Ipsilateral motor pathways to the lower limb after stroke: Insights and opportunities

Cleland, Brice T.; Madhavan, Sangeetha

doi:10.1002/jnr.24822

Cited by 22 publications

(20 citation statements)

References 112 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, it is possible that this activity is related to postural stabilization of the body during reaching. Indeed, extrapyramidal pathways such as the reticulospinal track have a prominent ipsilateral projection associated with postural control ( Cleland and Madhavan, 2021 ), and these pathways receive cortical input. We aimed to reduce postural demands in our task by having the participants seated in an upright hospital bed with the back fully supported; nonetheless, there are surely postural shifts associated with the reaching movement.…”

Section: Discussionmentioning

confidence: 99%

Left hemisphere dominance for bilateral kinematic encoding in the human brain

Merrick

Dixon

Breska

et al. 2022

eLife

View full text Add to dashboard Cite

Neurophysiological studies in humans and nonhuman primates have revealed movement representations in both the contralateral and ipsilateral hemispheres. Inspired by clinical observations, we ask if this bilateral representation differs for the left and right hemispheres. Electrocorticography was recorded in human participants during an instructed-delay reaching task, with movements produced with either the contralateral or ipsilateral arm. Using a cross-validated kinematic encoding model, we found stronger bilateral encoding in the left hemisphere, an effect that was present during preparation and was amplified during execution. Consistent with this asymmetry, we also observed better across-arm generalization in the left hemisphere, indicating similar neural representations for right and left arm movements. Notably, these left hemisphere electrodes were centered over premotor and parietal regions. The more extensive bilateral encoding in the left hemisphere adds a new perspective to the pervasive neuropsychological finding that the left hemisphere plays a dominant role in praxis.

show abstract

Section: Discussionmentioning

confidence: 99%

Left hemisphere dominance for bilateral kinematic encoding in the human brain

Merrick

Dixon

Breska

et al. 2022

eLife

View full text Add to dashboard Cite

show abstract

“…A potential explanation for this observation might derive from the limited number of crossing fibers in both tracts. 5,55 Considering the anatomical proximity of these crossing fibers and the relatively high overlap in explained variance in motor performance of all four tracts, one might assume that identical voxels were included in both tracts due to tracking inaccuracies or sampling biases. However, computing the overlap between all four masks yielded a negligible number of shared voxels.…”

Section: Anatomical Foundations Of Extrapyramidal Compensationmentioning

confidence: 99%

“…Stroke-related motor deficits are often caused by damage to the corticospinal tract (CST) and associated white matter (WM) changes are frequently assessed using anisotropy derived from diffusion MRI (dMRI). Studies commonly report a relationship between decreased anisotropy in various parts of the ipsilesional CST and the severity of motor impairment of the upper [1][2][3] and lower limbs [4][5][6] , highlighting anisotropy as a promising biomarker for motor recovery poststroke. 3 However, anisotropy measures have yet to find their way into clinical practice as individual predictions of motor impairment and recovery remain challenging for several reasons.…”

Section: Introductionmentioning

confidence: 99%

The role of corticospinal and extrapyramidal pathways in motor impairment after stroke

Paul

Cieslak

Hensel

et al. 2022

Preprint

View full text Add to dashboard Cite

Anisotropy of descending motor pathways has repeatedly been linked to the severity of motor impairment following stroke-related damage to the corticospinal tract (CST). Despite promising findings consistently tying anisotropy of the ipsilesional CST to motor outcome, anisotropy is not yet utilized as a biomarker for motor recovery in clinical practice as a conclusive understanding of degenerative processes in the ipsilesional CST and compensatory roles of other descending motor pathways is hindered by methodological constraints such as estimating anisotropy in voxels with multiple fiber directions, sampling biases, and confounds due to aging-related atrophy. The present study addressed these issues by combining diffusion spectrum imaging (DSI) with a novel compartmentwise analysis approach differentiating voxels with one dominant fiber direction (one-directional voxels) from voxels with multiple fiber directions. Compartmentwise anisotropy for bihemispheric CST and extrapyramidal tracts was compared between chronic stroke patients (N=25), age-matched controls (N=22), and young controls (N=24) and its associations with motor performance of the upper and lower limbs were assessed. Our results provide direct evidence for Wallerian degenration along the entire length of the ipsilesional CST reflected by decreased anisotropy in descending fibers compared to age-matched controls, while aging-related atrophy was observed more ubiquitously across compartments. Anisotropy of descending ipsilesional CST voxels showed a highly robust correlation with various aspects of upper and lower limb motor impairment, highlighting the behavioral relevance of Wallerian degeneration. Moreover, anisotropy measures of two-directional voxels within bihemispheric rubrospinal and reticulospinal tracts were linked to lower limb deficits, while anisotropy of two-directional contralesional rubrospinal voxels explained gross motor performance of the affected hand. Of note, the relevant extrapyramidal structures contained fibers crossing the midline, fibers potentially mitigating output from brain stem nuclei, and fibers transferring signals between the extrapyramidal system and the cerebellum. Thus, specific parts of extrapyramidal pathways seem to compensate for impaired gross arm and leg movements incurred through stroke-related CST lesions, while fine motor control of the paretic hand critically relies on ipsilesional CST integrity. Importantly, our findings suggest that the extrapyramidal system may serve as a compensatory structural reserve independent of post-stroke reorganization of extrapyramidal tracts. In summary, compartment-specific anisotropy of ipsilesional CST and extrapyramidal tracts explained distinct aspects of motor impairment, with both systems representing different pathophysiological mechanisms contributing to motor control post-stroke. Considering both systems in concert may help develop diffusion imaging biomarkers for specific motor functions after stroke.

show abstract

“…16 Recently, several studies have reported that the ipsilateral motor pathway plays a crucial role in compensating for motor impairment in both upper and lower limbs after subcortical brain injury. [17][18][19][20][21] This phenomenon can also be seen after spinal cord injury 22,23 ; therefore, ipsilateral M1 activation might help compensate for the functional deficit after movement disorders.…”

Section: Introductionmentioning

confidence: 99%

Para-Sports can Promote Functional Reorganization in the Ipsilateral Primary Motor Cortex of Lower Limbs Amputee

Nakanishi

Mizuguchi

Nakagawa

et al. 2021

Neurorehabil Neural Repair

View full text Add to dashboard Cite

Background. Drastic functional reorganization was observed in the ipsilateral primary motor cortex (M1) of a Paralympic long jumper with a unilateral below-knee amputation in our previous study. However, it remains unclear whether long-term para-sports are associated with ipsilateral M1 reorganization since only 1 athlete with amputation was investigated. Objective. This study aimed to investigate the relationship between the long-term para-sports and ipsilateral M1 reorganization after lower limb amputation. Methods. Lower limb rhythmic muscle contraction tasks with functional magnetic resonance imaging and T1-weighted structural imaging were performed in 30 lower limb amputees with different para-sports experiences in the chronic phase. Results. Brain activity in the ipsilateral primary motor and somatosensory areas (SM1) as well as the contralateral dorsolateral prefrontal cortex, SM1, and inferior temporal gyrus showed a positive correlation with the years of routine para-sports participation (sports years) during contraction of the amputated knee. Indeed, twelve of the 30 participants who exhibited significant ipsilateral M1 activation during amputated knee contraction had a relatively longer history of para-sports participation. No significant correlation was found in the structural analysis. Conclusions. Long-term para-sports could lead to extensive reorganization at the brain network level, not only bilateral M1 reorganization but also reorganization of the frontal lobe and visual pathways. These results suggest that the interaction of injury-induced and use-dependent cortical plasticity might bring about drastic reorganization in lower limb amputees.

show abstract

Ipsilateral motor pathways to the lower limb after stroke: Insights and opportunities

Cited by 22 publications

References 112 publications

Left hemisphere dominance for bilateral kinematic encoding in the human brain

Left hemisphere dominance for bilateral kinematic encoding in the human brain

The role of corticospinal and extrapyramidal pathways in motor impairment after stroke

Para-Sports can Promote Functional Reorganization in the Ipsilateral Primary Motor Cortex of Lower Limbs Amputee

Contact Info

Product

Resources

About