Gray matter asymmetry in asymptomatic carotid stenosis

Figures

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  FIGURE 1. Schematic diagram of two‐mediator serial mediation analysis. TIV, total intracranial volume; WMH, white matter hyperintensity

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  FIGURE 2. Group differences in VBM. (a) Primary and (b) validation results of group differences between SACS patients and controls in VBM, cluster‐level p < .05, FWE corrected. FWE, family wise error; L, left; R, right; SACS, severe asymptomatic carotid stenosis; VBM, voxel‐based morphometry. These maps were rendered by using the Surf Ice tool (https://www.nitrc.org/projects/surfice/) and MRIcroGL (https://www.nitrc.org/projects/mricrogl)

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  FIGURE 3. Gray matter asymmetries. (a) Mean AI distribution in SACS patients, elderly HC, and young adults. (b) Group comparisons in AI between SACS and elderly HC, between SACS and young adults, and between elderly HC and young adults. (c) Decoding maps. From left to right: (left) individual gray matter asymmetries of 483 subjects between the ages of 18 to 80 years with the SALD dataset, chronological age is both modeled as significantly linear age effect (positive linear with red‐yellow, and negative linear with green‐blue) and quadratic age effect (positive with violet; cluster‐level p < .05, FWE corrected); (middle) topography of principal gradient identified with functional connectivity from Margulies et al. (2016)) and Neurovault https://identifiers.org/neurovault.image:24346; (right) A metanalytic activation map related to “recall” (244 studies) from NeuroSynth (www.neurosynth.org; Yarkoni et al., 2011). G1, gradient 1; G2, gradient 2. FWE, family wise error; HC, healthy controls; SACS, severe asymptomatic carotid stenosis; SALD, Southwest University Adult Lifespan Dataset. These maps were rendered by using the Surf Ice tool (https://www.nitrc.org/projects/surfice/)

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  FIGURE 4. Individual AI maps and superimposed group AI maps in SACS patients. Individual differences in AI between SACS patients and pooled HC sample (n = 24). (a) Unthresholded Z maps of AI. (b) Thresholded Z maps of AI through comparing the ratio of [individual patient–group mean (HC)]/group std. (HC). The threshold level in B was set to Z value ≥3.1, corresponding to p < .001. The red boxes outline patients with left carotid stenosis. Superimposed probability maps based on the thresholded Z maps with both increased and decreased AI summed across the SACS patients after thresholded (|Z| ≥ 3.1) across SACS patients were displayed, in cortical (c) and slice (d) views. The color bar indicates number of patients with significant rightward (hot tone, up to 11) or leftward (cold tone, up to 4) AI in the same brain region. AI, asymmetry index; HC, healthy controls; SACS, severe asymptomatic carotid stenosis. These maps were visualized by using the BrainNet viewer (https://www.nitrc.org/projects/bnv/) and MRIcroGL (https://www.nitrc.org/projects/mricrogl)

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  FIGURE 5. The associations between neuropsychological measures, WMH, and GM asymmetries in SACS patients. (a) Immediate recall was significantly negatively correlated with AI in the pMTG. (b) Delayed recall was significantly negatively correlated with AI in the pMTG. (c) Adjusted WMH size (i.e., the ratio of WMH size and total intracranial volume) was significantly positively correlated with AI in OPER, PrG, pMTG, and the thalamus. AI, asymmetry index; OPER, operculum insulae; pMTG, posterior middle temporal gyrus; PrG, precentral gyrus; SACS, severe asymptomatic carotid stenosis; THALA, thalamus; WMH, white matter hyperintensity

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  FIGURE 6. Functional decoding and serial mediation. (a) Significant clusters showing significant atrophy in the left pMTG and significantly rightward AI in the right pMTG. (b) Meta‐coactivation maps and word clouds showing top terms associated with the bilateral pMTG using the NeuroSynth. (c) Metanalytical functional connectivity maps with the bilateral pMTG as seed regions. (d) Path model tested in proof‐of‐principle sample (n = 43). Solid lines indicate significant pathways. Dash lines indicate nonsignificant pathways. For each connection, the coefficient (a, b, c, a 2 , and b 2 ), its SE, and p‐value (p) are shown above the line. The mediation effect of the hypothesized serial pathway (a × b × c) and its 95% CI are shown in red, the mediation effect of left pMTG atrophy (a 2 × c) in green, and the mediation effect of atrophy alone (a × b 2 ) in blue. Direct effects are shown in orange; d is the direct effect adjusted only for covariates and d' is the direct effect adjusted for covariates and indirect effects. Covariate effects on mediators or outcomes with p < .05 are shown in gray. DR, delayed recall; IR, immediate recall; pMTG, posterior middle temporal gyrus; TIV, total intracranial…