Separable systems for recovery of finger strength and control after stroke

Xu, Jing; Ejaz, Naveed; Hertler, Benjamin; Branscheidt, Meret; Widmer, Mario; Faria, Andréia V.; Harran, Michelle D.; Cortes, Juan C.; Kim, Nathan; Celnik, Pablo; Kitago, Tomoko; Luft, Andreas R.; Krakauer, John W.; Diedrichsen, Jörn

doi:10.1152/jn.00123.2017

Cited by 108 publications

(166 citation statements)

References 57 publications

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“…An SAS can augment the magnitude of voluntary muscle contraction in control subjects and Parkinson's patients (Anzak et al, 2011a, b). In stroke patients, the recovery of strength might involve strengthening of non-corticospinal pathways, such as the reticulospinal tract (Xu et al, 2017). We argue that this may be different in spastic muscles of SCI participants because we observed smaller MVCs in the quadriceps muscle in people with higher reticulospinal gain.…”

Section: Functional Considerationsmentioning

confidence: 73%

Imbalanced Corticospinal and Reticulospinal Contributions to Spasticity in Humans with Spinal Cord Injury

Sangari

Perez

2019

J. Neurosci.

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Damage to the corticospinal and reticulospinal tract has been associated with spasticity in humans with upper motor neuron lesions. We hypothesized that these descending motor pathways distinctly contribute to the control of a spastic muscle in humans with incomplete spinal cord injury (SCI). To test this hypothesis, we examined motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation over the leg representation of the primary motor cortex, maximal voluntary contractions (MVCs), and the StartReact response (shortening in reaction time evoked by a startling stimulus) in the quadriceps femoris muscle in male and females with and without incomplete SCI. A total of 66.7% of the SCI participants showed symptoms of spasticity, whereas the other 33.3% showed no or low levels of spasticity. We found that participants with spasticity had smaller MEPs and MVCs and larger StartReact compared with participants with no or low spasticity and control subjects. These results were consistently present in spastic subjects but not in the other populations. Clinical scores of spasticity were negatively correlated with MEP-max and MVC values and positively correlated with shortening in reaction time. These findings provide evidence for lesser corticospinal and larger reticulospinal influences to spastic muscles in humans with SCI and suggest that these imbalanced contributions are important for motor recovery.

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Section: Functional Considerationsmentioning

confidence: 73%

Imbalanced Corticospinal and Reticulospinal Contributions to Spasticity in Humans with Spinal Cord Injury

Sangari

Perez

2019

J. Neurosci.

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“…The data showed good reliability for the major dependent variable, IHI ratio ( α = 0.74 and 0.79 for patients and controls, respectively; Participants and Methods). Figure shows the distribution of lesions defined using diffusion tensor images (details reported in our earlier publication).…”

Section: Resultsmentioning

confidence: 99%

“…Our cohort of patients was mild to moderately impaired in the acute stage (FMA INITIAL Mean = 41 ± 22; Table ). Motor recovery was quantified using three behavioral measures: FMA, Strength and an Individuation Index for finger (ability to move digits independently; Participants and Methods) . All three measures showed good early recovery (Strength: χ 2 = 28.07; p < 0.001, Individuation: χ 2 = 13.64; p < 0.001, and FMA: χ 2 = 28.07; p < 0.001), but then plateaued after the subacute stage (Fig ).…”

Section: Resultsmentioning

confidence: 99%

“…All patients’ and controls’ upper‐extremity motor impairment was determined with the Fugl‐Meyer Assessment (FMA), following the same schedule as premovement IHI. Hand function was also tested within ±4.6 days from the TMS experiment, as previously described . Briefly, participants were instructed to move each finger in isolation on an ergonomic device that measures the isometric force generated by each digit.…”

Section: Participants and Methodsmentioning

confidence: 99%

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Rethinking interhemispheric imbalance as a target for stroke neurorehabilitation

Branscheidt

Schambra

et al. 2019

Annals of Neurology

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Objective: Patients with chronic stroke have been shown to have failure to release interhemispheric inhibition (IHI) from the intact to the damaged hemisphere before movement execution (premovement IHI). This inhibitory imbalance was found to correlate with poor motor performance in the chronic stage after stroke and has since become a target for therapeutic interventions. The logic of this approach, however, implies that abnormal premovement IHI is causal to poor behavioral outcome and should therefore be present early after stroke when motor impairment is at its worst. To test this idea, in a longitudinal study, we investigated interhemispheric interactions by tracking patients' premovement IHI for one year following stroke. Methods: We assessed premovement IHI and motor behavior five times over a 1-year period after ischemic stroke in 22 patients and 11 healthy participants. Results: We found that premovement IHI was normal during the acute/subacute period and only became abnormal at the chronic stage; specifically, release of IHI in movement preparation worsened as motor behavior improved. In addition, premovement IHI did not correlate with behavioral measures cross-sectionally, whereas the longitudinal emergence of abnormal premovement IHI from the acute to the chronic stage was inversely correlated with recovery of finger individuation. Interpretation: These results suggest that interhemispheric imbalance is not a cause of poor motor recovery, but instead might be the consequence of underlying recovery processes. These findings call into question the rehabilitation strategy of attempting to rebalance interhemispheric interactions in order to improve motor recovery after stroke. ANN NEUROL 2019;85:502-513 I t has been proposed that one contributor to chronic hemiparesis is an imbalanced inhibitory interaction between the lesioned and intact hemispheres via transcallosal connections. This interhemispheric-competition model proposes that the two hemispheres, which normally exert mutual inhibition in healthy individuals, become imbalanced after stroke, and that unopposed inhibition from the healthy to the damaged side impedes recovery. 1 This framework is largely based on a seminal study that showed persistent premovement interhemispheric inhibition (IHI) from the contra-to ipsilesional motor cortex before movement execution in patients with chronic stroke. 2 This failure to release IHI before movement onset (abnormal premovement IHI) correlated with weakness and impaired finger tapping performance. 2 Influenced by this stroke-recovery View this article online at wileyonlinelibrary.com.

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“…These results also have 199 implications for rehabilitation of individual finger movements after stroke. The strength and 200 coordination of individual finger movements are impaired after stroke, recovering significantly 201 through the first year post-stroke but often leaving chronic deficits (Xu et al, 2017). Recent work 202 has suggested that this recovery and subsequent chronic impairment can be tracked through 203 MVPA of individual finger representations (Xu et al, 2015), although the to-date published results 204 of the fMRI data from this study report only average region-of-interest analyses (Ejaz et al,205 2018).…”

Section: Differential Modulation Of Finger Preferencementioning

confidence: 99%

Differential neural plasticity of individual fingers revealed by fMRI neurofeedback

Oblak

Lewis-Peacock

Sulzer

2020

Preprint

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Previous work has shown that fMRI activity patterns associated with individual fingers can be 1 shifted by temporary impairment of the hand (e.g. by gluing two fingers together for 24 hours). 2 Here, we investigated whether these neural activity patterns could be modulated endogenously 3 and whether any behavioral changes result from modulation of these patterns. We used decoded 4 neurofeedback in healthy individuals to encourage participants to shift the neural activity pattern in 5 sensorimotor cortex of the middle finger towards the index finger, and the ring finger towards the 6 little finger. We first mapped out the neural activity patterns for all fingers of the right hand in an 7 fMRI pattern localizer session. Then, in three subsequent neurofeedback sessions, participants 8 were rewarded after middle/ring finger presses according to their activity pattern overlap during 9 each trial. A force-sensitive keyboard was used to ensure that participants were not altering their 10 physical finger coordination patterns. We found evidence that participants could learn to shift 11 the activity pattern of the 4th digit (ring finger) but not of the 3rd digit (middle finger). Increased 12 variability of these activity patterns during the localizer session was associated with the ability 13 of participants to modulate them using neurofeedback. Participants also showed an increased 14 preference for the ring finger but not for the middle finger in a post-neurofeedback motor task. Our 15 results show that neural activity and behaviors associated with the ring finger are more readily 16 modulated than those associated with the middle finger. These results have broader implications 17 for rehabilitation of individual finger movements, which may be limited or enhanced by individual 18 finger plasticity after neurological injury. 19 1

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Separable systems for recovery of finger strength and control after stroke

Cited by 108 publications

References 57 publications

Imbalanced Corticospinal and Reticulospinal Contributions to Spasticity in Humans with Spinal Cord Injury

Imbalanced Corticospinal and Reticulospinal Contributions to Spasticity in Humans with Spinal Cord Injury

Rethinking interhemispheric imbalance as a target for stroke neurorehabilitation

Differential neural plasticity of individual fingers revealed by fMRI neurofeedback

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