The behavioral significance of coherent resting-state oscillations after stroke

Dubovik, Sviatlana; Pignat, Jean-Michel; Ptak, Radek; Aboulafia, Tatiana; Allet, Lara; Gillabert, Nicole; Magnin, Cécile; Albert, Fabien; Momjian-Mayor, Isabelle; Nahum, L. H.; Lascano, Agustina Maria; Michel, Christoph M.; Schnider, Armin; Guggisberg, Adrian G.

doi:10.1016/j.neuroimage.2012.03.024

Cited by 137 publications

(185 citation statements)

References 70 publications

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“…Connectivity measures were lower in patients than in controls in the alpha and beta frequency bands, but not in the delta frequency band. This is in line with the notion of coherence of resting state oscillations in the alpha band, but not in lower frequencies, being associated with cognitive and motor functioning [12, 25]. …”

Section: Discussionsupporting

confidence: 89%

“…For example, interhemispheric spectral asymmetry in the 0.5–25 Hz range estimated with the Brain Symmetry Index predicted that outcome and treatment effect [7, 8], whole brain partial least square models for delta power correlated with the severity of neurological deficit [9], and ipsilateral motor cortex connectivity were associated with effects of physical therapy [10]. In studies with high density arrays, various measures of functional connectivity revealed changes in both ipsi- and contralateral hemisphere that were related to functional recovery [11, 12]. Others have focused on interhemispheric connectivity, for example with TMS-EEG paradigms [13].…”

Section: Introductionmentioning

confidence: 99%

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Contralesional Brain Activity in Acute Ischemic Stroke

et al. 2018

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Background: The noninjured, contralateral hemisphere is increasingly acknowledged in the process of recovery from acute ischemic stroke. We estimated the value of conventional electroencephalography (EEG) recordings for identifying contralateral hemisphere involvement in relation to functional recovery. Methods: We analyzed 2-min epochs from 21 electrode EEG registrations of 18 patients with acute hemispheric ischemic stroke and compared with 18 age-matched controls. Outcome was dichotomized as good (modified Rankin Scale [mRS] 0–2) or poor (mRS 3–5 or death) at 3 months. Effects of the infarct on the ipsi-and contralateral hemispheres were analyzed by the delta/alpha ratio (DAR) and 2 measures of functional connectivity (magnitude squared coherence [MSC] and weighted phase lag index [WPLI]). Results: DAR was higher in patients than in controls, both in the ipsilateral and in the contralateral hemisphere (median 4.5 ± 6.7 ipsilateral and 2.4 ± 2.0 contralateral vs. 0.5 ± 0.5 in the control group, p < 0.001), indicating robust EEG changes in both lesioned and non-lesioned hemisphere. MSC and WPLI in the alpha and beta frequency bands were lower in patients than in controls in both hemispheres, indicating clear disturbances of functional connectivity (p < 0.05). In the poor outcome group, contralateral MSC and WPLI were lower than in the good outcome group, although these differences did not reach statistical significance. Conclusions: Short conventional EEG measurements show robust changes of brain activity and functional connectivity in both ipsilateral and contralateral hemispheres of patients with acute ischemic stroke. Changes of remote functional connectivity tend to interact with functional recovery. Future studies should estimate predictive values for individual patients and interactions with plasticity enhancing treatments.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Contralesional Brain Activity in Acute Ischemic Stroke

et al. 2018

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“…Alternatively, signals in the damaged and undamaged hemispheres might undergo hemisphere-specific changes that reduce their correlation. EEG signals (power, coherence) are abnormal both within and across hemispheres poststroke, and correlate with behavioral impairment (31,32).…”

Section: Discussionmentioning

confidence: 99%

Disruptions of network connectivity predict impairment in multiple behavioral domains after stroke

Siegel

Ramsey

Snyder

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

539

566

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Deficits following stroke are classically attributed to focal damage, but recent evidence suggests a key role of distributed brain network disruption. We measured resting functional connectivity (FC), lesion topography, and behavior in multiple domains (attention, visual memory, verbal memory, language, motor, and visual) in a cohort of 132 stroke patients, and used machine-learning models to predict neurological impairment in individual subjects. We found that visual memory and verbal memory were better predicted by FC, whereas visual and motor impairments were better predicted by lesion topography. Attention and language deficits were well predicted by both. Next, we identified a general pattern of physiological network dysfunction consisting of decrease of interhemispheric integration and intrahemispheric segregation, which strongly related to behavioral impairment in multiple domains. Network-specific patterns of dysfunction predicted specific behavioral deficits, and loss of interhemispheric communication across a set of regions was associated with impairment across multiple behavioral domains. These results link key organizational features of brain networks to brainbehavior relationships in stroke.stroke | functional connectivity | interhemispheric | memory | language A lthough structural damage from stroke is focal, remote dysfunction can occur in regions of the brain distant from the area of damage (1, 2). The set of regions that are directly damaged or indirectly affected is embedded within a larger functional network that is in dynamic balance with other networks in the brain. This framework posits that a lesion in a single location in the brain has the ability to disrupt brain functions far beyond the lesion boundaries (3-5).Numerous correlates of remote physiological dysfunction have been proposed, including abnormal task recruitment of contralesional brain areas (6-8), disruption of metabolism (9) or regional cerebral blood flow (10, 11), and more recently disruption of signal coherence (12-15).However, there is only a limited understanding of how remote physiological dysfunction is related to lesion topography (14, 16). Moreover, the behavioral relevance of reported physiological changes is unclear. Although some studies have reported significant correlation with behavioral impairment, the total amount of behavioral variance explained is unknown. Finally, because mechanisms of remote dysfunction have typically been examined in relatively small groups of individuals, their generalization at the population level is unknown. As a result, physiological measures of brain function are not used in the evaluation and treatment of stroke victims.More traditional lesion-symptom mapping studies have also used statistical methods to relate lesion topography to the severity of different behavioral deficits (17,18). An implicit assumption of these studies is that the strength of association between structural damage and behavior is the same irrespective of the behavior that is measured. However, it is also possi...

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“…Such source connectivity analyses have revealed that focal lesions and diffuse neurodegeneration are associated with a disruption of alpha-band coherence between clinically dysfunctional brain areas and the rest of the brain (Fig. 3) (Dubovik et al, 2013(Dubovik et al, , 2012Guggisberg et al, 2008b). Moreover, local decreases in alpha-band coherence between a given brain area and the rest of the brain are linearly correlated with neurological deficits.…”

Section: Electroencephalographymentioning

confidence: 98%

Variability of behavioural responses to transcranial magnetic stimulation: Origins and predictors

2015

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Transcranial magnetic stimulation (TMS) may modulate the excitability of local cortical stimulation sites and distant functionally interconnected regions for minutes, hours or even days. The effects of TMS suggest that it not only acts on activity of the stimulated area, but also on its connections with remote areas. Due to these properties one of the main rationales for the application of TMS in stroke patients is to improve imbalance in interhemispheric inhibition. However, given that TMS may have excitatory or inhibitory effects the impact of stimulation is not easy to predict. In this review, we discuss the different factors that determine the magnitude and quality of physiological and behavioural responses to TMS. Whether TMS is mainly excitatory or inhibitory not only depends on the parameters of stimulation such as pulse frequency and duration, but also on baseline activity of neural tissue before stimulation, or even on cognitive factors such as attention. A major challenge for the application of TMS as therapy method is to identify predictors of positive effects in individual patients. Neuroimaging studies measuring hemodynamic or electrophysiological responses show that changes in interhemispheric competition or adaptations of functional networks in patients with focal brain lesions may predict the individual response to brain stimulation. Such techniques have the potential to select the most appropriate among different intervention methods for an individual patient.

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The behavioral significance of coherent resting-state oscillations after stroke

Cited by 137 publications

References 70 publications

Contralesional Brain Activity in Acute Ischemic Stroke

Contralesional Brain Activity in Acute Ischemic Stroke

Disruptions of network connectivity predict impairment in multiple behavioral domains after stroke

Variability of behavioural responses to transcranial magnetic stimulation: Origins and predictors

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