Motor Imagery Strategies Research Articles

High performance wearable two-channel hybrid BCI system with eye closure assist.

Generally, eye closure (EC) and eye opening (EO)-based alpha blocking has widely recognized advantages, such as being easy to use, requiring little user training, while motor imagery (MI) is difficult for some users to have concrete feelings. This study presents a hybrid brain-computer interface (BCI) combining MI and EC strategies - such an approach aims to overcome some disadvantages of MI-based BCI, improve the performance and universality of the BCI. The EC/EO is employed to control the machine to switch in different states including forward, stop, changing direction motions, while the MI is used to control the machine to turn left or right for 90° by imagining the hands grasp motions when the system is switched into "changing direction" state. Additionally, a wearable two-channel EEG device is utilized in order to increase the efficiency of EEG processing and improving the practical utility. Results show that proposed hybrid system can generate four control commands with the average accuracy of 87.72%, which is higher than only using MI. Besides, it is possible to reach the same good accuracy using two-channel EEG as with usual multi-channel EEG.

From visual to motor strategies: Training in mental rotation of hands

Functional imaging studies on mental rotation of hands have consistently pointed to the importance of the motor network implying the use of motor simulations for task solving. There is some evidence that the putamen may be a critical modulator of processing egocentric spatial orientation in mental rotation of hands and implicit motor imagery strategies have been described involving hand motor areas. This recruitment of resources processing representations of the own body is used in therapeutic mental rotation training. However, studies are lacking that investigate training-induced changes on the neuronal level. We used functional MRI to study the effects of long-term training on the neuro-functional correlates of mental rotation of hands in healthy volunteers and compared the training group to a passive control group. From pre- to post training, we found a transition of activation from the anterior putamen in unskilled performance to the posterior putamen in skilled performance. We also found an increase in activation in motor cortices and the supramarginal gyrus after learning. By contrast, members of the control group showed no improvements in performance and no pre/post-test differences in cortical activity. In conclusion, these findings suggest that increased neural efficiency after training in mental rotation of hands manifests as a decrease in visual imagery in conjunction with increased recruitment of motor-related regions. This is consistent with the obtained behavioral effects depicting motor imagery mediating expertise in mental rotation of hands.

Motor Imagery and Its Effect on Complex Regional Pain Syndrome: An Integrative Review.

The motor imagery (MI) has been proposed as a treatment in the complex regional pain syndrome type 1 (CRPS-1), since it seems to promote a brain reorganization effect on sensory-motor areas of pain perception. The aim of this paper is to investigate, through an integrative critical review, the influence of MI on the CRPS-1, correlating their evidence to clinical practice. Research in PEDro, Medline, Bireme and Google Scholar databases was conducted. Nine randomized controlled trials (level 2), 1 non-controlled clinical study (level 3), 1 case study (level 4), 1 systematic review (level 1), 2 review articles and 1 comment (level 5) were found. We can conclude that MI has shown effect in reducing pain and functionality that remains after 6 months of treatment. However, the difference between the MI strategies for CRPS-1 is unknown as well as the intensity of mental stress influences the painful response or effect of MI or other peripheral neuropathies.

Motor imagery ability and internal representation of movement in children with probable developmental coordination disorder

It has been hypothesised that deficits in the functioning of the mirror neuron system (MNS) and internal modelling may contribute to the motor impairments associated with DCD. These processes can be explored behaviourally through motor imagery paradigms. Motor imagery proficiency of children with and without probable DCD (pDCD) was examined using a complex hand rotation task to explore whether motor imagery strategies could be used during more complex tasks. Forty-four boys aged 7–13years participated, 22 with pDCD (mean=9.90years±1.57) and 22 controls (mean=9.68years±1.53). Participants completed the task twice: with and without motor imagery instructions. Stimuli were presented in two rotational axes – palm/back, and eight 45° rotational steps. Both groups showed evidence of following the biomechanical and postural constraints of actual movements. Responses of children with pDCD were slower and less accurate than controls, with group differences increasing alongside task complexity. A greater impact of biomechanical constraints for accuracy was observed in the DCD group. The response characteristics of children with pDCD likely reflects a reduced capacity to mentally manipulate a body schema and reduced visuo-motor processing capabilities. Behaviourally, these processes are linked to MNS and internal modelling function, suggesting deficits in these systems may contribute to the movement difficulties characteristic of DCD.

Re-establishing the disrupted sensorimotor loop in deafferented and deefferented people: The case of spinal cord injuries

Acting efficiently in the world depends on the activity of motor and somatosensory systems, the integration of which is necessary for the proper functioning of the sensorimotor loop (SL). Profound alterations of SL functioning follow spinal cord injury (SCI), a condition that brings about a disconnection of the body from the brain. Such disconnection creates a substantial deprivation of somatosensorial inputs and motor outputs. Consequent somatic deficits and motor paralysis affect the body below the lesion level. A complete restoration of normal functions of the SL cannot be expected until basic neuroscience has found a way to re-establish the interrupted neural connectivity. Meanwhile, studies should focus on the development of technical solutions for dealing with the disruption of the sensorimotor loop. This review discusses the structural and functional adaptive reorganization of the brain after SCI, and the maladaptive mechanisms that impact on the processing of body related information, which alter motor imagery strategies and EEG signals. Studies that show how residual functions (e.g. face tactile sensitivity) may help people to restore a normal body image are also reviewed. Finally, data on how brain and residual body signals may be used to improve brain computer interface systems is discussed in relation to the issue of how such systems may help SCI people to re-enter the world and interact with objects and other individuals.

Children with unilateral cerebral palsy show diminished implicit motor imagery with the affected hand.

Motor imagery refers to the mental simulation of a motor action without producing an overt movement. Implicit motor imagery can be regarded as a first-person kinesthetic perceptual judgement, and addresses the capacity to engage into the manipulation of one's body schema. In this study, we examined whether children with unilateral cerebral palsy (CP) are able to engage in implicit motor imagery. A modified version of the hand laterality judgment task was employed. Erroneous responses, reaction times, and event-related potentials from the electroencephalograph were analysed. In 13 children with typical development (mean age 10y 7mo, SD 1y 2mo; seven male, six female), we observed the classic rotation direction effect. Specifically, when comparing outward rotated with inward rotated hand pictures, decreased accuracy and increased response times were observed. Event-related potentials analyses of the electroencephalogram revealed a more marked N1 and an enhanced rotation-related negativity. These findings suggest that an implicit motor imagery strategy was used to solve the task. However, in 10 children with unilateral CP (mean age 10y 7mo, SD 2y 5mo; five male, five female), these effects were observed only when the less-affected hand was involved. This observation suggests that children with CP could benefit from visual training strategies.

Predictive models to determine imagery strategies employed by children to judge hand laterality.

A commonly used paradigm to study motor imagery is the hand laterality judgment task. The present study aimed to determine which strategies young children employ to successfully perform this task. Children of 5 to 8 years old (N = 92) judged laterality of back and palm view hand pictures in different rotation angles. Response accuracy and response duration were registered. Response durations of the trials with a correct judgment were fitted to a-priori defined predictive sinusoid models, representing different strategies to successfully perform the hand laterality judgment task. The first model predicted systematic changes in response duration as a function of rotation angle of the displayed hand. The second model predicted that response durations are affected by biomechanical constraints of hand rotation. If observed data could be best described by the first model, this would argue for a mental imagery strategy that does not involve motor processes to solve the task. The second model reflects a motor imagery strategy to solve the task. In line with previous research, we showed an age-related increase in response accuracy and decrease in response duration in children. Observed data for both back and palm view showed that motor imagery strategies were used to perform hand laterality judgments, but that not all the children use these strategies (appropriately) at all times. A direct comparison of response duration patterns across age sheds new light on age-related differences in the strategies employed to solve the task. Importantly, the employment of the motor imagery strategy for successful task performance did not change with age.

Motor imagery is less efficient in adults with probable developmental coordination disorder: evidence from the hand rotation task.

The present study aimed to provide preliminary insight into the integrity of motor imagery (MI) in adults with probable developmental coordination disorder (pDCD). Based on a strong body of evidence indicating that paediatric samples of DCD often experience difficulties engaging MI, we hypothesised that young adults with pDCD would demonstrate similar difficulties. The performance of 12 young adults (19-35 years) with pDCD was compared to 47 age-matched controls on a traditional mental hand rotation task. Mean inverse efficiency scores were generated for each participant by dividing each participant's mean RT by their proportion of correct responses at each of the stimuli presentation conditions. Preliminary analysis revealed that the performance profiles of individuals with pDCD and age-matched controls showed evidence of being constrained by the biomechanical and postural constraints of real movement, suggesting that both groups engaged in an embodied (MI) strategy to complete the task. Despite engaging in a MI strategy, however, young adults with pDCD were nonetheless significantly less efficient when doing so, shown by significant main effects for group on all group efficiency comparisons. Based on the assumption that MI provides insight into the internal 'neural' action representation that precedes action, we argue that the less efficient MI performance demonstrated by young adults with pDCD may indicate inefficiencies engaging or implementing internal action representations. Implications and directions for future research are discussed.

Changes in hemodynamic signals accompanying motor imagery and motor execution of swallowing: A near-infrared spectroscopy study

In the present study we investigated hemodynamic changes in the brain in response to motor execution (ME) and motor imagery (MI) of swallowing using near-infrared spectroscopy (NIRS). Previous studies provide evidence that ME and MI of limb movements lead to comparable brain activation patterns indicating the potential value of MI for motor rehabilitation. In this context, identifying brain correlates of MI of swallowing may be potentially useful for the treatment of dysphagia. Fourteen healthy participants actively swallowed water (ME) and mentally imagined to swallow water (MI) in a randomized order while changes in concentration of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were assessed. MI and ME led to the strongest NIRS signal changes in the inferior frontal gyrus. During and after ME, oxy-Hb significantly increased, with a maximum peak around 15s after task onset. In contrast, oxy-Hb decreased during MI compared to a rest period probably because of motor inhibition mechanisms. Changes in deoxy-Hb were largely comparable between MI and ME, especially when participants used a kinesthetic motor imagery strategy during MI compared to no specific strategy. Hence, the present study provides new evidence concerning timing and topographical distribution of the hemodynamic response during ME and MI of swallowing.

Chronic Low Back Pain, Core Stability and Francis Bacon: Implications for Contemporary Physiotherapy – A Narrative Review

Abstract Background: Chronic low back pain (LBP) is the most common cause of disability, hence multiple attempts have been undertaken to develop therapeutic strategies aimed at addressing the issue. The most commonly used strategies include motor control exercises of deep core muscles that stabilize the lower back. However, on the practical side, they require application of special devices, such as ultrasonography or electromyography as well as instructions and support provided by trained personnel. Despite the lack of high-quality empirical evidence, these exercises are extensively used in clinical practice. Narrative Review: The vast body of literature collected suggests that the cause of chronic LBP should be sought in the structural and functional alterations within different levels of the central nervous system. These alterations and maladaptations apply to both the molecular and tissue levels. Nevertheless, successful treatment of these changes is currently possible due to an affordable, cognitive therapeutic approach. It encompasses a number of strategies that aim to restore the normal function of the nervous system using brain plasticity processes. These include graded motor imagery, mirror therapy, graded exposure, pain education, sensory training and pain coping strategies. Conclusions: Lack of clear advantage in the application of the core stability exercises over other, potentially cheaper alternatives, implies a shift-paradigm from the existing biomedical model of chronic LBP treatment towards modern cognitive approaches. As results of numerous studies confirm the validity of the approach aimed at restoring the structure and function of the central nervous system in contrast to the still common concept of treatment of the peripheral tissues of the body, more rigorous systematic reviews and meta-analysis are required. Evidence from this kind of evaluation may contribute to the shift in current beliefs regarding the treatment of chronic LBP.

Motor imagery ability in stroke patients: the relationship between implicit and explicit motor imagery measures

There is little consensus on how motor imagery ability should be measured in stroke patients. In particular it is unclear how two methods tapping different aspects of the motor imagery process relate to each other. The aim of this study was to investigate the relationship between implicit and explicit motor imagery ability by comparing performance of stroke patients and controls on a motor imagery questionnaire and a hand laterality judgment task (HLJT). Sixteen ischemic stroke patients (36 ± 13 weeks post-stroke) and 16 controls, matched by age (51 ± 10 years), gender (7 females) and handedness (3 left-handed), performed a HLJT and completed a motor imagery questionnaire. Our study shows that neither in the healthy controls nor in patients, a correlation is found between the HLJT and the motor imagery questionnaire. Although the patient group scored significantly lower than the control group on the visual motor imagery component (U = 60; p = 0.010) and the kinesthetic motor imagery component (U = 63.5; p = 0.015) of the questionnaire, there were no significant differences between patients and controls on accuracy scores of the HLJT. Analyses of the reaction time profiles of patients and controls showed that patient were still able to use an implicit motor imagery strategy in the HLJT task. Our results show that after stroke performance on tests that measure two different aspects of motor imagery ability, e.g., implicit and explicit motor imagery, can be differently affected. These results articulate the complex relation phenomenological experience and the different components of motor imagery have and caution the use of one tool as an instrument for use in screening, selecting and monitoring stroke patients in rehabilitation settings.

Does thumb posture influence the mental rotation of hands?

The function of thumb posture in mental rotation has not yet been studied intensely, despite its special role in manual action. To investigate if thumb posture modifies relative visual and proprioceptive contributions, we conducted two experiments comprising hand laterality judgement tasks with identical stimuli (left and right hands in palmar and dorsal views presented at four orientations). In half of the stimuli, all digits were extended, whereas in the other half the thumb was flexed into the palm of the hand. In the second experiment, participants’ thumbs were taped in the same flexed posture that was displayed in half of the stimuli one hour previous to and throughout the experiment. Results of both experiments revealed effects of orientation, side and view on reaction time, but an effect of stimulus thumb posture occurred only in the second experiment in which participants’ thumbs were fixed. In palmar view, stimuli rotated by 90° with fingers pointing towards the participant's midline had shorter reaction times than stimuli rotated (evidentially less comfortably) in the opposite direction. This finding suggests that participants applied motor imagery strategies for palmar but not for dorsal views of the hand, indicating a difference in visual and sensorimotor familiarity.

Functional Alteration of the DMN by Learned Regulation of the PCC Using Real-Time fMRI

The default mode network (DMN) is a network of brain regions that are active during rest and suppressed during a cognitively demanding task. Previous studies have shown that the DMN can be altered by development, aging, disorder, cognitive tasks and offline training. However, it's unclear whether activity in the DMN can be altered by real-time training. Recently, real-time functional magnetic resonance imaging (rtfMRI), as a novel neurofeedback technique, has been applied to train subjects to voluntarily control activities in specific brain regions. In the current study, it was found that by using rtfMRI to guide training, subjects were able to learn to decrease activity in the posterior cingulate cortex (PCC), which is a "key hub" in the DMN, using motor imagery strategy. After the real-time training, activity in the medial prefrontral cortex/ anterior cingulate cortex (MPFC/ACC) of the resting state DMN was decreased. By contrast, the control group without neurofeedback produced increased activity in the MPFC/ACC of the DMN during the post-training resting state. These findings suggest that this rtfMRI technique has great potential to be used in the regulation of the DMN and may be a novel approach for studying functional plasticity of the cortex.

Sensorimotor rhythm-based brain–computer interface training: the impact on motor cortical responsiveness

The main purpose of electroencephalography (EEG)-based brain–computer interface (BCI) technology is to provide an alternative channel to support communication and control when motor pathways are interrupted. Despite the considerable amount of research focused on the improvement of EEG signal detection and translation into output commands, little is known about how learning to operate a BCI device may affect brain plasticity. This study investigated if and how sensorimotor rhythm-based BCI training would induce persistent functional changes in motor cortex, as assessed with transcranial magnetic stimulation (TMS) and high-density EEG. Motor imagery (MI)-based BCI training in naïve participants led to a significant increase in motor cortical excitability, as revealed by post-training TMS mapping of the hand muscle's cortical representation; peak amplitude and volume of the motor evoked potentials recorded from the opponens pollicis muscle were significantly higher only in those subjects who develop a MI strategy based on imagination of hand grasping to successfully control a computer cursor. Furthermore, analysis of the functional brain networks constructed using a connectivity matrix between scalp electrodes revealed a significant decrease in the global efficiency index for the higher-beta frequency range (22–29 Hz), indicating that the brain network changes its topology with practice of hand grasping MI. Our findings build the neurophysiological basis for the use of non-invasive BCI technology for monitoring and guidance of motor imagery-dependent brain plasticity and thus may render BCI a viable tool for post-stroke rehabilitation.

An Integrated Motor Imagery Program to Improve Functional Task Performance in Neurorehabilitation: A Single-Blind Randomized Controlled Trial

Bovend'Eerdt TJ, Dawes H, Sackley C, Izadi H, Wade DT. An integrated motor imagery program to improve functional task performance in neurorehabilitation: a single-blind randomized controlled trial. Objective To investigate the feasibility of a motor imagery program integrated into physiotherapy and occupational therapy. Design A parallel-group, phase II, assessor-blind randomized controlled trial comparing motor imagery embedded in usual therapy with usual therapy only. Setting A neurologic rehabilitation center (Oxford, United Kingdom). Participants Inpatients and outpatients diagnosed with stroke, brain injury, or multiple sclerosis, participating in a rehabilitation program with sufficient language skills to undertake the intervention were recruited (N=30) and assessed at baseline, after 6 weeks (postintervention), and after 12 weeks (follow-up). Interventions A motor imagery strategy was developed that could be integrated into usual therapy, tailored to individual goals, and used for any activity. The control group received standard care. Main Outcome Measures Goal attainment scaling was used as the primary outcome measure. Other measures included the Barthel activities of daily living index and the Rivermead Mobility Index. Results Compliance with advised treatment was poor in 85% of the therapists and in 72% of the patients. Goal attainment scaling scores significantly improved at postintervention and follow-up (F 2,27=45.159; P<.001), but no significant difference was observed between the groups over time (F 1,28=.039; P=.845). Conclusions Therapist and patient compliance with performing the intervention was low, restricting the conclusions regarding the effectiveness of the integrated motor imagery program. Future studies will need to explore barriers and facilitators to uptake of this intervention in clinical practice. Trial recruitment and retention were good. The study demonstrated that imagery could be successfully integrated into usual therapy and tailored for a wide range of functional activities.

Quasi-movements: A novel motor–cognitive phenomenon

We introduce quasi-movements and define them as volitional movements which are minimized by the subject to such an extent that finally they become undetectable by objective measures. They are intended as overt movements, but the absence of the measurable motor responses and the subjective experience make quasi-movements similar to motor imagery. We used the amplitude dynamics of electroencephalographic alpha oscillations as a marker of the regional involvement of cortical areas in three experimental tasks: movement execution, kinesthetic motor imagery, and quasi-movements. All three conditions were associated with a significant suppression of alpha oscillations over the sensorimotor hand area of the contralateral hemisphere. This suppression was strongest for executed movements, and stronger for quasi-movements than for motor imagery. The topography of alpha suppression was similar in all three conditions. Proprioceptive sensations related to quasi-movements contribute to the assumption that the “sense of movement” can originate from central efferent processes. Quasi-movements are also congruent with the postulated continuity between motor imagery and movement preparation/execution. We also show that in healthy subjects quasi-movements can be effectively used in brain–computer interface research leading to a significantly smaller classification error (∼47% of relative decrease) in comparison to the errors obtained with conventionally used motor imagery strategies.

Cognitive rehabilitation of amnesia after virus encephalitis: A case report

A number of memory rehabilitation techniques have targeted people with various degrees of memory impairments. However, few studies have shown the contribution of preserved non-declarative memory capacity and errorless learning in the treatment of amnesic patients. The current case report describes the memory rehabilitation of a 44-year-old man with amnesia following viral encephalitis. The patient's procedural memory capacity had an important role in the use of a motor imagery strategy to remember people's names. It was further demonstrated that the application of a verbal learning technique was helpful in recalling new verbal information. These different memory rehabilitation techniques are discussed in terms of alternative possibilities in the rehabilitation of amnesic patients.

Primary somatosensory cortex, cortical somatosensory networks, and cortical somatosensory functions: Where does pain fit in?

Disruption of cortically-held working body schema has been associated with a variety of pain conditions. A motor imagery technique - the left right judgement task (LRJT) - has been used as an indirect assessment of the integrity of the working body schema. To date there is no LRJT specifically designed to investigate the body schema of persons with shoulder pain.To develop a shoulder specific LRJT and assess its validity and reliability.Cross-sectional repeated measures.Shoulder images were developed representing the shoulder in a variety of postures of graded complexity/awkwardness and degree of rotation. These images were digitally mirrored to represent both left and right shoulders. Participants viewed the images on a computer and determined whether images were of a left or right shoulder.1413 participants were recruited worldwide and performed the shoulder LRJT (laterality judgement). Mean response time (SD) for the task was 1738(741) ms. Mean accuracy (SD) was 93.5(9.2)%.Chronbach's Alpha for shoulder image response times was 0.95. Participants were fastest responding to images of simple postures and slowest to images corresponding to the more awkward postures (mean difference 520 ms, 95%CI 469–570 ms). Participants were fastest responding to the least rotated images and slowest responding to inverted images, (mean difference 981 ms, 95%CI 919–1043 ms).The shoulder specific LRJT proved to be highly reliable. Response times increased with complexity and rotation of images, implying a motor imagery strategy was used to complete the task, validating the task as a measure of shoulder joint implicit motor imagery. Abnormal performance cut-offs for age were reported. This result will enable further research examining the relationship between shoulder pain and body schema.