The neurophysiological basis of motor imagery

Feature-aware domain invariant representation learning for EEG motor imagery decoding

Electroencephalography (EEG)-based motor imagery (MI) is extensively utilized in clinical rehabilitation and virtual reality-based movement control. Decoding EEG-based MI signals is challenging because of the inherent spatio-temporal variability of the original signal representation, coupled with a low signal-to-noise ratio (SNR), which impedes the extraction of clean and robust features. To address this issue, we propose a multi-scale spatio-temporal domain-invariant representation learning method, termed MSDI. By decomposing the original signal into spatial and temporal components, the proposed method extracts invariant features at multiple scales from both components. To further constrain the representation to invariant domains, we introduce a feature-aware shift operation that resamples the representation based on its feature statistics and feature measure, thereby projecting the features into a domain-invariant space. We evaluate our proposed method via two publicly available datasets, BNCI2014-001 and BNCI2014-004, demonstrating state-of-the-art performance on both datasets. Furthermore, our method exhibits superior time efficiency and noise resistance.

Neural substrates of choking under pressure: A 7T-fMRI study

Performance decrement under excessive psychological pressure is known as "choking," yet its mechanisms and neural foundations remain underexplored. Hypothesizing that changes in the internal model could induce choking, we conducted a 7 T functional MRI introducing excessive pressure through a rare Jackpot condition that offers high rewards for successful performance. Twenty-nine volunteers underwent a visual reaching task. We monitored practice and main sessions to map the task's internal model through learning. Participants were pre-informed of four potential reward conditions upon success at the beginning of the main session task. The success rates in the Jackpot condition were significantly lower than in other conditions, indicative of choking. During the preparation phase, activations in the cerebellum and the middle temporal visual area (hMT+) were associated with Jackpot-specific failures. The cluster in the cerebellar hemisphere overlapped with the internal model regions identified by a learning-related decrease in activation during the practice session. We observed task-specific functional connectivity between the cerebellum and hMT+. These findings suggest a lack of sensory attenuation when an internal model predicting the outcome of one's actions is preloaded during motor preparation. Within the active inference framework of motor control, choking stems from the cerebellum's internal model modulation by psychological pressure, manifested through improper sensory attenuation.

Personalizedµ-transcranial alternating current stimulation improves online brain-computer interface control

Objective.A motor imagery (MI)-based brain-computer interface (BCI) enables users to engage with external environments by capturing and decoding electroencephalography (EEG) signals associated with the imagined movement of specific limbs. Despite significant advancements in BCI technologies over the past 40 years, a notable challenge remains: many users lack BCI proficiency, unable to produce sufficiently distinct and reliable MI brain patterns, hence leading to low classification rates in their BCIs. The objective of this study is to enhance the online performance of MI-BCIs in a personalized, biomarker-driven approach using transcranial alternating current stimulation (tACS).Approach.Previous studies have identified that the peak power spectral density value in sensorimotor idling rhythms is a neural correlate of participants' upper limb MI-BCI performances. In this active-controlled, single-blind study, we applied 20 min of tACS at the participant-specific, peakµfrequency in resting-state sensorimotor rhythms (SMRs), with the goal of enhancing resting-stateµSMRs.Main results.After tACS, we observed significant improvements in event-related desynchronizations (ERDs) ofµSMRs, and in the performance of an online MI-BCI that decodes left versus right hand commands in healthy participants (N= 10)-but not in an active control-stimulation control group (N= 10). Lastly, we showed a significant correlation between the resting-stateµSMRs andµERD, offering a mechanistic interpretation behind the observed changes in online BCI performances.Significance.Our research lays the groundwork for future non-invasive interventions designed to enhance BCI performances, thereby improving the independence and interactions of individuals who rely on these systems.

Assessing brain-muscle networks during motor imagery to detect covert command-following

BACKGROUND

In this study, we evaluated the potential of a network approach to electromyography and electroencephalography recordings to detect covert command-following in healthy participants. The motivation underlying this study was the development of a diagnostic tool that can be applied in common clinical settings to detect awareness in patients that are unable to convey explicit motor or verbal responses, such as patients that suffer from disorders of consciousness (DoC).

METHODS

We examined the brain and muscle response during movement and imagined movement of simple motor tasks, as well as during resting state. Brain-muscle networks were obtained using non-negative matrix factorization (NMF) of the coherence spectra for all the channel pairs. For the 15/38 participants who showed motor imagery, as indexed by common spatial filters and linear discriminant analysis, we contrasted the configuration of the networks during imagined movement and resting state at the group level, and subject-level classifiers were implemented using as features the weights of the NMF together with trial-wise power modulations and heart response to classify resting state from motor imagery.

RESULTS

Kinesthetic motor imagery produced decreases in the mu-beta band compared to resting state, and a small correlation was found between mu-beta power and the kinesthetic imagery scores of the Movement Imagery Questionnaire-Revised Second version. The full-feature classifiers successfully distinguished between motor imagery and resting state for all participants, and brain-muscle functional networks did not contribute to the overall classification. Nevertheless, heart activity and cortical power were crucial to detect when a participant was mentally rehearsing a movement.

CONCLUSIONS

Our work highlights the importance of combining EEG and peripheral measurements to detect command-following, which could be important for improving the detection of covert responses consistent with volition in unresponsive patients.

What we mean when we say semantic: Toward a multidisciplinary semantic glossary

Tulving characterized semantic memory as a vast repository of meaning that underlies language and many other cognitive processes. This perspective on lexical and conceptual knowledge galvanized a new era of research undertaken by numerous fields, each with their own idiosyncratic methods and terminology. For example, "concept" has different meanings in philosophy, linguistics, and psychology. As such, many fundamental constructs used to delineate semantic theories remain underspecified and/or opaque. Weak construct specificity is among the leading causes of the replication crisis now facing psychology and related fields. Term ambiguity hinders cross-disciplinary communication, falsifiability, and incremental theory-building. Numerous cognitive subdisciplines (e.g., vision, affective neuroscience) have recently addressed these limitations via the development of consensus-based guidelines and definitions. The project to follow represents our effort to produce a multidisciplinary semantic glossary consisting of succinct definitions, background, principled dissenting views, ratings of agreement, and subjective confidence for 17 target constructs (e.g., abstractness, abstraction, concreteness, concept, embodied cognition, event semantics, lexical-semantic, modality, representation, semantic control, semantic feature, simulation, semantic distance, semantic dimension). We discuss potential benefits and pitfalls (e.g., implicit bias, prescriptiveness) of these efforts to specify a common nomenclature that other researchers might index in specifying their own theoretical perspectives (e.g., They said X, but I mean Y).

Effects of motor imagery and action observation on pelvic floor and related structures in healthy women: A randomized controlled trial

The main aim was to assess the effects of motor imagery (MI) and action observation (AO) plus physical exercise (PE) on pelvic floor and related structures. Forty-four healthy women were randomized into three groups: MI, AO, or sham observation (SO) group. The outcome measures included the pelvic floor muscles (PFM) condition (including basal tone and strength), lumbo-pelvic motor control, and pain sensitivity. All women performed six sessions at the rate of 3 s/week (for 2 weeks). An initial assessment was carried out (T0), another one 1-week after starting the study (T1), and a third one at the end (T2). Results showed significant PFM strength gains in MI and AO groups, but not in the SO group. Regarding lumbo-pelvic motor control, both MI and AO groups obtained statistically significant changes between pre- and post-intervention Additionally, only the AO group showed significant improvements already at 1-week of intervention. Finally, all groups showed improved pain sensitivity in the likely area of referred menstrual pain post-intervention, with only the MI group showing changes 1 week after starting the intervention. In conclusion, results showed that adding MI and AO to PE program leads to an improvement of sensorimotor function of PFM and related structures in general. Despite finding no statistically significant inter-group differences, some findings such as strength gains or the lumbo-pelvic motor control improvements were only found in MI and AO groups, and this should be considered clinically.

Exploring the impact of aging on motor imagery abilities: a systematic review with meta-analysis

Objective

Explore motor imagery (MI) abilities in healthy older adults compared with healthy younger adults.

Methods

A systematic review with meta-analysis.

Results

Twenty-seven cross-sectional studies were included. Meta-analyses explored MI abilities between healthy older and younger adults for the ability to generate kinesthetic (60-70 years: g = -0.24, 95%CI = -1.61, 1.13; 70-80 years: g = -1.29, 95%CI = -2.75, 0.17), and visual modality (g = -0.08, 95%CI = -0.71, 0.86); vividness in kinesthetic (g = 0.14, 95%CI = -0.13, 0.41), IV (g = 0.11, 95%CI = -0.16, 0.38), and EV modalities (g = 0.05, 95%CI = -0.15, 0.24); mental chronometry in timed-up and go (seconds = 0.63, 95%CI = -0.02, 1.27), and linear walk (seconds = 0.75, 95%CI = -0.55, 2.06); and MI-execution time congruence (performance overestimation) in linear walk (g = -0.02, 95%CI = -0.73, 0.69). Mental chronometry in upper limb movements was analyzed visually in forest plot indicating tendencies of greater time in older adults. Hand recognition in hand laterality judgment task visual analysis revealed a poorer accuracy, greater response time and lower efficiency in older adults.

Conclusion

Vividness of MI in kinesthetic and visual modalities appears to be preserved in older adults. Tendencies for greater time in mental chronometry were observed in older adults in TUG, linear walk and upper limb tasks. Implicit MI assessed with hand laterality showed older adults have lower accuracy, longer response times and lower efficiency. The ability to generate MI in kinesthetic and visual modalities presented imprecise results, and no clear conclusions could be drawn on MI-execution temporal congruence due to imprecision. Further research is needed to potentially clarify these findings.

Systematic review registration

PROSPERO: CRD42023384916.

Motor Imagery EEG Classification Based on Multi-Domain Feature Rotation and Stacking Ensemble

BACKGROUND

Decoding motor intentions from electroencephalogram (EEG) signals is a critical component of motor imagery-based brain-computer interface (MI-BCIs). In traditional EEG signal classification, effectively utilizing the valuable information contained within the electroencephalogram is crucial.

OBJECTIVES

To further optimize the use of information from various domains, we propose a novel framework based on multi-domain feature rotation transformation and stacking ensemble for classifying MI tasks.

METHODS

Initially, we extract the features of Time Domain, Frequency domain, Time-Frequency domain, and Spatial Domain from the EEG signals, and perform feature selection for each domain to identify significant features that possess strong discriminative capacity. Subsequently, local rotation transformations are applied to the significant feature set to generate a rotated feature set, enhancing the representational capacity of the features. Next, the rotated features were fused with the original significant features from each domain to obtain composite features for each domain. Finally, we employ a stacking ensemble approach, where the prediction results of base classifiers corresponding to different domain features and the set of significant features undergo linear discriminant analysis for dimensionality reduction, yielding discriminative feature integration as input for the meta-classifier for classification.

RESULTS

The proposed method achieves average classification accuracies of 92.92%, 89.13%, and 86.26% on the BCI Competition III Dataset IVa, BCI Competition IV Dataset I, and BCI Competition IV Dataset 2a, respectively.

CONCLUSIONS

Experimental results show that the method proposed in this paper outperforms several existing MI classification methods, such as the Common Time-Frequency-Spatial Patterns and the Selective Extract of the Multi-View Time-Frequency Decomposed Spatial, in terms of classification accuracy and robustness.

Novel AIRTrode-based wearable electrode supports long-term, online brain-computer interface operations

Objective.Non-invasive electroencephalograms (EEG)-based brain-computer interfaces (BCIs) play a crucial role in a diverse range of applications, including motor rehabilitation, assistive and communication technologies, holding potential promise to benefit users across various clinical spectrums. Effective integration of these applications into daily life requires systems that provide stable and reliable BCI control for extended periods. Our prior research introduced the AIRTrode, a self-adhesive (A), injectable (I), and room-temperature (RT) spontaneously-crosslinked hydrogel electrode (AIRTrode). The AIRTrode has shown lower skin-contact impedance and greater stability than dry electrodes and, unlike wet gel electrodes, does not dry out after just a few hours, enhancing its suitability for long-term application. This study aims to demonstrate the efficacy of AIRTrodes in facilitating reliable, stable and long-term online EEG-based BCI operations.Approach.In this study, four healthy participants utilized AIRTrodes in two BCI control tasks-continuous and discrete-across two sessions separated by six hours. Throughout this duration, the AIRTrodes remained attached to the participants' heads. In the continuous task, participants controlled the BCI through decoding of upper-limb motor imagery (MI). In the discrete task, the control was based on decoding of error-related potentials (ErrPs).Main Results.Using AIRTrodes, participants demonstrated consistently reliable online BCI performance across both sessions and tasks. The physiological signals captured during MI and ErrPs tasks were valid and remained stable over sessions. Lastly, both the BCI performances and physiological signals captured were comparable with those from freshly applied, research-grade wet gel electrodes, the latter requiring inconvenient re-application at the start of the second session.Significance.AIRTrodes show great potential promise for integrating non-invasive BCIs into everyday settings due to their ability to support consistent BCI performances over extended periods. This technology could significantly enhance the usability of BCIs in real-world applications, facilitating continuous, all-day functionality that was previously challenging with existing electrode technologies.

A Scoping Review of Mental Practice in Athletes: How can Surgeons Learn?

INTRODUCTION

Mental imagery is a dynamic mental state involving the cognitive visualization and rehearsal of motor movements or positions without overt motor output. Mental imagery is known to have numerous benefits for skill acquisition within athletic performance and is often incorporated into elite athletic training programs. The literature on the effects of mental imagery in surgery, which shares many of the high-performance qualities of elite athletics, remains limited. It may be possible to extrapolate many of the benefits of mental imagery on skill acquisition and sports performance in athletics to the field of surgery. The purpose of the study is to qualitatively assess the components of mental imagery approaches used in high-level athletics to ultimately determine their applicability to surgical training.

METHODS

A scoping review was conducted using the Ovid Medline, Ovid EMBASE, Cochrane Central Register of Controlled Trials, and Google Scholar databases. Two reviewers screened through all abstracts and full texts according to predefined inclusion and exclusion criteria in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist. A thematic analysis was then performed on all studies included in the review.

RESULTS

Of 1252 citations, 19 studies met full inclusion and exclusion criteria. Five themes were identified in the thematic analysis (open vs closed events; internal vs external imagery; level of expertise; visual vs kinesthetic; psychological effects and physical factors).

DISCUSSION AND CONCLUSION

The use of mental imagery to enhance training and performance outside of medicine is widespread in the literature. Numerous studies have shown mental imagery can improve performance, decrease anxiety and shorten the learning curve in elite athletes. Surprisingly, the role of mental imagery within surgical training remains poorly explored. Given that the training undertaken by elite athletes and surgeons has many similarities, our scoping review and thematic analysis has identified 5 key areas for possible transferable practices whereby mental imagery could benefit surgical education.

Drawing behaviour influences ongoing thought patterns and subsequent memory

For millennia, humans have created drawings as a means of externalizing visual representations, and later, to aid communication and learning. Despite its cultural value, we understand little about the cognitive states elicited by drawing, and their downstream benefits. In two preregistered experiments, we explored these states; Undergraduate participants (Ns = 69, 60) encoded words by drawing or writing, periodically describing their thoughts using multi-dimensional experience sampling, a tool for characterizing the features of ongoing thought. Subsequent memory was tested via free recall. Contrasted with writing, drawing improved memory, and evoked thoughts that were more visual and elaborative. Recall was also dictated by the emergence of these thought patterns, with the former most important when drawing. Our findings establish that drawing elicits unique thought patterns that promote successful memory, providing an explanation for drawing's influential role in our everyday lives.

Could Motor Imagery Training Provide a Novel Load Management Solution for Athletes? Recommendations for Sport Medicine and Performance Practitioners

CONTEXT

Athletes often face the dual challenge of high training loads with insufficient time to recover. Equally, in any team, sports medicine and performance staff are required to progress training loads in healthy athletes and avoid prolonged reductions in training load in injured athletes. In both cases, the implementation of a well-established psychological technique known as motor imagery (MI) can be used to counteract adverse training adaptations such as excessive fatigue, reduced capacity, diminished performance, and heightened injury susceptibility.

STUDY DESIGN

Narrative overview.

LEVEL OF EVIDENCE

Level 5.

RESULTS

MI has been shown to enhance performance outcomes in a range of contexts including rehabilitation, skill acquisition, return-to-sport protocols, and strength and conditioning. Specific performance outcomes include reduction of strength loss and muscular atrophy, improved training engagement of injured and/or rehabilitating athletes, promotion of recovery, and development of sport-specific skills/game tactics. To achieve improvements in such outcomes, it is recommended that practitioners consider the following factors when implementing MI: individual skill level (ie, more time may be required for novices to obtain benefits), MI ability (ie, athletes with greater capacity to create vivid and controllable mental images of their performance will likely benefit more from MI training), and the perspective employed (ie, an internal perspective may be more beneficial for increasing neurophysiological activity whereas an external perspective may be better for practicing technique-focused movements).

CONCLUSION

We provide practical recommendations grounded in established frameworks on how MI can be used to reduce strength loss and fear of reinjury in athletes with acute injury, improve physical qualities in rehabilitating athletes, reduce physical loads in overtrained athletes, and to develop tactical and technical skills in healthy athletes.

Developmental trajectories of motor imagery in relation to physical fitness in children aged 7 to 14 years: A 1-year follow-up study

Motor imagery (MI) is fundamentally linked to the motor system. It improves motor learning and optimizes motor actions without physical execution, highlighting its unique role in rehabilitation programs and motor performance. Understanding the developmental trajectories of MI and the factors influencing its variability across ages could enable more effective, age-specific strategies for pediatric rehabilitation. This study assessed 65 children aged 7 to 14 years at two time points 1 year apart. MI ability was assessed using the Movement Imagery Questionnaire for Children, and physical fitness was evaluated using the SLOfit testing battery. Among the three perspectives assessed; internal visual imagery (IVI), external visual imagery (EVI), and kinesthetic imagery (KI), KI was unique in not correlating with age at both time points. The development of MI perspectives varied between athletes and non-athletes, with non-athletes showing a decline in IVI compared with athletes. This differential was further evidenced by significant differences in KI between the groups at the second assessment, with a similar trend observed at the first assessment. Of the physical fitness tests, only the 600-m run correlated consistently with KI at both assessments. Our findings suggest that regular participation in sports significantly affects KI performance, highlighting the importance of sports participation for the development of MI abilities in children. Future research should examine additional assessment points in different age groups and sport experience to better understand the development of MI and its potential implications for pediatric rehabilitation.

A multi-feature fusion graph attention network for decoding motor imagery intention in spinal cord injury patients

Objective.Electroencephalogram (EEG) signals exhibit temporal-frequency-spatial multi-domain feature, and due to the nonplanar nature of the brain surface, the electrode distributions follow non-Euclidean topology. To fully resolve the EEG signals, this study proposes a temporal-frequency-spatial multi-domain feature fusion graph attention network (GAT) for motor imagery (MI) intention recognition in spinal cord injury (SCI) patients.Approach.The proposed model uses phase-locked value (PLV) to extract spatial phase connectivity information between EEG channels and continuous wavelet transform to extract valid EEG information in the time-frequency domain. It then models as a graph data structure containing multi-domain information. The gated recurrent unit and GAT learn EEG's dynamic temporal-spatial information. Finally, the fully connected layer outputs the MI intention recognition results.Main results.After 10 times 10-fold cross-validation, the proposed model can achieve an average accuracy of 95.82%. Furthermore, this study analyses the event-related desynchronization/event-related synchronization and PLV brain network to explore the brain activity of SCI patients during MI.Significance.This study confirms the potential of the proposed model in terms of EEG decoding performance and provides a reference for the mechanism of neural activity in SCI patients.

Tactile imagery affects cortical responses to vibrotactile stimulation of the fingertip

Mental imagery is a crucial cognitive process, yet its underlying neural mechanisms remain less understood compared to perception. Furthermore, within the realm of mental imagery, the somatosensory domain is particularly underexplored compared to other sensory modalities. This study aims to investigate the influence of tactile imagery (TI) on cortical somatosensory processing. We explored the cortical manifestations of TI by recording EEG activity in healthy human subjects. We investigated event-related somatosensory oscillatory dynamics during TI compared to actual tactile stimulation, as well as somatosensory evoked potentials (SEPs) in response to short vibrational stimuli, examining their amplitude-temporal characteristics and spatial distribution across the scalp. EEG activity exhibited significant changes during TI compared to the no-imagery baseline. TI caused event-related desynchronization (ERD) of the contralateral μ-rhythm, with a notable correlation between ERD during imagery and real stimulation across subjects. TI also modulated several SEP components in sensorimotor and frontal areas, showing increases in the contralateral P100 and P300, contra- and ipsilateral P300, frontal P200, and parietal P600 components. The results clearly indicate that TI affects cortical processing of somatosensory stimuli, impacting EEG responses in various cortical areas. The assessment of SEPs in EEG could serve as a versatile marker of tactile imagery in practical applications. We propose incorporating TI in imagery-based brain-computer interfaces (BCIs) to enhance sensorimotor restoration and sensory substitution. This approach underscores the importance of somatosensory mental imagery in cognitive neuroscience and its potential applications in neurorehabilitation and assistive technologies.

The effects of telerehabilitation-based motor imagery training on motor imagery ability, motor function and physical performance in Duchenne muscular dystrophy

PURPOSE

To explore the effects of telerehabilitation-based motor imagery (Tele-MI) training on motor imagery ability (MI), motor function, and performance in children with Duchenne muscular dystrophy (DMD).

METHODS

The research involved twenty-three children with DMD and twelve healthy children. DMD cohort were randomized into two groups: treatment [Tele-MI training and telerehabilitation-based physiotherapy program (Tele-PTP), n = 12] and control (Tele-PTP, n = 11). MI ability [Kinesthetic and Visual Imagery Questionnaire-10 (KVIQ-10), Motor Imagery Questionnaire for Children (MIQ-C), mental chronometry tests], motor function [Motor Function Measure (MFM), North Star Ambulation Assessment, Four Square Step Test] and timed performance were assessed at baseline and after 8-week training.

RESULTS

MI ability scores of DMD cohort were lower than healthy children. A large interaction effect was found for KVIQ-10 visual and total, MIQ-C internal visual and kinesthetic scores, and delta time of 10-meter walk test of mental chronometry (η2 > 0.14). The small-medium interaction effect was found in motor function and ambulation results (η2<0.14).

CONCLUSIONS

This study demonstrated that Tele-MI training improved MI ability of DMD cohort. The small-to-medium effects of Tele-MI training on motor function, particularly those involving the trunk, have demonstrated its potential as a complementary approach in rehabilitation to improve motor functions in children with DMD.

CLINICAL TRIAL REGISTRATION NUMBER AND URL

NCT06109103 (https://clinicaltrials.gov/study/NCT06109103?term=merve%20bora%20zereyak&rank=1).

Neural-Targeted Rehabilitation Strategies to Address Neuroplasticity After Joint Injury

In patients with musculoskeletal injury, changes have been observed within the central nervous system that contribute to altered movement planning. This maladaptive neuroplasticity potentially explains the clinical disconnect where residual neuromuscular dysfunction and high rates of reinjury are often observed even after individuals clear return-to-activity functional testing. An improved understanding of these neural changes could therefore serve as a guide for facilitating a more complete recovery and minimizing risk of reinjury. Therefore, we propose a paradigm of neural-targeted rehabilitation to augment commonly used therapeutic techniques targeting sensorimotor function to better address maladaptive plasticity. Although most treatments have the capability to modify neural function, optimizing these treatments and combining them with integrative therapies (eg, implementation of motor learning strategies, transcranial direct current stimulation) may enhance neural efficiency and facilitate return to activity in patients with musculoskeletal injury. To complete this model, consideration of affective aspects of movement and associated interventions must also be considered to improve the durability of these changes.

Exploring temporal congruence in motor imagery and movement execution in non-specific chronic low back pain

Chronic non-specific low back pain (NSCLBP) is linked to sensorimotor dysfunctions and altered motor planning, likely due to neuroplastic changes. Motor imagery (MI) and movement execution share neural pathways, but the relationship between imagined and executed movements in NSCLBP patients remains underexplored. This study aimed to assess the temporal congruence between imagined and executed movements in NSCLBP sufferers, with secondary goals of investigating group differences in movement chronometry, psychological well-being, and disability, as well as possible correlations among these factors. Fifty-six participants, including 28 NSCLBP patients and 28 asymptomatic subjects (AS), performed lumbar flexion and Timed Up and Go (TUG) tasks. NSCLBP patients showed significant temporal incongruence in both tasks, executing movements more slowly than imagined, whereas AS displayed incongruence only in the TUG task. NSCLBP patients also took longer to imagine and execute lumbar flexion movements compared to AS, with correlations observed between execution delays, higher disability, and greater fear of movement. The findings highlight a lack of temporal congruence in NSCLBP patients, especially in lumbar flexion, emphasizing the complex relationship between chronic pain, motor ability, and psychological factors. These results suggest that integrated treatment approaches addressing cognitive and emotional aspects are crucial for managing NSCLBP.

Implicit motor imagery: examining motor vs. visual strategies in laterality judgments among older adults

Cognitive states like motor imagery (MI; simulating actions without overtly executing them) share a close correspondence with action execution, and hence, activate the motor system in a similar way. However, as people age, reduction in specific cognitive abilities like motor action simulation and action planning/prediction are commonly experienced. The present study examined the effect of visual-spatial processing for both typical and challenging upper-limb movements using the Hand Laterality Judgment Task (HLJT), in which participants were asked to judge whether the depicted hand is a left or right hand. Several main findings emerged: (1) Compared to younger adults, older adults exhibited slower responses and greater error rates in both Experiment 1 and 2. This suggests that visual-spatial transformations undergo alterations with age; (2) Older adults displayed higher error rates with realistic hands at both back and palm viewpoints of the hands compared to younger adults. However, this pattern did not hold for response times; (3) Participants responded faster to medial hand orientations (i.e., closer to the midline of the body) compared to lateral hand orientations (i.e., farther from the midline of the body) for palm-views in both Experiment 1 and Experiment 2. Given that we observed better performance on medial orientations compared to lateral orientations, this suggests that participants follow the same motor rules and biomechanical constraints of the represented movement. Novel information is provided about differences in individuals' use of strategies (visual vs. motor imagery) to solve the HLJT for both mannequin and real hands.

Effects of Motor Learning on Corticospinal Tract Excitability During Motor Imagery

We aimed to examine the effects of motor performance improvements produced by practice on corticospinal tract excitability during motor imagery (MI) of identical movements. Participants performed a motor task with no guidelines displayed on the monitor (performance test); the participants only imagined performing the task without performing the movement (MI test), and the participants performed the power output and then adjusted it (exercise). The output force conditions were 20, 40, and 60% of the maximum voluntary contraction, and the objective was for 21 participants to learn each output force condition. The outcome of the performance test was calculated as the difference between the actual motor output and the target. During the MI test, we applied a single transcranial magnetic stimulation during imagery, assessed the corticospinal tract excitability of the right first dorsal interosseous by motor-evoked potential (MEP) amplitude, and recorded the vividness of the MI in each trial. We evaluated performance and MI before practice (Pre-test), after 150 practice sessions (Post-test 1), and after another 150 practice sessions (Post-test 2). The MEP amplitude was significantly reduced at Post-test 2 compared to Pre-test. The vividness of the MI improved with practice. Corticospinal tract excitability during MI decreased as motor performance improved. Thus, actual motor practice was also reflected in the MI of the exercise. Performance improvement was accompanied by a decrease in redundant activity, enhancing the efficiency and appropriateness of the exercise.

Understanding effects of observing affordance-driven action during motor imagery through EEG analysis

The aim of this paper is to investigate the impact of observing affordance-driven action during motor imagery. Affordance-driven action refers to actions that are initiated based on the properties of objects and the possibilities they offer for interaction. Action observation (AO) and motor imagery (MI) are two forms of motor simulation that can influence motor responses. We examined combined AO + MI, where participants simultaneously engaged in AO and MI. Two different kinds of combined AO + MI were employed. Participants imagined and observed the same affordance-driven action during congruent AO + MI, whereas in incongruent AO + MI, participants imagined the actual affordance-driven action while observing a distracting affordance involving the same object. EEG data were analyzed for the N2 component of event-related potential (ERP). Our study found that the N2 ERP became more negative during congruent AO + MI, indicating strong affordance-related activity. The maximum source current density (0.00611 μ A/mm2 ) using Low-Resolution Electromagnetic Tomography (LORETA) was observed during congruent AO + MI in brain areas responsible for planning motoric actions. This is consistent with prefrontal cortex and premotor cortex activity for AO + MI reported in the literature. The stronger neural activity observed during congruent AO + MI suggests that affordance-driven actions hold promise for neurorehabilitation.

Brain state and dynamic transition patterns of motor imagery revealed by the bayes hidden markov model

Motor imagery (MI) is a high-level cognitive process that has been widely applied to brain-computer inference (BCI) and motor recovery. In practical applications, however, huge individual differences and unclear neural mechanisms have seriously hindered the application of MI and BCI systems. Thus, it is urgently needed to explore MI from a new perspective. Here, we applied a hidden Markov model (HMM) to explore the dynamic organization patterns of left- and right-hand MI tasks. Eleven distinct HMM states were identified based on MI-related EEG data. We found that these states can be divided into three metastates by clustering analysis, showing a highly organized structure. We also assessed the probability activation of each HMM state across time. The results showed that the state probability activation of task-evoked have similar trends to that of event-related desynchronization/synchronization (ERD/ERS). By comparing the differences in temporal features of HMM states between left- and right-hand MI, we found notable variations in fractional occupancy, mean life time, mean interval time, and transition probability matrix across stages and states. Interestingly, we found that HMM states activated in the left occipital lobe had higher occupancy during the left-hand MI task, and conversely, during the right-hand MI task, HMM states activated in the right occipital lobe had higher occupancy. Moreover, significant correlations were observed between BCI performance and features of HMM states. Taken together, our findings explored dynamic networks underlying the MI-related process and provided a complementary understanding of different MI tasks, which may contribute to improving the MI-BCI systems.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11571-024-10099-9.

The assumed motor capabilities of a partner influence motor imagery in a joint serial disc transfer task

Motor imagery (MI) of one's own movements is thought to involve the sub-threshold activation of one's own motor codes. Movement coordination during joint action is thought to occur because co-actors integrate a simulation of their own actions with the simulated actions of the partner. The present experiments gained insight into MI of joint action by investigating if and how the assumed motor capabilitiesof the imaginary partner affected MI. Participants performed a serial disc transfer task alone and then imagined performing the same task alone and with an imagined partner. In the individual tasks, participants transferred all four discs. In the joint task, participants imagined themselves transferring the first 2 discs and a partner transferring the last 2 discs. The description of the imagined partner (high/low performer) was manipulated across blocks to determine if participants adapted their MI of the joint task based on the partner's characteristics. Results revealed that imagined movement times (MTs) were shorter when the description of the imagined partner was a 'high' performer compared to a 'low' performer. Interestingly, participants not only adjusted the partner's portion of the task, but they also adjusted their own portion of the task - imagined MTs of the first disc transfers were shorter when imagining performing the task with a high performer than with a low performer. These findings suggest that MI is based on the simulation of one's own response code, and that the adaptation of MI to their partner's movements influences the MI of one's own movements.

Effects of motor imagery using virtual reality on pain sensitivity and affect in healthy individuals: a prospective randomized crossover study

OBJECTIVE

Exercise induces a hypoalgesic response and improves affect. However, some individuals are unable to exercise for various reasons. Motor imagery, involving kinesthetic and visual imagery without physical movement, activates brain regions associated with these benefits and could be an alternative for those unable to exercise. Virtual reality also enhances motor imagery performance because of its illusion and embodiment. Therefore, we examined the effects of motor imagery combined with virtual reality on pain sensitivity and affect in healthy individuals.

DESIGN

Randomized crossover study.

SETTING

Laboratory.

SUBJECTS

Thirty-six participants (women: 18) were included.

METHODS

Each participant completed three 10-min experimental sessions, comprising actual exercise, motor imagery only, and motor imagery combined with virtual reality. Hypoalgesic responses and affective improvement were assessed using the pressure-pain threshold and the Positive and Negative Affect Schedule, respectively.

RESULTS

All interventions significantly increased the pressure-pain threshold at the thigh (P < .001). Motor imagery combined with virtual reality increased the pressure-pain threshold more than motor imagery alone, but the threshold was similar to that of actual exercise (both P ≥ .05). All interventions significantly decreased the negative affect of the Positive and Negative Affect Schedule (all P < .05).

CONCLUSIONS

Motor imagery combined with virtual reality exerted hypoalgesic and affective-improvement effects similar to those of actual exercise.

CLINICAL TRIALS REGISTRATION

The study was enrolled in the UMIN Clinical Trials Registry (registration number: UMIN000046095). The website for registration information is https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000052614.

Non-visual spatial strategies are effective for maintaining precise information in visual working memory

Visual working memory content is commonly thought to be composed of a precise visual representation of stimulus information (e.g., color, shape). Nevertheless, previous research has shown that individuals represent this visual information in different formats, historically dichotomized into "verbal" and "visual" formats. With growing popular knowledge of aphantasia, or the absence of sensory mental imagery, recent studies have demonstrated that individuals with aphantasia perform similarly to individuals with typical imagery on visual working memory tasks. This suggest that the use of non-visual strategies may be sufficient to perform visual working memory tasks, which were previously thought to be strictly visual. To investigate the effects of different strategies on performance in a visual working memory task, we recruited individuals across the visual imagery spectrum and tested their ability to identify relatively small (3°), medium (6°), or large (10°) changes in the degree of orientation of gratings held in working memory. Subsequently, participants indicated the extent to which they used five different strategies: visual, spatial, verbal, semantic, and sensorimotor. Results revealed that individuals with aphantasia and typical imagery performed similarly to each other across all task difficulty levels. Individuals with typical imagery dominantly used visuospatial strategies, but surprisingly, individuals with aphantasia overwhelmingly preferred the use of non-visual spatial and sensorimotor strategies over verbal strategies. These results suggest that non-visual spatial and sensorimotor strategies can be adopted in visual working memory tasks and these strategies are equally effective as visuospatial strategies. This calls for a rethinking of the "visual" versus "verbal" dichotomy, and provides evidence for the use of other non-visual mental representations in working memory tasks.

Enhancing EEG-Based MI-BCIs with Class-Specific and Subject-Specific Features Detected by Neural Manifold Analysis

This paper presents an innovative approach leveraging Neuronal Manifold Analysis of EEG data to identify specific time intervals for feature extraction, effectively capturing both class-specific and subject-specific characteristics. Different pipelines were constructed and employed to extract distinctive features within these intervals, specifically for motor imagery (MI) tasks. The methodology was validated using the Graz Competition IV datasets 2A (four-class) and 2B (two-class) motor imagery classification, demonstrating an improvement in classification accuracy that surpasses state-of-the-art algorithms designed for MI tasks. A multi-dimensional feature space, constructed using NMA, was built to detect intervals that capture these critical characteristics, which led to significantly enhanced classification accuracy, especially for individuals with initially poor classification performance. These findings highlight the robustness of this method and its potential to improve classification performance in EEG-based MI-BCI systems.

The cerebellum and the Mirror Neuron System: A matter of inhibition? From neurophysiological evidence to neuromodulatory implications. A narrative review

Mirror neurons show activity during both the execution (AE) and observation of actions (AO). The Mirror Neuron System (MNS) could be involved during motor imagery (MI) as well. Extensive research suggests that the cerebellum is interconnected with the MNS and may be critically involved in its activities. We gathered evidence on the cerebellum's role in MNS functions, both theoretically and experimentally. Evidence shows that the cerebellum plays a major role during AO and MI and that its lesions impair MNS functions likely because, by modulating the activity of cortical inhibitory interneurons with mirror properties, the cerebellum may contribute to visuomotor matching, which is fundamental for shaping mirror properties. Indeed, the cerebellum may strengthen sensory-motor patterns that minimise the discrepancy between predicted and actual outcome, both during AE and AO. Furthermore, through its connections with the hippocampus, the cerebellum might be involved in internal simulations of motor programs during MI. Finally, as cerebellar neuromodulation might improve its impact on MNS activity, we explored its potential neurophysiological and neurorehabilitation implications.

The multisensory nature of human action imagery

Imagination can appeal to all our senses and may, therefore, manifest in very different qualities (e.g., visual, tactile, proprioceptive, or kinesthetic). One line of research addresses action imagery that refers to a process by which people imagine the execution of an action without actual body movements. In action imagery, visual and kinesthetic aspects of the imagined action are particularly important. However, other sensory modalities may also play a role. The purpose of the paper will be to address issues that include: (i) the creation of an action image, (ii) how the brain generates images of movements and actions, (iii) the richness and vividness of action images. We will further address possible causes that determine the sensory impression of an action image, like task specificity, instruction and experience. In the end, we will outline open questions and future directions.

A theoretical perspective on action consequences in action imagery: internal prediction as an essential mechanism to detect errors: a commentary on Rieger et al. 2023

In this position paper, the authors support with recent behavioral findings the theory of internal simulations during motor imagery, initiated in the 90's. In this commentary, I will provide additional evidence from other research groups to support this theory and discuss the neurophysiological basis of inhibition (surround inhibition, inhibition within the primary cortex) and internal models (including the cerebellum).

Supraspinal Activation Induced by Visual Kinesthetic Illusion Modulates Spinal Excitability

Repetitive passive movement (RPM) enhances reciprocal inhibition. RPM is more effective when performed rapidly and at wide joint angles. However, patients with limited joint range of motion may not receive the most effective RPM. Therefore, having an alternative method for performing RPM in patients who cannot perform actual exercise due to limited joint motion is necessary. This study investigated the effects of RPM on spinal excitability using a visual kinesthetic illusion. Participants included 17 healthy adults (7 women). Measurements were taken before, during, and immediately after the intervention. We established two intervention conditions: the control condition, in which participants focused their attention forward, and the illusion condition, in which participants watched a video about RPM. F-waves from the tibialis anterior and soleus muscles were measured, and F-wave persistence and F/M amplitude ratios were analyzed. Under the illusion condition, compared with the preintervention condition, the F/M amplitude ratio of the tibialis anterior increased by approximately 44% during the intervention (p < 0.05), whereas the F-wave persistence of the soleus decreased by approximately 23% from the immediate start of the intervention (p < 0.05). This study suggests that a visual kinesthetic illusion can increase the spinal excitability of the tibialis anterior, whereas reciprocal inhibition can decrease the spinal excitability of the soleus.

User Evaluation of a Shared Robot Control System Combining BCI and Eye Tracking in a Portable Augmented Reality User Interface

This study evaluates an innovative control approach to assistive robotics by integrating brain-computer interface (BCI) technology and eye tracking into a shared control system for a mobile augmented reality user interface. Aimed at enhancing the autonomy of individuals with physical disabilities, particularly those with impaired motor function due to conditions such as stroke, the system utilizes BCI to interpret user intentions from electroencephalography signals and eye tracking to identify the object of focus, thus refining control commands. This integration seeks to create a more intuitive and responsive assistive robot control strategy. The real-world usability was evaluated, demonstrating significant potential to improve autonomy for individuals with severe motor impairments. The control system was compared with an eye-tracking-based alternative to identify areas needing improvement. Although BCI achieved an acceptable success rate of 0.83 in the final phase, eye tracking was more effective with a perfect success rate and consistently lower completion times (p<0.001). The user experience responses favored eye tracking in 11 out of 26 questions, with no significant differences in the remaining questions, and subjective fatigue was higher with BCI use (p=0.04). While BCI performance lagged behind eye tracking, the user evaluation supports the validity of our control strategy, showing that it could be deployed in real-world conditions and suggesting a pathway for further advancements.

Changes in corticospinal excitability during motor imagery by physical practice of a force production task: Effect of the rate of force development during practice

Transcranial magnetic stimulation studies have indicated that the physical practice of a force production task increases corticospinal excitability during motor imagery (MI) of that task. However, it is unclear whether this practice-induced facilitation of corticospinal excitability during MI depends on a repeatedly practiced rate of force development (RFD). We aimed to investigate whether corticospinal excitability during MI of an isometric force production task is facilitated only when imagining the motor task with the same RFD as the physically practiced RFD. Furthermore, we aimed to examine whether corticospinal excitability during MI only occurs immediately after physical practice or is maintained. Twenty-eight right-handed young adults practiced isometric ramp force production using right index finger abduction. Half of the participants (high group) practiced the force production with high RFD, and the other half (low group) practiced the force production with low RFD. Questionnaire scores indicating MI ability were similar in the two groups. We examined the force error relative to the target force during the force production task without visual feedback, and motor evoked potential (MEP) amplitudes of the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles during the MI of the force production task under practiced and unpracticed RFD conditions before, immediately after, and 20 min after physical practice. Our results demonstrated that the force error in both RFD conditions significantly decreased immediately after physical practice, irrespective of the RFD condition practiced. In the high group, the MEP amplitude of the FDI muscle during MI in the high RFD condition significantly increased immediately after practice compared to that before, whereas the MEP amplitude 20 min after practice was not significantly different from that before practice. Conversely, the MEP amplitude during MI in the high RFD condition did not change significantly in the low group, and neither group had significant changes in MEP amplitude during MI in the low RFD condition. The facilitatory effect of corticospinal excitability during MI with high RFD observed only immediately after physical practice in the high RFD condition may reflect short-term functional changes in the primary motor cortex induced by physical practice.

Evaluating the real-world usability of BCI control systems with augmented reality: a user study protocol

Brain-computer interfaces (BCI) enable users to control devices through their brain activity. Motor imagery (MI), the neural activity resulting from an individual imagining performing a movement, is a common control paradigm. This study introduces a user-centric evaluation protocol for assessing the performance and user experience of an MI-based BCI control system utilizing augmented reality. Augmented reality is employed to enhance user interaction by displaying environment-aware actions, and guiding users on the necessary imagined movements for specific device commands. One of the major gaps in existing research is the lack of comprehensive evaluation methodologies, particularly in real-world conditions. To address this gap, our protocol combines quantitative and qualitative assessments across three phases. In the initial phase, the BCI prototype's technical robustness is validated. Subsequently, the second phase involves a performance assessment of the control system. The third phase introduces a comparative analysis between the prototype and an alternative approach, incorporating detailed user experience evaluations through questionnaires and comparisons with non-BCI control methods. Participants engage in various tasks, such as object sorting, picking and placing, and playing a board game using the BCI control system. The evaluation procedure is designed for versatility, intending applicability beyond the specific use case presented. Its adaptability enables easy customization to meet the specific user requirements of the investigated BCI control application. This user-centric evaluation protocol offers a comprehensive framework for iterative improvements to the BCI prototype, ensuring technical validation, performance assessment, and user experience evaluation in a systematic and user-focused manner.

Overestimation associated with walking and balance function in individuals diagnosed with a stroke

BACKGROUND

An estimation error is the difference between motor imagery and actual motor time. Previous studies have reported that overestimation (motor imagery time < actual motor time) is related to physical functions in healthy individuals. However, this finding is unclear among individuals diagnosed with a stroke.

OBJECTIVE

We investigated whether overestimation is related to physical function in individuals diagnosed with a stroke.

METHODS

This study included 71 individuals diagnosed with a stroke (mean age, 67.2 ± 13.4 years; mean time since stroke, 68.4 ± 44.7 days). Imagined timed up and go test (iTUGT) was performed to assess the estimation error. First, the iTUGT was performed; subsequently, the TUGT was performed. The estimation error was calculated by subtracting the TUGT from the iTUGT, with two standard deviations (2 SDs) being calculated. Furthermore, patients were classified into appropriate estimation (AE, within ±2 SD) and overestimation (OE, over -2 SD) groups. Both groups were tested using the estimation error, iTUGT, TUGT, Berg Balance Scale (BBS), and Brunnstrom Recovery Stage (BRS). Subsequently, a correlation analysis was performed.

RESULTS

The OE group had a significantly higher estimation error than the AE group (OE: -7.08 ± 6.87 s, AE: -0.29 ± 1.53 s, P < .001). Moreover, the OE group had significantly lower TUGT and BBS than the AE group. The estimation error was correlated with the TUGT, BBS, and lower-limb BRS (ρ = -0.454, 0.431, 0.291, respectively; P < .05).

CONCLUSIONS

Overestimation was associated with TUGT and balance function in individuals diagnosed with a stroke.

Motor imagery ability of children with duchenne muscular dystrophy: Reliability and validity of kinesthetic and Visual Imagery Questionnaire-10, and its association with cognitive status

PURPOSE

To investigate validity and reliability of the Kinesthetic and Visual Imagery Questionnaire-10 (KVIQ-10) in children with Duchenne Muscular Dystrophy (DMD), to compare the motor imagery (MI) ability with age-matched controls, and to examine the relationship between MI ability and cognitive status.

METHODS

The research involved 38 children who were diagnosed with DMD, as well as 20 healthy controls aged between 7 and 18 years. The KVIQ-10 was assessed for its test-retest reliability, internal consistency, construct and concurrent validity. The Motor Imagery Questionnaire for Children (MIQ-C) was selected as the gold standard test for concurrent validity. Cognitive function was assessed using the Modified Mini Mental Test (MMMT) and Montreal Cognitive Assessment (MoCA).

RESULTS

KVIQ-10 showed excellent test-retest reliability (ICC>0.90) and high internal consistency (Cronbach's alpha>0.70). A moderate-to-strong association was found between KVIQ-10 and MIQ-C subscales (p < 0.001). KVIQ-10 and MIQ-C subscores were statistically lower in the DMD group (p ≤ 0.05). A correlation was found between MoCA and KVIQ-10 in children with DMD (p ≤ 0.05).

CONCLUSIONS

The KVIQ-10 is a reliable and valid measure to assess the MI ability of children with DMD whose imagery ability was determined to be impaired.

CLINICAL TRIAL REGISTRATION NUMBER AND URL

NCT05559710 (https://classic.

CLINICALTRIALS

gov/ct2/show/NCT05559710?term=NCT05559710&draw=2&rank=1).

Does the Effect of Mental Fatigue Created by Motor Imagery on Upper Extremity Functions Change with Diaphragmatic Breathing Exercises? A Randomized, Controlled, Single-Blinded Trial

Background and Objectives: This study focused on the impact of mental fatigue induced by motor imagery on upper limb function, an area with limited research compared to lower limb performance. It aimed to explore how diaphragmatic breathing exercises influence these effects. Materials and Methods: This study included 30 participants, and Group 1 participated in 12 sessions of diaphragmatic breathing exercises under the supervision of a physiotherapist; Group 2 did not receive any intervention. For all the participants, mental fatigue was induced with motor imagery before and after the intervention, and evaluations were performed before and after mental fatigue. Upper extremity functions were evaluated using isometric elbow flexion strength, hand grip strength, upper extremity reaction time and endurance, finger reaction time, the nine-hole peg test, shoulder position sense, light touch-pressure threshold, and two-point discrimination. Results: The study results showed that after mental fatigue, there was a decrease in isometric elbow flexion strength, nondominant hand grip strength, and nondominant upper extremity endurance, and an increase in nondominant tactile sensation (p < 0.05). No changes were found in two-point discrimination, nine-hole peg test time, and position sense on either side (p > 0.05). The effect of mental fatigue on isometric elbow flexion strength and nondominant grip strength showed significant improvement following diaphragmatic breathing exercises (p < 0.05). Conclusions: This study found that mental fatigue from motor imagery can impact elbow flexion, hand grip strength, upper extremity endurance, and tactile sensitivity. Breathing exercises may help improve strength parameters affected by mental fatigue. It is crucial to consider these effects on upper extremity functions in rehabilitation programs.

Neural correlates of motor imagery and execution in real-world dynamic behavior: evidence for similarities and differences

A large body of evidence shows that motor imagery and action execution behaviors result from overlapping neural substrates, even in the absence of overt movement during motor imagery. To date it is unclear how neural activations in motor imagery and execution compare for naturalistic whole-body movements, such as walking. Neuroimaging studies have not directly compared imagery and execution during dynamic walking movements. Here we recorded brain activation with mobile EEG during walking compared to during imagery of walking, with mental counting as a control condition. We asked 24 healthy participants to either walk six steps on a path, imagine taking six steps, or mentally count from one to six. We found beta and alpha power modulation during motor imagery resembling action execution patterns; a correspondence not found performing the control task of mental counting. Neural overlap occurred early in the execution and imagery walking actions, suggesting activation of shared action representations. Remarkably, a distinctive walking-related beta rebound occurred both during action execution and imagery at the end of the action suggesting that, like actual walking, motor imagery involves resetting or inhibition of motor processes. However, we also found that motor imagery elicits a distinct pattern of more distributed beta activity, especially at the beginning of the task. These results indicate that motor imagery and execution of naturalistic walking involve shared motor-cognitive activations, but that motor imagery requires additional cortical resources.

Virtual Reality Action Observation and Motor Imagery to Enhance Neuroplastic Capacity in the Human Motor Cortex: A Pilot Double-blind, Randomized Cross-over Trial

Neuroplasticity is important for learning, development and recovery from injury. Therapies that can upregulate neuroplasticity are therefore of interest across a range of fields. We developed a novel virtual reality action observation and motor imagery (VR-AOMI) intervention and evaluated whether it could enhance the efficacy of mechanisms of neuroplasticity in the human motor cortex of healthy adults. A secondary question was to explore predictors of the change in neuroplasticity following VR-AOMI. A pre-registered, pilot randomized controlled cross-over trial was performed. Twenty right-handed adults (13 females; mean age: 23.0 ± 4.53 years) completed two experimental conditions in separate sessions; VR-AOMI and control. We used intermittent theta burst stimulation (iTBS) to induce long term potentiation-like plasticity in the motor cortex and recorded motor evoked potentials at multiple timepoints as a measure of corticospinal excitability. The VR-AOMI task did not significantly increase the change in MEP amplitude following iTBS when compared to the control task (Group × Timepoint interaction p = 0.17). However, regression analysis identified the change in iTBS response following VR-AOMI was significantly predicted by the baseline iTBS response in the control task. Specifically, participants that did not exhibit the expected increase in MEP amplitude following iTBS in the control condition appear to have greater excitability following iTBS in the VR-AOMI condition (r = -0.72, p < 0.001). Engaging in VR-AOMI might enhance capacity for neuroplasticity in some people who typically do not respond to iTBS. VR-AOMI may prime the brain for enhanced neuroplasticity in this sub-group.

The Development and Evaluation of the Kinesthetic Motor Imagery of Pelvic Floor Muscle Contraction Questionnaire (KMI-PFQ) in Spanish Women

Practitioners have begun using motor imagery (MI) for preventing and treating some pelvic floor disorders. Due to requirements for imagining before performing a MI intervention and because there are few instruments available for assessing this specific ability in the pelvic floor musculature, we sought to develop and test a new MI questionnaire, the Kinesthetic Motor Imagery of Pelvic Floor Muscle Contraction Questionnaire (KMI-PFQ). We focused in this study on the development and analysis of the instrument's factorial structure and internal reliability in a participant sample of 162 healthy Spanish women (M age = 20.1, SD = 2.2 years). We developed and evaluated the KMI-PFQ's psychometric properties, finding it to have good internal consistency, with Cronbach's α = .838, ω coefficient = .839, and an intraclass correlation coefficient = .809, with two factors ("ability" and "mental effort") explaining 58.36% of response variance. The standard error of measurement was 3.58, and the minimal detectable change was 9.92. No floor or ceiling effects were identified. There was also good convergent validity as seen by statistically significant positive correlations between KMI-PFQ scores and the revised-Movement Image Questionnaire and Vividness of Visual Imagery Questionnaire. There were no statistically significant correlations between KMI-PFQ scores and the Orientation to Life Questionnaire. The KMI-PFQ is a valid and reliable instrument for measuring kinesthetic ability to feel/imagine pelvic floor muscle contractions in healthy Spanish women.

Effects of finger pinch motor imagery on short-latency afferent inhibition and corticospinal excitability

Motor imagery is a cognitive process involving the simulation of motor actions without actual movements. Despite the reported positive effects of motor imagery training on motor function, the underlying neurophysiological mechanisms have yet to be fully elucidated. Therefore, the purpose of the present study was to investigate how sustained tonic finger-pinching motor imagery modulates sensorimotor integration and corticospinal excitability using short-latency afferent inhibition (SAI) and single-pulse transcranial magnetic stimulation (TMS) assessments, respectively. Able-bodied individuals participated in the study and assessments were conducted under two experimental conditions in a randomized order between participants: (1) participants performed motor imagery of a pinch task while observing a visual image displayed on a monitor (Motor Imagery), and (2) participants remained at rest with their eyes fixed on the monitor displaying a cross mark (Control). For each condition, sensorimotor integration and corticospinal excitability were evaluated during sustained tonic motor imagery in separate sessions. Sensorimotor integration was assessed by SAI responses, representing inhibition of motor-evoked potentials (MEPs) in the first dorsal interosseous muscle elicited by TMS following median nerve stimulation. Corticospinal excitability was assessed by MEP responses elicited by single-pulse TMS. There was no significant difference in the magnitude of SAI responses between motor imagery and Control conditions, while MEP responses were significantly facilitated during the Motor Imagery condition compared to the Control condition. These findings suggest that motor imagery facilitates corticospinal excitability, without altering sensorimotor integration, possibly due to insufficient activation of the somatosensory circuits or lack of afferent feedback during sustained tonic motor imagery.

Motor imagery for paediatric neurorehabilitation: how much do we know? Perspectives from a systematic review

Background

Motor Imagery (MI) is a cognitive process consisting in mental simulation of body movements without executing physical actions: its clinical use has been investigated prevalently in adults with neurological disorders.

Objectives

Review of the best-available evidence on the use and efficacy of MI interventions for neurorehabilitation purposes in common and rare childhood neurological disorders.

Methods

systematic literature search conducted according to PRISMA by using the Scopus, PsycArticles, Cinahl, PUBMED, Web of Science (Clarivate), EMBASE, PsychINFO, and COCHRANE databases, with levels of evidence scored by OCEBM and PEDro Scales.

Results

Twenty-two original studies were retrieved and included for the analysis; MI was the unique or complementary rehabilitative treatment in 476 individuals (aged 5 to 18 years) with 10 different neurological conditions including, cerebral palsies, stroke, coordination disorders, intellectual disabilities, brain and/or spinal cord injuries, autism, pain syndromes, and hyperactivity. The sample size ranged from single case reports to cohorts and control groups. Treatment lasted 2 days to 6 months with 1 to 24 sessions. MI tasks were conventional, graded or ad-hoc. MI measurement tools included movement assessment batteries, mental chronometry tests, scales, and questionnaires, EEG, and EMG. Overall, the use of MI was stated as effective in 19/22, and uncertain in the remnant studies.

Conclusion

MI could be a reliable supportive/add-on (home-based) rehabilitative tool for pediatric neurorehabilitation; its clinical use, in children, is highly dependent on the complexity of MI mechanisms, which are related to the underlying neurodevelopmental disorder.

A scoping review on the use of consumer-grade EEG devices for research

BACKGROUND

Commercial electroencephalography (EEG) devices have become increasingly available over the last decade. These devices have been used in a wide variety of fields ranging from engineering to cognitive neuroscience.

PURPOSE

The aim of this study was to chart peer-review articles that used consumer-grade EEG devices to collect neural data. We provide an overview of the research conducted with these relatively more affordable and user-friendly devices. We also inform future research by exploring the current and potential scope of consumer-grade EEG.

METHODS

We followed a five-stage methodological framework for a scoping review that included a systematic search using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. We searched the following online databases: PsycINFO, MEDLINE, Embase, Web of Science, and IEEE Xplore. We charted study data according to application (BCI, experimental research, validation, signal processing, and clinical) and location of use as indexed by the first author's country.

RESULTS

We identified 916 studies that used data recorded with consumer-grade EEG: 531 were reported in journal articles and 385 in conference papers. Emotiv devices were used most, followed by the NeuroSky MindWave, OpenBCI, interaXon Muse, and MyndPlay Mindband. The most common usage was for brain-computer interfaces, followed by experimental research, signal processing, validation, and clinical purposes.

CONCLUSIONS

Consumer-grade EEG is a useful tool for neuroscientific research and will likely continue to be used well into the future. Our study provides a comprehensive review of their application, as well as future directions for researchers who plan to use these devices.

Motor imagery ability scores are related to cortical activation during gait imagery

Motor imagery (MI) is the mental execution of actions without overt movements that depends on the ability to imagine. We explored whether this ability could be related to the cortical activity of the brain areas involved in the MI network. To this goal, brain activity was recorded using high-density electroencephalography in nineteen healthy adults while visually imagining walking on a straight path. We extracted Event-Related Desynchronizations (ERDs) in the θ, α, and β band, and we measured MI ability via (i) the Kinesthetic and Visual Imagery Questionnaire (KVIQ), (ii) the Vividness of Movement Imagery Questionnaire-2 (VMIQ), and (iii) the Imagery Ability (IA) score. We then used Pearson's and Spearman's coefficients to correlate MI ability scores and average ERD power (avgERD). Positive correlations were identified between VMIQ and avgERD of the middle cingulum in the β band and with avgERD of the left insula, right precentral area, and right middle occipital region in the θ band. Stronger activation of the MI network was related to better scores of MI ability evaluations, supporting the importance of testing MI ability during MI protocols. This result will help to understand MI mechanisms and develop personalized MI treatments for patients with neurological dysfunctions.

Differences in motor imagery abilities in active and sedentary individuals: new insights from backward-walking imagination

Evidence has shown that imagining a complex action, like backward-walking, helps improve the execution of the gesture. Despite this, studies in sport psychology have provided heterogeneous results on the use of motor imagery (MI) to improve performance. We aimed to fill this gap by analyzing how sport experience influences backward-walking MI processes in a sample of young women (n = 41, mean age = 21 ± 2.2) divided into Active and Sedentary. All participants were allocated to two randomized mental chronometric tasks, in which they had first to imagine and then execute forward-walking (FW) and backward-walking (BW). The Isochrony Efficiency measured the difference between imagination and execution times in both conditions (FW and BW). Moreover, we analyzed the ability to vividly imagine FW and BW within various perspectives in both groups through the Vividness of Movement Imagery Questionnaire (VMIQ-2). Findings showed that active individuals performed better in the BW imagery task when compared to sedentary ones (F1,39 = 4.98; p = 0.03*), while there were no differences between groups in the FW imagery task (F1,39 = .10; p = 0.75). Further, VMIQ-2 had evidenced that the ability to imagine backward is influenced by perspective used. Specifically, the use of internal visual imagery (IVI) led to worse Isochrony Efficiency (t32,25 = 2.16; p = 0.04*), while the use of kinesthetic imagery (KIN) led to better Isochrony Efficiency (t32,25 =  - 2.34; p = 0.03*). These results suggest a close relation between motor experience and complex motor imagery processes and open new insights for studying these mental processes.

Graded motor imagery and its phases for individuals with phantom limb pain following amputation: A scoping review

OBJECTIVE

Three-phase graded motor imagery (limb laterality, explicit motor imagery, and mirror therapy) has been successful in chronic pain populations. However, when applied to phantom limb pain, an amputation-related pain, investigations often use mirror therapy alone. We aimed to explore evidence for graded motor imagery and its phases to treat phantom limb pain.

DATA SOURCES

A scoping review was conducted following the JBI Manual of Synthesis and Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews. Thirteen databases, registers, and websites were searched.

REVIEW METHODS

Published works on any date prior to the search (August 2023) were included that involved one or more graded motor imagery phases for participants ages 18+ with amputation and phantom limb pain. Extracted data included study characteristics, participant demographics, treatment characteristics, and outcomes.

RESULTS

Sixty-one works were included representing 19 countries. Most were uncontrolled studies (31%). Many participants were male (75%) and had unilateral amputations (90%) of varying levels, causes, and duration. Most works examined one treatment phase (92%), most often mirror therapy (84%). Few works (3%) reported three-phase intervention. Dosing was inconsistent across studies. The most measured outcome was pain intensity (95%).

CONCLUSION

Despite the success of three-phase graded motor imagery in other pain populations, phantom limb pain research focuses on mirror therapy, largely ignoring other phases. Participant demographics varied, making comparisons difficult. Future work should evaluate graded motor imagery effects and indicators of patient success. The represented countries indicate that graded motor imagery phases are implemented internationally, so future work could have a widespread impact.

Exploring Methodological Issues in Mental Practice for Upper-Extremity Function Following Stroke-Related Paralysis: A Scoping Review

In this scoping review, we aimed to comprehensively clarify the methodology of Mental practice (MP) by systematically mapping studies documenting the application of MP to post-stroke paralytic upper-extremity function. Specifically, when is an MP intervention most commonly applied after stroke onset? What is the corresponding MP load (intervention time, number of intervention days, and intervention period)? What are the most common methods of Motor Imagery (MI) recall and MI tasks used during the application of MP? Is MP often used in conjunction with individual rehabilitation? What are the paralyzed side's upper-limb and cognitive function levels at the start of an MP intervention? The research questions were identified according to PRISMA-ScR. The PubMed, Scopus, Medline, and Cochrane Library databases were used to screen articles published until 19 July 2022. In total, 694 English-language articles were identified, of which 61 were finally included. Most of the studies were conducted in the chronic phase after stroke onset, with limited interventions in the acute or subacute phase. The most common intervention time was ≤30 min and intervention frequency was 5 times/week in MP. An audio guide was most commonly used to recall MI during MP, and 50 studies examined the effects of MP in combination with individual rehabilitation. The Fugl-Meyer Assessment mean for the 38 studies, determined using the Fugl-Meyer Assessment, was 30.3 ± 11.5. Additional research with the aim of unifying the widely varying MP methodologies identified herein is warranted.

Motor imagery ability in children and adolescents with cerebral palsy: a systematic review and evidence map

Background

Cerebral palsy (CP) refers to a group of permanent movement and posture disorders. Motor imagery (MI) therapy is known to provide potential benefits, but data on MI ability in children and adolescents with CP is lacking.

Objective

A systematic review was performed to explore MI abilities in children and adolescents with CP compared to typically developed (TD) subjects.

Methods

We searched on PubMed, Web of Science (WOS), EBSCO, Google Scholar, and PEDro including observational studies. Methodological quality was assessed with the modified Newcastle-Ottawa Scale and evidence map was created to synthesize the evidence qualitatively and quantitatively.

Results

Seven cross-sectional studies were selected, which included 174 patients with CP and 321 TD subjects. Three studies explored explicit MI, two MI-execution synchrony, and four implicit MI domains. Methodological quality ranged from 6 to 8 stars. Moderate evidence supported the absence of differences in vividness between the groups. As there was only limited evidence, establishing a clear direction for the results was not possible, especially for the capacity to generate MI, mental chronometry features, and MI-execution synchrony domains. Moderate evidence supported a lower efficiency in cases for hand recognition, derived from a lower accuracy rate, while reaction time remained similar between the two groups. Moderate evidence indicated that patients with CP and TD controls showed similar features on whole-body recognition.

Conclusion

Moderate evidence suggests that patients with CP present a reduced ability in hand recognition, which is not observed for whole-body recognition compared to healthy controls. Severe limitations concerning sample size calculations and validity of assessment tools clearly limits establishing a direction of results, especially for explicit MI and MI-Execution synchrony domains. Further research is needed to address these limitations to enhance our comprehension of MI abilities in children, which is crucial for prescribing suitable MI-based therapies in this child population.

Cognitive Motor Dissociation: Gap Analysis and Future Directions

BACKGROUND

Patients with disorders of consciousness who are behaviorally unresponsive may demonstrate volitional brain responses to motor imagery or motor commands detectable on functional magnetic resonance imaging or electroencephalography. This state of cognitive motor dissociation (CMD) may have prognostic significance.

METHODS

The Neurocritical Care Society's Curing Coma Campaign identified an international group of experts who convened in a series of monthly online meetings between September 2021 and April 2023 to examine the science of CMD and identify key knowledge gaps and unmet needs.

RESULTS

The group identified major knowledge gaps in CMD research: (1) lack of information about patient experiences and caregiver accounts of CMD, (2) limited epidemiological data on CMD, (3) uncertainty about underlying mechanisms of CMD, (4) methodological variability that limits testing of CMD as a biomarker for prognostication and treatment trials, (5) educational gaps for health care personnel about the incidence and potential prognostic relevance of CMD, and (6) challenges related to identification of patients with CMD who may be able to communicate using brain-computer interfaces.

CONCLUSIONS

To improve the management of patients with disorders of consciousness, research efforts should address these mechanistic, epidemiological, bioengineering, and educational gaps to enable large-scale implementation of CMD assessment in clinical practice.

Cortical Reorganization after Limb Loss: Bridging the Gap between Basic Science and Clinical Recovery

Despite the increasing incidence and prevalence of amputation across the globe, individuals with acquired limb loss continue to struggle with functional recovery and chronic pain. A more complete understanding of the motor and sensory remodeling of the peripheral and central nervous system that occurs postamputation may help advance clinical interventions to improve the quality of life for individuals with acquired limb loss. The purpose of this article is to first provide background clinical context on individuals with acquired limb loss and then to provide a comprehensive review of the known motor and sensory neural adaptations from both animal models and human clinical trials. Finally, the article bridges the gap between basic science researchers and clinicians that treat individuals with limb loss by explaining how current clinical treatments may restore function and modulate phantom limb pain using the underlying neural adaptations described above. This review should encourage the further development of novel treatments with known neurological targets to improve the recovery of individuals postamputation.Significance Statement In the United States, 1.6 million people live with limb loss; this number is expected to more than double by 2050. Improved surgical procedures enhance recovery, and new prosthetics and neural interfaces can replace missing limbs with those that communicate bidirectionally with the brain. These advances have been fairly successful, but still most patients experience persistent problems like phantom limb pain, and others discontinue prostheses instead of learning to use them daily. These problematic patient outcomes may be due in part to the lack of consensus among basic and clinical researchers regarding the plasticity mechanisms that occur in the brain after amputation injuries. Here we review results from clinical and animal model studies to bridge this clinical-basic science gap.

Modulation of lower limb muscle corticospinal excitability during various types of motor imagery

Motor imagery (MI) is used for rehabilitation and sports training. Previous studies focusing on the upper limb have investigated the effects of MI on corticospinal excitability in the muscles involved in the imagined movement (i.e., the agonist muscles). The present study focused on several lower-limb movements and investigated the influences of MI on corticospinal excitability in the lower limb muscles. Twelve healthy individuals (ten male and two female individuals) participated in this study. Motor-evoked potentials (MEP) from the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and soleus (SOL) muscles were elicited through transcranial magnetic stimulation (TMS) to the primary motor cortex during MI of knee extension, knee flexion, ankle dorsiflexion, and ankle plantarflexion and at rest. The results showed that the RF MEPs were significantly increased during MI in knee extension, ankle dorsiflexion, and ankle plantarflexion but not in knee flexion, compared with those at rest. The TA MEPs were significantly increased during MI in knee extension and foot dorsiflexion, while MEPs were not significantly different during MI in knee flexion and foot dorsiflexion than those at rest. For the BF and SOL muscles, there was no significant MEP modulation in either MI. These results demonstrated that corticospinal excitability of the RF and TA muscles was facilitated during MI of movements in which they are active and during MI of lower-limb movements in which they are not involved. On the contrary, corticospinal excitability of the BF and SOL muscles was not facilitated by MI of lower-limb movements. These results suggest that facilitation of corticospinal excitability depends on the muscle and the type of lower-limb MI.