Increased fractional anisotropy in the motor tracts of Parkinson's disease suggests compensatory neuroplasticity or selective neurodegeneration

Mole, Jilu P.; Subramanian, Leena; Bracht, Tobias; Morris, Huw R.; Metzler‐Baddeley, Claudia; Linden, David Edmund Johannes

doi:10.1007/s00330-015-4178-1

Cited by 98 publications

(100 citation statements)

References 33 publications

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“…In PD, it has been widely used in evaluating structural changes in the substantia nigra, but its applications are not restricted to subcortical structures. Reduced FA was detected in the precentral gyrus and SMA in PD, whereas another study assessing diffusion MRI changes across motor tracts found increased FA in the corticospinal and thalamus‐motor cortex tracts in patients when compared with controls . These rather unexpected findings highlight the possibility of microstructural changes being far more extensive than previously thought, encompassing complex pathways involved in the initiation and control of movement.…”

Section: Structural Changes In the Motor Cortex Of Pdmentioning

confidence: 76%

Imaging of Motor Cortex Physiology in Parkinson's Disease

Burciu

Vaillancourt

2018

Movement Disorders

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There is abundant evidence that the pathophysiology of Parkinson's disease (PD) is not confined to the nigrostriatal dopaminergic pathway but propagates along the cortico‐basal ganglia‐thalamo‐cortical neural network. A critical node in this functional circuit impacted by PD is the primary motor cortex (M1), which plays a key role in generating neural impulses that regulate movements. The past several decades have lay witness to numerous in vivo neuroimaging techniques that provide a window into the function and structure of M1. A consistent observation from numerous studies is that during voluntary movement, but also at rest, the functional activity of M1 is altered in PD relative to healthy individuals, and it relates to many of the motor signs. Although this abnormal functional activity can be partially restored with acute dopaminergic medication, it continues to deteriorate with disease progression and may predate structural degeneration of M1. The current review discusses the evidence that M1 is fundamental to the pathophysiology of PD, as measured by neuroimaging techniques such as positron emission tomography, single‐photon emission computed tomography, electroencephalography, magnetoencephalography, and functional and structural MRI. Although novel treatments that target the cortex will not cure PD, they could significantly slow down and alter the progressive course of the disease and thus improve clinical care for this degenerative disease. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society

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Section: Structural Changes In the Motor Cortex Of Pdmentioning

confidence: 76%

Imaging of Motor Cortex Physiology in Parkinson's Disease

Burciu

Vaillancourt

2018

Movement Disorders

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“…These metrics, therefore, provide complementary information about microstructural damage. Considering them in combination in MS, as well as in other conditions affecting the integrity of white matter (Mole et al, ), can improve our understanding of tissue pathology and may offer more accurate measurement of the effect of novel therapeutic interventions for prevention, neuroprotection or repair.…”

Section: Discussionmentioning

confidence: 99%

Comparing MRI metrics to quantify white matter microstructural damage in multiple sclerosis

Lipp

Jones

Bells

et al. 2019

Human Brain Mapping

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Quantifying white matter damage in vivo is becoming increasingly important for investigating the effects of neuroprotective and repair strategies in multiple sclerosis (MS). While various approaches are available, the relationship between MRI‐based metrics of white matter microstructure in the disease, that is, to what extent the metrics provide complementary versus redundant information, remains largely unexplored. We obtained four microstructural metrics from 123 MS patients: fractional anisotropy (FA), radial diffusivity (RD), myelin water fraction (MWF), and magnetisation transfer ratio (MTR). Coregistration of maps of these four indices allowed quantification of microstructural damage through voxel‐wise damage scores relative to healthy tissue, as assessed in a group of 27 controls. We considered three white matter tissue‐states, which were expected to vary in microstructural damage: normal appearing white matter ( NAWM ), T2‐weighted hyperintense lesional tissue without T1‐weighted hypointensity ( T2L ), and T1‐weighted hypointense lesional tissue with corresponding T2‐weighted hyperintensity ( T1L ). All MRI indices suggested significant damage in all three tissue‐states, the greatest damage being in T1L . The correlations between indices ranged from r = 0.18 to r = 0.87. MWF was most sensitive when differentiating T2L from NAWM , while MTR was most sensitive when differentiating T1L from NAWM and from T2L . Combining the four metrics into one, through a principal component analysis, did not yield a measure more sensitive to damage than any single measure. Our findings suggest that the metrics are (at least partially) correlated with each other, but sensitive to the different aspects of pathology. Leveraging these differences could be beneficial in clinical trials testing the effects of therapeutic interventions.

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“…It is common to report asymmetry or group difference in bundle volume (Catani et al, 2007;Chenot et al, 2019;Song et al, 2014), diffusion values within the bundle of interest (average fractional anisotropy, mean diffusivity, etc.) (De Erausquin & Alba-Ferrara, 2013;Kimura-Ohba et al, 2016;Ling et al, 2012;Mole et al, 2016) or values along the bundle (called profilometry and tractometry) (Cousineau et al, 2017;Dayan et al, 2016;Yeatman, Dougherty, Myall, Wandell, & Feldman, 2012;Yeatman, Richie-Halford, Smith, Keshavan, & Rokem, 2018). Spatial distribution of cortical terminations of streamlines can help to identify cortical regions with underlying WM connections affected by a condition (Behrens et al, 2003;Donahue et al, 2016;Johansen-Berg et al, 2004;Mars et al, 2011;Rushworth, Behrens, & Johansen-Berg, 2005).…”

Section: Bundle Segmentationmentioning

confidence: 99%

Tractostorm: The what, why, and how of tractography dissection reproducibility

Rheault

Benedictis

Daducci

et al. 2020

Human Brain Mapping

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Investigative studies of white matter (WM) brain structures using diffusion MRI (dMRI) tractography frequently require manual WM bundle segmentation, often called “virtual dissection.” Human errors and personal decisions make these manual segmentations hard to reproduce, which have not yet been quantified by the dMRI community. It is our opinion that if the field of dMRI tractography wants to be taken seriously as a widespread clinical tool, it is imperative to harmonize WM bundle segmentations and develop protocols aimed to be used in clinical settings. The EADC‐ADNI Harmonized Hippocampal Protocol achieved such standardization through a series of steps that must be reproduced for every WM bundle. This article is an observation of the problematic. A specific bundle segmentation protocol was used in order to provide a real‐life example, but the contribution of this article is to discuss the need for reproducibility and standardized protocol, as for any measurement tool. This study required the participation of 11 experts and 13 nonexperts in neuroanatomy and “virtual dissection” across various laboratories and hospitals. Intra‐rater agreement (Dice score) was approximately 0.77, while inter‐rater was approximately 0.65. The protocol provided to participants was not necessarily optimal, but its design mimics, in essence, what will be required in future protocols. Reporting tractometry results such as average fractional anisotropy, volume or streamline count of a particular bundle without a sufficient reproducibility score could make the analysis and interpretations more difficult. Coordinated efforts by the diffusion MRI tractography community are needed to quantify and account for reproducibility of WM bundle extraction protocols in this era of open and collaborative science.

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Increased fractional anisotropy in the motor tracts of Parkinson's disease suggests compensatory neuroplasticity or selective neurodegeneration

Cited by 98 publications

References 33 publications

Imaging of Motor Cortex Physiology in Parkinson's Disease

Imaging of Motor Cortex Physiology in Parkinson's Disease

Comparing MRI metrics to quantify white matter microstructural damage in multiple sclerosis

Tractostorm: The what, why, and how of tractography dissection reproducibility

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