Brain activity during observation and motor imagery of different balance tasks: An fMRI study

Do menstrual symptoms affect motor imagery skills in young women?

PURPOSE

To examine the relationship between menstrual symptoms and motor imagery skills in young women.

METHODS

A total of 117 women between the ages of 18-40 were included in the study. Visual Analog Scale (VAS) for the menstrual pain intensity, the Menstrual Symptom Questionnaire (MSQ) for the menstrual-related symptoms, and the Kinesthetic and Visual Imagery Questionnaire-20 (KVIQ-20) for the motor imagery were used. All measurements were conducted on the first or second day of the menstruation, depending on when the subject declared subjectively experiencing most symptoms.

RESULTS

The relationship between menstruation symptoms and visual imagery (VI) and kinesthetic imagery (KI) skills was examined. A weak negative correlation was found between MSQ_negative effects/somatic complaints and KVIQ-20_KI (p = .040, r = -.199). The relationship between menstrual pain intensity and KVIQ-20 items was examined. The strongest relationship was found between VAS and KVIQ-20_knee_VI and KVIQ-20_hip_VI (p = 003, r = -.288; p = 005, r = -.270; p = 004, respectively). A weak negative correlation was also found between VAS and KVIQ-20_VI_total and KVIQ-20_KI_total (p = 0.004, r = -.275; p = 0.19, r = -.227, respectively).

DISCUSSION

This is the first study to examine menstrual symptoms in women in detail and reveal their relationship with motor imagery skills. Menstrual symptoms, especially negative effects/somatic complaints seen during menstruation, negatively affect kinesthetic imagery ability. In addition; chronic menstrual pain has a negative effect on both kinesthetic and visual imagery abilities. Considering the impairments in motor imagery skills due to negative effects/somatic complaints during menstruation and chronic menstrual pain, adding motor imagery training to treatment programs aimed at improving women's health may have positive effects.

Motor Cortex Activation Patterns in Both Hemispheres Induced by Motor Imagery in Patients With Right- and Left-Sided Cerebral Infarction: An fNIRS Study

This study aimed to explore the neuroimaging basis of motor imagery (MI) in stroke rehabilitation, particularly focusing on the brain activation patterns during MI tasks. Additionally, this study may provide insights into clinical rehabilitation strategies. A total of 40 right-handed stroke patients from Zhejiang Rehabilitation Medical Center were assigned to either the right-sided or left-sided cerebral infarction group. They were right-handed and recruited from Zhejiang Rehabilitation Medical Center. A portable near-infrared brain function imaging system was used to detect changes in oxyhemoglobin concentration in the bilateral sensorimotor cortex, premotor cortex, and supplementary motor area during the MI task. Activated channels and intensity changes in brain regions under the MI state were observed and analyzed. In patients with right-sided cerebral infarction, brain activation was left-lateralized during both left- and right-limb MI. Patients with left-sided cerebral infarction exhibited left lateralization during right-limb MI and right lateralization during left-limb MI. Functional near-infrared spectroscopy was utilized to investigate the activation of motor-related brain regions during MI after stroke. These regions of interest were associated with hand motor tasks and were successfully activated during the MI task. Following infarction, the activation of the MI cortex was asymmetric. When imagining movements on the dominant-hand side, MI becomes more vivid and activates bilateral motor cortex areas.

Static and temporal dynamic changes in brain activity in patients with post-stroke balance dysfunction: a pilot resting state fMRI

Objective

The aim of this study was to investigate the characteristics of brain activity changes in patients with post-stroke balance dysfunction and their relationship with clinical assessment, and to construct a classification model based on the extreme Gradient Boosting (XGBoost) algorithm to discriminate between stroke patients and healthy controls (HCs).

Methods

In the current study, twenty-six patients with post-stroke balance dysfunction and twenty-four HCs were examined by resting-state functional magnetic resonance imaging (rs-fMRI). Static amplitude of low frequency fluctuation (sALFF), static fractional ALFF (sfALFF), static regional homogeneity (sReHo), dynamic ALFF (dALFF), dynamic fALFF (dfALFF) and dynamic ReHo (dReHo) values were calculated and compared between the two groups. The values of the imaging metrics for the brain regions with significant differences were used in Pearson correlation analyses with the Berg Balance Scale (BBS) scores and as features in the construction of the XGBoost model.

Results

Compared to HCs, the brain regions with significant functional abnormalities in patients with post-stroke balance dysfunction were mainly involved bilateral insula, right fusiform gyrus, right lingual gyrus, left thalamus, left inferior occipital gyrus, left inferior temporal gyrus, right calcarine fissure and surrounding cortex, left precuneus, right median cingulate and paracingulate gyri, right anterior cingulate and paracingulate gyri, bilateral supplementary motor area, right putamen, and left cerebellar crus II. XGBoost results show that the model constructed based on static imaging features has the best classification prediction performance.

Conclusion

In conclusion, this study provided evidence of functional abnormalities in local brain regions in patients with post-stroke balance dysfunction. The results suggested that the abnormal brain regions were mainly related to visual processing, motor execution, motor coordination, sensorimotor control and cognitive function, which contributed to our understanding of the neuropathological mechanisms of post-stroke balance dysfunction. XGBoost is a promising machine learning method to explore these changes.

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.

Motor imagery does not effectively improve walking-related performance in older adults: A randomised controlled trial

BACKGROUND

Inaccurate perception of one's physical abilities is potentially related to age-related declines in motor planning and can lead to changes in walking. Motor imagery training is effective at improving balance and walking in older adults, but most research has been conducted on older adults following surgery or in those with a history of falls. Deficits in motor imagery ability are associated with reduced executive function in older adults with cognitive impairment.

OBJECTIVES

To determine whether walking-specific motor imagery training could improve walking performance (physical and imagined) in healthy older adults, and identify the relationship between actual and imagined movement, motor imagery accuracy and executive function across 5 different walking tasks in healthy older adults.

METHODS

A cohort of 53 community dwelling older adults took part in a 4-wk randomized controlled trial to assess the effect of motor imagery training on the physical and imagined performance of 5 walking-related tasks (3 narrow path walking tasks, Timed-up and go and step-over test), together with motor imagery clarity using the kinesthetic and visual imagery questionnaire (KVIQ-10). The association between physical performance, motor imagery accuracy and executive function were identified at baseline.

RESULTS

Four weeks of motor imagery training did not improve walking-specific performance (imagined or physical) compared to no-training. Motor imagery training did improve the visual clarity of imagined non-walking tasks. Executive function was significantly correlated with 2 out of 5 imagined walking tasks and 4 out of 5 physical walking tasks but was not associated with motor imagery accuracy.

CONCLUSION

Four weeks of motor imagery training is not effective at improving performance in walking-related tasks in healthy older adults. This lack of improvement may be due in part to the high functional ability of the cohort. Future research should assess the relationship between motor planning and executive function with more complex walking tasks.

TRIAL REGISTRATION

ANZCTR registration (ACTRN12619001784101).

Efficacy of Action Observation Therapy on Gait, Balance and Mobility Impairments: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Action Observation Therapy (AOT) has been proposed to improve gait, balance and mobility in subjects with neurological and musculoskeletal disorders. The current review aimed to investigate AOT effects in subjects with gait, balance and mobility impairments.

METHODS

A systematic literature search was performed using PubMed/MEDLINE, EMBASE and Scopus databases from inception until May 2023. Randomized controlled trials investigating effects of AOT on gait, balance and mobility in subjects with any type of clinical condition were included. Two reviewers performed data extraction and methodological quality assessment using the revised Cochrane risk of bias tool for randomized trials. The overall effects were reported as mean difference (MD) or standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

Thirty-one studies were included. Low evidence supported AOT to enhance walking speed (SMD: 0.40; 95% CI: 0.17, 0.62; I2 = 0%), stride length (SMD: 0.35; 95% CI 0.05, 0.66; I2 = 0%) and single limb support duration (MD: 4.1%; 95% CI: 1.0, 7.2, I2 = 0%) after stroke. Low evidence supported AOT to improve walking distance (MD: 56.8 m; 95% CI; 39.2, 74.4 m) and dynamic (SMD: 0.40; 95% CI: 0.04, 0.76; I2 = 0%) and static (SMD: 0.69; 95% CI: 0.32, 1.05; I2 = 0%) balance, while very low evidence supported AOT to enhance mobility (MD: -1.48 s; 95% CI; -2.2, -0.8 s; I2 = 0%) after stroke. Moderate evidence supported AOT to improve dynamic balance in subjects with Parkinson's disease (SMD: 0.44; 95% CI: 0.09, 0.79; I2 = 28%), while low evidence supported AOT to enhance dynamic balance (SMD: 0.61; 95% CI: 0.15, 1.08; I2 = 27%) and mobility (MD: -2.08 s; 95% CI; -3.5, -0.6 s; I2 = 0%) in patients with orthopedic conditions.

CONCLUSION

AOT improved gait, balance and mobility after stroke, dynamic balance in patients with Parkinson's disease and dynamic balance and mobility in patients with orthopedic conditions. However, evidence certainty was generally low and further high-quality studies are needed.

TRIAL REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews (n. CRD42021240626).

Safety and efficacy of motor imagery-based physical activity in high-risk pregnancy: A randomized controlled study

OBJECTIVE

This study aimed to investigate the acute effects of motor imagery-based physical activity on maternal well-being, maternal blood pressure, heart rate, oxygen saturation, fetal heart rate, and uterine contractions in women with high-risk pregnancies.

METHODS

This randomized controlled trial was conducted in Izmir Tepecik Education and Research Hospital from August 2023 to January 2024. Seventy-six women with high-risk pregnancies were randomized into two groups: a motor imagery group (n = 38, diaphragmatic-breathing exercise and motor imagery-based physical activity) and a control group (n = 38, diaphragmatic-breathing exercise). Maternal well-being was determined using the Numerical Rating Scale-11. Digital sphygmomanometry was used to measure maternal heart rate and blood pressure, pulse oximetry for oxygen saturation, and cardiotocography for fetal heart rate and uterine contractions. Assessments were performed pre-intervention, mid-intervention, and post-intervention.

RESULTS

There were no significant differences in baseline characteristics between groups (P > 0.05). There was a significant main effect of time in terms of maternal well-being and maternal heart rate (P = 0.001 and P = 0.015). In addition, there was a significant main effect of the group on oxygen saturation (P = 0.025). The overall group-by-time interaction was significant for maternal well-beingm with an effect size of 0.05 (P = 0.041).

CONCLUSION

The combination of diaphragmatic-breathing exercises and a motor imagery-based physical activity program in women with high-risk pregnancies was determined to have no adverse effects on the fetus, did not induce uterine contractions, and resulted in a significant improvement in maternal well-being and oxygen saturation. Thus, imagery-based physical activity can be used in high-risk pregnancies where physical activity and exercise are not recommended.

Effects of Anodal tDCS Applied Over the Cerebellum Combined with Physical Therapy on Center of Gravity Sway in a Patient with Cerebellar Ataxia: A Single-Case Study

Damage to the cerebellum results in dysfunctional standing postural control. Patients with cerebellar ataxia have a larger sway in the center of gravity (COG) while standing. Transcranial direct current stimulation (tDCS) has been applied in the rehabilitation of patients with central nervous system disorders; however, its effect on COG sway in patients with cerebellar ataxia remains unknown. We aimed to confirm the effects of anodal cerebellar tDCS (ctDCS) combined with physical therapy on COG sway in a patient with cerebellar ataxia using a retrospective ABA single-case study design. This study involved a patient with left cerebellar hemorrhage. Walking and postural balance rehabilitation were conducted in phase A. Anodal ctDCS was combined with the walking and postural balance rehabilitation in phase B. We measured COG sway in the open- and closed-eyes standing conditions daily throughout all the phases. In the open-eyes standing condition, there was no significant change in COG sway in phase B. Conversely, in the closed-eyes standing condition, the circumferential area, total sway path length, and anteroposterior sway path length decreased in phase B. No change was observed in the mediolateral sway path length. The combination of anodal ctDCS and physical therapy may decrease COG sway in patients with cerebellar ataxia in the closed-eyes standing condition, and its effect may be greater in the anteroposterior direction.

Effects of high-intensity interval training in a cold environment on arterial stiffness and cerebral hemodynamics in sedentary Chinese college female students post-COVID-19

Many patients with COVID-19 experience increased arterial stiffness and abnormal cerebral hemodynamics. Although previous studies have explored the effects of cold environments on cardiovascular health and cerebral hemodynamics, there is still no research on the changes in cardiovascular and cerebral hemodynamics in sedentary female students recovering from COVID-19 while performing high-intensity interval training (HIIT) in cold environments. This study investigates the effects of 1 week of HIIT in a cold environment on cerebral hemodynamics and arterial stiffness (AS) in sedentary female college students, providing new insights into the pathophysiological mechanisms in this specific context. Thirty-six participants were randomly divided into a control group (n = 12), a room temperature (RE) group (n = 12), and a cold environment (CE) group (n = 12). HIIT was performed for four 4-min running training sessions, with a 4-min interval between each training session, The training duration was 1 week, with a frequency of 2 sessions per day, while the control group did not undergo any training. After training, the AS in the CE group significantly decreased (p < 0.05), with an average reduction of 11% in brachial-ankle pulse wave velocity, showing a significantly greater improvement compared to the RE group and the control group (p < 0.05), while no significant changes were observed in the RE group (p > 0.05). In the Y-Balance Tests (YBTs), the concentrations of cerebral oxygenated hemoglobin and total hemoglobin significantly increased (p < 0.05) during unilateral leg support tests in both the CE and RE groups, and the increase of CE group is greater than that of RE group. In contrast, in the control group, the concentrations of cerebral oxygenated hemoglobin and total hemoglobin significantly decreased during left leg support (p < 0.05). Our study found that performing HIIT in a cold environment not only effectively reduces AS in sedentary female college students after COVID-19, improves cardiovascular function, but also significantly enhances cerebral hemodynamics, helping them alleviate the negative impacts of post-COVID-19 sequelae and sedentary behavior on health. Future research should further explore the mechanisms by which sedentary behavior, post-COVID-19 recovery status, and adaptation to cold environments collectively influence cardiovascular function and cerebral hemodynamics, providing a more comprehensive understanding of these factors.

Rebalance the Inhibitory System in the Elderly Brain: Influence of Balance Learning on GABAergic Inhibition and Functional Connectivity

Aging involves complex processes that impact the structure, function, and metabolism of the human brain. Declines in both structural and functional integrity along with reduced local inhibitory tone in the motor areas, as indicated by reduced γ-aminobutyric acid (GABA) levels, are often associated with compromised motor performance in elderly adults. Using multimodal neuroimaging techniques including magnetic resonance spectroscopy (MRS), diffusion magnetic resonance imaging (MRI), functional MRI as well as transcranial magnetic stimulation to assess short-interval intracortical inhibition (SICI), this study explores whether these age-related changes can be mitigated by motor learning. The investigation focused on the effects of long-term balance learning (3 months) on intracortical inhibition, metabolism, structural, and functional connectivity in the cortical sensorimotor network among an elderly cohort. We found that after 3 months of balance learning, subjects significantly improved balance performance, upregulated sensorimotor cortical GABA levels and ventral sensorimotor network functional connectivity (VSN-FC) compared to a passive control group. Furthermore, correlation analysis suggested a positive association between baseline VSN-FC and balance performance, between baseline VSN-FC and SICI, and between improvements in balance performance and upregulation in SICI in the training group, though these correlations did not survive the false discovery rate correction. These findings demonstrate that balance learning has the potential to counteract aging-related decline in functional connectivity and cortical inhibition on the "tonic" (MRS) and "functional" (SICI) level and shed new light on the close interplay between the GABAergic system, functional connectivity, and behavior.

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.

Transcranial Direct-Current Stimulation Over the Primary Motor Cortex and Cerebellum Improves Balance and Shooting Accuracy in Elite Ice Hockey Players

PURPOSE

To investigate the effects of transcranial direct-current stimulation (tDCS) applied over the primary motor cortex (M1) and cerebellum on balance control and shooting accuracy in elite ice hockey players.

METHODS

Twenty-one elite ice hockey players underwent anodal tDCS over the M1 (a-tDCSM1), anodal tDCS over the cerebellum (a-tDCSCB), concurrent dual-site anodal tDCS over the M1 and the cerebellum (a-tDCSM1+CB), and sham stimulation (tDCSSHAM). Before and after receiving tDCS (2 mA for 15 min), participants completed an ice hockey shooting-accuracy test, Pro-Kin balance test (includes stance test and proprioceptive assessment), and Y-balance test in randomized order.

RESULTS

For static balance performance, the ellipse area in the 2-legged stance with eyes open and the 1-legged stance with the dominant leg significantly improved following a-tDCSM1, a-tDCSCB, and concurrent dual-site a-tDCSM1+CB, compared with tDCSSHAM (all P < .05, Cohen d = 0.64-1.06). In dynamic balance performance, the average trace error of the proprioceptive assessment and the composite score of the Y-balance test with the dominant leg significantly improved following a-tDCSM1 and concurrent dual-site a-tDCSM1+CB (all P < .05, Cohen d = 0.77-1.00). For the ice hockey shooting-accuracy test, shooting-accuracy while standing on the unstable platform significantly increased following a-tDCSM1 (P = .010, Cohen d = 0.81) and a-tDCSCB (P = .010, Cohen d = 0.92) compared with tDCSSHAM.

CONCLUSION

tDCS could potentially be a valuable tool in enhancing static and dynamic balance and shooting accuracy on unstable platforms in elite ice hockey players.

Enhancing motor imagery practice using synchronous action observation

In this paper, we discuss a variety of ways in which practising motor actions by means of motor imagery (MI) can be enhanced via synchronous action observation (AO), that is, by AO + MI. We review the available research on the (mostly facilitatory) behavioural effects of AO + MI practice in the early stages of skill acquisition, discuss possible theoretical explanations, and consider several issues related to the choice and presentation schedules of suitable models. We then discuss considerations related to AO + MI practice at advanced skill levels, including expertise effects, practical recommendations such as focussing attention on specific aspects of the observed action, using just-ahead models, and possible effects of the perspective in which the observed action is presented. In section "Coordinative AO + MI", we consider scenarios where the observer imagines performing an action that complements or responds to the observed action, as a promising and yet under-researched application of AO + MI training. In section "The dual action simulation hypothesis of AO + MI", we review the neurocognitive hypothesis that AO + MI practice involves two parallel action simulations, and we consider opportunities for future research based on recent neuroimaging work on parallel motor representations. In section "AO + MI training in motor rehabilitation", we review applications of AO, MI, and AO + MI training in the field of neurorehabilitation. Taken together, this evidence-based, exploratory review opens a variety of avenues for future research and applications of AO + MI practice, highlighting several clear advantages over the approaches of purely AO- or MI-based practice.

Action observation perspective influences the effectiveness of combined action observation and motor imagery training for novices learning an Osoto Gari judo throw

Combined action observation and motor imagery (AOMI) training improves motor skill performance, but limited research has investigated possible moderating factors for this intervention. This study examined the influence of action observation (AO) perspective on the effectiveness of AOMI training for novices learning a 'shadow' Osoto Gari judo throw. Thirty novice participants were randomly assigned to AOMI training that displayed egocentric footage (AOMIEGO) or allocentric footage (AOMIALLO) of the Osoto Gari, or Control training. A motor learning design incorporating pre-test (Day 1), acquisition (Days 2-6), post-test (Day 7), and retention-test (Day 14) was adopted. Motor skill performance, self-efficacy, and mental representation structures were recorded as measures of learning. There were mixed effects for motor skill performance across the three training conditions utilized in this study, with AOMIALLO training significantly reducing error scores for final right hip flexion angle and peak right ankle velocity compared to AOMIEGO training. Self-efficacy increased for all training conditions over time. Both AOMIEGO and AOMIALLO training led to improved functional changes in mental representation structures over time compared to Control training. The findings suggest AOMI training led to improved perceptual-cognitive scaffolding, irrespective of AO perspective, and offer some support for the use of AOMIALLO training to facilitate novice learning of complex, serial motor skills in sport.

A survey of brain functional network extraction methods using fMRI data

Functional network (FN) analyses play a pivotal role in uncovering insights into brain function and understanding the pathophysiology of various brain disorders. This paper focuses on classical and advanced methods for deriving brain FNs from functional magnetic resonance imaging (fMRI) data. We systematically review their foundational principles, advantages, shortcomings, and interrelations, encompassing both static and dynamic FN extraction approaches. In the context of static FN extraction, we present hypothesis-driven methods such as region of interest (ROI)-based approaches as well as data-driven methods including matrix decomposition, clustering, and deep learning. For dynamic FN extraction, both window-based and windowless methods are surveyed with respect to the estimation of time-varying FN and the subsequent computation of FN states. We also discuss the scope of application of the various methods and avenues for future improvements.

Effects of virtual reality-based robot therapy combined with task-oriented therapy on upper limb function and cerebral cortex activation in patients with stroke

BACKGROUND

This study aimed to investigate the effects of virtual reality (VR)-based robot therapy combined with task-oriented therapy on cerebral cortex activation and upper limb function in patients with stroke.

METHODS

This study included 46 patients with hemiplegia within 1 year of stroke onset. Patients were divided into an experimental group (n = 23) and a control group (n = 23) using a computer randomization program. The experimental group received VR-based robot and task-oriented therapies, whereas the control group received only task-oriented therapy. All participants received interventions for 40 minutes per session, 5 times a week, for 8 weeks. For the pre- and post-evaluation of all participants, the Fugl-Meyer Assessment for the upper extremity, manual function test, motor activity log, and Jebsen-Taylor Hand Function Test were used to evaluate changes in upper limb function and motor-evoked potential amplitudes were measured to compare cerebral cortex activation.

RESULTS

In comparison to the control group, experimental group demonstrated an improvement in the function of the upper limb (P < .01) and activation of the cerebral cortex (P < .01).

CONCLUSION

The combined intervention of VR-based robot and task-oriented therapies is valuable for improving upper limb function and cerebral cortex activation in patients with stroke.

Effect of concurrent action observation, peripheral nerve stimulation and motor imagery on dexterity in patients after stroke: a pilot study

Research to improve and expand treatment options for motor impairment after stroke remains an important issue in rehabilitation as the reduced ability to move affected limbs is still a limiting factor in the selection of training content for stroke patients. The combination of action observation and peripheral nerve stimulation is a promising method for inducing increased excitability and plasticity in the primary motor cortex of healthy subjects. In addition, as reported in the literature, the use of action observation and motor imagery in conjunction has an advantage over the use of one or the other alone in terms of the activation of motor-related brain regions. The aim of the pilot study was thus to combine these findings into a multimodal approach and to evaluate the potential impact of the concurrent application of the three methods on dexterity in stroke patients. The paradigm developed accordingly was tested with 10 subacute patients, in whom hand dexterity, thumb-index pinch force and thumb tapping speed were measured for a baseline assessment and directly before and after the single intervention. During the 10-min session, patients were instructed to watch a repetitive thumb-index finger tapping movement displayed on a monitor and to imagine the sensations that would arise from physically performing the same motion. They were also repeatedly electrically stimulated at the wrist on the motorically more affected body side and asked to place their hand behind the monitor for the duration of the session to support integration of the displayed hand into their own body schema. The data provide a first indication of a possible immediate effect of a single application of this procedure on the dexterity in patients after stroke.

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.

Postural control and cognitive flexibility in skilled athletes: Insights from dual-task performance and event-related potentials

Athletes of skill-oriented sports (hereinafter referred to as "skilled athletes"), such as gymnasts and rhythmic gymnasts, have demonstrated better postural control than nonathletes. However, previous studies have mainly focused on single postural tasks and have not considered how skilled athletes use and allocate attentional resources during postural control. This research used the event-related potential (ERP) to explore the postural control performance of skilled athletes under cognitive processes and their utilization and allocation of attentional resources. A dual-task paradigm was used to simulate the actual situation in sports. 26 skilled athletes and 26 nonathletes were required to perform postural control and task-switching simultaneously. The results showed that skilled athletes demonstrated more postural control stability and a higher accuracy of task-switching than nonathletes in all dual tasks. Compared with nonathletes, they showed a stable enhanced N1 (electrodes: Oz, O1, and O2) amplitude during three postures. Moreover, larger N2 component on Fz, FCz, and Cz and theta band power was found in the frontal cortex (on Fz, FCz) of skilled athletes under feet together and single leg standing posture. The study illustrated that skilled athletes show greater frontal activation during dual tasks, which allows for more rational and flexible brain attentional resource input and allocation in cognitive processes, this may be due to long-term professional training, which enables them to have a higher level of automation of postural control and cognitive flexibility. This study's results offer valuable insights into the interplay between postural control and multitasking in skilled athletes, and its outcomes carry significant implications for the training and assessment of athletes across various sports.

Real-time motion-enabling positron emission tomography of the brain of upright ambulatory humans

BACKGROUND

Mobile upright PET devices have the potential to enable previously impossible neuroimaging studies. Currently available options are imagers with deep brain coverage that severely limit head/body movements or imagers with upright/motion enabling properties that are limited to only covering the brain surface.

METHODS

In this study, we test the feasibility of an upright, motion-compatible brain imager, our Ambulatory Motion-enabling Positron Emission Tomography (AMPET) helmet prototype, for use as a neuroscience tool by replicating a variant of a published PET/fMRI study of the neurocorrelates of human walking. We validate our AMPET prototype by conducting a walking movement paradigm to determine motion tolerance and assess for appropriate task related activity in motor-related brain regions. Human participants (n = 11 patients) performed a walking-in-place task with simultaneous AMPET imaging, receiving a bolus delivery of F18-Fluorodeoxyglucose.

RESULTS

Here we validate three pre-determined measure criteria, including brain alignment motion artifact of less than <2 mm and functional neuroimaging outcomes consistent with existing walking movement literature.

CONCLUSIONS

The study extends the potential and utility for use of mobile, upright, and motion-tolerant neuroimaging devices in real-world, ecologically-valid paradigms. Our approach accounts for the real-world logistics of an actual human participant study and can be used to inform experimental physicists, engineers and imaging instrumentation developers undertaking similar future studies. The technical advances described herein help set new priorities for facilitating future neuroimaging devices and research of the human brain in health and disease.

Development and Validation of the Combined Action Observation and Motor Imagery Ability Questionnaire

Combined use of action observation and motor imagery (AOMI) is an increasingly popular motor-simulation intervention, which involves observing movements on video while simultaneously imagining the feeling of movement execution. Measuring and reporting participant imagery-ability characteristics are essential in motor-simulation research, but no measure of AOMI ability currently exists. Accordingly, the AOMI Ability Questionnaire (AOMI-AQ) was developed to address this gap in the literature. In Study 1, two hundred eleven participants completed the AOMI-AQ and the kinesthetic imagery subscales of the Movement Imagery Questionnaire-3 and Vividness of Motor Imagery Questionnaire-2. Following exploratory factor analysis, an 8-item AOMI-AQ was found to correlate positively with existing motor-imagery measures. In Study 2, one hundred seventy-four participants completed the AOMI-AQ for a second time after a period of 7-10 days. Results indicate a good test-retest reliability for the AOMI-AQ. The new AOMI-AQ measure provides a valid and reliable tool for researchers and practitioners wishing to assess AOMI ability.

Re-emergent Tremor in Parkinson's Disease: Evidence of Pathologic β and Prokinetic γ Activity

BACKGROUND

Re-emergent tremor is characterized as a continuation of resting tremor and is often highly therapy refractory. This study examines variations in brain activity and oscillatory responses between resting and re-emergent tremors in Parkinson's disease.

METHODS

Forty patients with Parkinson's disease (25 males, mean age, 66.78 ± 5.03 years) and 40 age- and sex-matched healthy controls were included in the study. Electroencephalogram and electromyography signals were simultaneously recorded during resting and re-emergent tremors in levodopa on and off states for patients and mimicked by healthy controls. Brain activity was localized using the beamforming technique, and information flow between sources was estimated using effective connectivity. Cross-frequency coupling was used to assess neuronal oscillations between tremor frequency and canonical frequency oscillations.

RESULTS

During levodopa on, differences in brain activity were observed in the premotor cortex and cerebellum in both the patient and control groups. However, Parkinson's disease patients also exhibited additional activity in the primary sensorimotor cortex. On withdrawal of levodopa, different source patterns were observed in the supplementary motor area and basal ganglia area. Additionally, levodopa was found to suppress the strength of connectivity (P < 0.001) between the identified sources and influence the tremor frequency-related coupling, leading to a decrease in β (P < 0.001) and an increase in γ frequency coupling (P < 0.001).

CONCLUSIONS

Distinct variations in cortical-subcortical brain activity are evident in tremor phenotypes. The primary sensorimotor cortex plays a crucial role in the generation of re-emergent tremor. Moreover, oscillatory neuronal responses in pathological β and prokinetic γ activity are specific to tremor phenotypes. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Posture enhancement with cerebellum transcranial electrical stimulation: a systematic review of current methods and findings

Recently, transcranial electrical stimulation (tES) has gained increasing popularity among researchers, especially for recovery and improvement, but interpretation of these results is difficult due to variations in study methods and outcome measurements. The main goal of this study was to better understand the postural and balance indicators affected by cerebellar tES, as the cerebellum is the main brain region responsible for controlling balance. For this systematic literature review, three databases were searched for articles where the cerebellum was stimulated by any type of tES in either healthy participants or those with neurologic disorders. Postural, dynamic, and/or static stability measurements were recorded, and risk of bias was assessed on the PEDro scale. A total of 21 studies were included in the analysis. 17 studies reported improvements after application of tES. 14 studies stimulated the cerebellum unilaterally and 15 used this modality for 20 min. Moreover, all studies exclusively used transcranial direct current as the type of stimulation. Evaluation of PEDro results showed that studies included in the analysis utilized good methodology. Although there were some inconsistencies in study results, overall, it was demonstrated that tES can improve balance and postural index under both healthy and neurological conditions. Further research of bilateral cerebellar stimulation or the use of transcranial alternating current stimulation, transcranial random noise stimulation, and transcranial pulsed current stimulation is needed for a more comprehensive assessment of the potential positive effects of cerebellar tES on the balance system.

Dual-task gait training improves cognition and resting-state functional connectivity in Parkinson's disease with postural instability and gait disorders

OBJECTIVES

To assess whether dual-task gait/balance training with action observation training (AOT) and motor imagery (MI) ameliorates cognitive performance and resting-state (RS) brain functional connectivity (FC) in Parkinson's disease (PD) patients with postural instability and gait disorders (PIGD).

METHODS

21 PD-PIGD patients were randomized into 2 groups: (1) DUAL-TASK + AOT-MI group performed a 6-week training consisting of AOT-MI combined with practicing observed-imagined gait and balance exercises; and (2) DUAL-TASK group performed the same exercises combined with landscape-videos observation. At baseline and after training, all patients underwent a computerized cognitive assessment, while 17 patients had also RS-fMRI scans. Cognitive and RS-FC changes (and their relationships) over time within and between groups were assessed.

RESULTS

After training, all PD-PIGD patients improved accuracy in a test assessing executive-attentive (mainly dual-task) skills. DUAL-TASK + AOT-MI patients showed increased RS-FC within the anterior salience network (aSAL), and reduced RS-FC within the anterior default mode network (aDMN), right executive control network and precuneus network. DUAL-TASK patients showed increased RS-FC within the visuospatial network, only. Group × Time interaction showed that, compared to DUAL-TASK group, DUAL-TASK + AOT-MI cases had reduced RS-FC within the aDMN, which correlated with higher accuracy in a dual-task executive-attentive test.

CONCLUSIONS

In PD-PIGD patients, both trainings promote cognitive improvement and brain functional reorganization. DUAL-TASK + AOT-MI training induced specific functional reorganization changes of extra-motor brain networks, which were related with improvement in dual-task performance.

Effectiveness of synchronous action observation and mental practice on upper extremity motor recovery after stroke

The purpose of this quasi-experimental pretest-posttest control group study was to examine the effect of group synchronous action observation/mental practice intervention compared to usual rehabilitation care on upper extremity motor recovery after stroke. The intervention group (n = 25) received usual care, consisting of a minimum of 3 hours of rehabilitation services per day, 5 days a week, plus group synchronous action observation/mental practice sessions 3 times per week and the control group (n = 26) received usual care. Outcome measures included the Kinesthetic and Visual Imagery Questionnaire Short Version (KVIQ-10), the Fugl-Meyer Assessment (FMA-UE) of affected upper extremity motor function only and The Box and Block Test (BBT). Although there were no statistically significant differences in upper extremity motor function between the two groups, a subgroup analysis of the intervention group identified statistically significant (FMA-UE: p < .001; BBT: p = .04) and Minimally Important Clinical Differences on upper extremity motor recovery between patients with behaviors demonstrating more versus less commitment to the intervention. Group synchronous action observation/mental practice is a promising intervention for patients demonstrating commitment to actively participating in the intervention to improve outcomes on upper extremity motor recovery after stroke.

Event-Related EEG Desynchronization Reveals Enhanced Motor Imagery From the Third Person Perspective by Manipulating Sense of Body Ownership With Virtual Reality for Stroke Patients

Virtual reality (VR)-based rehabilitation training holds great potential for post-stroke motor recovery. Existing VR-based motor imagery (MI) paradigms mostly focus on the first-person perspective, and the benefit of the third-person perspective (3PP) remains to be further exploited. The 3PP is advantageous for movements involving the back or those with a large range because of its field coverage. Some movements are easier to imagine from the 3PP. However, the 3PP training efficiency may be unsatisfactory, which may be attributed to the difficulty encountered when generating a strong sense of ownership (SOO). In this work, we attempt to enhance a visual-guided 3PP MI in stroke patients by eliciting the SOO over a virtual avatar with VR. We propose to achieve this by inducing the so-called out-of-body experience (OBE), which is a full-body illusion (FBI) that people misperceive a 3PP virtual body as his/her own (i.e., generating the SOO to the virtual body). Electroencephalography signals of 13 stroke patients are recorded while MI of the affected upper limb is being performed. The proposed paradigm is evaluated by comparing event-related desynchronization (ERD) with a control paradigm without FBI induction. The results show that the proposed paradigm leads to a significantly larger ERD during MI, indicating a bilateral activation pattern consistent with that in previous studies. In conclusion, 3PP MI can be enhanced in stroke patients by eliciting the SOO through induction of the "OBE" FBI. This study offers more possibilities for virtual rehabilitation in stroke patients and can further facilitate VR application in rehabilitation.

Developing a novel dual-injection FDG-PET imaging methodology to study the functional neuroanatomy of gait

Gait is an excellent indicator of physical, emotional, and mental health. Previous studies have shown that gait impairments in ageing are common, but the neural basis of these impairments are unclear. Existing methodologies are suboptimal and novel paradigms capable of capturing neural activation related to real walking are needed. In this study, we used a hybrid PET/MR system and measured glucose metabolism related to both walking and standing with a dual-injection paradigm in a single study session. For this study, 15 healthy older adults (10 females, age range: 60.5-70.7 years) with normal cognition were recruited from the community. Each participant received an intravenous injection of [18F]-2-fluoro-2-deoxyglucose (FDG) before engaging in two distinct tasks, a static postural control task (standing) and a walking task. After each task, participants were imaged. To discern independent neural functions related to walking compared to standing, we applied a bespoke dose correction to remove the residual 18F signal of the first scan (PETSTAND) from the second scan (PETWALK) and proportional scaling to the global mean, cerebellum, or white matter (WM). Whole-brain differences in walking-elicited neural activity measured with FDG-PET were assessed using a one-sample t-test. In this study, we show that a dual-injection paradigm in healthy older adults is feasible with biologically valid findings. Our results with a dose correction and scaling to the global mean showed that walking, compared to standing, increased glucose consumption in the cuneus (Z = 7.03), the temporal gyrus (Z = 6.91) and the orbital frontal cortex (Z = 6.71). Subcortically, we observed increased glucose metabolism in the supraspinal locomotor network including the thalamus (Z = 6.55), cerebellar vermis and the brainstem (pedunculopontine/mesencephalic locomotor region). Exploratory analyses using proportional scaling to the cerebellum and WM returned similar findings. Here, we have established the feasibility and tolerability of a novel method capable of capturing neural activations related to actual walking and extended previous knowledge including the recruitment of brain regions involved in sensory processing. Our paradigm could be used to explore pathological alterations in various gait disorders.

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.

Observing an expert's action swapped with an observer's face increases corticospinal excitability during combined action observation and motor imagery

This study aimed to examine whether observing an expert's action swapped with an observer's face increases corticospinal excitability during combined action observation and motor imagery (AOMI). Twelve young males performed motor imagery of motor tasks with different difficulties while observing the actions of an expert performer and an expert performer with a swapped face. Motor tasks included bilateral wrist dorsiflexion (EASY) and unilateral two-ball rotating motions (DIFF). During the AOMI of EASY and DIFF, single-pulse transcranial magnetic stimulation was delivered to the left primary motor cortex, and motor-evoked potentials (MEPs) were obtained from the extensor carpi ulnaris and first dorsal interosseous muscles of the right upper limb, respectively. Visual analogue scale (VAS) assessed the subjective similarity of the expert performer with the swapped face in the EASY and DIFF to the participants themselves. The MEP amplitude in DIFF was larger in the observation of the expert performer with the swapped face than that of the expert performer (P = 0.012); however, the corresponding difference was not observed in EASY (P = 1.000). The relative change in the MEP amplitude from observing the action of the expert performer to that of the expert performer with the swapped face was positively correlated with VAS only in DIFF (r = 0.644, P = 0.024). These results indicate that observing the action of an expert performer with the observer's face enhances corticospinal excitability during AOMI, depending on the task difficulty and subjective similarity between the expert performer being observed and the observer.

Attention and motor profiles in children with developmental coordination disorder: A neuropsychological and neuroimaging investigation

AIM

This study aimed to (1) quantify attention and executive functioning in children with developmental coordination disorder (DCD), (2) assess whether some children with DCD are more likely to show attention difficulties, and (3) characterize brain correlates of motor and attention deficits.

METHOD

Fifty-three children (36 with DCD and 17 without) aged 8 to 10 years underwent T1-weighted and diffusion-weighted magnetic resonance imaging, and standardized attention and motor assessments. Parents completed questionnaires of executive functioning and symptoms of inattention and hyperactivity. We assessed regional cortical thickness and surface area, and cerebellar, callosal, and primary motor tract structure.

RESULTS

Analyses of covariance and one-sample t-tests identified impaired attention, non-motor processing speed, and executive functioning in children with DCD, yet partial Spearman's rank correlation coefficients revealed these were unrelated to one another or the type or severity of the motor deficit. Robust regression analyses revealed that cortical morphology in the posterior cingulate was associated with both gross motor skills and inattentive symptoms in children with DCD, while gross motor skills were also associated with left corticospinal tract (CST) morphology.

INTERPRETATION

Children with DCD may benefit from routine attention and hyperactivity assessments. Alterations in the posterior cingulate and CST may be linked to impaired forward modelling during movements in children with DCD. Overall, alterations in these regions may explain the high rate of non-motor impairments in children with DCD.

WHAT THIS PAPER ADDS

Children with developmental coordination disorder have difficulties in attention, processing speed, and executive functioning. Non-motor impairments were not interrelated or correlated with the type or severity of motor deficit. Posterior cingulate morphology was associated with gross motor skills and inattention. Gross motor skills were also associated with left corticospinal tract morphology.

Early sleep after action observation plus motor imagery improves gait and balance abilities in older adults

Action observation plus motor imagery (AOMI) is a rehabilitative approach to improve gait and balance performance. However, limited benefits have been reported in older adults. Early sleep after motor practice represents a strategy to enhance the consolidation of trained skills. Here, we investigated the effects of AOMI followed by early sleep on gait and balance performance in older adults. Forty-five older adults (mean age: 70.4 ± 5.2 years) were randomized into three groups performing a 3-week training. Specifically, AOMI-sleep and AOMI-control groups underwent observation and motor imagery of gait and balance tasks between 8:00 and 10:00 p.m. or between 8:00 and 10:00 a.m. respectively, whereas Control group observed landscape video-clips. Participants were assessed for gait performance, static and dynamic balance and fear of falling before and after training and at 1-month follow-up. The results revealed that early sleep after AOMI training sessions improved gait and balance abilities in older adults compared to AOMI-control and Control groups. Furthermore, these benefits were retained at 1-month after the training end. These findings suggested that early sleep after AOMI may represent a safe and easy-applicable intervention to minimize the functional decay in older adults.

Guidelines for reporting action simulation studies (GRASS): Proposals to improve reporting of research in motor imagery and action observation

Researchers from multiple disciplines have studied the simulation of actions through motor imagery, action observation, or their combination. Procedures used in these studies vary considerably between research groups, and no standardized approach to reporting experimental protocols has been proposed. This has led to under-reporting of critical details, impairing the assessment, replication, synthesis, and potential clinical translation of effects. We provide an overview of issues related to the reporting of information in action simulation studies, and discuss the benefits of standardized reporting. We propose a series of checklists that identify key details of research protocols to include when reporting action simulation studies. Each checklist comprises A) essential methodological details, B) essential details that are relevant to a specific mode of action simulation, and C) further points that may be useful on a case-by-case basis. We anticipate that the use of these guidelines will improve the understanding, reproduction, and synthesis of studies using action simulation, and enhance the translation of research using motor imagery and action observation to applied and clinical settings.

Temporo-Parietal cortex activation during motor imagery in older adults: A case study of Baduanjin

Age-associated cognitive and motor decline is related to central nervous system injury in older adults. Motor imagery training (MIT), as an emerging rehabilitative intervention, can activate neural basis similar to that in actual exercise, so as to promote motor function in older adults. The complex motor skills rely on the functional integration of the cerebral cortex. Understanding the neural mechanisms underlying motor imagery in older adults would support its application in motor rehabilitation and slowing cognitive decline. Based on this, the present study used functional near infrared spectroscopy (fNIRS) to record the changes in oxygen saturation in older adults (20 participants; mean age, 64.8 ± 4.5 years) during Baduanjin motor execution (ME) and motor imagery (MI). ME significantly activated the left postcentral gyrus, while the oxy-hemoglobin concentration in the right middle temporal gyrus increased significantly during motor imagery. These results indicate that advanced ME activates brain regions related to sensorimotor function, and MI increases the activation of the frontal-parietal cortex related to vision. In older adults, MI overactivated the temporo-parietal region associated with vision, and tend to be activated in the right brain.

Advances in Stroke Neurorehabilitation

Stroke is one of the leading causes of disability worldwide despite recent advances in hyperacute interventions to lessen the initial impact of stroke. Stroke recovery therapies are crucial in reducing the long-term disability burden after stroke. Stroke recovery treatment options have rapidly expanded within the last decade, and we are in the dawn of an exciting era of multimodal therapeutic approaches to improve post-stroke recovery. In this narrative review, we highlighted various promising advances in treatment and technologies targeting stroke rehabilitation, including activity-based therapies, non-invasive and minimally invasive brain stimulation techniques, robotics-assisted therapies, brain-computer interfaces, pharmacological treatments, and cognitive therapies. These new therapies are targeted to enhance neural plasticity as well as provide an adequate dose of rehabilitation and improve adherence and participation. Novel activity-based therapies and telerehabilitation are promising tools to improve accessibility and provide adequate dosing. Multidisciplinary treatment models are crucial for post-stroke neurorehabilitation, and further adjuvant treatments with brain stimulation techniques and pharmacological agents should be considered to maximize the recovery. Among many challenges in the field, the heterogeneity of patients included in the study and the mixed methodologies and results across small-scale studies are the cardinal ones. Biomarker-driven individualized approaches will move the field forward, and so will large-scale clinical trials with a well-targeted patient population.

Imagery, emotion, and bioinformational theory: From body to brain

The bioinformational theory of emotional imagery is a model of the hypothetical mental representations activated when people imagine emotionally engaging events, and was initially proposed to guide research and practice in the use of imaginal exposure as a treatment for fear and anxiety (Lang, 1979). In this 50 year overview, we discuss the development of bioinformational theory and its impact on the study of psychophysiology and psychopathology, most importantly assessing its viability and predictions in light of more recent brain-based studies of neural functional activation. Bioinformational theory proposes that narrative imagery, typically cued by language scripts, activates an associative memory network in the brain that includes stimulus (e.g., agents, contexts), semantic (e.g., facts and beliefs) and, most critically for emotion, response information (e.g., autonomic and somatic) that represents relevant real-world coping actions and reactions. Psychophysiological studies in healthy and clinical samples reliably find measurable response output during aversive and appetitive narrative imagery. Neuroimaging studies confirm that emotional imagery is associated with significant activation in motor regions of the brain, as well as in regions implicated in episodic and semantic memory retrieval, supporting the bioinformational view that narrative imagery prompts mental simulation of events that critically includes the actions and reactions engaged in emotional contexts.

Motor learning without physical practice: The effects of combined action observation and motor imagery practice on cup-stacking speed

In this study we explored training effects for combined action observation and motor imagery (AO + MI) instructions on a complex cup-stacking task, without physical practice. Using a Graeco-Latin Square design, we randomly assigned twenty-six participants into four groups. This counterbalanced the within-participant factor of practice condition (AO + MI, AO, MI, Control) across four cup-stacking tasks, which varied in their complexity. On each of the three consecutive practice days participants experienced twenty trials under each of the three mental practice conditions. On each trial, a first-person perspective video depicted bilateral cup-stacking performed by an experienced model. During AO, participants passively observed this action, responding only to occasional colour cues. For AO + MI, participants imagined performing the observed action and synchronised their concurrent MI with the display. For MI, a sequence of pictures cued imagery of each stage of the task. Analyses revealed a significant main effect of practice condition both at the 'surprise' post-test (Day 3) and at the one-week retention test. At both time points movement execution times were significantly shorter for AO + MI compared with AO, MI and the Control. Execution times were also shorter overall at the retention compared with the post-test. These results demonstrate that a complex novel motor task can be acquired without physical training. Practitioners can therefore use AO + MI practice to supplement physical practice and optimise skill learning.

Effects of an Acute High Intensity Exercise Bout on Retention of Explicit, Strategic Locomotor Learning in Individuals With Chronic Stroke

BACKGROUND

Exercise priming, pairing high intensity exercise with a motor learning task, improves retention of upper extremity tasks in individuals after stroke, but has shown no benefit to locomotor learning. This difference may relate to the type of learning studied. Upper extremity studies used explicit, strategic tasks; locomotor studies used implicit sensorimotor adaptation (split-belt treadmill). Since walking is an important rehabilitation goal, it is crucial to understand under which circumstances exercise priming may improve retention of a newly learned walking pattern.

OBJECTIVE

Determine the impact of exercise priming on explicit, strategic locomotor learning task retention in chronic stroke survivors.

METHODS

Chronic stroke survivors (>6 months) performed 2 treadmill walking sessions. Visual feedback was used to train increased step length. Participants were assigned to control group (no exercise), continuous exercise (5 minutes high intensity), or long-interval exercise (15 minutes high/moderate intervals). After day 1 learning, participants either rested or performed exercise. On day 2, retention of the learned walking pattern was tested.

RESULTS

All groups learned on day 1 (P < .001). The 2 priming groups showed significant changes in blood lactate and heart rate after exercise priming, the resting control group did not (P < .001). On day 2, there was no significant between-group difference in cued or un-cued task retention (P = .963 and .287, respectively).

CONCLUSIONS

Exercise priming did not affect retention of an explicit locomotor task in chronic stroke survivors. Further work should explore subgroups of individuals for whom priming may have selective clinical benefit to locomotor learning.ClinicalTrials.gov Identifier: NCT03726047.

Inter-task transfer of force gains is facilitated by motor imagery

Introduction

There is compelling evidence that motor imagery (MI) contributes to improve muscle strength. While strong effects have been observed for finger muscles, only few experiments with moderate benefits were conducted within applied settings targeting large upper or lower limb muscles. The aim of the present study was therefore to extend the investigation of embedded MI practice designed to improve maximal voluntary strength on a multi-joint dynamic exercise involving the lower limbs. Additionally, we tested whether targeting the content of MI on another movement than that physically performed and involving the same body parts might promote inter-task transfer of strength gains.

Methods

A total of 75 participants were randomly assigned into three groups who underwent a physical training on back squat. During inter-trial recovery periods, a first MI group (n = 25) mentally rehearsed the back squat, while a second MI group (n = 25) performed MI of a different movement involving the lower limbs (deadlift). Participants from the control group (n = 25) completed a neutral cognitive task during equivalent time. Strength and power gains were assessed ecologically using a velocity transducer device at 4 different time periods.

Results

Data first revealed that participants who engaged in MI of the back squat improved their back squat performance (p < 0.03 and p < 0.01, respectively), more than the control group (p < 0.05), hence supporting the positive effects of MI on strength. Data further supported the inter-task transfer of strength gains when MI targeted a movement that was not physically trained (p = 0.05).

Discussion

These findings provide experimental support for the use of MI during physical training sessions to improve and transfer force development.

Effects of neurofeedback on standing postural control task with combined imagined and executed movements

Introduction

Motor imagery (MI) is a method of imagining movement without actual movement, and its use in combination with motor execution (ME) enhances the effects of motor learning. Neurofeedback (NFB) is another method that promotes the effects of MI. This study aimed to investigate the effects of NFB on combined MI and ME (MIME) training in a standing postural control task.

Methods

Sixteen participants were randomly divided into MIME and MIME + NFB groups and performed 10 trials of a postural control task on an unstable board, with nine trials of MI in between. Electroencephalogram was assessed during MI, and the MIME + NFB group received neurofeedback on the degree of MI via auditory stimulation. A postural control task using an unstable board was performed before and after the MIME task, during which postural instability was evaluated.

Results

Postural instability was reduced after the MIME task in both groups. In addition, the root mean square, which indicates the sway of the unstable board, was significantly reduced in the MIME + NFB group compared to that in the MIME group.

Conclusion

Our results indicate that MIME training is effective for motor learning of standing postural control. Furthermore, when MI and ME are combined, the feedback on the degree of MI enhances the learning effect.

The optimal method for improving postural balance in healthy young and older people: specific training for postural tasks encountered in personal physical practice

It is well known that regular exercise or physical activity (training) improves postural balance in healthy young and older subjects, but the optimal exercise or physical activity (i.e., likely to induce the greatest postural improvements) and the context in which it is carried out remain to be explored and determined for each population. The most beneficial adaptations would depend, in particular, on gestural conditions (body position, movement and gesture practiced) and material conditions (nature of the ground surface, sports equipment used, type of environment - stable or changing). In fact, the global postural adaptations induced by training do not result from the transfer between different trained and untrained postural tasks, but are the sum of the adaptations related to each trained postural task in healthy young and older subjects. Based on current knowledge, optimal training programs should include the full range of postural tasks encountered in personal physical practice for each population. To date, the method of implementing progressive postural balance tasks with different degrees of difficulty and instability has been used as the effective method to improve postural balance, but it should not be considered as the reference method. Instead, it should be considered as a complementary method to the one based on specific postural tasks. An intervention strategy is proposed for young and older adults consisting of three different steps (general, oriented and specific/ecologic training). However, some parameters still need to be explored and possibly reconsidered in future studies to improve postural balance in an optimal way.

Postural instability in HIV infection: relation to central and peripheral nervous system markers

OBJECTIVES

Determine the independent contributions of central nervous system (CNS) and peripheral nervous system (PNS) metrics to balance instability in people with HIV (PWH) compared with people without HIV (PWoH).

METHODS

Volumetric MRI (CNS) and two-point pedal discrimination (PNS) were tested as substrates of stance instability measured with balance platform posturography.

DESIGN

125 PWH and 88 PWoH underwent balance testing and brain MRI.

RESULTS

The PWH exhibited stability deficits that were disproportionately greater with eyes closed than eyes open compared with PWoH. Further analyses revealed that greater postural imbalance measured as longer sway paths correlated with smaller cortical and cerebellar lobular brain volumes known to serve sensory integration; identified brain/sway path relations endured after accounting for contributions from physiological and disease factors as potential moderators; and multiple regression identified PNS and CNS metrics as independent predictors of postural instability in PWH that differed with the use of visual information to stabilize balance. With eyes closed, temporal volumes and two-point pedal discrimination were significant independent predictors of sway; with eyes open, occipital volume was an additional predictor of sway. These relations were selective to PWH and were not detected in PWoH.

CONCLUSION

CNS and PNS factors were independent contributors to postural instability in PWH. Recognizing that myriad inputs must be detected by peripheral systems and brain networks to integrate sensory and musculoskeletal information for maintenance of postural stability, age- or disease-related degradation of either or both nervous systems may contribute to imbalance and liability for falls.

Differences in Cortical Area Activity and Motor Imagery Vivid-Ness during Evaluation of Motor Imagery Tasks in Right and Left Hemiplegics

The ability to develop vivid motor imagery (MI) is important for effective mental practice. Therefore, we aimed to determine differences in the MI clarity and cortical area activity between patients with right hemiplegia and left hemiplegia after stroke in an MI task. In total, 11 participants with right hemiplegia and 14 with left hemiplegia were categorized into two groups. The MI task required the flexion and extension of the finger on the paralyzed side. Considering that MI vividness changes with MI practice, we measured the MI vividness and cortical area activity during the task before and after MI practice. MI vividness was evaluated subjectively using the visual analog scale, and cerebral hemodynamics during the task were measured using near-infrared spectroscopy in cortical regions during the MI task. The MI sharpness and cortical area activity in the MI task were significantly lower in the right hemiplegia group than in the left hemiplegia group. Therefore, when practicing mental practices with right hemiplegia, it is necessary to devise ways by which to increase MI vividness.

Identifying the changes in the cortical activity of various brain regions for different balance tasks: A review

BACKGROUND

Balance support is critical to a person's overall function and health. Previous neuroimaging studies have shown that cortical structures play an essential role in postural control.

OBJECTIVE

This review aims to identify differences in the pattern of neural activity induced by balance tasks with different balance control requirements.

METHODS

Seventy-four articles were selected from the field of balance training and were examined based on four brain function detection technologies.

RESULTS

In general, most studies focused on the activity changes of various cortical areas during training at different difficulty levels, but more and more attention has also begun to focus on the functional changes of other cortical and deep subcortical structures. Our analysis also revealed the neglect of certain task types.

CONCLUSION

Based on these results, we identify and discuss future research directions that may contribute to a clear understanding of neural functional plasticity under different tasks.

Recognizable Rehabilitation Movements of Multiple Unilateral Upper Limb: an fMRI Study of Motor Execution and Motor Imagery

BACKGROUND

This paper presents a study investigating the recognizability of multiple unilateral upper limb movements in stroke rehabilitation.

METHODS

A functional magnetic experiment is employed to study motor execution (ME) and motor imagery (MI) of four movements for the unilateral upper limb: hand-grasping, hand-handling, arm-reaching, and wrist-twisting. The functional magnetic resonance imaging (fMRI) images of ME and MI tasks are statistically analyzed to delineate the region of interest (ROI). Then parameter estimation associated with ROIs for each ME and MI task are evaluated, where differences in ROIs for different movements are compared using analysis of covariance (ANCOVA).

RESULTS

All movements of ME and MI tasks activate motor areas of the brain, and there are significant differences (p<0.05) in ROIs evoked by different movements. The activation area is larger when executing the hand-grasping task instead of the others.

CONCLUSION

The four movements we propose can be adopted as MI tasks, especially for stroke rehabilitation, since they are highly recognizable and capable of activating more brain areas during MI and ME.

Short-term balance consolidation relies on the primary motor cortex: a rTMS study

Structural and functional adaptations occur in the primary motor cortex (M1) after only a few balance learning sessions. Nevertheless, the role of M1 in consolidating balance tasks remains to be discussed, as direct evidence is missing due to the fact that it is unclear whether adaptations in M1 are indeed the driving force for balance improvements or merely the consequence of improved balance. The aim of the present study was to investigate whether the primary motor cortex is involved in the learning and consolidation of balance tasks. Thirty participants were randomly allocated into a repetitive transcranial magnetic stimulation (rTMS) or sham-rTMS group. The experimental design included a single balance acquisition phase, followed by either 15 min of low-frequency rTMS (1 Hz at 115% of resting motor threshold to disrupt the involvement of M1) or sham-rTMS, and finally a retention test 24 h later. During the acquisition phase, no differences in balance improvements were observed between the two groups. However, significant differences between the rTMS and the sham-rTMS group were found from the end of the acquisition phase to the retention test. While the rTMS group had a performance loss, the sham-rTMS group displayed significant off-line gains (p = 0.001). For the first time, this finding may propose a causal relationship between the involvement of M1 and the acquisition and consolidation of a balance task.

Enhancing upper-limb neurorehabilitation in chronic stroke survivors using combined action observation and motor imagery therapy

Introduction

For people who have had a stroke, recovering upper-limb function is a barrier to independence. When movement is difficult, mental practice can be used to complement physical therapy. In this within-participants study we investigated the effects of combined action observation and motor imagery (AO + MI) therapy on upper-limb recovery in chronic stroke survivors.

Methods

A Graeco-Latin Square design was used to counterbalance four mental practice conditions (AO + MI, AO, MI, Control) across four cup-stacking tasks of increasing complexity. Once a week, for five consecutive weeks, participants (n = 10) performed 16 mental practice trials under each condition. Each trial displayed a 1st person perspective of a cup-stacking task performed by an experienced model. For AO, participants watched each video and responded to an occasional color cue. For MI, participants imagined the effort and sensation of performing the action; cued by a series of still-images. For combined AO + MI, participants observed a video of the action while they simultaneously imagined performing the same action in real-time. At three time points (baseline; post-test; two-week retention test) participants physically executed the three mentally practiced cup-stacking tasks, plus a fourth unpractised sequence (Control), as quickly and accurately as possible.

Results

Mean movement execution times were significantly reduced overall in the post-test and the retention test compared to baseline. At retention, movement execution times were significantly shorter for combined AO + MI compared to both MI and the Control. Individual participants reported clinically important changes in quality of life (Stroke Impact Scale) and positive qualitative experiences of AO + MI (social validation).

Discussion

These results indicate that when physical practice is unsuitable, combined AO + MI therapy could offer an effective adjunct for neurorehabilitation in chronic stroke survivors.

Continual Learning of a Transformer-Based Deep Learning Classifier Using an Initial Model from Action Observation EEG Data to Online Motor Imagery Classification

The motor imagery (MI)-based brain computer interface (BCI) is an intuitive interface that enables users to communicate with external environments through their minds. However, current MI-BCI systems ask naïve subjects to perform unfamiliar MI tasks with simple textual instruction or a visual/auditory cue. The unclear instruction for MI execution not only results in large inter-subject variability in the measured EEG patterns but also causes the difficulty of grouping cross-subject data for big-data training. In this study, we designed an BCI training method in a virtual reality (VR) environment. Subjects wore a head-mounted device (HMD) and executed action observation (AO) concurrently with MI (i.e., AO + MI) in VR environments. EEG signals recorded in AO + MI task were used to train an initial model, and the initial model was continually improved by the provision of EEG data in the following BCI training sessions. We recruited five healthy subjects, and each subject was requested to participate in three kinds of tasks, including an AO + MI task, an MI task, and the task of MI with visual feedback (MI-FB) three times. This study adopted a transformer- based spatial-temporal network (TSTN) to decode the user's MI intentions. In contrast to other convolutional neural network (CNN) or recurrent neural network (RNN) approaches, the TSTN extracts spatial and temporal features, and applies attention mechanisms along spatial and temporal dimensions to perceive the global dependencies. The mean detection accuracies of TSTN were 0.63, 0.68, 0.75, and 0.77 in the MI, first MI-FB, second MI-FB, and third MI-FB sessions, respectively. This study demonstrated the AO + MI gave an easier way for subjects to conform their imagery actions, and the BCI performance was improved with the continual learning of the MI-FB training process.

The relationship between drop vertical jump action-observation brain activity and kinesiophobia after anterior cruciate ligament reconstruction: A cross-sectional fMRI study

BACKGROUND

Injury and reconstruction of anterior cruciate ligament (ACL) result in central nervous system alteration to control the muscles around the knee joint. Most individuals with ACL reconstruction (ACLR) experience kinesiophobia which can prevent them from returning to activity and is associated with negative outcomes after ACLR. However, it is unknown if kinesiophobia alters brain activity after ACL injury.

OBJECTIVES

To compare brain activity between an ACLR group and matched uninjured controls during an action-observation drop vertical jump (AO-DVJ) paradigm and to explore the association between kinesiophobia and brain activity in the ACLR group.

METHODS

This cross-sectional study enrolled 26 individuals, 13 with ACLR (5 males and 8 females, 20.62 ± 1.93 years, 1.71 ± 0.1 m, 68.42 ± 14.75 kg) and 13 matched uninjured controls (5 males and 8 females, 22.92 ± 3.17 years, 1.74 ± 0.10 m, 70.48 ± 15.38 kg). Individuals were matched on sex and activity level. Participants completed the Tampa Scale of Kinesiophobia-11 (TSK-11) to evaluate the level of movement-related fear. To assay the brain activity associated with a functional movement, the current study employed an action-observation/motor imagery paradigm during functional magnetic resonance imaging (fMRI).

RESULTS

The ACLR group had lower brain activity in the right ventrolateral prefrontal cortex relative to the uninjured control group. Brain activity of the left cerebellum Crus I and Crus II, the right cerebellum lobule IX, amygdala, middle temporal gyrus, and temporal pole were positively correlated with TSK-11 scores in the ACLR group.

CONCLUSION

Brain activity for the AO-DVJ paradigm was different between the ACLR group and uninjured controls. Secondly, in participants with ACLR, there was a positive relationship between TSK-11 scores and activity in brain areas engaged in fear and cognitive processes during the AO-DVJ paradigm.

Cerebello-cortical functional connectivity may regulate reactive balance control in older adults with mild cognitive impairment

Background

Older adults with mild cognitive impairment (OAwMCI) experience a two-fold increased risk of falling compared to their cognitively intact counterparts. This increased risk could be attributed to impairments in balance control mechanisms (both volitional and reactive), however, the exact neural substrates contributing to the balance impairments remain unclear. While changes in functional connectivity (FC) networks in volitional balance control tasks have been well highlighted, the relationship between these changes and reactive balance control has not been examined. Therefore, this study aims to explore the relationship between FC networks of the brain obtained during resting state fMRI (no visualization or active task performed) and behavioral measures on a reactive balance task in OAwMCI.

Methods

Eleven OAwMCI (< 25/30 on MoCA, > 55 years) underwent fMRI and were exposed to slip-like perturbations on the Activestep treadmill. Postural stability, i.e., dynamic center of mass motion state (i.e., its position and velocity) was computed to determine reactive balance control performance. The relationship between reactive stability and FC networks was explored using the CONN software.

Results

OAwMCI with greater FC in default mode network-cerebellum (r² = 0.43, p < 0.05), and sensorimotor-cerebellum (r² = 0.41, p < 0.05) network exhibited lower reactive stability. Further, people with lower FC in middle frontal gyrus-cerebellum (r² = 0.37, p < 0.05), frontoparietal-cerebellum (r² = 0.79, p < 0.05) and cerebellar network-brainstem (r² = 0.49, p < 0.05) exhibited lower reactive stability.

Conclusion

Older adults with mild cognitive impairment demonstrate significant associations between reactive balance control and cortico-subcortical regions involved in cognitive-motor control. Results indicate that the cerebellum and its communications with higher cortical centers could be potential substrates contributing to impaired reactive responses in OAwMCI.

A Method for Using Video Presentation to Increase Cortical Region Activity during Motor Imagery Tasks in Stroke Patients

Previous studies have reported that stroke patients have difficulty recalling the motor imagery (MI) of a task, also known as MI vividness. Research on combining MI with action observation is gaining importance as a method to improve MI vividness. We enrolled 10 right-handed stroke patients and compared MI vividness and cortical activity under different presentation methods (no inverted image, inverted image of another individual’s hand, and an inverted image of the patient’s nonparalyzed hand) using near-infrared spectroscopy. Images of the nonparalyzed upper limb were inverted to make the paralyzed upper limb appear as if it were moving. Three tasks (non inverted image, AO + MI (other hand), AO + MI (own hand)) were randomly performed on 10 stroke patients. MI vividness was significantly higher when the inverted image of the nonparalyzed upper limb was presented compared to the other conditions (p < 0.01). The activity of the cortical regions was also significantly enhanced (p < 0.01). Our study highlights the potential application of inverted images of a stroke patient’s own nonparalyzed hand in mental practice to promote the motor recovery of stroke patients. This technique achieved higher levels of MI vividness and cortical activity when performing motor tasks.