Constrained-induced movement therapy promotes motor function recovery by enhancing the remodeling of ipsilesional corticospinal tract in rats after stroke

Repetitive transcranial magnetic stimulation and constraint-induced movement therapy combined in the treatment of post-stroke movement disorders: a narrative review

Stroke is a significant cardiovascular and cerebrovascular condition and is among the primary causes of prolonged neurological impairment globally. Approximately 55%-75% of stroke survivors will experience some form of long-term sensorimotor impairment. Post-stroke, the upper limb typically exhibits restricted mobility, complicating daily chores for 70% of patients and impairing normal limb utilization. Repetitive Transcranial Magnetic Stimulation (rTMS), a prominent non-invasive neuromodulation technique designed to enhance functional recovery post-stroke, has garnered significant attention in clinical studies. Likewise, constraint-induced movement therapy (CIMT) has been extensively employed in therapeutic settings to promote neuroplasticity. However, there remain several issues with it in practical application. Recently, considerable focus has been directed toward a novel treatment known as rTMS in conjunction with obligatory motor therapy. This can circumvent the issues associated with conventional treatments and optimize the advantages of both. This article discusses the present status of clinical research with rTMS and CIMT.

Constraint-Induced Movement Therapy Promotes Contralesional Red Nucleus Plasticity and Increases Bilateral Motor Cortex-to-Red Nucleus Projections After a Large-Area Stroke

For decades, scientists have explored the patterns of neural network remodeling that occur after a stroke. Several studies have shown that both motor cortexes (MCs) undergo crucial remodeling after cerebral ischemia. However, the mechanism by which corticofugal fibers are remodeled is not well understood. Therefore, this study was aimed at investigating the changes in the bilateral red nucleus (RN) and MC-RN projections during recovery from a large-area stroke in a rat stroke model with or without constraint-induced movement therapy (CIMT). A large-area middle cerebral artery occlusion (MCAO) model was established in rats using the Longa method. CIMT was initiated 7 days after MCAO and continued for 1, 2, or 3 weeks. Rats in the control group underwent spontaneous recovery. Locomotor impairment was evaluated using the CatWalk automated gait analysis system, and overall neurological function was evaluated with the modified neurological severity score. Bilateral MC-RN projections were visualized by labeling fiber tracts with an anterograde tracer. Postsynaptic density 95 (PSD95), growth-associated protein 43 (GAP43), and synaptophysin expression levels in the RN were detected using western blotting and immunohistochemistry. The results showed that CIMT promoted motor recovery after a stroke, increased levels of GAP43 and PSD95 in the contralesional but not ipsilesional RN, and increased projections from the MC to the bilateral RN. Thus, CIMT promotes neuroplasticity after a large-area stroke by stimulating axon outgrowth, improving postsynaptic membrane function in the contralesional RN, and increasing bilateral projections of the MC-RN. These results provide evidence for the therapeutic efficacy of CIMT in restoring motor function and help with understanding RN plasticity after a large-area stroke.

Constraint-induced movement therapy combined with intermittent theta-burst stimulation improve synaptic plasticity by inhibiting neutrophils extracellular traps formation in ipsilateral primary motor cortex of stroke rats

The effect of Constraint-induced movement therapy (CIMT) or Intermittent theta-burst stimulation (iTBS) alone is limited in improving motor function after a stroke. In this study, we explored the efficacy and possible mechanisms in combination of CIMT and iTBS through behavioral evaluation, RNA sequencing, Golgi staining, transmission electronic microscope (TEM), high-performance liquid chromatography (HPLC), western blotting (WB) and immunofluorescence. Firstly, we observed that combination therapy is safe and effective, and it can significantly reduce the number of immature dendritic spines and increase the number of functional dendritic spines, the amount of glutamate (Glu) and the expression of Glu1 receptor (Glu1R). Meanwhile, we have found a significant reduction in neutrophil extracellular traps (NETs) in the combination group, and correlation analysis showed that the number of NETs is negatively correlated with the number of functional dendritic spines and the expression of Glu1R. After Cl-amidine ((S) - N - (1-amino-5- (2-chloroacetamiprid) -1-oxopentan-2-yl) benzamide 2,2,2-trifluoroacetate salt, PAD4 inhibitors) application, combined therapy did not further improve motor function and the expression of Glu1R. Our results proved that CIMT combined with iTBS therapy is a better therapeutic intervention. It improved motor function and synaptic plasticity after a stroke by promoting the transformation of functional dendritic spines and the expression of Glu1R in the ipsilateral primary motor cortex. The reduction of NETs generation is one of the key targets within it.

Constraint-Induced Movement Therapy (CIMT) and Neural Precursor Cell (NPC) Transplantation Synergistically Promote Anatomical and Functional Recovery in a Hypoxic-Ischemic Mouse Model

Cerebral palsy (CP) is a common neurodevelopmental disorder characterized by pronounced motor dysfunction and resulting in physical disability. Neural precursor cells (NPCs) have shown therapeutic promise in mouse models of hypoxic-ischemic (HI) perinatal brain injury, which mirror hemiplegic CP. Constraint-induced movement therapy (CIMT) enhances the functional use of the impaired limb and has emerged as a beneficial intervention for hemiplegic CP. However, the precise mechanisms and optimal application of CIMT remain poorly understood. The potential synergy between a regenerative approach using NPCs and a rehabilitation strategy using CIMT has not been explored. We employed the Rice-Vannucci HI model on C57Bl/6 mice at postnatal day (PND) 7, effectively replicating the clinical and neuroanatomical characteristics of hemiplegic CP. NPCs were transplanted in the corpus callosum (CC) at PND21, which is the age corresponding to a 2-year-old child from a developmental perspective and until which CP is often not formally diagnosed, followed or not by Botulinum toxin injections in the unaffected forelimb muscles at PND23, 26, 29 and 32 to apply CIMT. Both interventions led to enhanced CC myelination and significant functional recovery (as shown by rearing and gait analysis testing), through the recruitment of endogenous oligodendrocytes. The combinatorial treatment indicated a synergistic effect, as shown by newly recruited oligodendrocytes and functional recovery. This work demonstrates the mechanistic effects of CIMT and NPC transplantation and advocates for their combined therapeutic potential in addressing hemiplegic CP.

Global research hotspots and trends in constraint-induced movement therapy in rehabilitation over the past 30 years: a bibliometric and visualization study

Background

Stroke is a cerebrovascular disease with high prevalence and mortality, and upper limb hemiparesis is a major factor limiting functional recovery in stroke patients. Improvement of motor function in stroke patients through various forms of constraint-induced movement therapy (CITM) has been recognized as safe and effective in recent years. This research field lacks a comprehensive systematic and clear vein combing analysis, analyzing the literature research of CIMT in the field of rehabilitation in the past three decades, summarizing the research hotspots and cutting-edge trends in this field, in an effort to offer ideas and references for subsequent researchers.

Methods

Relevant literature on CIMT in rehabilitation was collected from 1996 to 2024 within the Web of Science database's core dataset by using CiteSpace6.1, VOSviewer1.6.18, R-bibliometrix4.6.1, Pajek5.16, Scimago Graphica 1.0.26 software for visualization and analysis.

Results

There were 970 papers in all United States was ranked first with 401 papers. Alabama Univ was ranked first for institutions with 53 papers. Neurorehabilitation and Neural Repair was ranked first for journals with 78 papers, and Taub E was ranked first for author publications with 64 papers. Research keywords were CIMT, stroke rehabilitation, upper extremity function, lower extremity gait balance, randomized controlled trials, physical therapy techniques (transcranial magnetic stimulation and sensory amplitude electrical stimulation), primary motor cortex plasticity, lateral dominance (spatial behaviors), cerebral vascular accidents, activities of daily living, hand function, disability, functional restoration, bimanual training, aphasia, acquired invalidity, type A Botulinum toxin and joystick riding toys.

Conclusion

The current state of research shows that CIMT still has a vast potential for development in the field of rehabilitation research. The research hotspots are the clinical efficacy of CIMT combined with other therapies (botulinum toxin type A, transcranial direct current stimulation, virtual reality, mirror therapy, robotic-assisted) to enhance the functionality of upper limb hemiparesis in stroke patients, the mechanism of CIMT to improve the plasticity of the motor cortex through electrophysiological and imaging methods, and improvement of lower limb gait balance function in stroke patients and aphasia applications, the optimal intervention time and dose, and exploration of CIMT in new settings such as robot-assisted, telemedicine, and home rehabilitation.

Clinical potential and neuroplastic effect of targeted virtual reality based intervention for distal upper limb in post-stroke rehabilitation: a pilot observational study

PURPOSE

A library of Virtual Reality (VR) tasks has been developed for targeted post-stroke rehabilitation of distal upper extremities. The objective of this pilot study was to evaluate the clinical potential of the targeted VR-based therapeutic intervention in a small cohort of patients specifically with chronic stroke. Furthermore, our aim was to explore the possible neuronal reorganizations in corticospinal pathways in response to the distal upper limb targeted VR-intervention.

METHODOLOGY

Five patients with chronic stroke were enrolled in this study and were given VR-intervention of 20 sessions of 45 min each. Clinical Scales, cortical-excitability measures (using Transcranial Magnetic Stimulation): Resting Motor Threshold (RMT), and Motor Evoked Potential (MEP) amplitude, task-specific performance metrics i.e., Time taken to complete the task (TCT), smoothness of trajectory, relative % error were evaluated pre- and post-intervention to evaluate the intervention-induced improvements.

RESULTS

Pre-to post-intervention improvements were observed in Fugl-Meyer Assessment (both total and wrist/hand component), Modified Barthel Index, Stroke Impact Scale, Motor Assessment Scale, active range of motion at wrist, and task-specific outcome metrics. Pre-to post-intervention ipsilesional RMT reduced (mean ∼9%) and MEP amplitude increased (mean ∼29µV), indicating increased cortical excitability at post-intervention.

CONCLUSION

VR-training exhibited improved motor outcomes and cortical-excitability in patients with stroke. Neurophysiological changes observed in terms of improved cortical-excitability might be a consequence of plastic reorganization induced by VR-intervention.

Corticospinal tract: a new hope for the treatment of post-stroke spasticity

Stroke is the third leading cause of death and disability worldwide. Post-stroke spasticity (PSS) is the most common complication of stroke but represents only one of the many manifestations of upper motor neuron syndrome. As an upper motor neuron, the corticospinal tract (CST) is the only direct descending motor pathway that innervates the spinal motor neurons and is closely related to the recovery of limb function in patients with PSS. Therefore, promoting axonal remodeling in the CST may help identify new therapeutic strategies for PSS. In this review, we outline the pathological mechanisms of PSS, specifically their relationship with CST, and therapeutic strategies for axonal regeneration of the CST after stroke. We found it to be closely associated with astroglial scarring produced by astrocyte activation and its secretion of neurotrophic factors, mainly after the onset of cerebral ischemia. We hope that this review offers insight into the relationship between CST and PSS and provides a basis for further studies.

Progress in the clinical application of constraint-induced therapy following stroke since 2014

Stroke is a group of cerebrovascular diseases with high prevalence and mortality rate. Stroke can induce many impairments, including motor and cognitive dysfunction, aphasia/dysarthria, dysphagia, and mood disorders, which may reduce the quality of life among the patients. Constraint-induced therapy has been proven to be an effective treatment method for stroke rehabilitation. It has been widely used in the recovery of limb motor dysfunction, aphasia, and other impairment like unilateral neglect after stroke. In recent years, constraint-induced therapy can also combine with telehealth and home rehabilitation. In addition, constraint-induced therapy produces significant neuroplastic changes in the central nervous system. Functional magnetic resonance imaging, diffusion tensor imaging, and other imaging/electrophysiology methods have been used to clarify the mechanism and neuroplasticity. However, constraint-induced therapy has some limitations. It can only be used under certain conditions, and the treatment time and effectiveness are controversial. Further research is needed to clarify the mechanism and effectiveness of CI therapy.

The Mechanism and Clinical Application of Constraint-Induced Movement Therapy in Stroke Rehabilitation

Constraint-induced movement therapy (CIMT) has been widely applied in stroke rehabilitation, and most relevant studies have shown that CIMT helps improve patients' motor function. In practice, however, principal issues include inconsistent immobilization durations and methods, while incidental issues include a narrow application scope and an emotional impact. Although many studies have explored the possible internal mechanisms of CIMT, a mainstream understanding has not been established.

Neurofunctional and neuroimaging readouts for designing a preclinical stem-cell therapy trial in experimental stroke

With the aim of designing a preclinical study evaluating an intracerebral cell-based therapy for stroke, an observational study was performed in the rat suture model of ischemic stroke. Objectives were threefold: (i) to characterize neurofunctional and imaging readouts in the first weeks following transient ischemic stroke, according to lesion subtype (hypothalamic, striatal, corticostriatal); (ii) to confirm that intracerebral administration does not negatively impact these readouts; and (iii) to calculate sample sizes for a future therapeutic trial using these readouts as endpoints. Our results suggested that the most relevant endpoints were side bias (staircase test) and axial diffusivity (AD) (diffusion tensor imaging). Hypothalamic-only lesions did not affect those parameters, which were close to normal. Side bias in striatal lesions reached near-normal levels within 2 weeks, while rats with corticostriatal lesions remained impaired until week 14. AD values were decreased at 4 days and increased at 5 weeks post-surgery, with a subtype gradient: hypothalamic < striatal < corticostriatal. Intracerebral administration did not impact these readouts. After sample size calculation (18-147 rats per group according to the endpoint considered), we conclude that a therapeutic trial based on both readouts would be feasible only in the framework of a multicenter trial.

Fluoxetine regulates the neuronal differentiation of neural stem cells transplanted into rat brains after stroke by increasing the 5HT level

Fluoxetine, a 5-HT uptake inhibitor, has been adopted for the treatment of post-stroke depression in recent years. It has been confirmed to induce neuronal regeneration in vivo, but its effect on inducing stem cell differentiation after transplantation has not yet been verified. To evaluate its regulatory effect on stem cell differentiation, fluoxetine was used in this study to treat rats with cerebral ischemia after neural stem cell (NSC) transplantation. The results showed that the proportion of NSCs differentiating into neurons significantly increased after fluoxetine treatment. In NSC adherent culture, the addition of 5-HT but not of fluoxetine significantly increased the neuronal differentiation ratio of NSCs. Moreover, the addition of 5-HT2A or 5-HT3A antagonists inhibited this effect. In addition, Western blotting revealed that the increase in 5-HT inhibited ERK2 phosphorylation and upregulated neurogenin1 expression. In conclusion, fluoxetine increased the 5-HT level and promoted neuronal differentiation, thereby upregulating neurogenin1 expression and downregulating ERK2 phosphorylation.

Cerebral Ischemia-Reperfusion Is Associated With Upregulation of Cofilin-1 in the Motor Cortex

Cerebral ischemia is one of the leading causes of death. Reperfusion is a critical stage after thrombolysis or thrombectomy, accompanied by oxidative stress, excitotoxicity, neuroinflammation, and defects in synapse structure. The process is closely related to the dephosphorylation of actin-binding proteins (e.g., cofilin-1) by specific phosphatases. Although studies of the molecular mechanisms of the actin cytoskeleton have been ongoing for decades, limited studies have directly investigated reperfusion-induced reorganization of actin-binding protein, and little is known about the gene expression of actin-binding proteins. The exact mechanism is still uncertain. The motor cortex is very important to save nerve function; therefore, we chose the penumbra to study the relationship between cerebral ischemia-reperfusion and actin-binding protein. After transient middle cerebral artery occlusion (MCAO) and reperfusion, we confirmed reperfusion and motor function deficit by cerebral blood flow and gait analysis. PCR was used to screen the high expression mRNAs in penumbra of the motor cortex. The high expression of cofilin in this region was confirmed by immunohistochemistry (IHC) and Western blot (WB). The change in cofilin-1 expression appears at the same time as gait imbalance, especially maximum variation and left front swing. It is suggested that cofilin-1 may partially affect motor cortex function. This result provides a potential mechanism for understanding cerebral ischemia-reperfusion.

Axonal remodeling of the corticospinal tract during neurological recovery after stroke

Stroke remains the leading cause of long-term disability. Hemiparesis is one of the most common post-stroke motor deficits and is largely attributed to loss or disruption of the motor signals from the affected motor cortex. As the only direct descending motor pathway, the corticospinal tract (CST) is the primary pathway to innervate spinal motor neurons, and thus, forms the neuroanatomical basis to control the peripheral muscles for voluntary movements. Here, we review evidence from both experimental animals and stroke patients, regarding CST axonal damage, functional contribution of CST axonal integrity and remodeling to neurological recovery, and therapeutic approaches aimed to enhance CST axonal remodeling after stroke. The new insights gleaned from preclinical and clinical studies may encourage the development of more rational therapeutics with a strategy targeted to promote axonal rewiring for corticospinal innervation, which will significantly impact the current clinical needs of subacute and chronic stroke treatment.

Motor tract reorganization after acute central nervous system injury: a translational perspective

Acute central nervous system injuries are among the most common causes of disability worldwide, with widespread social and economic implications. Motor tract injury accounts for the majority of this disability; therefore, there is impetus to understand mechanisms underlying the pathophysiology of injury and subsequent reorganization of the motor tract that may lead to recovery. After acute central nervous system injury, there are changes in the microenvironment and structure of the motor tract. For example, ischemic stroke involves decreased local blood flow and tissue death from lack of oxygen and nutrients. Traumatic injury, in contrast, causes stretching and shearing injury to microstructures, including myelinated axons and their surrounding vessels. Both involve blood-brain barrier dysfunction, which is an important initial event. After acute central nervous system injury, motor tract reorganization occurs in the form of cortical remapping in the gray matter and axonal regeneration and rewiring in the white matter. Cortical remapping involves one cortical region taking on the role of another. cAMP-response-element binding protein is a key transcription factor that can enhance plasticity in the peri-infarct cortex. Axonal regeneration and rewiring depend on complex cell-cell interactions between axons, oligodendrocytes, and other cells. The RhoA/Rho-associated coiled-coil containing kinase signaling pathway plays a central role in axon growth/regeneration through interactions with myelin-derived axonal growth inhibitors and regulation of actin cytoskeletal dynamics. Oligodendrocytes and their precursors play a role in myelination, and neurons are involved through their voltage-gated calcium channels. Understanding the pathophysiology of injury and the biology of motor tract reorganization may allow the development of therapies to enhance recovery after acute central nervous system injury. These include targeted rehabilitation, novel pharmacotherapies, such as growth factors and axonal growth inhibitor blockade, and the implementation of neurotechnologies, such as central nervous system stimulators and robotics. The translation of these advances depends on careful alignment of preclinical studies and human clinical trials. As experimental data mount, the future is one of optimism.

Constraint-induced movement therapy enhances AMPA receptor-dependent synaptic plasticity in the ipsilateral hemisphere following ischemic stroke

Constraint-induced movement therapy (CIMT) can promote the recovery of motor function in injured upper limbs following stroke, which may be associated with upregulation of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) at synapses in the ipsilateral sensorimotor cortex in our previous study. However, AMPAR distribution is tightly regulated, and only AMPARs on the postsynaptic membrane can mediate synaptic transmission. We speculated that synaptic remodeling induced by movement-associated synaptic activity can promote functional recovery from stroke. To test this hypothesis, we compared AMPAR expression on the postsynaptic membrane surface in a rat model of ischemic stroke induced by middle cerebral artery occlusion (MCAO) with versus without CIMT, which consisted of daily running wheel training for 2 weeks starting on day 7 after MCAO. The results showed that CIMT increased the number of glutamate receptor (GluR)2-containing functional synapses in the ipsilateral sensorimotor cortex, and reduced non-GluR2 AMPARs in the ipsilateral sensorimotor cortex and hippocampal CA3 region. In addition, CIMT enhanced AMPAR expression on the surface of post-synaptic membrane in the ipsilateral sensorimotor cortex and hippocampus. Thus, CIMT promotes the recovery of motor function of injured upper limbs following stroke by enhancing AMPAR-mediated synaptic transmission in the ischemic hemisphere. These findings provide supporting evidence for the clinical value of CIMT for restoring limb movement in stroke patients. All experimental procedures and protocols were approved by the Department of Laboratory Animal Science of Fudan University, China (approval No. 201802173S) on March 3, 2018.

A Review of Exercise-Induced Neuroplasticity in Ischemic Stroke: Pathology and Mechanisms

After ischemic stroke, survivors experience motor dysfunction and deterioration of memory and cognition. These symptoms are associated with the disruption of normal neuronal function, i.e., the secretion of neurotrophic factors, interhemispheric connections, and synaptic activity, and hence the disruption of the normal neural circuit. Exercise is considered an effective and feasible rehabilitation strategy for improving cognitive and motor recovery following ischemic stroke through the facilitation of neuroplasticity. In this review, our aim was to discuss the mechanisms by which exercise-induced neuroplasticity improves motor function and cognitive ability after ischemic stroke. The associated mechanisms include increases in neurotrophins, improvements in synaptic structure and function, the enhancement of interhemispheric connections, the promotion of neural regeneration, the acceleration of neural function reorganization, and the facilitation of compensation beyond the infarcted tissue. We also discuss some common exercise strategies and a novel exercise therapy, robot-assisted movement, which might be widely applied in the clinic to help stroke patients in the future.

Constraint-induced movement therapy improves functional recovery after ischemic stroke and its impacts on synaptic plasticity in sensorimotor cortex and hippocampus

Constraint-induced movement therapy (CIMT) has proven to be an effective way to restore functional deficits following stroke in human and animal studies, but its underlying neural plasticity mechanism remains unknown. Accumulating evidence indicates that rehabilitation after stroke is closely associated with synaptic plasticity. We therefore investigated the impact of CIMT on synaptic plasticity in ipsilateral and contralateral brain of rats following stroke. Rats were subjected to 90 minutes of transient middle cerebral artery occlusion (MCAO). CIMT was performed from 7 days after stroke and lasted for two weeks. Modified Neurology Severity Score (mNSS) and the ladder rung walking task tests were conducted at 7,14 and 21 days after stroke. Golgi-Cox staining was used to observe the plasticity changes of dendrites and dendritic spines. The expression of glutamate receptors (GluR1, GluR2 and NR1) were examined by western blot. Our data suggest that the dendrites and dendritic spines are damaged to varying degrees in bilateral sensorimotor cortex and hippocampus after acute stroke. CIMT treatment enhances the plasticity of dendrites and dendritic spines in the ipsilateral and contralateral sensorimotor cortex, increases the expression of synaptic GluR2 in ipsilateral sensorimotor cortex, which may be mechanisms for CIMT to improve functional recovery after ischemic stroke.

Modified constraint-induced movement therapy alters synaptic plasticity of rat contralateral hippocampus following middle cerebral artery occlusion

Modified constraint-induced movement therapy is an effective treatment for neurological and motor impairments in patients with stroke by increasing the use of their affected limb and limiting the contralateral limb. However, the molecular mechanism underlying its efficacy remains unclear. In this study, a middle cerebral artery occlusion (MCAO) rat model was produced by the suture method. Rats received modified constraint-induced movement therapy 1 hour a day for 14 consecutive days, starting from the 7^th day after middle cerebral artery occlusion. Day 1 of treatment lasted for 10 minutes at 2 r/min, day 2 for 20 minutes at 2 r/min, and from day 3 onward for 20 minutes at 4 r/min. CatWalk gait analysis, adhesive removal test, and Y-maze test were used to investigate motor function, sensory function as well as cognitive function in rodent animals from the 1^st day before MCAO to the 21^st day after MCAO. On the 21^st day after MCAO, the neurotransmitter receptor-related genes from both contralateral and ipsilateral hippocampi were tested by micro-array and then verified by western blot assay. The glutamate related receptor was shown by transmission electron microscopy and the glutamate content was determined by high-performance liquid chromatography. The results of behavior tests showed that modified constraint-induced movement therapy promoted motor and sensory functional recovery in the middle cerebral artery-occluded rats, but had no effect on cognitive function. The modified constraint-induced movement therapy upregulated the expression of glutamate ionotropic receptor AMPA type subunit 3 (Gria3) in the hippocampus and downregulated the expression of the beta3-adrenergic receptor gene Adrb3 and arginine vasopressin receptor 1A, Avpr1a in the middle cerebral artery-occluded rats. In the ipsilateral hippocampus, only Adra2a was downregulated, and there was no significant change in Gria3. Transmission electron microscopy revealed a denser distribution the more distribution of postsynaptic glutamate receptor 2/3, which is an α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor, within 240 nm of the postsynaptic density in the contralateral cornu ammonis 3 region. The size and distribution of the synaptic vesicles within 100 nm of the presynaptic active zone were unchanged. Western blot analysis showed that modified constraint-induced movement therapy also increased the expression of glutamate receptor 2/3 and brain-derived neurotrophic factor in the hippocampus of rats with middle cerebral artery occlusion, but had no effect on Synapsin I levels. Besides, we also found modified constraint-induced movement therapy effectively reduced glutamate content in the contralateral hippocampus. This study demonstrated that modified constraint-induced movement therapy is an effective rehabilitation therapy in middle cerebral artery-occluded rats, and suggests that these positive effects occur via the upregulation of the postsynaptic membrane α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor expression. This study was approved by the Institutional Animal Care and Use Committee of Fudan University, China (approval No. 201802173S) on March 3, 2018.

Constraint induced movement therapy promotes contralesional-oriented structural and bihemispheric functional neuroplasticity after stroke

The mechanism behind constraint-induced movement therapy (CIMT) in promoting motor recovery after stroke remains unclear. We explored the bilateral structural and functional reorganization of the brain induced by CIMT after left middle cerebral artery occlusion (MCAO) in rats. CIMT started on the 8^th day (D8) after MCAO surgery and lasted for 3 weeks. Skilled walking was assessed by Foot-Fault tests. The efferent neuron network innervating the paralyzed forelimb was labeled by pseudorabies virus (PRV) to explore neuron recruitment. Synapsin Ⅰ was used as an indicator of the number of synapses. Additionally, C-fos expression 1 h after walking was detected to explore the activation of the brain. As a result, CIMT significantly improved skilled walking and elicited more neuron recruitment into the innervating network of a paralyzed forelimb in the contralesional rather than the ipsilesional motor cortex and red nucleus. CIMT also increased the synapse number in the contralesional cortex but there was no corresponding effect in the intact ipsilesional cortex. Furthermore, MCAO decreased ipsilesional motor cortex activation, but CIMT partially compensated for this by increasing the number of activated neurons (c-fos⁺) in both the left and right motor cortex. In conclusion, the contralesional motor cortex and red nucleus might play more important roles than corresponding ipsilesional regions in structural reorganization during CIMT-induced motor recovery after stroke. However, CIMT promotes bilateral motor cortex activity without a side preference.