Sensorimotor Event-related Desynchronization Research Articles

Priming Intermittent Theta Burst Stimulation for Hemiparetic Upper Limb After Stroke: A Randomized Controlled Trial.

Intermittent theta burst stimulation (iTBS) creates a state with increased excitability that permits treatment modalities to induce neuroplasticity and motor learning. Continuous theta burst stimulation before iTBS may induce metaplasticity and boost the facilitatory effect of iTBS. This study investigated the effects of priming iTBS (ie, applying continuous theta burst stimulation before iTBS) on poststroke hemiparetic upper limb recovery. In this randomized controlled trial, 42 patients with chronic stroke were recruited and randomly allocated to 10 sessions of either priming iTBS, nonpriming iTBS, or sham stimulation to the ipsilesional motor cortex, immediately before robot-assisted training. Outcomes included Fugl-Meyer Assessment-Upper Extremity, Action Research Arm Test and mean movement velocity during each robot-assisted training session. Twenty-one patients were enrolled for measuring the sensorimotor beta event-related desynchronization induced by either mirror visual feedback or movement. The Fugl-Meyer Assessment-Upper Extremity scores revealed a significant time-by-group interaction (P=0.011). Priming and nonpriming iTBS were both superior to sham stimulation in post hoc comparisons; however, the superiority was diminished at follow-up. Among patients with a higher functioning upper limb, priming iTBS yielded a significantly greater improvement in Fugl-Meyer Assessment-Upper Extremity scores than nonpriming iTBS (P=0.025) and sham stimulation (P=0.029) did. No significant interaction was found when analyzing the Action Research Arm Test and mean movement velocity. Priming iTBS enhanced the patients' mirror visual feedback-induced high beta sensorimotor event-related desynchronization over their ipsilesional hemisphere. Priming and nonpriming iTBS are both superior to sham stimulation in enhancing treatment gains from robot-assisted training, and patients with a higher functioning upper limb may experience more benefits from priming iTBS. Priming iTBS may facilitate poststroke motor learning by enhancing the permissiveness of the ipsilesional sensorimotor area to therapeutic sensory modalities, such as the mirror visual feedback. URL: https://www. gov; Unique identifier: NCT04034069.

Event-Related Desynchronization During Mirror Visual Feedback: A Comparison of Older Adults and People After Stroke.

Event-related desynchronization (ERD), as a proxy for mirror neuron activity, has been used as a neurophysiological marker for motor execution after mirror visual feedback (MVF). Using EEG, this study investigated ERD upon the immediate effects of single-session MVF in unimanual arm movements compared with the ERD effects occurring without a mirror, in two groups: stroke patients with left hemiplegia and their healthy counterparts. During EEG recordings, each group performed one session of mirror therapy training in three task conditions: with a mirror, with no mirror, and with a covered mirror. An asymmetry index was calculated from the subtraction of the event-related spectrum perturbations between the C3 and C4 electrodes located over the sensorimotor cortices contralateral and ipsilateral to the moved arm. Results of the effect of task versus group in contralateral and ipsilateral motor areas showed that there was a significant effect of task condition at the contralateral motor area in the high beta band (17–35 Hz) at C3. High beta ERD showed that the suppression was greater over the contralateral hemisphere than it was over the ipsilateral hemisphere in both study groups. The magnitude of low beta (12–16 Hz) ERD in patients with stroke was more suppressed in contralesional C3 under the no mirror compared to that of the covered mirror and similarly more suppressed in ipsilesional C4 ERD under the no mirror compared to that of the mirror condition. The correlation analysis revealed that the magnitude of ERSP power correlated significantly with arm severity in the low and high beta bands in patients with stroke, and a higher asymmetry index in the low beta band was associated with higher arm functioning under the no-mirror condition. There was a shift in sensorimotor ERD toward the contralateral hemisphere as induced by MVF accompanying unimanual movement in both stroke patients and healthy controls. The use of ERD in the low beta band as a neurophysiological marker to indicate the relationships between the amount of MVF-induced ERD attenuation and motor severity, and the outcome indicator for improving stroke patients’ neuroplasticity in clinical trials using MVF are warranted to be explored in the future.

The Effects of Priming Intermittent Theta Burst Stimulation on Movement-Related and Mirror Visual Feedback-Induced Sensorimotor Desynchronization.

The potential benefits of priming intermittent theta burst stimulation (iTBS) with continuous theta burst stimulation (cTBS) have not been examined in regard to sensorimotor oscillatory activities recorded in electroencephalography (EEG). The objective of this study was to investigate the modulatory effect of priming iTBS (cTBS followed by iTBS) delivered to the motor cortex on movement-related and mirror visual feedback (MVF)-induced sensorimotor event-related desynchronization (ERD), compared with iTBS alone, on healthy adults. Twenty participants were randomly allocated into Group 1: priming iTBS—cTBS followed by iTBS, and Group 2: non-priming iTBS—sham cTBS followed by iTBS. The stimulation was delivered to the right primary motor cortex daily for 4 consecutive days. EEG was measured before and after 4 sessions of stimulation. Movement-related ERD was evaluated during left-index finger tapping and MVF-induced sensorimotor ERD was evaluated by comparing the difference between right-index finger tapping with and without MVF. After stimulation, both protocols increased movement-related ERD and MVF-induced sensorimotor ERD in high mu and low beta bands, indicated by significant time effects. A significant interaction effect favoring Group 1 in enhancing movement-related ERD was observed in the high mu band [F(1,18) = 4.47, p = 0.049], compared with Group 2. Our experiment suggests that among healthy adults priming iTBS with cTBS delivered to the motor cortex yields similar effects with iTBS alone on enhancing ERD induced by MVF-based observation, while movement-related ERD was more enhanced in the priming iTBS condition, specifically in the high mu band.

Kinesthetic illusion induced by visual stimulation influences sensorimotor event-related desynchronization in stroke patients with severe upper-limb paralysis: A pilot study

Repetition of motor imagery improves the motor function of patients with stroke. However, patients who develop severe upper-limb paralysis after chronic stroke often have an impaired ability to induce motor imagery. We have developed a method to passively induce kinesthetic perception using visual stimulation (kinesthetic illusion induced by visual stimulation [KINVIS]). This pilot study further investigated the effectiveness of KINVIS in improving the induction of kinesthetic motor imagery in patients with severe upper-limb paralysis after stroke. Twenty participants (11 with right hemiplegia and 9 with left hemiplegia; mean time from onset [±standard deviation], 67.0±57.2 months) with severe upper-limb paralysis who could not extend their paretic fingers were included in this study. The ability to induce motor imagery was evaluated using the event-related desynchronization (ERD) recorded during motor imagery before and after the application of KINVIS for 20 min. The alpha- and beta-band ERDs around the premotor, primary sensorimotor, and posterior parietal cortices of the affected and unaffected hemispheres were evaluated during kinesthetic motor imagery of finger extension and before and after the intervention. Beta-band ERD recorded from the affected hemisphere around the sensorimotor area showed a significant increase after the intervention, while the other ERDs remained unchanged. In patients with chronic stroke who were unable to extend their paretic fingers for a prolonged period of time, the application of KINVIS, which evokes kinesthetic perception, improved their ability to induce motor imagery. Our findings suggest that although KINVIS is a passive intervention, its short-term application can induce changes related to the motor output system.

Enhancing mirror visual feedback with intermittent theta burst stimulation in healthy adults.

Excitatory brain stimulation, in the form of intermittent theta burst stimulation (iTBS), combined with mirror visual feedback (MVF), is hypothesized to promote neuroplasticity and motor performance. This study aimed to investigate the combined effects of iTBS with mirror training (MT) on the MVF-induced sensorimotor event-related desynchronization (ERD) and the non-dominant hand motor performance in healthy adults. Eighteen healthy right-handed subjects were randomly assigned to one of three groups (Group 1: iTBS plus MT, Group 2: iTBS plus sham MT, or Group 3: sham iTBS plus MT). For participants in Groups 1 and 3, motor training was performed for 15 minutes for the right hand over four consecutive days, with MVF superimposing on their inactive left hand behind a mirror. Participants in Group 2 received the same right-hand motor training, but the mirror was covered without MVF. iTBS or sham iTBS was applied daily over the right primary motor cortex prior to the training. Electroencephalography at pre/post-training was recorded while participants performed right-hand movement under mirror and direct view. Motor performance was assessed at baseline and post-training. Baseline comparisons demonstrated that a shift in sensorimotor ERD towards the right hemisphere was induced by MVF, in mu-1 (8-10 Hz) (p = 0.002), mu-2 (10-12 Hz) (p = 0.004) and beta-1 (12-16 Hz) (p = 0.049) bands. After the training, participants in Group 1 showed a stronger MVF-induced sensorimotor ERD in mu-1 (p = 0.017) and mu-2 (p = 0.009) bands than those in Group 3. No significant between-group difference in motor outcomes was observed. iTBS appears to prime subjects' brain to be more receptive to MVF.

Neurophysiological Evidence of Motor Network Reorganization in Myotonic Dystrophy Type 1: A Pilot Magnetoencephalographic Study.

Myotonic dystrophy type 1 is the most common muscular dystrophy in adults. Although brain involvement is well recognized, the relationship between cortical motor control and voluntary movement has not been sufficiently explored. This study aims at assessing magnetoencephalographic (MEG) rhythms at oscillatory and connectivity levels to map central motor control. Magnetoencephalographic data were acquired from healthy subjects and five myotonic dystrophy type 1 subjects during resting state and foot movement. Resting state EEG band power, event-related desynchronization/synchronization, functional connectivity, and network features (node strength and betweenness centrality) were estimated. A statistical comparison of these indexes between the two groups was run; a linear correlation between event-related desynchronization and motor performance was obtained. Myotonic dystrophy type 1 subjects showed higher theta power over central motor regions and lower beta power over frontal areas, with a decrease of beta node strength over the dominant hemisphere and an increase of betweenness centrality over the vertex. Foot movement in the most impaired myotonic dystrophy type 1 subjects was inefficient in evoking event-related desynchronization. In less severely impaired participants, dominant foot movement was related to a bilateral sensorimotor event-related desynchronization. Results provide proof of a central dysfunction of movement. Identification of neurophysiological motor patterns in myotonic dystrophy type 1 could provide a guide for tailored therapy.

Subjective Vividness of Kinesthetic Motor Imagery Is Associated With the Similarity in Magnitude of Sensorimotor Event-Related Desynchronization Between Motor Execution and Motor Imagery

In the field of psychology, it has been well established that there are two types of motor imagery such as kinesthetic motor imagery (KMI) and visual motor imagery (VMI), and the subjective evaluation for vividness of motor imagery each differs across individuals. This study aimed to examine how the motor imagery ability assessed by the psychological scores is associated with the physiological measure using electroencephalogram (EEG) sensorimotor rhythm during KMI task. First, 20 healthy young individuals evaluated subjectively how vividly they can perform each of KMI and VMI by using the Kinesthetic and Visual Imagery Questionnaire (KVIQ). We assessed their motor imagery abilities by summing each of KMI and VMI scores in KVIQ (KMItotal and VMItotal). Second, in physiological experiments, they repeated two strengths (10 and 40% of maximal effort) of isometric voluntary wrist-dorsiflexion. Right after each contraction, they also performed its KMI. The scalp EEGs over the sensorimotor cortex were recorded during the tasks. The EEG power is known to decrease in the alpha-and-beta band (7–35 Hz) from resting state to performing state of voluntary contraction (VC) or motor imagery. This phenomenon is referred to as event-related desynchronization (ERD). For each strength of the tasks, we calculated the maximal peak of ERD during VC, and that during its KMI, and measured the degree of similarity (ERDsim) between them. The results showed significant negative correlations between KMItotal and ERDsim for both strengths (p < 0.05) (i.e., the higher the KMItotal, the smaller the ERDsim). These findings suggest that in healthy individuals with higher motor imagery ability from a first-person perspective, KMI efficiently engages the shared cortical circuits corresponding with motor execution, including the sensorimotor cortex, with high compliance.

Recruitment of Additional Corticospinal Pathways in the Human Brain with State-Dependent Paired Associative Stimulation.

Standard brain stimulation protocols modify human motor cortex excitability by modulating the gain of the activated corticospinal pathways. However, the restoration of motor function following lesions of the corticospinal tract requires also the recruitment of additional neurons to increase the net corticospinal output. For this purpose, we investigated a novel protocol based on brain state-dependent paired associative stimulation.Motor imagery (MI)-related electroencephalography was recorded in healthy males and females for brain state-dependent control of both cortical and peripheral stimulation in a brain-machine interface environment. State-dependency was investigated with concurrent, delayed, and independent stimulation relative to the MI task. Specifically, sensorimotor event-related desynchronization (ERD) in the β-band (16-22 Hz) triggered peripheral stimulation through passive hand opening by a robotic orthosis and transcranial magnetic stimulation to the respective cortical motor representation, either synchronously or subsequently. These MI-related paradigms were compared with paired cortical and peripheral input applied independent of the brain state. Cortical stimulation resulted in a significant increase in corticospinal excitability only when applied brain state-dependently and synchronously to peripheral input. These gains were resistant to a depotentiation task, revealed a nonlinear evolution of plasticity, and were mediated via the recruitment of additional corticospinal neurons rather than via synchronization of neuronal firing. Recruitment of additional corticospinal pathways may be achieved when cortical and peripheral inputs are applied concurrently, and during β-ERD. These findings resemble a gating mechanism and are potentially important for developing closed-loop brain stimulation for the treatment of hand paralysis following lesions of the corticospinal tract.SIGNIFICANCE STATEMENT The activity state of the motor system influences the excitability of corticospinal pathways to external input. State-dependent interventions harness this property to increase the connectivity between motor cortex and muscles. These stimulation protocols modulate the gain of the activated pathways, but not the overall corticospinal recruitment. In this study, a brain-machine interface paired peripheral stimulation through passive hand opening with transcranial magnetic stimulation to the respective cortical motor representation during volitional β-band desynchronization. Cortical stimulation resulted in the recruitment of additional corticospinal pathways, but only when applied brain state-dependently and synchronously to peripheral input. These effects resemble a gating mechanism and may be important for the restoration of motor function following lesions of the corticospinal tract.

Sensorimotor event-related desynchronization represents the excitability of human spinal motoneurons

Amplitudes of mu and beta (7–26Hz) oscillations measured by electroencephalography over the sensorimotor areas are suppressed during motor imagery as well as during voluntary movements. This phenomenon is referred to as event-related desynchronization (ERD) and is known to reflect motor cortical excitability. The increased motor cortical excitability associated with ERD during hand motor imagery would induce a descending cortical volley to spinal motoneurons, resulting in facilitation of spinal motoneuronal excitability. Therefore, in the present study, we tested the association of ERD during motor imagery with the excitability of spinal motoneurons in 15 healthy participants. Spinal excitability was tested using the F-wave recorded from the right abductor pollicis brevis muscle. The F-wave results from antidromic activation of spinal motoneurons and is induced by peripheral nerve stimulation. Participants performed 5s of motor imagery of right thumb abduction following 7s of rest. The right median nerve was stimulated at wrist level when the ERD magnitude of the contralateral hand sensorimotor area exceeded predetermined thresholds during motor imagery. The results showed ERD magnitude during hand motor imagery was associated with an increase in F-wave persistence, but not with the response average of F-wave amplitude or F-wave latency. These findings suggest that the ERD magnitude may be a biomarker representing increases in the excitability of both cortical and spinal levels.

Importance of baseline in event-related desynchronization during a combination task of motor imagery and motor observation

Objective. Event-related desynchronization (ERD) or synchronization (ERS) refers to the modulation of any EEG rhythm in response to a particular event. It is typically quantified as the ratio between a baseline and a task condition (the event). Here, we focused on the sensorimotor mu-rhythm. We explored the effects of different baselines on mu-power and ERD of the mu-rhythm during a motor imagery task. Methods. Eighteen healthy subjects performed motor imagery tasks while EEGs were recorded. Five different baseline movies were shown. For the imagery task a right-hand opening/closing movie was shown. Power and ERD of the mu-rhythm recorded over C3 and C4 for the different baselines were estimated. Main Results. 50% of the subjects showed relatively high mu-power for specific baselines only, and ERDs of these subjects were strongly dependent on the baseline used. In 17% of the subjects no preference was found. Contralateral ERD of the mu-rhythm was found in about 67% of the healthy volunteers, with a significant baseline preference in about 75% of that subgroup. Significance. The sensorimotor ERD quantifies activity of the brain during motor imagery tasks. Selection of the optimal baseline increases ERD.

Acute effects of L-dopa on event-related desynchronization in Parkinson's disease.

We tested whether dispersible L-dopa has acute effects on event-related desynchronization (ERD) of the mu rhythm in patients with idiopathic Parkinson's disease (IPD). ERD to voluntary movement is delayed in akinetic IPD patients and improves after chronic L-dopa treatment. We evaluated ERD to self-paced finger movement in 14 IPD patients (before and 30-40 min after oral administration of dispersible L-dopa) and in 10 normal subjects. Sensorimotor ERD onset contralateral to movement was significantly delayed in IPD patients compared to normal subjects. This abnormality was no longer significant after L-dopa treatment. We conclude that a single dose of dispersible L-dopa can improve not only motor performance in IPD patients but also the timing of cortical activation of sensorimotor areas during motor programming.

Event-related desynchronization in reaction time paradigms: a comparison with event-related potentials and corticospinal excitability

Objectives: To study cortical activity in different motor tasks, we compared event-related desynchronization (ERD) and event-related potentials (ERPs) in different reaction time (RT) paradigms with the time course of corticospinal excitability. Methods: Nine right-handed, normal subjects performed right or left thumb extensions in simple, choice and go/no go auditory RT paradigms. Eight subjects had participated in a previous study evaluating changes in corticospinal excitability during the same paradigms. Twenty-nine EEG channels with electrooculogram and bilateral EMG monitoring were collected. ERPs and ERD of 10 and 18–22 Hz bands were obtained with respect to tone administration and EMG onset. Results: Trials with movement showed lateralized ERP components, corresponding to the motor potential (MP), both in the averages on the tone and on EMG. The MP corresponded well in time and location to the rise in corticospinal excitability on the moving side observed in the previous study. Sensorimotor ERD, followed by event-related synchronization (ERS), was present for trials with movements and for the no go. ERD was present contralaterally during movement preparation and in no go trials, while it was bilateral during motor execution. No go ERD was followed more rapidly by ERS than in trials with movement. This finding suggests that in no go trials, there is a brief active process in the sensorimotor areas. ERD and ERS do not correspond, respectively, in time and location to increases and decreases in corticospinal excitability. In fact, ERD is bilateral during movement execution, when corticospinal inhibition of the side at rest is observed. Contralateral no go ERS occurs later than corticospinal inhibition, which is bilateral. Conclusions: These findings may suggest that ERD is compatible with both corticospinal activation and inhibition, ERS indicating the removal of either, resulting in cortical idling.