Structural and functional brain changes following four weeks of unimanual motor training: evidence from fMRI-guided diffusion MRI tractography

Reid, Lee B.; Mv, Sale; Cunnington, Ross; Mattingley, Jason B.; Rose, Sarah E.

doi:10.1101/088328

Cited by 4 publications

(12 citation statements)

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“…270 Behavioural improvements and anatomical homogeneity in this study were greater is typically reported in trials of CP therapy. within the bounds of an approval originally granted by the University of Queensland Human Research Ethics Committee, for which participants gave written informed consent.…”

Section: %supporting

confidence: 53%

“…Participant numbers were independently calculated to achieve an 80% power of detecting a significant difference Due to the dearth of literature reporting diffusion changes observed in children with CP undergoing longitudinal therapy, the amounts of expected longitudinal change were based on a healthy adult ('HA') dataset from a recent study, in which 24 healthy adults practiced a novel finemotor task with their non-dominant hand for ten minutes a day for four weeks. 270 This study found substantial improvements in task performance that were accompanied by changes in functional MRI, cortical thickness (voxel-based analysis), TMS maps and the delineated corticospinal tract FA in the 'trained' hemisphere. Importantly, in this study, both ROI seeded tractography and surface-fMRI seeded tractography were conducted.…”

Section: Diffusion Mri Tractographymentioning

confidence: 98%

“…By contrast, surface-fMRI guided tractography required only 42 participants to detect the same degree of change at a 65% scan-session success rate, due to its substantially lower test-retest error in the UCP cohort. According to a motor learning study in healthy adults, 270 this method can also be expected to display greater mean FA changes than an ROI based approach, presumably due to its greater anatomical specificity ( Figure 27). When the expected degree of change for surface-fMRI guided tractography was raised to a more realistic 1.5% -slightly under half of the degree of change demonstrated in the aforementioned study -this number fell further, to 21.…”

Section: Diffusion Mri Tractographymentioning

confidence: 99%

“…To ascertain the impact choice of methodology on required participant numbers, both methods were tested for FA changes between 1% and 3%: values reported in the aforementioned study ( Such change has been demonstrated in healthy adults who mastered a unilateral motor task. 270 Unlike adults, the presence of pathology makes it less likely that sulcal boundaries are functional boundaries in children with CP.…”

Section: Diffusion Mri Tractographymentioning

confidence: 99%

“…These effect sizes are based on published literature and brain changes measured in a longitudinal motor-learning study of healthy adults. 270,271 Population-appropriate variances were calculated by applying methods from this study to images from children with unilateral CP. This work pertains specifically to studies wishing to detect the amplitude of structural and/or microstructural measures in specific motor-related regions.…”

Section: Introductionmentioning

confidence: 99%

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Measuring motor-training induced neuroplasticity using diffusion and functional MRI: a sensitive, pathology-robust approach

Reid¹

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Brain injury constitutes a significant health burden worldwide, and outcomes are generally poor. To improve treatment, we must better understand how injury affects brain function, how the brain responds to learning pressures (neuroplasticity), and the interaction between the two. This is difficult, however, because of current technological shortcomings.This thesis focusses on the measurement of neuroplasticity in response to motor training in situations such as rehabilitation following brain injury. Although the principles and methods discussed generalise to many forms of brain pathology, discussion is generally focussed on unilateral cerebral palsy (UCP) because altered brain-development in UCP makes analyses particularly difficult. This begins with a literature review (Chapter 2) that outlines UCP, rehabilitative approaches, and the relationship between atypical brain organisation and early-life brain injury. Also discussed is how novel rehabilitation strategies may stem from studying brain changes induced by rehabilitation, and why the most informative findings are likely to come from studies utilising multiple imaging modalities.Blood Oxygen-Level Dependent Functional Magnetic Resonance Imaging (fMRI) measures brain activity indirectly and has been used to study neuroplasticity in both healthy participants and those with brain pathology. Although fMRI confounds are well understood, no published work has explored their cumulative effect when brain injury is present. Resultantly, confounds have largely been ignored, leading to heterogeneous findings that have provided little toward understanding brain changes, biologically speaking. Chapter 3 examines the cumulative effect of fMRI confounds, assumptions, and other issues, when attempting to measure neuroplasticity in participants with brain injury. This work concludes that, although fMRI can be expected to locate approximate regions of brain activation in an individual scan, numerous confounding factors make its interpretation, in terms of neuroplasticity, difficult without additional information acquired through alternative means.Diffusion MRI (dMRI) is an imaging modality that is typically used to identify the brain's white-matter pathways and calculate metrics that are influenced by factors such as myelination or axonal density. Standard dMRI analyses are ill suited to studying brain injury due to their reliance on brain 'atlases' which indicate relationships between brain regions and brain functions. Brain pathology can prevent reliable atlas registration, and alter relationships between structure and function. Chapter 4 details a novel dMRI analysis designed to measure neuroplasticity, addressing the need for a sensitive and reliable alternative to standalone-fMRI. This method utilises surface-based fMRI analyses, rather than brain atlases, to locate regions involved in motor execution. Corticospinal (CST) and thalamocortical tracts emanating from these regions are delineated using dMRI tractography and iii machine learning. This method was app...

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Section: %supporting

confidence: 53%

Section: Diffusion Mri Tractographymentioning

confidence: 98%

Section: Diffusion Mri Tractographymentioning

confidence: 99%

Section: Diffusion Mri Tractographymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measuring motor-training induced neuroplasticity using diffusion and functional MRI: a sensitive, pathology-robust approach

Reid¹

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Reconstructing the somatotopic organization of the corticospinal tract remains a challenge for modern tractography methods

He,

Zhang,

Pan

et al. 2023

Human Brain Mapping

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The corticospinal tract (CST) is a critically important white matter fiber tract in the human brain that enables control of voluntary movements of the body. The CST exhibits a somatotopic organization, which means that the motor neurons that control specific body parts are arranged in order within the CST. Diffusion magnetic resonance imaging (MRI) tractography is increasingly used to study the anatomy of the CST. However, despite many advances in tractography algorithms over the past decade, modern, state‐of‐the‐art methods still face challenges. In this study, we compare the performance of six widely used tractography methods for reconstructing the CST and its somatotopic organization. These methods include constrained spherical deconvolution (CSD) based probabilistic (iFOD1) and deterministic (SD‐Stream) methods, unscented Kalman filter (UKF) tractography methods including multi‐fiber (UKF2T) and single‐fiber (UKF1T) models, the generalized q‐sampling imaging (GQI) based deterministic tractography method, and the TractSeg method. We investigate CST somatotopy by dividing the CST into four subdivisions per hemisphere that originate in the leg, trunk, hand, and face areas of the primary motor cortex. A quantitative and visual comparison is performed using diffusion MRI data (N = 100 subjects) from the Human Connectome Project. Quantitative evaluations include the reconstruction rate of the eight anatomical subdivisions, the percentage of streamlines in each subdivision, and the coverage of the white matter–gray matter (WM–GM) interface. CST somatotopy is further evaluated by comparing the percentage of streamlines in each subdivision to the cortical volumes for the leg, trunk, hand, and face areas. Overall, UKF2T has the highest reconstruction rate and cortical coverage. It is the only method with a significant positive correlation between the percentage of streamlines in each subdivision and the volume of the corresponding motor cortex. However, our experimental results show that all compared tractography methods are biased toward generating many trunk streamlines (ranging from 35.10% to 71.66% of total streamlines across methods). Furthermore, the coverage of the WM–GM interface in the largest motor area (face) is generally low (under 40%) for all compared tractography methods. Different tractography methods give conflicting results regarding the percentage of streamlines in each subdivision and the volume of the corresponding motor cortex, indicating that there is generally no clear relationship, and that reconstruction of CST somatotopy is still a large challenge. Overall, we conclude that while current tractography methods have made progress toward the well‐known challenge of improving the reconstruction of the lateral projections of the CST, the overall problem of performing a comprehensive CST reconstruction, including clinically important projections in the lateral (hand and face areas) and medial portions (leg area), remains an important challenge for diffusion MRI tractography.

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Measuring neuroplasticity associated with cerebral palsy rehabilitation: An MRI based power analysis

Reid

Pagnozzi

Fiori

et al. 2017

Intl J of Devlp Neuroscience

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Researchers in the field of child neurology are increasingly looking to supplement clinical trials of motor rehabilitation with neuroimaging in order to better understand the relationship between behavioural training, brain changes, and clinical improvements. Randomised controlled trials are typically accompanied by sample size calculations to detect clinical improvements but, despite the large cost of neuroimaging, not equivalent calculations for concurrently acquired imaging neuroimaging measures of changes in response to intervention. To aid in this regard, a power analysis was conducted for two measures of brain changes that may be indexed in a trial of rehabilitative therapy for cerebral palsy: cortical thickness of the impaired primary sensorimotor cortex, and fractional anisotropy of the impaired, delineated corticospinal tract. Power for measuring fractional anisotropy was assessed for both region-of-interest-seeded and fMRI-seeded diffusion tractography. Taking into account practical limitations, as well as data loss due to behavioural and image-processing issues, estimated required participant numbers were 101, 128 and 59 for cortical thickness, region-of-interest-based tractography, and fMRI-seeded tractography, respectively. These numbers are not adjusted for study attrition. Although these participant numbers may be out of reach of many trials, several options are available to improve statistical power, including careful preparation of participants for scanning using mock simulators, careful consideration of image processing options, and enrolment of as homogeneous a cohort as possible. This work suggests that smaller and moderate sized studies give genuine consideration to harmonising scanning protocols between groups to allow the pooling of data.

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Structural and functional brain changes following four weeks of unimanual motor training: evidence from fMRI-guided diffusion MRI tractography

Cited by 4 publications

References 44 publications

Measuring motor-training induced neuroplasticity using diffusion and functional MRI: a sensitive, pathology-robust approach

Measuring motor-training induced neuroplasticity using diffusion and functional MRI: a sensitive, pathology-robust approach

Reconstructing the somatotopic organization of the corticospinal tract remains a challenge for modern tractography methods

Measuring neuroplasticity associated with cerebral palsy rehabilitation: An MRI based power analysis

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