Motor imagery and action observation: Modulation of sensorimotor brain rhythms during mental control of a brain–computer interface

ObjectiveThis study investigates the impact of a continuously presented visual feedback in the form of a grasping hand on the modulation of sensorimotor EEG rhythms during online control of a brain–computer interface (BCI).MethodsTwo groups of participants were trained to use left or right hand motor imagery to control a specific output signal on a computer monitor: the experimental group controlled a moving hand performing an object-related grasp (‘realistic feedback’), whereas the control group controlled a moving bar (‘abstract feedback’). Continuous feedback was realized by using the outcome of a real-time classifier which was based on EEG signals recorded from left and right central sites.ResultsThe classification results show no difference between the two feedback groups. For both groups, ERD/ERS analysis revealed a significant larger ERD during feedback presentation compared to an initial motor imagery screening session without feedback. Increased ERD during online BCI control was particularly found for the lower alpha (8–10 Hz) and for the beta bands (16–20, 20–24 Hz).ConclusionsThe present study demonstrates that visual BCI feedback clearly modulates sensorimotor EEG rhythms. When the feedback provides equivalent information on both the continuous and final outcomes of mental actions, the presentation form (abstract versus realistic) does not influence the performance in a BCI, at least in initial training sessions.SignificanceThe present results are of practical interest for classifier development and BCI use in the field of motor restoration.     

On the control of brain-computer interfaces by users with cerebral palsy

ObjectiveBrain-computer interfaces (BCIs) have been proposed as a potential assistive device for individuals with cerebral palsy (CP) to assist with their communication needs. However, it is unclear how well-suited BCIs are to individuals with CP. Therefore, this study aims to investigate to what extent these users are able to gain control of BCIs.MethodsThis study is conducted with 14 individuals with CP attempting to control two standard online BCIs (1) based upon sensorimotor rhythm modulations, and (2) based upon steady state visual evoked potentials.ResultsOf the 14 users, 8 are able to use one or other of the BCIs, online, with a statistically significant level of accuracy, without prior training. Classification results are driven by neurophysiological activity and not seen to correlate with occurrences of artifacts. However, many of these users’ accuracies, while statistically significant, would require either more training or more advanced methods before practical BCI control would be possible.ConclusionsThe results indicate that BCIs may be controlled by individuals with CP but that many issues need to be overcome before practical application use may be achieved.SignificanceThis is the first study to assess the ability of a large group of different individuals with CP to gain control of an online BCI system. The results indicate that six users could control a sensorimotor rhythm BCI and three a steady state visual evoked potential BCI at statistically significant levels of accuracy (SMR accuracies; mean ± STD, 0.821 ± 0.116, SSVEP accuracies; 0.422 ±  0.069).     

Toward a high-throughput auditory P300-based brain–computer interface

ObjectiveBrain–computer interface (BCI) technology can provide severely disabled people with non-muscular communication. For those most severely disabled, limitations in eye mobility or visual acuity may necessitate auditory BCI systems. The present study investigates the efficacy of the use of six environmental sounds to operate a 6 × 6 P300 Speller.MethodsA two-group design was used to ascertain whether participants benefited from visual cues early in training. Group A (N = 5) received only auditory stimuli during all 11 sessions, whereas Group AV (N = 5) received simultaneous auditory and visual stimuli in initial sessions after which the visual stimuli were systematically removed. Stepwise linear discriminant analysis determined the matrix item that elicited the largest P300 response and thereby identified the desired choice.ResultsOnline results and offline analyses showed that the two groups achieved equivalent accuracy. In the last session, eight of 10 participants achieved 50% or more, and four of these achieved 75% or more, online accuracy (2.8% accuracy expected by chance). Mean bit rates averaged about 2 bits/min, and maximum bit rates reached 5.6 bits/min.ConclusionsThis study indicates that an auditory P300 BCI is feasible, that reasonable classification accuracy and rate of communication are achievable, and that the paradigm should be further evaluated with a group of severely disabled participants who have limited visual mobility.SignificanceWith further development, this auditory P300 BCI could be of substantial value to severely disabled people who cannot use a visual BCI.     

Sensorimotor interaction between somatosensory painful stimuli and motor sequences affects both anticipatory alpha rhythms and behavior as a function of the event side

It has been shown that concomitant painful stimulation and simple movement at the same hand is related to decreased anticipatory alpha event-related desynchronization (ERD) and reduced pain intensity, possibly due to the interference between somatosensory and motor information processing (Babiloni et al. [6]). Here, we tested the hypothesis that such interference also affects motor performance during sequential movements. Visual warning stimuli were followed by imperative stimuli associated to electrical painful stimulation at left or right middle finger; imperative stimuli triggered motor sequences with right index finger. Electroencephalographic data (N = 10, 128 electrodes) were spatially enhanced by surface Laplacian transformation. Cortical activity as revealed by the alpha event-related desynchronization (ERD) was compared in “Pain + ipsilateral movement” condition (movements and painful stimuli performed at the right hand) vs. “Pain + contralateral movement” condition (painful stimuli at left hand and movements performed at the right hand). Results showed that compared with the “Pain + contralateral movement” condition, the “Pain + ipsilateral movement” condition induced lower anticipatory alpha ERD (about 10–12 Hz) in left sensorimotor area, lower subjective pain rate, and delayed movement initiation at the group level. These findings suggest that anticipatory alpha rhythms may underlie cortical preparatory sensorimotor processes preceding somatosensory painful and the initiation of sequential motor events occurring at unilateral or bilateral hand.     

Could the beta rebound in the EEG be suitable to realize a “brain switch”?

ObjectivePerforming foot motor imagery is accompanied by a peri-imagery ERD and a post-imagery beta ERS (beta rebound). Our aim was to study whether the post-imagery beta rebound is a suitable feature for a simple “brain switch”. Such a brain switch is a specifically designed brain–computer interface (BCI) with the aim to detect only one predefined brain state (e.g. EEG pattern) in ongoing brain activity.MethodOne EEG (Laplacian) recorded at the vertex during cue-based brisk foot motor imagery was analysed in 5 healthy subjects. The peri-imagery ERD and the post-imagery beta rebound (ERS) were analysed in detail between 6 and 40 Hz and classified with two support vector machines.ResultsThe ERD was detected in ongoing EEG (simulation of asynchronous BCI) with a true positive rate (TPR) of 28.4% ± 13.5 and the beta rebound with a TPR of 59.2% ± 20.3. In single runs with 30 cues each, the TPR for beta rebound detection was 78.6% ± 12.8. The false positive rate was always kept below 10%.ConclusionThe findings suggest that the beta rebound at Cz during foot motor imagery is a relatively stable and reproducible phenomenon detectable in single EEG trials.SignificanceOur results indicate that the beta rebound is a suitable feature to realize a “brain switch” with one single EEG (Laplacian) channel only.     

Using a motor imagery questionnaire to estimate the performance of a Brain–Computer Interface based on object oriented motor imagery

ObjectivesThe primary objective was to test whether motor imagery (MI) questionnaires can be used to detect BCI ‘illiterate’. The second objective was to test how different MI paradigms, with and without the physical presence of the goal of an action, influence a BCI classifier.MethodsKinaesthetic (KI) and visual (VI) motor imagery questionnaires were administered to 30 healthy volunteers. Their EEG was recorded during a cue-based, simple imagery (SI) and goal oriented imagery (GOI).ResultsThe strongest correlation (Pearson r² = 0.53, p = 1.6e-5) was found between KI and SI, followed by a moderate correlation between KI and GOI (r² = 0.33, p = 0.001) and a weak correlation between VI and SI (r² = 0.21, p = 0.022) and VI and GOI (r² = 0.17, p = 0.05). Classification accuracy was similar for SI (71.1 ± 7.8%) and GOI (70.5 ± 5.9%) though corresponding classification features differed in 70% participants. Compared to SI, GOI improved the classification accuracy in ‘poor’ imagers while reducing the classification accuracy in ‘very good’ imagers.ConclusionThe KI score could potentially be a useful tool to predict the performance of a MI based BCI. The physical presence of the object of an action facilitates motor imagination in ‘poor’ able-bodied imagers.SignificanceAlthough this study shows results on able-bodied people, its general conclusions should be transferable to BCI based on MI for assisted rehabilitation of the upper extremities in patients.     

Inhibition of the anterior intraparietal area and the dorsal premotor cortex interfere with arbitrary visuo-motor mapping

ObjectiveThe contribution of the human anterior intraparietal area and the dorsal premotor cortex to arbitrary visuo-motor mapping during grasping were tested.MethodsTrained right-handed subjects reached for and pincer-grasped a cube with the right hand in the absence of visual feedback after the cube location had been displayed for 200 ms. During the reaching movements, the colour of the cube changed and visual feedback about the change of colour was provided for 100 ms at 500 ms after movement onset (at the time of peak grasp aperture). Depending on colour, subjects were instructed to either pincer-grasp the cube in a horizontal or vertical grasp position with the latter necessitating wrist rotation (experiment 1) or to pincer-grasp and transport the cube to either a left or right target position (experiment 2). Within two consecutive 200 ms time windows (TMS 1 and 2) starting 500 ms and 700 ms after movement onset, respectively, double pulses of supra-threshold transcranial magnetic stimulation (inter-stimulus interval: 100 ms) were delivered over (i) the left primary motor cortex (90° vertically angulated coil position, control stimulation), (ii) the left dorsal premotor cortex or (ii) the left anterior intraparietal area.ResultsCompared to control stimulation, stimulation of the anterior intraparietal area, but not of the dorsal premotor cortex, at TMS 1 delayed the times to wrist rotation (experiment 1) and hand transport (experiment 2). Compared to control stimulation, stimulation of the dorsal premotor cortex, but not of the anterior intraparietal area, at TMS 2 delayed both wrist rotation (experiment 1) and hand transport (experiment 2).ConclusionsWe contend that the anterior intraparietal area and the dorsal premotor cortex are both involved albeit at different phases during the mapping of arbitrary visual cues with goal directed grasp and transport movements.SignificanceThese data add to the current understanding of how human cortical areas work in concert during manual activities.     

Towards a user-friendly brain–computer interface: Initial tests in ALS and PLS patients

ObjectivePatients usually require long-term training for effective EEG-based brain–computer interface (BCI) control due to fatigue caused by the demands for focused attention during prolonged BCI operation. We intended to develop a user-friendly BCI requiring minimal training and less mental load.MethodsTesting of BCI performance was investigated in three patients with amyotrophic lateral sclerosis (ALS) and three patients with primary lateral sclerosis (PLS), who had no previous BCI experience. All patients performed binary control of cursor movement. One ALS patient and one PLS patient performed four-directional cursor control in a two-dimensional domain under a BCI paradigm associated with human natural motor behavior using motor execution and motor imagery. Subjects practiced for 5–10 min and then participated in a multi-session study of either binary control or four-directional control including online BCI game over 1.5–2 h in a single visit.ResultsEvent-related desynchronization and event-related synchronization in the beta band were observed in all patients during the production of voluntary movement either by motor execution or motor imagery. The online binary control of cursor movement was achieved with an average accuracy about 82.1 ± 8.2% with motor execution and about 80% with motor imagery, whereas offline accuracy was achieved with 91.4 ± 3.4% with motor execution and 83.3 ± 8.9% with motor imagery after optimization. In addition, four-directional cursor control was achieved with an accuracy of 50–60% with motor execution and motor imagery.ConclusionPatients with ALS or PLS may achieve BCI control without extended training, and fatigue might be reduced during operation of a BCI associated with human natural motor behavior.SignificanceThe development of a user-friendly BCI will promote practical BCI applications in paralyzed patients.     

Motivation modulates the P300 amplitude during brain–computer interface use

ObjectiveThis study examined the effect of motivation as a possible psychological influencing variable on P300 amplitude and performance in a brain–computer interface (BCI) controlled by event-related potentials (ERP).MethodsParticipants were instructed to copy spell a sentence by attending to cells of a randomly flashing 7 * 7 matrix. Motivation was manipulated by monetary reward. In two experimental groups participants received 25 (N = 11) or 50 (N = 11) Euro cent for each correctly selected character; the control group (N = 11) was not rewarded. BCI performance was defined as the overall percentage of correctly selected characters (correct response rate = CRR).ResultsParticipants performed at an average of 99%. At electrode location Cz the P300 amplitude was positively correlated to self-rated motivation. The P300 amplitude of the most motivated participants was significantly higher than that of the least motivated participants. Highly motivated participants were able to communicate correctly faster with the ERP-BCI than less motivated participants.ConclusionsMotivation modulates the P300 amplitude in an ERP-BCI.SignificanceMotivation may contribute to variance in BCI performance and should be monitored in BCI settings.     

Watching object related movements modulates mirror-like activity in parietal brain regions

ObjectiveWe studied the activation of cortical motor and parietal areas during the observation of object related grasping movements. By manipulating the type of an object (realistic versus abstract) and the type of grasping (correct versus incorrect), we addressed the question how observing such object related movements influences cortical rhythmicity, especially the mu-rhythm, in the context of an “extended” human mirror neuron system (MNS).MethodsMultichannel electroencephalogram (EEG) was recorded during the observation of different object-related grasping actions in twenty healthy subjects. Different movies were presented, showing sequences of correct or incorrect hand grasping actions related to an abstract or realistic (daily life) object.ResultsEvent-related de/synchronization (ERD/ERS) analyses revealed a larger ERD in the upper alpha (10–12 Hz), beta (16–20 Hz) and gamma (36–40 Hz) frequency bands over parietal brain regions depending on the type of grasping. The type of object only influenced ERD patterns in the gamma band range (36–40 Hz) at parietal sites suggesting a strong relation of gamma band activity and cortical object representation. Abstract and realistic objects produced lower beta band synchronization at central sites only, whereas depending on the type of grasping an ERS in the upper alpha band (10–12 Hz) was observed.ConclusionDepending on the type of the grasped object and the type of grasping stronger parietal cortical activation occurred during movement observation.SignificanceDiscussing the results in terms of an “extended” human mirror neuron system (MNS), it could be concluded that beside sensorimotor areas a stronger involvement of parietal brain regions was found depending on the type of object and grasping movement observed.     

An automated and fast approach to detect single-trial visual evoked potentials with application to brain–computer interface

ObjectiveThis study aims (1) to develop an automated and fast approach for detecting visual evoked potentials (VEPs) in single trials and (2) to apply the single-trial VEP detection approach in designing a real-time and high-performance brain–computer interface (BCI) system.MethodsThe single-trial VEP detection approach uses common spatial pattern (CSP) as a spatial filter and wavelet filtering (WF) a temporal–spectral filter to jointly enhance the signal-to-noise ratio (SNR) of single-trial VEPs. The performance of the joint spatial–temporal–spectral filtering approach was assessed in a four-command VEP-based BCI system.ResultsThe offline classification accuracy of the BCI system was significantly improved from 67.6 ± 12.5% (raw data) to 97.3 ± 2.1% (data filtered by CSP and WF). The proposed approach was successfully implemented in an online BCI system, where subjects could make 20 decisions in one minute with classification accuracy of 90%.ConclusionsThe proposed single-trial detection approach is able to obtain robust and reliable VEP waveform in an automatic and fast way and it is applicable in VEP based online BCI systems.SignificanceThis approach provides a real-time and automated solution for single-trial detection of evoked potentials or event-related potentials (EPs/ERPs) in various paradigms, which could benefit many applications such as BCI and intraoperative monitoring.     

A portable auditory P300 brain–computer interface with directional cues

ObjectivesThe main objective of the current study was to implement and evaluate a P300 based brain–computer interface (BCI) speller that uses directional cues of auditory stimuli, which are presented over headphones. The interstimulus interval (ISI) was successively reduced to determine the optimal combination of speed and accuracy. The study further aimed at quantifying the differences in subjective workload between the auditory and the visual P300 spelling application. The influence of workload, mood and motivation on BCI performance and P300 amplitude was investigated.MethodsTwenty healthy participants performed auditory and visual spelling tasks in an EEG experiment with online feedback.ResultsSixteen of twenty participants performed at or above a level necessary for satisfactory communication (?70% spelling accuracy) with the auditory BCI. Average bit rates of up to 2.76 bits/min (best subject 7.43 bits/min) were achieved. A significantly higher workload was reported for the auditory speller compared to the visual paradigm. Motivation significantly influenced P300 amplitude at Pz in the auditory condition.ConclusionsThe results of the online study suggest that the proposed paradigm offers a means of communication for most healthy users.SignificanceThe described auditory BCI can serve as a communication channel for completely paralyzed patients.     

Functional neuronal activity and connectivity within the subthalamic nucleus in Parkinson’s disease

ObjectiveCharacterization of the functional neuronal activity and connectivity within the subthalamic nucleus (STN) in patients with Parkinson’s disease (PD).MethodsSingle units were extracted from micro-electrode recording (MER) of 18 PD patients who underwent STN deep brain stimulation (DBS) surgery. The firing rate and pattern of simultaneously recorded spike trains and their coherence were analyzed. To provide a precise functional assignment of position to the observed activities, for each patient we mapped its classified multichannel STN MERs to a generic atlas representation with a sensorimotor part and a remaining part.ResultsWithin the sensorimotor part we found significantly higher mean firing rate (P < 0.05) and significantly more burst-like activity (P < 0.05) than within the remaining part. The proportion of significant coherence in the beta band (13–30 Hz) is significantly higher in the sensorimotor part of the STN than elsewhere (P =  0.015).ConclusionsThe STN sensorimotor part distinguishes itself from the remaining part with respect to beta coherence, firing rate and burst-like activity and postoperatively was found as the preferred target area.SignificanceOur firing behavior analysis may help to discriminate the STN sensorimotor part for the placement of the DBS electrode.     

1 Hz rTMS of the left posterior parietal cortex (PPC) modifies sensorimotor timing

In order to investigate the relevance of the left posterior parietal cortex (PPC) for precise sensorimotor timing we applied 1 Hz repetitive transcranial magnetic stimulation (rTMS) over left PPC, right PPC and visual cortex of healthy participants for 10 min, respectively. The impact on sensorimotor timing of the right hand was assessed using a synchronization task that required subjects to synchronize their right index finger taps with respect to constant auditory, visual or auditory–visual pacing. Our results reveal reduced negative tap-to-pacer asynchronies following rTMS of the left PPC in all pacing conditions. This effect lasted for about 5 min after cessation of rTMS. Right PPC and visual cortex stimulation did not yield any significant behavioural effects. Since suppression of left PPC modified right-hand synchronization accuracy independent of the pacing signal's modality, the present data support the significance of left PPC for anticipatory motor control over a primary role in multisensory integration. The present data suggest that 1 Hz rTMS might interrupt a matching process of anticipated and real sensorimotor feedback within PPC. Alternatively, downregulation of left PPC activity may affect M1 excitability via functional connections leading to a delay in motor output and, thus, smaller tap-to-pacer asynchronies.     

Effects of transcranial direct current stimulation on esophageal motility in patients with gastroesophageal reflux disease

ObjectiveTo evaluate the effects of transcranial direct current stimulation (tDCS) on esophageal peristalsis in patients with gastroesophageal reflux disease (GERD).MethodsPatients with GERD preliminary diagnosis were included in a randomized double-blind sham-controlled study. Esophageal manometry was performed before and during transcranial direct current stimulation (tDCS) of the right precentral cortex. Half of patients were randomly assigned to anodal, half to sham stimulation. Distal waves amplitude and pathological waves percentage were measured, after swallowing water boli, for ten subsequent times. Last, a 24 h pH-bilimetry was done to diagnose non-erosive reflux disease (NERD) or functional heartburn (FH). The values obtained before and during anodal or sham tDCS were compared.ResultsSixty-eight patients were enrolled in the study. Distal waves mean amplitude increased significantly only during anodal tDCS in NERD (p = 0.00002) and FH subgroups (p = 0.008) while percentage of pathological waves strongly decreased only in NERDs (p = 0.002).ConclusionsTranscranial stimulation can influence cortical control of esophageal motility and improve pathological motor pattern in NERD and FH but not in erosive reflux disease (ERD) patients.SignificancePathophysiological processes in GERD are not only due to peripheral damage but to central neural control involvement as well. In ERD patients dysfunctions of the cortico-esophageal circuit seem to be more severe and may affect central nervous system physiology.     

Improving the knowledge of epilepsy and reducing epilepsy-related stigma among children using educational video and educational drama—A comparison of the effectiveness of both interventions

PurposeThis study was intended to compare the effectiveness of educational animated video and educational drama in improving the knowledge of epilepsy and reducing epilepsy-related stigma among children aged 9–11 years.MethodThe first group of children involved in the study (n₁ = 762) watched a video and then completed a questionnaire on epilepsy. The second group (n₂ = 400) completed the questionnaire after participating in a drama. Both groups were retested 6 months later by the same questionnaire, which was also completed by a control group (n₃ = 180) not subjected to intervention.ResultsBoth groups subjected to intervention achieved significantly higher scores (P < 0.001) than the control group on knowledge of epilepsy and on attitudes towards children with the disease. Educational video was more effective than drama in improving knowledge of epilepsy. On the other hand, there was no significant difference (P > 0.05) between the two kinds of intervention regarding attitudes towards children with this disease.ConclusionThe results suggest that both interventions could be used to reduce epilepsy-related stigma in this age group.     

An amplitude-modulated visual stimulation for reducing eye fatigue in SSVEP-based brain–computer interfaces

ObjectiveA high-frequency steady-state visual evoked potential (SSVEP) has been suggested for the reduction of eye fatigue for SSVEP-based brain–computer interfaces (BCIs). However, the poor performance of high-frequency SSVEP requires a novel stimulus of better performance even with low eye fatigue. As an alternative to the high-frequency SSVEP, we explore the SSVEP response to an amplitude-modulated stimulus (AM-SSVEP) to verify its availability for brain–computer interfaces (BCIs).MethodsAn amplitude-modulated stimulus was generated as the product of two sine waves at a carrier frequency (f_c) and a modulating frequency (f_m). The carrier frequency was higher than 40 Hz to reduce eye fatigue, and the modulating frequency ranged around the α-band (9–12 Hz) to utilize low-frequency harmonic information. Four targets were used in combinations of three different modulating frequencies and two different carrier frequencies in the offline experiment, and two additional targets were added with one additional modulating and one carrier frequency in online experiments.ResultsIn the AM-SSVEP spectra, seven harmonic components were identified at 2f_c, 2f_m, f_c ± f_m, f_c ± 3f_m, and 2f_c − 4f_m. Using an optimized combination of the harmonic frequencies, online experiments demonstrated that the accuracy of the AM-SSVEP was equivalent to that of the low-frequency SSVEP. Furthermore, subject evaluation indicated that an AM stimulus caused lower eye fatigue and less sensing of flickering than a low-frequency stimulus, in a manner similar to a high-frequency stimulus.ConclusionsThe actual stimulus frequencies of AM-SSVEPs are in the high-frequency band, resulting in reduced eye fatigue. Furthermore, AM-SSVEPs can utilize both fundamental stimulus frequencies and non-integer harmonic frequencies including low frequencies for SSVEP recognition. The feasibility of AM-SSVEP with high BCI performance and low eye fatigue was confirmed through offline and online experiments.SignificanceAM-SSVEPs combine the advantages of both low- and high-frequency SSVEPs – high power and low eye fatigue, respectively. AM-SSVEP-based BCI systems exploit these advantages, making them promising for application in practical BCI systems.     

Face stimuli effectively prevent brain–computer interface inefficiency in patients with neurodegenerative disease

ObjectivesRecently, we proposed a new stimulation paradigm for brain computer interfaces (BCI) based on event-related potentials (ERP), i.e. flashing characters with superimposed pictures of well-known faces. This new face flashing (FF) paradigm significantly outperformed the commonly used character flashing (CF) approach, i.e. simply highlighting characters.MethodsIn the current study we assessed the impact of face stimuli on BCI inefficiency in patients with neurodegenerative disease, i.e. on their inability to communicate by means of a BCI. Healthy participants (N = 16) and those with neurodegenerative disease (N = 9) performed spelling tasks using CF and FF paradigms.ResultsOnline performance with FF was significantly increased as compared to CF in both, healthy and impaired users. Importantly, two patients who were classified “highly inefficient” with the classic CF stimulation were able to spell with high accuracy using FF. Our results particularly emphasize great benefit of the FF paradigm for those users displaying low signal-to-noise ratio of the recorded ERPs in the classic stimulation approach.ConclusionIn conclusion, we confirm previously reported results now systematically validated in an online setting and display specifically beneficial effects of FF for motor-impaired users.SignificanceThe FF paradigm thus constitutes a big step forward against the BCI inefficiency phenomenon.     

Cortical involvement in the sensory and motor symptoms of primary restless legs syndrome

BackgroundRestless legs syndrome (RLS) is characterized by closely interrelated motor and sensory disorders. Two types of involuntary movement can be observed: periodic leg movements during wakefulness (PLMW) and periodic leg movements during sleep (PLMS). Basal ganglia dysfunction in primary RLS has often been suggested. However, clinical observations raise the hypothesis of sensorimotor cortical involvement in RLS symptoms. Here, we explored cortical function via movement-related beta and mu rhythm reactivity.MethodsTwelve patients with idiopathic, primary RLS were investigated and compared with 10 healthy subjects. In the patient group, we analyzed event-related beta and mu (de)synchronization (ERD/S) for PLMS and PLMW during a suggested immobilization test (SIT). An ERD/S analysis was also performed in patients and controls during self-paced right ankle dorsal flexion at 8:30 PM (i.e., the symptomatic period for patients) and 8:30 AM (the asymptomatic period).ResultsBefore PLMS, there was no ERD. Intense ERS was recorded after PLMS. As with voluntary movement, cortical ERD was always observed before PLMW. After PLMW, ERS had a diffuse scalp distribution. Furthermore, the ERS and ERD amplitudes and durations for voluntary movement were greater during the symptomatic period than during the asymptomatic period and in comparison with healthy controls, who presented an evening decrease in these parameters. Patients and controls had similar ERD and ERS patterns in the morning.ConclusionOn the basis of a rhythm reactivity study, we conclude that the symptoms of RLS are related to cortical sensorimotor dysfunction.     

Effect of cued training on motor evoked potential and cortical silent period in people with Parkinson’s disease

ObjectiveTo examine whether training under visual cues could enhance motor cortical excitability and intracortical inhibition in individuals with Parkinson’s disease (PD).MethodsThis was a single blinded cross-over study. Eight individuals with PD received two sessions of 30-min pinch-grip training with and without visual cues. The visual cue was given in form of an arrow that indicated the pre-set force level on a computer screen. Outcome measures consisted of peak motor evoked potential (MEP) and cortical silent period (CSP) of the first dorsal interosseus as well as behavioural tests including Purdue pegboard test, tapping speed in 30 s, and the maximum pinch grip force exerted by the thumb and index finger.ResultsAfter cued training, there were significant increases in the peak MEP, CSP duration and tapping speed (all p < 0.05). In contrast, there was no change in all outcome measures after training under the non-cued condition.ConclusionsThirty minutes of pinch-grip training with visual cues could enhance motor cortical excitability and intracortical inhibition in individuals with PD.SignificanceThe findings on the neurophysiological changes after cued-training may inform further clinical application of visual cues to maximize motor improvement and corticomotor plasticity in people with PD.