Motor network reorganization after motor imagery training in stroke patients with moderate to severe upper limb impairment

Effects of task-based mirror therapy on upper limb motor function in hemiplegia: study protocol for a randomized controlled clinical trial

BACKGROUND AND PURPOSE

Research to date has lacked definitive evidence to determine whether mirror therapy promotes the recovery of upper extremity function after stroke. Considering that previous studies did not stratify patients based on structural retention, this may be one of the reasons for the negative results obtained in many trials. The goal evaluates the efficacy of TBMT (utilizing an innovatively designed mirror) versus standard occupational therapy for stroke patient's upper limb functionality.

METHODS AND ANALYSIS

This single-center randomized controlled trial will involve 50 patients with stroke. All patients will be randomly assigned to either the task-based mirror therapy or the control group. The interventions will be performed 5 days per week for 4 weeks. The primary outcomes will be the mean change in scores on both the FMA-UE and modified Barthel Index (MBI) from baseline to 4 weeks intervention and at 12 weeks follow-up between the two groups and within groups. The other outcomes will include the Action Research Arm Test (ARAT), the Nine Hole Peg Test (9HPT), the Functional Independence Measure, and MRI.

DISCUSSION

This trial will not only to establish that task-based mirror therapy (TBMT) could improve the recovery of hand function after stroke but also to explore the underlying mechanisms. We expect that this finding will clarify the brain activation and brain network mechanisms underlying the improvement of hand function with task-oriented mirror therapy and lead to new ideas for stroke hand function rehabilitation.

TRIAL REGISTRATION

URL: https://www.chictr.org.cn ; Unique identifier: ChiCTR2300068855. Registered on March 1, 2023.

The effects of visual skills training on cognitive and executive functions in stroke patients: a systematic review with meta-analysis

The visual system and associated skills are of particular importance in stroke rehabilitation. The process of neuroplasticity involved in restoring cognitive function during this period is mainly based on anatomical and physiological mechanisms. However, there is little evidence-based knowledge about the effects of visual skills training that could be used to improve therapeutic outcomes in cognitive rehabilitation. A computerized systematic literature search was conducted in the PubMed, Medline, and Web of Science databases from 1 January 1960 to 11 Febuary 2024. 1,787 articles were identified, of which 24 articles were used for the calculation of weighted standardized mean differences (SMD) after screening and eligibility verification. The findings revealed moderate effects for global cognitive function (SMD = 0.62) and activities of daily living (SMD = 0.55) as well as small effects for executive function (SMD = 0.20) - all in favor of the intervention group. The analyses indicate that the results may not be entirely robust, and should therefore be treated with caution when applied in practice. Visual skills training shows positive effects in improving cognitive and executive functions, especially in combination with high cognitive load and in an early phase of rehabilitation. An improvement in activities of daily living can also be observed with this type of intervention. The high heterogeneity of the studies and different treatment conditions require the identification of a relationship between certain visual skills and executive functions in future research.

Motor imagery therapy improved upper limb motor function in stroke patients with hemiplegia by increasing functional connectivity of sensorimotor and cognitive networks

Background

Motor imagery therapy (MIT) showed positive effects on upper limbs motor function. However, the mechanism by which MIT improves upper limb motor function is not fully understood. Therefore, our purpose was to investigate the changes in functional connectivity (FC) within and outside the sensorimotor network (SMN) induced by MIT associated with improvement in upper limb motor function in stroke patients.

Methods

A total of 26 hemiplegic stroke patients were randomly divided into MIT (n = 13) and control (n = 13) groups. Fugl-Meyer Assessment Upper Extremity Scale (FMA-UL), Modified Barthel Index (MBI) and resting-state functional magnetic resonance imaging (rs-fMRI) were evaluated in the two groups before treatment and 4 weeks after treatment. The efficacy of MIT on motor function improvement in stroke patients with hemiplegia was evaluated by comparing the FMA-UL and MBI scores before and after treatment in the two groups. Furthermore, the FC within the SMN and between the SMN and the whole brain was measured and compared before and after different treatment methods in stroke patients. The correlation analysis between the improvement of upper limbs motor function and changes in FC within the SMN and between the SMN and the whole brain was examined.

Results

The FCs between ipsilesional primary motor cortex (M1.I) and contralateral supplementary motor area (SMA.C), M1.I and ipsilesional SMA (SMA.I), and SMA.C and contralateral dorsolateral premotor cortex (DLPM.C) significantly increased in the control group but decreased in the MIT group; while the FC between SMA.C and contralateral primary somatosensory cortex (S1.C) significantly increased in the control group but showed no significant difference in the MIT group. The FCs between M1.I and the ipsilesional hippocampal gyrus and ipsilesional middle frontal gyrus significantly decreased in the control group but increased in the MIT group; while the FC in the contralateral anterior cingulate cortex significantly increased in the MIT group but there was no significant difference in the control group. The results of the correlation analysis showed that the differences in abnormal intra-FCs within the SMN negatively correlated with the differences in FMA and MBI, and the difference in abnormal inter-FCs of the SMN positively correlated with the differences in FMA and MBI.

Conclusions

MIT can improve upper limb motor function and daily activities of stroke patients, and the improvement effect of conventional rehabilitation therapy (CRT) combined with MIT is significantly higher than that of CRT alone. CRT may improve the upper limb motor function of stroke patients with hemiplegia mainly through the functional reorganization between SMN, while MIT may mainly increase the interaction between SMN and other brain networks.

Effectiveness and brain mechanism of multi-target transcranial alternating current stimulation (tACS) on motor learning in stroke patients: study protocol for a randomized controlled trial

BACKGROUND

Transcranial alternating current stimulation (tACS) has proven to be an effective treatment for improving cognition, a crucial factor in motor learning. However, current studies are predominantly focused on the motor cortex, and the potential brain mechanisms responsible for the therapeutic effects are still unclear. Given the interconnected nature of motor learning within the brain network, we have proposed a novel approach known as multi-target tACS. This study aims to ascertain whether multi-target tACS is more effective than single-target stimulation in stroke patients and to further explore the potential underlying brain mechanisms by using techniques such as transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI).

METHODS

This study employs a double-blind, sham-controlled, randomized controlled trial design with a 2-week intervention period. Both participants and outcome assessors will remain unaware of treatment allocation throughout the study. Thirty-nine stroke patients will be recruited and randomized into three distinct groups, including the sham tACS group (SS group), the single-target tACS group (ST group), and the multi-target tACS group (MT group), at a 1:1:1 ratio. The primary outcomes are series reaction time tests (SRTTs) combined with electroencephalograms (EEGs). The secondary outcomes include motor evoked potential (MEP), central motor conduction time (CMCT), short interval intracortical inhibition (SICI), intracortical facilitation (ICF), magnetic resonance imaging (MRI), Box and Block Test (BBT), and blood sample RNA sequencing. The tACS interventions for all three groups will be administered over a 2-week period, with outcome assessments conducted at baseline (T0) and 1 day (T1), 7 days (T2), and 14 days (T3) of the intervention phase.

DISCUSSION

The study's findings will determine the potential of 40-Hz tACS to improve motor learning in stroke patients. Additionally, it will compare the effectiveness of multi-target and single-target approaches, shedding light on their respective improvement effects. Through the utilization of techniques such as TMS and MRI, the study aims to uncover the underlying brain mechanisms responsible for the therapeutic impact. Furthermore, the intervention has the potential to facilitate motor learning efficiency, thereby contributing to the advancement of future stroke rehabilitation treatment.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2300073465. Registered on 11 July 2023.

Three-phase Enriched Environment Improves Post-stroke Gait Dysfunction via Facilitating Neuronal Plasticity in the Bilateral Sensorimotor Cortex: A Multimodal MRI/PET Analysis in Rats

The three-phase Enriched Environment (EE) paradigm has been shown to promote post-stroke functional improvement, but the neuronal mechanisms are still unclear. In this study, we applied a multimodal neuroimaging protocol combining magnetic resonance imaging (MRI) and positron emission tomography (PET) to examine the effects of post-ischemic EE treatment on structural and functional neuroplasticity in the bilateral sensorimotor cortex. Rats were subjected to permanent middle cerebral artery occlusion. The motor function of the rats was examined using the DigiGait test. MRI was applied to investigate the EE-induced structural modifications of the bilateral sensorimotor cortex. [18F]-fluorodeoxyglucose PET was used to detect glucose metabolism. Blood oxygen level-dependent (BOLD)-functional MRI (fMRI) was used to identify the regional brain activity and functional connectivity (FC). In addition, the expression of neuroplasticity-related signaling pathways including neurotrophic factors (BDNF/CREB), axonal guidance proteins (Robo1/Slit2), and axonal growth-inhibitory proteins (NogoA/NgR) as well as downstream proteins (RhoA/ROCK) in the bilateral sensorimotor cortex were measured by Western blots. Our results showed the three-phase EE improved the walking ability. Structural T2 mapping imaging and diffusion tensor imaging demonstrated that EE benefited structure integrity in the bilateral sensorimotor cortex. PET-MRI fused images showed improved glucose metabolism in the corresponding regions after EE intervention. Specifically, the BOLD-based amplitude of low-frequency fluctuations showed that EE increased spontaneous activity in the bilateral motor cortex and ipsilateral sensory cortex. In addition, FC results showed increased sensorimotor connectivity in the ipsilateral hemisphere and increased interhemispheric motor cortical connectivity and motor cortical-thalamic connectivity following EE intervention. In addition, a strong correlation was found between increased functional connectivity and improved motor performance of limbs. Specifically, EE regulated the expression of neuroplasticity-related signaling, involving BDNF/CREB, Slit2/Robo1, as well as the axonal growth-inhibitory pathways Nogo-A/Nogo receptor and RhoA/ROCK in the bilateral sensorimotor cortex. Our results indicated that the three-phase enriched environment paradigm enhances neuronal plasticity of the bilateral sensorimotor cortex and consequently ameliorates post-stroke gait deficits. These findings might provide some new clues for the development of EE and thus facilitate the clinical translation of EE.

An Overview of the Body Schema and Body Image: Theoretical Models, Methodological Settings and Pitfalls for Rehabilitation of Persons with Neurological Disorders

Given the widespread debate on the definition of the terms "Body Schema" and "Body Image", this article presents a broad overview of the studies that have investigated the nature of these types of body representations, especially focusing on the innovative information about these two representations that could be useful for the rehabilitation of patients with different neurological disorders with motor deficits (especially those affecting the upper limbs). In particular, we analyzed (i) the different definitions and explicative models proposed, (ii) the empirical settings used to test them and (iii) the clinical and rehabilitative implications derived from the application of interventions on specific case reports. The growing number of neurological diseases with motor impairment in the general population has required the development of new rehabilitation techniques and a new phenomenological paradigm placing body schema as fundamental and intrinsic parts for action in space. In this narrative review, the focus was placed on evidence from the application of innovative rehabilitation techniques and case reports involving the upper limbs, as body parts particularly involved in finalistic voluntary actions in everyday life, discussing body representations and their functional role.

Neuroimaging prognostic factors for treatment response to motor imagery training after stroke

The efficacy of motor imagery training for motor recovery is well acknowledged, but with substantial inter-individual variability in stroke patients. To help optimize motor imagery training therapy plans and screen suitable patients, this study aimed to explore neuroimaging biomarkers explaining variability in treatment response. Thirty-nine stroke patients were randomized to a motor imagery training group (n = 22, received a combination of conventional rehabilitation therapy and motor imagery training) and a control group (n = 17, received conventional rehabilitation therapy and health education) for 4 weeks of interventions. Their demography and clinical information, brain lesion from structural MRI, spontaneous brain activity and connectivity from rest fMRI, and sensorimotor brain activation from passive motor task fMRI were acquired to identify prognostic factors. We found that the variability of outcomes from sole conventional rehabilitation therapy could be explained by the reserved sensorimotor neural function, whereas the variability of outcomes from motor imagery training + conventional rehabilitation therapy was related to the spontaneous activity in the ipsilesional inferior parietal lobule and the local connectivity in the contralesional supplementary motor area. The results suggest that additional motor imagery training treatment is also efficient for severe patients with damaged sensorimotor neural function, but might be more effective for patients with impaired motor planning and reserved motor imagery.

Individual-specific memory reinstatement patterns within human face-selective cortex

Humans have the remarkable ability to vividly retrieve sensory details of past events. According to the theory of sensory reinstatement, during remembering, brain regions involved in the sensory processing of prior events are reactivated to support this perception of the past. Recently, several studies have emphasized potential transformations in the spatial organization of reinstated activity patterns. In particular, studies of scene stimuli suggest a clear anterior shift in the location of retrieval activations compared with those during perception. However, it is not clear that such transformations occur universally, with evidence lacking for other important stimulus categories, particularly faces. Critical to addressing these questions, and to studies of reinstatement more broadly, is the growing importance of considering meaningful variations in the organization of sensory systems across individuals. Therefore, we conducted a multi-session neuroimaging study to first carefully map individual participants face-selective regions within ventral temporal cortex (VTC), followed by a second session to examine the correspondence of activity patterns during face memory encoding and retrieval. Our results showed distinct configurations of face-selective regions within the VTC across individuals. While a significant degree of overlap was observed between face perception and memory encoding, memory retrieval engagement exhibited a more selective and constricted reinstatement pattern within these regions. Importantly, these activity patterns were consistently tied to individual-specific neural substrates, but did not show any consistent direction of spatial transformation (e.g., anteriorization). To provide further insight to these findings, we also report on unique human intracranial recordings from VTC under the same experimental conditions. Our findings highlight the importance of considering individual variations in functional neuroanatomy in the context of assessing the nature of cortical reinstatement. Consideration of such factors will be important for establishing general principles shaping the neural transformations that occur from perception to memory.

Brain network characteristics between subacute and chronic stroke survivors in active, imagery, passive movement task: a pilot study

Background

The activation patterns and functional network characteristics between stroke survivors and healthy individuals based on resting-or task-state neuroimaging and neurophysiological techniques have been extensively explored. However, the discrepancy between stroke patients at different recovery stages remains unclear.

Objective

To investigate the changes in brain connectivity and network topology between subacute and chronic patients, and hope to provide a basis for rehabilitation strategies at different stages after stroke.

Methods

Fifteen stroke survivors were assigned to the subacute group (SG, N = 9) and chronic group (CG, N = 6). They were asked to perform hand grasping under active, passive, and MI conditions when recording EEG. The Fugl-Meyer Assessment Upper Extremity subscale (FMA_UE), modified Ashworth Scale (MAS), Manual Muscle Test (MMT), grip and pinch strength, modified Barthel Index (MBI), and Berg Balance Scale (BBS) were measured.

Results

Functional connectivity analyses showed significant interactions on frontal, parietal and occipital lobes connections in each frequency band, particularly in the delta band. The coupling strength of premotor cortex, M1, S1 and several connections linked to frontal, parietal, and occipital lobes in subacute subjects were lower than in chronic subjects in low alpha, high alpha, low beta, and high beta bands. Nodal clustering coefficient (CC) analyses revealed that the CC in chronic subjects was higher than in subacute subjects in the ipsilesional S1 and occipital area, contralesional dorsolateral prefrontal cortex and parietal area. Characteristic path length (CPL) analyses showed that CPL in subacute subjects was lower than in chronic subjects in low beta, high beta, and gamma bands. There were no significant differences between subacute and chronic subjects for small-world property.

Conclusion

Subacute stroke survivors were characterized by higher transfer efficiency of the entire brain network and weak local nodal effects. Transfer efficiency was reduced, the local nodal role was strengthened, and more neural resources needed to be mobilized to perform motor tasks for chronic survivors. Overall, these results may help to understand the remodeling pattern of the brain network for different post-stroke stages on task conditions and the mechanism of spontaneous recovery.

Brain Activation Evoked by Motor Imagery in Pediatric Patients with Complete Spinal Cord Injury

BACKGROUND AND PURPOSE

Currently, there is no effective treatment for pediatric patients with complete spinal cord injury. Motor imagery has been proposed as an alternative to physical training for patients who are unable to move voluntarily. Our aim was to reveal the potential mechanism of motor imagery in the rehabilitation of pediatric complete spinal cord injury.

MATERIALS AND METHODS

Twenty-six pediatric patients with complete spinal cord injury and 26 age- and sex-matched healthy children as healthy controls were recruited. All participants underwent the motor imagery task-related fMRI scans, and additional motor execution scans were performed only on healthy controls. First, we compared the brain-activation patterns between motor imagery and motor execution in healthy controls. Then, we compared the brain activation of motor imagery between the 2 groups and compared the brain activation of motor imagery in pediatric patients with complete spinal cord injury and that of motor execution in healthy controls.

RESULTS

In healthy controls, compared with motor execution, motor imagery showed increased activation in the left inferior parietal lobule and decreased activation in the left supplementary motor area, paracentral lobule, middle cingulate cortex, and right insula. In addition, our results revealed that the 2 groups both activated the bilateral supplementary motor area, middle cingulate cortex and left inferior parietal lobule, and supramarginal gyrus during motor imagery. Compared with healthy controls, higher activation in the bilateral paracentral lobule, supplementary motor area, putamen, and cerebellar lobules III-V was detected in pediatric complete spinal cord injury during motor imagery, and the activation of these regions was even higher than that of healthy controls during motor execution.

CONCLUSIONS

Our study demonstrated that part of the motor imagery network was functionally preserved in pediatric complete spinal cord injury and could be activated through motor imagery. In addition, higher-level activation in sensorimotor-related regions was also found in pediatric complete spinal cord injury during motor imagery. Our findings may provide a theoretic basis for the application of motor imagery training in pediatric complete spinal cord injury.