Large-Scale Phase Synchrony Reflects Clinical Status After Stroke: An EEG Study

Kawano, Teiji; Hattori, Noriaki; Uno, Yutaka; Kitajo, Keiichi; Hatakenaka, Megumi; Yagura, Hajime; Fujimoto, Hiroaki; Yoshioka, Tomomi; Nagasako, Michiko; Otomune, Hironori; Miyai, Ichiro

doi:10.1177/1545968317697031

Cited by 41 publications

(49 citation statements)

References 27 publications

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“…Functional connectivity in several different frequency bands were investigated, with connectivity in the alpha band providing the strongest association with anodal tDCS response. Previous studies have demonstrated the functional significance of alpha oscillations which have been associated with post stroke subacute clinical status, motor performance and functional recovery (Dubovik et al, ; Kawano et al, ; Westlake et al, ). Furthermore, studies have reported alpha oscillations are associated with attention, memory, motor learning and performance (Harris, Dux, Jones, & Mattingley, ; Jensen, Gelfand, Kounios, & Lisman, ; Mottaz et al, ; Pollok, Boysen, & Krause, ).…”

Section: Discussionmentioning

confidence: 99%

Neuroplasticity and network connectivity of the motor cortex following stroke: A transcranial direct current stimulation study

Hordacre

Moezzi

Ridding

2018

Human Brain Mapping

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Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that has potential for clinical utility in neurorehabilitation. However, recent evidence indicates that the responses to tDCS are highly variable. This study investigated whether electroencephalographic (EEG) measures of functional connectivity of the target network were associated with the response to ipsilesional anodal tDCS in stroke survivors. Ten chronic stroke patients attended two experimental sessions in a randomized cross-over trial and received anodal or sham tDCS. Single-pulse transcranial magnetic stimulation was used to quantify change in corticospinal excitability following tDCS. At the beginning of each session, functional connectivity was estimated using the debiased-weighted phase lag index from EEG recordings at rest. Magnetic resonance imaging identified lesion location and lesion volume. Partial least squares regression identified models of connectivity which maximally accounted for variance in anodal tDCS responses. Stronger connectivity of a network with a seed approximating the stimulated ipsilesional motor cortex, and clusters of electrodes approximating the ipsilesional parietal cortex and contralesional frontotemporal cortex in the alpha band (8-13 Hz) was strongly associated with a greater increase of corticospinal excitability following anodal tDCS. This association was not observed following sham stimulation. Addition of a structural measure(s) of injury (lesion volume) provided an improved model fit for connectivity between the seed electrode and ipsilesional parietal cortex, but not the contralesional frontotemporal cortex. TDCS has potential to greatly assist stroke rehabilitation and functional connectivity appears a robust and specific biomarker of response which may assist clinical translation of this therapy.

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Section: Discussionmentioning

confidence: 99%

Neuroplasticity and network connectivity of the motor cortex following stroke: A transcranial direct current stimulation study

Hordacre

Moezzi

Ridding

2018

Human Brain Mapping

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“…This method provides evidence that attentional top-down control not only coordinates the sensory input to the cortex by thalamic gating, but also changes the cortical excitability and effective connectivity that mediates cortical gating between TR regions. The observation of perturbation effects caused by direct use of TMS-EEG will allow the characterization of excitability and effective connectivity changes according to the task at hand as well as changes due to diseases which impair networks such as stroke [61].…”

Section: Discussionmentioning

confidence: 99%

Probing dynamical cortical gating of attention with concurrent TMS-EEG

Okazaki

Mizuno

Kitajo

2019

Preprint

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HighlightsAttention-regulated cortical excitability and effective connectivity were probed by TMS-EEG.Stronger TMS evoked potentials were observed in the task-relevant visual hemisphere. Strong effective connectivity between task-relevant visual cortex and other areas were found. AbstractBackground: Attention facilitates gating of information from the sending brain area to receiving areas, with this being achieved by dynamical change in effective connectivity between cortices.However, it is difficult to assess effective connectivity, which refers to the causal influence of one cortical area on another.Objective: The aim of this study is to directly probe the effective connectivity between cortical areas, which is modulated by covertly shifted attention, excluding the thalamic influence.Methods: Transcranial magnetic stimulation (TMS) was used to directly perturb the right retinotopic visual cortex in task-relevant (TR) and task-irrelevant (TIR) networks, and the impact of this was tracked to other areas by concurrent use of electroencephalography (EEG).Results: Key finding was that TMS to the TR hemisphere led to a stronger evoked potential than did stimulation to the TIR hemisphere. Moreover, stronger beta-and gamma-band effective connectivities assessed as lagged phase synchronizations between stimulated areas and other areas were observed when TMS was delivered to the TR area. These effects were more enhanced when they preceded more prominent alpha lateralization, which is known to be associated with gating information. Conclusion:Our results indicate that attention-regulated cortical excitability and feedforward dynamical effective connectivity can be probed by direct cortical stimulation to the TR or TIR area, thereby bypassing thalamic gating. These results bear out the idea that TMS-EEG could help to characterize changes in the functional architecture of brain networks that are required for rapid adaptation to the environment or due to brain diseases.

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“…The ability to directly modulate brain rhythms in a frequency and target-specific manner may provide insights into the functional roles of rhythmic activity. Moreover, this technique has clinical potential: modulation of impaired oscillations and synchrony may alleviate symptoms in patients with attention deficit hyperactivity disorder (Barry et al, 2003), Alzheimer's disease (Prichep et al, 2006), depression (Vuga et al, 2006), obsessive-compulsive disorder (Sherlin and Congedo, 2005), schizophrenia (Lee et al, 2006), and stroke (Kawano et al, 2017). each frequency (red line in panels A and C).…”

Section: Discussionmentioning

confidence: 99%

Frequency- and area-specific entrainment of intrinsic cortical oscillations by repetitive transcranial magnetic stimulation

Okazaki

Nakagawa

Mizuno

et al. 2018

Preprint

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Neural oscillations are ubiquitous throughout the cortex, but the frequency of oscillations differs from area to area. To elucidate the mechanistic architectures establishing various rhythmic activities, we tested whether spontaneous neural oscillations in different cortical modules can be entrained by direct perturbation with distinct frequencies of transcranial magnetic stimulation (TMS). While recording the electroencephalogram (EEG), we applied single-pulse TMS (sTMS) and repetitive TMS (rTMS) at 5, 11, and 23 Hz to motor or visual cortex. To assess entrainment, defined as phase locking of intrinsic oscillations to periodic external force , we examined local and global modulation of the phase-locking factor (PLF). sTMS triggered transient phase locking in a wide frequency band with distinct PLF peaks at 21 Hz in the motor cortex and 8 Hz in the visual cortex. With TMS pulse trains of 11 Hz over visual cortex and 23 Hz over motor cortex, phase locking was progressively enhanced at the stimulation frequency and lasted for a few cycles after the stimulation terminated. Moreover, such local entrainment propagated to other cortical regions, suggesting that rTMS entrained intrinsic neural oscillations locally and globally via network nodes. Because the entrainment was frequency-specific for each target site, these frequencies may correspond to the natural frequency of each cortical module and of the global networks. rTMS enables direct manipulation of the brain and is thus useful for investigating the causal roles of synchronous neural oscillations and synchrony in brain functions, and for the treatment of clinical symptoms associated with impaired oscillations and synchrony.Significance StatementWe provide the first evidence for area- and frequency-specific entrainment by frequency-tuned repetitive transcranial magnetic stimulation (rTMS), and the propagation of this entrainment to other areas. Our results indicate that rTMS at the natural frequency of each cortical system is particularly effective for entraining oscillatory phase. Moreover, local entrainment led to global entrainment in functionally coupled areas. The ability to control brain rhythms in the intact human brain is highly beneficial for studying the causal roles of rhythmic activity in brain function. Moreover, this modulatory technique has the potential to treat patients with impaired rhythmic networks in disorders such as schizophrenia and stroke.

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Large-Scale Phase Synchrony Reflects Clinical Status After Stroke: An EEG Study

Abstract: The PSIs correlated with performance on the activities of daily living scale but not with scores on a pure motor impairment scale. These results suggest that large-scale phase synchrony represented by IH-PSIs provides a novel surrogate marker for clinical status after stroke.

Cited by 41 publications

References 27 publications

Neuroplasticity and network connectivity of the motor cortex following stroke: A transcranial direct current stimulation study

Neuroplasticity and network connectivity of the motor cortex following stroke: A transcranial direct current stimulation study

Probing dynamical cortical gating of attention with concurrent TMS-EEG

Frequency- and area-specific entrainment of intrinsic cortical oscillations by repetitive transcranial magnetic stimulation

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