Movement Imagery Research Articles

Real-Time Subject-Independent Pattern Classification of Overt and Covert Movements from fNIRS Signals

Recently, studies have reported the use of Near Infrared Spectroscopy (NIRS) for developing Brain–Computer Interface (BCI) by applying online pattern classification of brain states from subject-specific fNIRS signals. The purpose of the present study was to develop and test a real-time method for subject-specific and subject-independent classification of multi-channel fNIRS signals using support-vector machines (SVM), so as to determine its feasibility as an online neurofeedback system. Towards this goal, we used left versus right hand movement execution and movement imagery as study paradigms in a series of experiments. In the first two experiments, activations in the motor cortex during movement execution and movement imagery were used to develop subject-dependent models that obtained high classification accuracies thereby indicating the robustness of our classification method. In the third experiment, a generalized classifier-model was developed from the first two experimental data, which was then applied for subject-independent neurofeedback training. Application of this method in new participants showed mean classification accuracy of 63% for movement imagery tasks and 80% for movement execution tasks. These results, and their corresponding offline analysis reported in this study demonstrate that SVM based real-time subject-independent classification of fNIRS signals is feasible. This method has important applications in the field of hemodynamic BCIs, and neuro-rehabilitation where patients can be trained to learn spatio-temporal patterns of healthy brain activity.

Amplitude of Sensorimotor Mu Rhythm Is Correlated with BOLD from Multiple Brain Regions: A Simultaneous EEG-fMRI Study.

The mu rhythm is a field oscillation in the ∼10Hz range over the sensorimotor cortex. For decades, the suppression of mu (event-related desynchronization) has been used to index movement planning, execution, and imagery. Recent work reports that non-motor processes, such as spatial attention and movement observation, also desynchronize mu, raising the possibility that the mu rhythm is associated with the activity of multiple brain regions and systems. In this study, we tested this hypothesis by recording simultaneous resting-state EEG-fMRI from healthy subjects. Independent component analysis (ICA) was applied to extract the mu components. The amplitude (power) fluctuations of mu were estimated as a time series using a moving-window approach, which, after convolving with a canonical hemodynamic response function (HRF), was correlated with blood-oxygen-level-dependent (BOLD) signals from the entire brain. Two main results were found. First, mu power was negatively correlated with BOLD from areas of the sensorimotor network, the attention control network, the putative mirror neuron system, and the network thought to support theory of mind. Second, mu power was positively correlated with BOLD from areas of the salience network, including anterior cingulate cortex and anterior insula. These results are consistent with the hypothesis that sensorimotor mu rhythm is associated with multiple brain regions and systems. They also suggest that caution should be exercised when attempting to interpret mu modulation in terms of a single brain network.

Comparing PETTLEP imagery against observation imagery on vividness and ease of movement imagery

The present study compared the effects of: (a) PETTLEP imagery (e.g. imaging in the environment), (b) prior-observation (i.e. observing prior to imaging), and (c) traditional imagery (e.g. imaging sat in a quiet room) on the ease and vividness of external visual imagery (EVI), internal visual imagery (IVI), and kinaesthetic imagery (KI) of movements. Fifty-two participants (28 female, 24 male, Mage = 19.60 years, SD = 1.59) imaged the movements described in the Vividness of Movement Imagery Questionnaire-2 under the three conditions in a counterbalanced order. Vividness and ease of imaging ratings were recorded for each movement. A repeated measure MANOVA revealed that ease and vividness ratings for EVI, IVI, and KI were higher during the PETTLEP imagery condition compared to the traditional imagery condition, and vividness of EVI was higher during the observation imagery condition compared to traditional imagery. Findings indicate that incorporating PETTLEP elements into the imagery instructions leads to easier and more vivid movement EVI, IVI, and KI imagery.

Paired Associative Stimulation Using Brain-Computer Interfaces for Stroke Rehabilitation: A Pilot Study.

Conventional therapies do not provide paralyzed patients with closed-loop sensorimotor integration for motor rehabilitation. Paired associative stimulation (PAS) uses brain-computer interface (BCI) technology to monitor patients’ movement imagery in real-time, and utilizes the information to control functional electrical stimulation (FES) and bar feedback for complete sensorimotor closed loop. To realize this approach, we introduce the recoveriX system, a hardware and software platform for PAS. After 10 sessions of recoveriX training, one stroke patient partially regained control of dorsiflexion in her paretic wrist. A controlled group study is planned with a new version of the recoveriX system, which will use a new FES system and an avatar instead of bar feedback.

Block design enhances classification of 3D reach targets from electroencephalographic signals

To date, decoding accuracy of actual or imagined pointing movements to targets in 3D space from electroencephalographic (EEG) signals has remained modest. The reason may pertain to the fact that these movements activate essentially the same neural networks. In this study, we aimed at testing whether repetitive pointing movements to each of the targets promotes the development of segregated neural patterns, resulting in enhanced decoding accuracy. Six human subjects generated slow or fast repetitive pointing movements with their right dominant arm to one of five targets distributed in 3D space, followed by repetitive imagery of movements to the same target or to a different target. Nine naive subjects generated both repetitive and non-repetitive slow actual movements to each of the five targets to test the effect of block design on decoding accuracy. In order to assure that base line drift and low frequency motion artifacts do not contaminate the data, the data were high-pass filtered in 4–30Hz, leaving out the delta and gamma band. For the repetitive trials, the model decoded target location with 81% accuracy, which is significantly higher than chance level. The average decoding rate of target location was only 30% for the non-repetitive trials, which is not significantly different than chance level. A subset of electrodes, mainly over the contralateral sensorimotor areas, was found to provide most of the discriminative features for all tested conditions. Time proximity between trained and tested blocks was found to enhance decoding accuracy of target location both by target non-specific and specific mechanisms. Our findings suggest that movement repetition promotes the development of distinct neural patterns, presumably by the formation of target-specific kinesthetic memory.

EEG Event-Related Desynchronization of patients with stroke during motor imagery of hand movement

Brain Computer Interfaces (BCI) can be used for therapeutic purposes to improve voluntary motor control that has been affected post stroke. For this purpose, desynchronization of sensorimotor rhythms of the electroencephalographic signal (EEG) can be used. But it is necessary to study what happens in the affected motor cortex of this people. In this article, we analyse EEG recordings of hemiplegic stroke patients to determine if it is possible to detect desynchronization in the affected motor cortex during the imagination of movements of the affected hand. Six patients were included in the study; four evidenced desynchronization in the affected hemisphere, one of them showed no results and the EEG recordings of the last patient presented high noise level. These results suggest that we could use the desynchronization of sensorimotor rhythms of the EEG signal as a BCI paradigm in a rehabilitation programme.

Enhancing voluntary imitation through attention and motor imagery.

Action observation activates brain areas involved in performing the same action and has been shown to increase motor learning, with potential implications for neurorehabilitation. Recent work indicates that the effects of action observation on movement can be increased by motor imagery or by directing attention to observed actions. In voluntary imitation, activation of the motor system during action observation is already increased. We therefore explored whether imitation could be further enhanced by imagery or attention. Healthy participants observed and then immediately imitated videos of human hand movement sequences, while movement kinematics were recorded. Two blocks of trials were completed, and after the first block participants were instructed to imagine performing the observed movement (Imagery group, N = 18) or attend closely to the characteristics of the movement (Attention group, N = 15), or received no further instructions (Control group, N = 17). Kinematics of the imitated movements were modulated by instructions, with both Imagery and Attention groups being closer in duration, peak velocity and amplitude to the observed model compared with controls. These findings show that both attention and motor imagery can increase the accuracy of imitation and have implications for motor learning and rehabilitation. Future work is required to understand the mechanisms by which these two strategies influence imitation accuracy.

The role of the cerebellum in motor imagery

ObjectiveAlthough it is well documented that the cerebellum plays a role in motor imagery (MI), its exact role in MI is still obscure. Since motor imagery and execution of movement share common pathways, and the cerebellum has an inhibitory effect on the motor cortex, we speculated that the cerebellum also has an inhibitory role on MI. MethodsTo test this hypothesis, 12 healthy individuals aged 27–47 years (mean age 33.3 years) were enrolled in the study. Subjects were asked to imagine two different tasks, one complex (MI-c) and one simple (MI-s) motor task. The intensity of anodal cerebellar transcranial direct current stimulation (ctDCS) was set at 2mA for 20min. Sham ctDCS consisted of 30s current stimulation. ResultsMI-s resulted in significantly increased log MEP amplitude during MI, compared with control MEP amplitude,(p=0.000). The increase in log MEP amplitude during MI disappeared after anodal ctDCS. Before sham ctDCS, both MI-s and MI-c resulted in log MEP amplitude increases (p=0.000). This facilitator effect of both MI-c and MI-s on log MEP amplitude was also persistent after sham ctDCS (p=0.000). ConclusionsThe study demonstrates for the first time that the cerebellum has an inhibitory effect on MI. SignificanceCombining ctDCS with MI significantly modulates corticomotor excitability.

ID 265 – Hand flexor and extensor muscles cortical representations during motor imagery: Topographic and neurophysiological differences

Objective To study the topography and neurophysiological differences in cortical motor representations of hand flexor and extensor muscles during motor imagery (MI). Methods Seven healthy volunteers (age 27 ± 3.4) were enrolled. Navigated transcranial magnetic stimulation was performed for mapping mm. Flexor digitorum superficialis, extensor digitorum communis cortical areas at rest and during MI (fingers flexion or extension). We assessed cortical excitability changes by the dynamics of motor threshold (MT) and paired stimuli with interstimulus intervals 2 ms (SICI) and 12 ms (ICF). Results The localization of flexor and extensor “hotspots” was different with a range of 1 cm. MT decreased during MI significantly from 50% to 47% at the flexor hotspot and from 47% to 46% at the extensor hotspot compared to resting state. There was observed the decrease of ICF during MI of both movements compared to resting state. SICI was reduced during imagery of flexion and enhanced during imagery of extension movement. Conclusions Further we will train the participants to imagine hand extension with brain–computer interface with evaluation the neurophysiological difference between trained and untrained. Topographic and neurophysiological differences of cortical motor representations of differentiated movements during MI can be the basis of new non-invasive brain–computer interface approach.

Emotion Regulation through Movement: Unique Sets of Movement Characteristics are Associated with and Enhance Basic Emotions.

We have recently demonstrated that motor execution, observation, and imagery of movements expressing certain emotions can enhance corresponding affective states and therefore could be used for emotion regulation. But which specific movement(s) should one use in order to enhance each emotion? This study aimed to identify, using Laban Movement Analysis (LMA), the Laban motor elements (motor characteristics) that characterize movements whose execution enhances each of the basic emotions: anger, fear, happiness, and sadness. LMA provides a system of symbols describing its motor elements, which gives a written instruction (motif) for the execution of a movement or movement-sequence over time. Six senior LMA experts analyzed a validated set of video clips showing whole body dynamic expressions of anger, fear, happiness and sadness, and identified the motor elements that were common to (appeared in) all clips expressing the same emotion. For each emotion, we created motifs of different combinations of the motor elements common to all clips of the same emotion. Eighty subjects from around the world read and moved those motifs, to identify the emotion evoked when moving each motif and to rate the intensity of the evoked emotion. All subjects together moved and rated 1241 motifs, which were produced from 29 different motor elements. Using logistic regression, we found a set of motor elements associated with each emotion which, when moved, predicted the feeling of that emotion. Each emotion was predicted by a unique set of motor elements and each motor element predicted only one emotion. Knowledge of which specific motor elements enhance specific emotions can enable emotional self-regulation through adding some desired motor qualities to one's personal everyday movements (rather than mimicking others' specific movements) and through decreasing motor behaviors which include elements that enhance negative emotions.

簡易脳波計を用いた脚運動に関する運動意図の抽出

The research objective is to design an electric wheelchair BCI interface that the user can feel free to use. In this study, we measured the EEG of legs movement and moter imagery by using consumer EEG device as the pre-study stage. Task of 3 kind, movement and motor imagery with video and motor imagery only.The data at the time of raising the legs wavelet transform. After that, plot the event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) graph. From these results to verify whether it is possible extract the Motion intent by the user.

EEG pattern decoding of rhythmic individual finger imaginary movements of one hand

The results of four-class classification of the motor imagery EEG patterns corresponding to the right hand finger movements (little finger, thumb, index and middle fingers) of eight healthy subjects are presented in this study. The motor imagery of individual right-hand finger movements was executed by the subjects in a prescribed rhythm and the trials contained no external stimuli. Classification was performed by means of a specially developed two-level committee of classifiers on the basis of support vector machine and artificial neural networks at the first level and by generalizing an artificial neural network at the second level. The area under the EEG signal curve and the curve length calculated in a sliding time window for sites F3, C3, and Cz of the International 10?20 System were selected as the key features of signals from the sensorimotor and adjoining frontal cortical areas contralateral to the movements. The average accuracy of four-class singletrial classification for all subjects was 50 ± 7 [SD] (maximum, 58%) for the pair of sites F3–C3 and 46 ± 11% [SD] (maximum 62%) for the pair of sites C3–Cz with a theoretical guessing level 25%.

Korean Trojan Women: Performing Wartime Sexual Violence

Aida Karic’s The Trojan Women: An Asian Story (2007), an international collaboration between a Bosnian-born director and a Korean choreographer, a Korean composer, and a Korean theatre company, was first produced at the Schauspielhaus Wien in Austria and then toured to the United States and South Korea. Karic’s The Trojan Women interweaves the history of Japanese military sexual slavery, particularly of Korean survivors, with Euripides’s The Trojan Women. It relies on identifiable markers of Koreanness, such as the musical style of pansori and the visual imagery of shamanic ritual movement, to locate the narrative as a Korean tragedy. I argue that the re-visioning of these Korean cultural forms, such as the use of cloth in the ritual scene, offers a symbolic reclamation of violated bodies while providing a redressive space for the audience to witness the long history of wartime sexual violence against women.

Neural and cortical analysis of swallowing and detection of motor imagery of swallow for dysphagia rehabilitation-A review.

Swallowing is an essential function in our daily life; nevertheless, stroke or other neurodegenerative diseases can cause the malfunction of swallowing function, ie, dysphagia. The objectives of this review are to understand the neural and cortical basis of swallowing and tongue, and review the latest techniques on the detection of motor imagery of swallow (MI-SW) and motor imagery of tongue movements (MI-TM), so that a practical system can be developed for the rehabilitation of poststroke dysphagia patients. Specifically, we firstly describe the swallowing process and how the swallowing function is assessed clinically. Secondly, we review the techniques that performed the neural and cortical analysis of swallowing and tongue based on different modalities such as functional magnetic resonance imaging, positron emission tomography, near-infrared spectroscopy (NIRS), and magnetoencephalography. Thirdly, we review the techniques that performed detection and analysis of MI-SW and MI-TM for dysphagia stroke rehabilitation based on electroencephalography (EEG) and NIRS. Finally, discussions on the advantages and limitations of the studies are presented; an example system and future research directions for the rehabilitation of stroke dysphagia patients are suggested.

Effect of 30%MVC motor imagery of thumb opposition movement on the accuracy of movement and the excitability of the spinal nerve function

Effect of 30%MVC motor imagery of thumb opposition movement on the accuracy of movement and the excitability of the spinal nerve function

Effects of vibratory stimulation-induced kinesthetic illusions on the neural activities of patients with stroke.

[Purpose] This study evaluated the influence of vibratory stimulation-induced kinesthetic illusion on brain function after stroke. [Subjects] Twelve healthy individuals and 13 stroke patients without motor or sensory loss participated. [Methods] Electroencephalograms were taken at rest and during vibratory stimulation. As a neurophysiological index of brain function, we measured the μ-rhythm, which is present mainly in the kinesthetic cortex and is attenuated by movement or motor imagery and compared the data using source localization analyses in the Standardized Low Resolution Brain Electromagnetic Tomography (sLORETA) program. [Results] At rest, μ-rhythms appeared in the sensorimotor and supplementary motor cortices in both healthy controls and stroke patients. Under vibratory stimulation, no μ-rhythm appeared in the sensorimotor cortex of either group. Moreover, in the supplementary motor area, which stores the motor imagery required for kinesthetic illusions, the μ-rhythms of patients were significantly stronger than those of the controls, although the μ-rhythms of both groups were reduced. Thus, differences in neural activity in the supplementary motor area were apparent between the subject groups. [Conclusion] Kinesthetic illusions do occur in patients with motor deficits due to stroke. The neural basis of the supplementary motor area in stroke patients may be functionally different from that found in healthy controls.

Mental Imagery in Spinal Cord Injury: A Systematic Review

Background: The immense potential of structural and functional reorganization of central nervous system i.e., neuro-plasticity following any injury serves the key mechanism behind the recovery of sensory-motor functions. One of the ways of enhancing this reorganization is through the technique of mental imagery. Mental imagery has been studied in various neurological conditions such as stroke and spinal cord injury (SCI) and has been seen to be quite effective in bringing about functional gains. But the research and literature available, particularly in SCI, is quite diverse and inconclusive. This review was, hence, conducted with the aim of understanding the concept of mental imagery and its therapeutic potential in spinal cord injury. Method: A systematic literature search, using PRISMA 2009 guidelines, was conducted according to the set inclusion and exclusion criteria. After the initial screening, 25 articles were finally selected for the review. These were independently reviewed by two reviewers. The articles selected included mixed designs (reviews, experimental studies and observational studies) and were published between 1990- September 2014. Results: The review revealed that the common techniques used to study mental imagery were mental chronometry, mental rotation and questionnaires. Apart from these, the vividness of imagery perceived during movement simulation were assessed using Movement Imagery Questionnaire (MIQ), MIQ-R (Revised), Kinesthetic and Visual Imagery Questionnaire (KVIQ), Vividness of Motor Imagery Questionnaire (VMIQ), Time Dependent Motor Imagery (TDMI) screening test etc. Two types of imagery perspectives were discussed about: external (a perspective that involves primarily a visual representation of motor task, i.e., third person); and internal (involves kinesthetic and visual representation from inside, i.e., first person of the simulated movements). Conclusion: The therapeutic benefits of mental imagery were mixed, with more weightage going towards motor recovery as compared to pain and other sensory areas. However, few questions still remained regarding the best methods of practice of mental imagery and the details of the techniques used with proper protocols.

Motor imagery, perspective taking and gender differences: a VVIQ2-based study

Scientific literature highlighted gender differences in spatial orientation. In particular, men and women differ in terms of the navigational processes they use in daily life. Scientific literature highlighted that women use analytical strategies while men tend to use holistic strategies. Furthermore, studies exploring gender differences in self-reported dream perspectives reported that women dream mainly in first person and men mainly in third person. This work used Vividness of Movement Imagery Questionnaire-2 to verify if gender differences in perspective taking last also in motor imagery practice. The aim of VVIQ2 questionnaire is to determine the vividness of movement imagery. In the VVIQ2, the image can be obtained watching oneself while performing the movement from an external point of view (External Visual Imagery), or from an internal point of view, as if you were looking out through your own eyes while performing the movement (Internal Visual Imagery). The Questionnaire was administered to students of Sports Sciences Degree from University of Salerno.

Coupling the effect of mental practice and Pilates on ambulation of individuals with multiple sclerosis: Five case studies

Pilates, a popular form of exercise, greatly emphasizes on the strengthening of the core muscles; however, the efficacy of exercise program can be impaired in patients with cognitive impairments. To bridge this gap, mental practice of a desired task can help to mentally simulate a given action and retain many properties of the corresponding real action. This study tries to gain preliminary understanding on the effectiveness of the combination of mental practice and core-strengthening Pilates exercises. To explore the effectiveness of mental practice and Pilates-based training on core strength, balance and mobility in multiple sclerosis (MS) patients. This study highlights a single center case series describing the outcomes in ambulant patients with MS treated with mental practice and Pilates. Five volunteer ambulant individuals with stable relapsing-remitting MS participated in 20 individualized sessions, spread over 10-week duration. Pilates with mental practice session was delivered by a physiotherapist. Each session comprised 20 min of mental practice followed by 40 min of core-strengthening Pilates exercises. All the included patients were screened with Movement Imagery Questionnaire-Revised Second Version to determine if they are were able to effectively engage in imagery practice. A range of outcomes were measured: Timed up and go, chair stand test, curl-ups, the abdominal angle through leg raises, and the Activities-specific Balance Confidence Scale before and after the intervention. Group data analysis indicated significant improvement between baseline and post-intervention phases for all the tested parameters. This study provides preliminary insight into this novel combination technique to improve balance and mobility in ambulant people with MS. Mental practice played an important role in keeping the patient's compliance, which was analyzed through structured interviews. Variations in response to the intervention are evident.

Common spatial pattern-based feature extraction from the best time segment of BCI data

Feature extraction is one of the most crucial stages in the field of brain computer interface (BCI). Because of its ability to directly influence the performance of BCI systems, recent studies have generally investigated how to modify existing methods or develop novel techniques. One of the most successful and well-known methods in BCI applications is the common spatial pattern (CSP). In existing CSP-based methods, the spatial filters were extracted either by using the whole data trial or by dividing the trials into a number of overlapping/nonoverlapping time segments. In this paper, we developed a CSP-based moving window technique to obtain the most distinguishable CSP features and increase the classifier performance by finding the best time segment of electroencephalogram trials. The extracted features were tested by using support vector machines (SVMs). The performance of the classifier was measured in terms of classification accuracy and kappa coefficient (κ) . The proposed method was successfully applied to the two-dimensional cursor movement imagery data sets, which were acquired from three healthy human subjects in two sessions on different days. The experiments proved that instead of using the whole data length of EEG trials, extracting CSP features from the best time segment provides higher classification accuracy and κ rates.