Structural Plasticity of the Primary and Secondary Olfactory cortices: Increased Gray Matter Volume Following Surgical Treatment for Chronic Rhinosinusitis. (15th December 2018)

• Record Type: Journal Article
• Authors: Whitcroft, K.L.; Fischer, J.; Han, P.; Raue, C.; Bensafi, M.; Gudziol, V.; Andrews, P.; Hummel, T.
• Is Part Of: Neuroscience. Volume 395(2018)
• Page Start: 22
• Page End: 34
• Publication Date: 2018-12-15
• Subjects: ACC anterior cingulate cortex -- CRS chronic rhinosinusitis -- DARTEL Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra -- GM gray matter -- OB olfactory bulb -- OFC orbitofrontal cortex -- OSN olfactory sensory neuron -- PC piriform cortex -- ROI region of interest -- VBM voxel-based morphometry -- WM white matter; olfaction -- gray matter volume -- structural plasticity -- chronic rhinosinusitis -- functional endoscopic sinus surgery; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2018.10.011
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Chronic rhinosinusitis (CRS) causes peripheral olfactory dysfunction that can be corrected with surgical treatment. CRS is therefore a good model to study structural plasticity within olfactory eloquent brain regions, using VBM. Surgical treatment led to increased gray matter volume in primary and secondary olfactory networks, after three months. Change in right olfactory bulb volume correlated with change in right orbitofrontal cortex gray matter volume. Abstract: Functional plasticity of the adult brain is well established. Recently, the structural counterpart to such plasticity has been suggested by neuroimaging studies showing experience-dependent differences in gray matter (GM) volumes. Within the primary and secondary olfactory cortices, reduced GM volumes have been demonstrated in patients with olfactory loss. However, these cross-sectional studies do not provide causal evidence for GM volume change, and thereby structural plasticity. Disorders of the peripheral olfactory system, such as chronic rhinosinusitis (CRS), provide an ideal model to study GM structural plasticity, given that patients may experience long periods of olfactory impairment, followed by near complete recovery with treatment. We therefore performed a prospective longitudinal study in patients undergoing surgical treatment for CRS. We used voxel-based morphometry (VBM) to investigate GM volume change in 12 patients (M:F = 7:5; 47.2 ± 14.9 years), 3 months post-op. There was a significant improvement in olfactory function according to birhinal psychophysical testing. We performed a voxel-wise region of interest analysis, with significance corrected for number of regions ( p < 0.0036corr ). We found significantly increased post-operative GM volumes within the primary (left piriform cortex, right amygdala) and secondary (right orbitofrontal cortex, caudate nucleus, hippocampal–parahippocampal complex and bilateral temporal poles) olfactory networks, and decreased GM volumes within the secondary network only (left caudate nucleus and temporal pole, bilateral hippocampal–parahippocampal complex). As a control measure, we assessed GM change within V1, S1 and A1, where there were no suprathreshold voxels. To our knowledge, this is the first study to demonstrate GM structural plasticity within the primary and secondary olfactory cortices, following restoration of olfaction.