter, Moa G, Fransson, Peter, Mårtensson, Gustav, Postma, Elbrich M, Nordin, Love Engström, Westman, Eric, Boesveldt, Sanne, Lundström, Johan N
• Format: Article
• Language: English
• Subjects: Adult; anosmia; Bayes Theorem; Brain Mapping; Female; homotopic connectivity; Humans; Magnetic Resonance Imaging; Male; Medicin och hälsovetenskap; Neural Pathways - diagnostic imaging; Neural Pathways - physiology; Neural Pathways - physiopathology; Olfaction Disorders - congenital; Olfaction Disorders - diagnostic imaging; Olfaction Disorders - physiopathology; Olfactory Cortex - diagnostic imaging; Olfactory Cortex - physiology; Olfactory Cortex - physiopathology; Original; regional homogeneity; resting-state; sensory loss; Smell - physiology
• ISSN: 1047-3211; 1460-2199; 1460-2199
• DOI: 10.1093/cercor/bhaa217

Abstract Congenital blindness is associated with atypical morphology and functional connectivity within and from visual cortical regions; changes that are hypothesized to originate from a lifelong absence of visual input and could be regarded as a general (re) organization principle of sensory cortices. Challenging this is the fact that individuals with congenital anosmia (lifelong olfactory sensory loss) display little to no morphological changes in the primary olfactory cortex. To determine whether olfactory input from birth is essential to establish and maintain normal functional connectivity in olfactory processing regions, akin to the visual system, we assessed differences in functional connectivity within the olfactory cortex between individuals with congenital anosmia (n = 33) and matched controls (n = 33). Specifically, we assessed differences in connectivity between core olfactory processing regions as well as differences in regional homogeneity and homotopic connectivity within the primary olfactory cortex. In contrast to congenital blindness, none of the analyses indicated atypical connectivity in individuals with congenital anosmia. In fact, post-hoc Bayesian analysis provided support for an absence of group differences. These results suggest that a lifelong absence of olfactory experience has a limited impact on the functional connectivity in the olfactory cortex, a finding that indicates a clear difference between sensory modalities in how sensory cortical regions develop.