Cortical dynamics within and between parietal and motor cortex in essential tremor

Coombes, Stephen; Chung, Jae Woo; Archer, Derek B.; Okun, Michael S.; Hess, Christopher W.; Shukla, Aparna Wagle; Vaillancourt, David E.

doi:10.1002/mds.27522

Cited by 20 publications

(14 citation statements)

References 64 publications

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“…For example, increased force tremor Á in essential tremor was found to correlate with sensorimotor and parietal BOLD Á signal (Archer et al, 2018). Moreover, high-density EEG in essential tremor patients revealed reduced sensorimotor beta-band desynchronization and bi-directional connectivity between the motor and parietal cortices that was related to feedback induced exacerbation of force tremor of the arm (Roy et al, 2018). These differences in findings for dystonic tremor and essential tremor suggest functionally disparate higher-level cortical mechanisms that will need further exploration.…”

Section: Visual Feedback Increases Force Tremor In Dystonic Tremormentioning

confidence: 93%

Network-level connectivity is a critical feature distinguishing dystonic tremor and essential tremor

DeSimone

Archer

Vaillancourt

et al. 2019

Brain

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Dystonia is a movement disorder characterized by involuntary muscle co-contractions that give rise to disabling movements and postures. A recent expert consensus labelled the incidence of tremor as a core feature of dystonia that can affect body regions both symptomatic and asymptomatic to dystonic features. We are only beginning to understand the neural network-level signatures that relate to clinical features of dystonic tremor. At the same time, clinical features of dystonic tremor can resemble that of essential tremor and present a diagnostic confound for clinicians. Here, we examined network-level functional activation and connectivity in patients with dystonic tremor and essential tremor. The dystonic tremor group included primarily cervical dystonia patients with dystonic head tremor and the majority had additional upper-limb tremor. The experimental paradigm included a precision grip-force task wherein online visual feedback related to force was manipulated across high and low spatial feedback levels. Prior work using this paradigm in essential tremor patients produced exacerbation of grip-force tremor and associated changes in functional activation. As such, we directly compared the effect of visual feedback on grip-force tremor and associated functional network-level activation and connectivity between dystonic tremor and essential tremor patient cohorts to better understand disease-specific mechanisms. Increased visual feedback similarly exacerbated force tremor during the grip-force task in dystonic tremor and essential tremor cohorts. Patients with dystonic tremor and essential tremor were characterized by distinct functional activation abnormalities in cortical regions but not in the cerebellum. We examined seed-based functional connectivity from the sensorimotor cortex, globus pallidus internus, ventral intermediate thalamic nucleus, and dentate nucleus, and observed abnormal functional connectivity networks in dystonic tremor and essential tremor groups relative to controls. However, the effects were far more widespread in the dystonic tremor group as changes in functional connectivity were revealed across cortical, subcortical, and cerebellar regions independent of the seed location. A unique pattern for dystonic tremor included widespread reductions in functional connectivity compared to essential tremor within higher-level cortical, basal ganglia, and cerebellar regions. Importantly, a receiver operating characteristic determined that functional connectivity z-scores were able to classify dystonic tremor and essential tremor with 89% area under the curve, whereas combining functional connectivity with force tremor yielded 94%. These findings point to network-level connectivity as an important feature that differs substantially between dystonic tremor and essential tremor and should be further explored in implementing appropriate diagnostic and therapeutic strategies.

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Section: Visual Feedback Increases Force Tremor In Dystonic Tremormentioning

confidence: 93%

Network-level connectivity is a critical feature distinguishing dystonic tremor and essential tremor

DeSimone

Archer

Vaillancourt

et al. 2019

Brain

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“…8,11,35 In addition, there is an active debate as to whether cerebellar dysfunction/degeneration 3,[36][37][38] or network-wide oscillatory abnormalities underlie ET. 29,[39][40][41][42] Although we did not directly address it in this study, the independence of tremor and dysmetria suggests that different neurophysiological mechanisms could underlie tremor and ataxia in ET. There is evidence that increased activation in primary motor cortex and the supplementary motor association cortices positively correlates with tremor (3-8Hz) in ET.…”

Section: Neurophysiological Mechanism Of Tremor and Ataxia In Etmentioning

confidence: 94%

“…Postmortem human studies indicate the presence of morphological changes in the Purkinje and Basket cells of the cerebellum, 38,43 and neuroimaging studies have confirmed abnormal cerebellar activity and connectivity in ET. 3,28,29,39,40 Interestingly, hypoactivity of cerebellar lobules I to V correlates with force variability in ET. 28 Thus, it is possible that cerebellar abnormalities underlie ataxic symptoms in ET.…”

Section: Neurophysiological Mechanism Of Tremor and Ataxia In Etmentioning

confidence: 97%

Quantitative Separation of Tremor and Ataxia in Essential Tremor

Casamento‐Moran

Yacoubi

Wilkes

et al. 2020

Annals of Neurology

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Objective This study addresses an important problem in neurology, distinguishing tremor and ataxia using quantitative methods. Specifically, we aimed to quantitatively separate dysmetria, a cardinal sign of ataxia, from tremor in essential tremor (ET). Methods In Experiment 1, we compared 19 participants diagnosed with ET undergoing thalamic deep brain stimulation (DBS; ETDBS) to 19 healthy controls (HC). We quantified tremor during postural tasks using accelerometry and dysmetria with fast, reverse‐at‐target goal‐directed movements. To ensure that endpoint accuracy was unaffected by tremor, we quantified dysmetria in selected trials manifesting a smooth trajectory to the endpoint. Finally, we manipulated tremor amplitude by switching DBS ON and OFF to examine its effect on dysmetria. In Experiment 2, we compared 10 ET participants with 10 HC to determine whether we could identify and distinguish dysmetria from tremor in non‐DBS ET. Results Three findings suggest that we can quantify dysmetria independently of tremor in ET. First, ETDBS and ET exhibited greater dysmetria than HC and dysmetria did not correlate with tremor (R2 < 0.01). Second, even for trials with tremor‐free trajectories to the target, ET exhibited greater dysmetria than HC (p < 0.01). Third, activating DBS reduced tremor (p < 0.01) but had no effect on dysmetria (p > 0.2). Interpretation We demonstrate that dysmetria can be quantified independently of tremor using fast, reverse‐at‐target goal‐directed movements. These results have important implications for the understanding of ET and other cerebellar and tremor disorders. Future research should examine the neurophysiological mechanisms underlying each symptom and characterize their independent contribution to disability. ANN NEUROL 2020;88:375–387.

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“…The actual channel location map was mapped onto the BESA template channel location map, which in turn, was coregistered to the Montreal Neurological Institute (MNI) brain template. Dipoles were excluded if they were located outside of the MNI brain, or if their residual variance was >15% (Misra et al, 2017b; Roy et al, 2018a).…”

Section: Methodsmentioning

confidence: 99%

Altered neural oscillations within and between sensorimotor cortex and parietal cortex in chronic jaw pain

Wang

Misra²,

et al. 2019

NeuroImage: Clinical

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Pain perception is associated with priming of the motor system and the orienting of attention in healthy adults. These processes correspond with decreases in alpha and beta power in the sensorimotor and parietal cortices. The goal of the present study was to determine whether these findings extend to individuals with chronic pain. Individuals with chronic jaw pain and pain-free controls anticipated and experienced a low pain or a moderate pain-eliciting heat stimulus. Although stimuli were calibrated for each subject, stimulus temperature was not different between groups. High-density EEG data were collected during the anticipation and heat stimulation periods and were analyzed using independent component analyses, EEG source localization, and measure projection analyses. Direct directed transfer function was also estimated to identify frequency specific effective connectivity between regions. Between group differences were most evident during the heat stimulation period. We report three novel findings. First, the chronic jaw pain group had a relative increase in alpha and beta power and a relative decrease in theta and gamma power in sensorimotor cortex. Second, the chronic jaw pain group had a relative increase in power in the alpha and beta bands in parietal cortex. Third, the chronic jaw pain group had less connectivity strength in the beta and gamma bands between sensorimotor cortex and parietal cortex. Our findings show that the effect of chronic pain attenuates rather than magnifies neural responses to heat stimuli. We interpret these findings in the context of system-level changes in intrinsic sensorimotor and attentional circuits in chronic pain.

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Cortical dynamics within and between parietal and motor cortex in essential tremor

Cited by 20 publications

References 64 publications

Network-level connectivity is a critical feature distinguishing dystonic tremor and essential tremor

Network-level connectivity is a critical feature distinguishing dystonic tremor and essential tremor

Quantitative Separation of Tremor and Ataxia in Essential Tremor

Altered neural oscillations within and between sensorimotor cortex and parietal cortex in chronic jaw pain

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