Synaptic plasticity in thalamic nuclei enhanced by motor skill training in rat with transient middle cerebral artery occlusion

Specific connectivity optimizes learning in thalamocortical loops

Thalamocortical loops have a central role in cognition and motor control, but precisely how they contribute to these processes is unclear. Recent studies showing evidence of plasticity in thalamocortical synapses indicate a role for the thalamus in shaping cortical dynamics through learning. Since signals undergo a compression from the cortex to the thalamus, we hypothesized that the computational role of the thalamus depends critically on the structure of corticothalamic connectivity. To test this, we identified the optimal corticothalamic structure that promotes biologically plausible learning in thalamocortical synapses. We found that corticothalamic projections specialized to communicate an efference copy of the cortical output benefit motor control, while communicating the modes of highest variance is optimal for working memory tasks. We analyzed neural recordings from mice performing grasping and delayed discrimination tasks and found corticothalamic communication consistent with these predictions. These results suggest that the thalamus orchestrates cortical dynamics in a functionally precise manner through structured connectivity.

Exercise Promotes Tissue Regeneration: Mechanisms Involved and Therapeutic Scope

Exercise has well-recognized beneficial effects on the whole body. Previous studies suggest that exercise could promote tissue regeneration and repair in various organs. In this review, we have summarized the major effects of exercise on tissue regeneration primarily mediated by stem cells and progenitor cells in skeletal muscle, nervous system, and vascular system. The protective function of exercise-induced stem cell activation under pathological conditions and aging in different organs have also been discussed in detail. Moreover, we have described the primary molecular mechanisms involved in exercise-induced tissue regeneration, including the roles of growth factors, signaling pathways, oxidative stress, metabolic factors, and non-coding RNAs. We have also summarized therapeutic approaches that target crucial signaling pathways and molecules responsible for exercise-induced tissue regeneration, such as IGF1, PI3K, and microRNAs. Collectively, the comprehensive understanding of exercise-induced tissue regeneration will facilitate the discovery of novel drug targets and therapeutic strategies.

Aerobic Physical Exercise as a Non-medical Intervention for Brain Dysfunction: State of the Art and Beyond

Brain disorders, including stroke, Alzheimer's disease, depression, and chronic pain, are difficult to effectively treat. These major brain disorders have high incidence and mortality rates in the general population, and seriously affect not only the patient's quality of life, but also increases the burden of social medical care. Aerobic physical exercise is considered an effective adjuvant therapy for preventing and treating major brain disorders. Although the underlying regulatory mechanisms are still unknown, systemic processes may be involved. Here, this review aimed to reveal that aerobic physical exercise improved depression and several brain functions, including cognitive functions, and provided chronic pain relief. We concluded that aerobic physical exercise helps to maintain the regulatory mechanisms of brain homeostasis through anti-inflammatory mechanisms and enhanced synaptic plasticity and inhibition of hippocampal atrophy and neuronal apoptosis. In addition, we also discussed the cross-system mechanisms of aerobic exercise in regulating imbalances in brain function, such as the “bone-brain axis.” Furthermore, our findings provide a scientific basis for the clinical application of aerobic physical exercise in the fight against brain disorders.

The role of plasticity in the recovery of consciousness

Disorders of consciousness (DOCs), i.e., coma, vegetative state, and minimally conscious state are the consequences of a severe brain injury that disrupts the brain ability to generate consciousness. Recovery from DOCs requires functional and structural changes in the brain. The sites where these plastic changes take place vary according to the pathophysiology of the DOC. The ascending reticular activating system of the brainstem and its complex connections with the thalamus and cortex are involved in the pathophysiology of coma. Subcortical structures, such as the striatum and globus pallidus, together with thalamocortical and corticothalamic projections, the basal forebrain, and several networks among different cortical areas are probably involved in vegetative and minimally conscious states. Some mechanisms of plasticity that allegedly operate in each of these sites to promote recovery of consciousness will be discussed in this chapter. While some mechanisms of plasticity work at a local level, others produce functional changes in complex neuronal networks, for example by entraining neuronal oscillations. The specific mechanisms of brain plasticity represent potential targets for future treatments aiming to restore consciousness in patients with severe DOCs.

Mini Review (Part I): An Experimental Concept on Exercise and Ischemic Conditioning in Stroke Rehabilitation

Stroke remains a leading cause of adult death and disability. Poststroke rehabilitation is vital for reducing the long-term sequelae of brain ischemia. Recently, physical exercise training has been well established as an effective rehabilitation tool, but its efficacy depends on exercise parameters and the patient's capacities, which are often altered following a major cerebrovascular event. Thus, ischemic conditioning as a rehabilitation intervention was considered an “exercise equivalent,” but the investigation is still in its relative infancy. In this mini-review, we discuss the potential for physical exercise or ischemic conditioning and its relation to angiogenesis, neurogenesis, and plasticity in stroke rehabilitation. This allows the readers to understand the context of the research and the application of ischemic conditioning in poststroke rehabilitation.

Spontaneous Neuronal Plasticity in the Contralateral Motor Cortex and Corticospinal Tract after Focal Cortical Infarction in Hypertensive Rats

OBJECTIVES

In this study, we investigated the spontaneous neural plasticity on the contralateral side in hypertensive rats, including the expression of nerve growth factors (synaptophysin [SYN] and growth-associated protein 43 [GAP-43]), and the association between nerve fiber sprouting and redistribution, and the recovery of motor functions following sensorimotor cortical infarction.

METHODS

Initially, Sprague-Dawley rats were induced with renal hypertension by the bilateral renal arteries clips method. Further, they were induced with cerebral ischemia by the middle cerebral artery electrocoagulation method; 70 male rats completed the study. We compared the changes in the corticospinal tract (CST) and the expressions of SYN and GAP-43 on the contralateral side in rats with cerebral infarction using immunohistochemical staining, western blot, and biotinylated dextran amine (BDA) tracing analyses. The recovery of motor function in rats after cortical infarction was evaluated by the foot-fault and beam-walk tests.

RESULTS

The motor behavior tests revealed that the motor function of rats could recover to various degrees after focal cortical infarction. Compared with the sham-operated group, the SYN and GAP-43 levels increased in the motor cortex of the opposite hemisphere within 28 days after middle cerebral artery occlusion (MCAO). The increase in SYN and GAP-43 expressions presented differently in layers Ⅱ, Ⅲ, and Ⅴ. The amount of BDA-positive fibers also increased significantly in the denervated cervical spinal gray matter on day 56 post-MCAO.

CONCLUSIONS

The increases in SYN and GAP-43 on the contralateral side of the motor cortex could promote CST sprouting and rewiring in the spinal cord gray matter and also spontaneous motor function recovery after cortical infarction.

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.

Exacerbation of Brain Injury by Post-Stroke Exercise Is Contingent Upon Exercise Initiation Timing

Accumulating evidence has demonstrated that post-stroke physical rehabilitation may reduce morbidity. The effectiveness of post-stroke exercise, however, appears to be contingent upon exercise initiation. This study assessed the hypothesis that very early exercise exacerbates brain injury, induces reactive oxygen species (ROS) generation, and promotes energy failure. A total of 230 adult male Sprague-Dawley rats were subjected to middle cerebral artery (MCA) occlusion for 2 h, and randomized into eight groups, including two sham injury control groups, three non-exercise and three exercise groups. Exercise was initiated after 6 h, 24 h and 3 days of reperfusion. Twenty-four hours after completion of exercise (and at corresponding time points in non-exercise controls), infarct volumes and apoptotic cell death were examined. Early brain oxidative metabolism was quantified by examining ROS, ATP and NADH levels 0.5 h after completion of exercise. Furthermore, protein expressions of angiogenic growth factors were measured in order to determine whether post-stroke angiogenesis played a role in rehabilitation. As expected, ischemic stroke resulted in brain infarction, apoptotic cell death and ROS generation, and diminished NADH and ATP production. Infarct volumes and apoptotic cell death were enhanced (p < 0.05) by exercise that was initiated after 6 h of reperfusion, but decreased by late exercise (24 h, 3 days). This exacerbated brain injury at 6 h was associated with increased ROS levels (p < 0.05), and decreased (p < 0.05) NADH and ATP levels. In conclusion, very early exercise aggravated brain damage, and early exercise-induced energy failure with ROS generation may underlie the exacerbation of brain injury. These results shed light on the manner in which exercise initiation timing may affect post-stroke rehabilitation.

Enhanced apoptosis from early physical exercise rehabilitation following ischemic stroke

The effectiveness of the rehabilitative benefits of physical exercise appears to be contingent upon when the exercise is initiated after stroke. The present study assessed the hypothesis that very early exercise increases the extent of apoptotic cell death via increased expression of proapoptotic proteins in a rat stroke model. Adult male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 hr using an intraluminal filament and assigned to four nonexercise and three exercise groups. Exercise on a Rota-Rod was initiated for 30 min at 6 hr (considered very early), at 24 hr (early), and at 3 days (relatively late) after reperfusion. At 24 hr after exercise, apoptotic cell death was determined. At 3 and 24 hr after exercise, the expression of pro- and antiapoptotic proteins was evaluated through Western blotting. As expected, ischemic stroke significantly increased the levels of apoptotic cell death. Compared with the stroke group without exercise, apoptotic cell death was further increased (P < 0.05) at 6 hr but not at 24 hr or 3 days with exercise. This exacerbated cell injury was associated with increased expression of proapoptotic proteins (BAX and caspase-3). The expression of Bcl-2, an antiapoptotic protein, was not affected by exercise. In ischemic stroke, apoptotic cell death was enhanced by very early exercise in association with increased expression of proapoptotic proteins. These results shed light on the time-sensitive effect of exercise in poststroke rehabilitation. © 2016 Wiley Periodicals, Inc.

Early rehabilitation aggravates brain damage after stroke via enhanced activation of nicotinamide adenine dinucleotide phosphate oxidase (NOX)

INTRODUCTION

Although physical exercise has emerged as a potential therapeutic modality for functional deficits following ischemic stroke, the extent of this effect appears to be contingent upon the time of exercise initiation. In the present study, we assessed how exercise timing affected brain damage through hyperglycolysis-associated NADPH oxidase (NOX) activation.

METHODS

Using an intraluminal filament, adult male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2h and assigned to one non-exercise and three exercise groups. Exercise on Rota-rod was initiated for 30min at 6h (considered very early), at 24h (early), and at day 3 (relatively late) after reperfusion. Lactate production was measured 30min after exercise completion, and NOX activity and protein expression of NOX subunits (p47(phox), gp91(phox), p22(phox) and p67(phox)) and glucose transporter 1 and 3 (Glut-1 and -3) were measured at 3 and 24h after exercise. Apoptotic cell death was determined at 24h after exercise.

RESULTS

Lactate production and Glut-1 and Glut-3 expression were increased after very early exercise (6h), but not after late exercise (3 days), suggesting hyperglycolysis. NOX activity was increased with the initiation of exercise at 6h (P<0.05), but not 24h or 3 days, following stroke. Early (6 and 24h), but not late (3 days), post-stroke exercise was associated with increased (P<0.05) expression of the NOX protein subunit p47(phox), gp91(phox)and p67(phox). This may have led to the enhanced apoptosis observed after early exercise in ischemic rats.

CONCLUSION

Hyperglycolysis and NOX activation was associated with an elevation in apoptotic cell death after very early exercise, and the detrimental effect of exercise on stroke recovery began to decrease when exercise was initiated 24h after reperfusion.

Modulation of Synaptic Plasticity by Exercise Training as a Basis for Ischemic Stroke Rehabilitation

In recent years, rehabilitation of ischemic stroke draws more and more attention in the world, and has been linked to changes of synaptic plasticity. Exercise training improves motor function of ischemia as well as cognition which is associated with formation of learning and memory. The molecular basis of learning and memory might be synaptic plasticity. Research has therefore been conducted in an attempt to relate effects of exercise training to neuroprotection and neurogenesis adjacent to the ischemic injury brain. The present paper reviews the current literature addressing this question and discusses the possible mechanisms involved in modulation of synaptic plasticity by exercise training. This review shows the pathological process of synaptic dysfunction in ischemic roughly and then discusses the effects of exercise training on scaffold proteins and regulatory protein expression. The expression of scaffold proteins generally increased after training, but the effects on regulatory proteins were mixed. Moreover, the compositions of postsynaptic receptors were changed and the strength of synaptic transmission was enhanced after training. Finally, the recovery of cognition is critically associated with synaptic remodeling in an injured brain, and the remodeling occurs through a number of local regulations including mRNA translation, remodeling of cytoskeleton, and receptor trafficking into and out of the synapse. We do provide a comprehensive knowledge of synaptic plasticity enhancement obtained by exercise training in this review.

Aerobic exercise effects on neuroprotection and brain repair following stroke: a systematic review and perspective

Aerobic exercise (AE) enhances neuroplasticity and improves functional outcome in animal models of stroke, however the optimal parameters (days post-stroke, intensity, mode, and duration) to influence brain repair processes are not known. We searched PubMed, CINAHL, PsychInfo, the Cochrane Library, and the Central Register of Controlled Clinical Trials, using predefined criteria, including all years up to July 2013 (English language only). Clinical studies were included if participants had experienced an ischemic or hemorrhagic stroke. We included animal studies that utilized any method of global or focal ischemic stroke or intracerebral hemorrhage. Any intervention utilizing AE-based activity with the intention of improving cardiorespiratory fitness was included. Of the 4250 titles returned, 47 studies (all in animal models) met criteria and measured the effects of exercise on brain repair parameters (lesion volume, oxidative damage, inflammation and cell death, neurogenesis, angiogenesis and markers of stress). Our synthesized findings show that early-initiated (24-48h post-stroke) moderate forced exercise (10m/min, 5-7 days per week for about 30min) reduced lesion volume and protected perilesional tissue against oxidative damage and inflammation at least for the short term (4 weeks). The applicability and translation of experimental exercise paradigms to clinical trials are discussed.

Motor skills training promotes motor functional recovery and induces synaptogenesis in the motor cortex and striatum after intracerebral hemorrhage in rats

We investigated the effects of motor skills training on several types of motor function and synaptic plasticity following intracerebral hemorrhage (ICH) in rats. Male Wistar rats were injected with collagenase into the left striatum to induce ICH, and they were randomly assigned to the ICH or sham groups. Each group was divided into the motor skills training (acrobatic training) and control (no exercise) groups. The acrobatic group performed acrobatic training from 4 to 28 days after surgery. Motor functions were assessed by motor deficit score, the horizontal ladder test and the wide or narrow beam walking test at several time points after ICH. The number of ΔFosB-positive cells was counted using immunohistochemistry to examine neuronal activation, and the PSD95 protein levels were analyzed by Western blotting to examine synaptic plasticity in the bilateral sensorimotor cortices and striata at 14 and 29 days after ICH. Motor skills training following ICH significantly improved gross motor function in the early phase after ICH and skilled motor coordinated function in the late phase. The number of ΔFosB-positive cells in the contralateral sensorimotor cortex in the acrobatic group significantly increased compared to the control group. PSD95 protein expression in the motor cortex significantly increased in the late phase, and in the striatum, the protein level significantly increased in the early phase by motor skills training after ICH compared to no training after ICH. We demonstrated that motor skills training improved motor function after ICH in rats and enhanced the neural activity and synaptic plasticity in the striatum and sensorimotor cortex.

Long-term neuroprotection induced by regional brain cooling with saline infusion into ischemic territory in rats: a behavioral analysis

The neuroprotective effect of hypothermia has long been recognized. Our recent studies have demonstrated the significant therapeutic value of local brain cooling in the ischemic territory prior to reperfusion in stroke, with reduced infarction and inflammatory responses up to 48 hours of reperfusion. The goal of this study was to determine if local brain cooling, produced by infusion of cold saline, could induce long-term functional improvement after stroke. A hollow filament was used to block the middle cerebral artery (MCA) for 3 hours, and then to locally infuse the ischemic territory with 6 ml cold saline (20 degrees C) for 10 minutes prior to reperfusion. This brain cooling infusion induced a significant (p < 0.01) decrease in neurologic deficits and significantly (p < 0.01) improved motor behavior in ischemic rats after 14 days of reperfusion, compared with ischemic rats without local cold saline infusion. This improvement continued for up to 28 days after reperfusion. No significant difference in motor performance was observed between the brain cooling infusion and normal control groups. Significant (p < 0.01) reductions in infarct volume were also evident. In conclusion, a local cerebral hypothermia induced by local saline infusion prior to reperfusion produced a long-term functional recovery after ischemic stroke. A therapeutic procedure, which combines prereperfusion infusion into an ischemic region with coincident cerebral hypothermia and perhaps subsequent recanalization of an occluded intracranial vessel, may improve the outcome for stroke patients.

Predictors of early post ischemic stroke apathy and depression: a cross-sectional study

BACKGROUND

Apathy and depression are important neuropsychiatric disorders that can occur after a stroke but the etiology and risk factors are not well understood. The purpose of this study was to identify risk factors for apathy and depression following a stroke.

METHODS

Patients with an acute stroke who met the inclusion criteria were recruited from our hospital, and general information was recorded from patient charts. The Apathy Evaluation Scale, Clinician Version (AES-C) was used to evaluate these patients within 2 weeks after the stroke. The Montreal Cognitive Assessment (MoCA), mini-mental state examination (MMSE), Hamilton Depression Scale (HAMD), Mattis Dementia Rating Scale Initiation/Perseveration subset (MDRS I/P), Frontal Assessment Battery (FAB) and Stroop Color-Word Association Test were employed to evaluate emotion, cognitive function and executive function. The patients were divided into two groups: the apathy group and the non-apathy group. We also divided the patients into two groups based on whether or not they had post-stroke depression. The clinical characteristics and scores on the MoCA, MMSE, HAMD and MDRS I/P were compared between the apathy and non-apathy groups as well as between patients with and without depression. Logistic regression analysis was performed to identify risk factors for apathy and depression following a stroke.

RESULTS

A total of 75 patients with acute stroke were recruited. Of these, 25 (33.3%) developed apathy and 12 (16%) developed depression. Multivariate logistic regression analysis indicated that a history of cerebrovascular disease (OR: 6.45, 95% CI: 1.48-28.05, P = 0.013), low HbA1c (OR: 0.31, 95% CI: 0.12-0.81, P = 0.017) and a low MDRS I/P score (OR: 0.84, 95% CI: 0.74, 0.96, P = 0.010) were risk factors for post-stroke apathy. Additionally, multivariate logistic regression indicated that a low MDRS I/P (OR: 0.85, 95% CI: 0.75, 0.97, P = 0.015) was associated with post-stroke depression.

CONCLUSIONS

Three risk factors for post-stroke apathy were identified as a history of cerebrovascular disease, low HbA1c and lower MDRS I/P scores. A low MDRS I/P score was also identified as a risk factor for post-stroke depression. These results may be useful to clinicians in recognizing and treating apathy and depression in patients after a stroke.

Progesterone influences postischemic synaptogenesis in the CA1 region of the hippocampus in rats

Synaptogenesis is considered necessary for learning and memory. Recently, it has been suggested that progesterone (PROG) effects synaptogenesis of the cerebellar Purkinje cell, helps alleviate symptoms of multiple sclerosis and helps arrest spinal cord neurodegeneration. However, it is unclear whether PROG influences synaptic plasticity in central nervous system neurons after global cerebral ischemia. The purpose of the present study was to reveal PROG's influence on postischemic synaptogenesis in the CA1 region of the hippocampus in rats. Global cerebral ischemia was induced in male Sprague-Dawley rats by the 4-vessel occlusion (4-VO) method. To determine the amount of synaptogenesis, growth-associated protein 43 (GAP-43) and synaptophysin (SYP) expression were examined by immunohistochemical, reverse transcription-polymerase chain reaction (RT-PCR) and western blot techniques. Histological and behavioral tests were used to indicate the effect of PROG on global cerebral ischemia. Recovery times were 3, 7, 14, 21, and 35 days after surgery. We found that PROG increased the expression of GAP-43 and SYP. In addition, there was a significant increase in neuronal cell density and improvement ability to remain on an accelerating rotarod observed in the 4-VO rats treated with PROG compared to vehicle. We propose that PROG helped enable synaptogenesis in the CA1 region of therat hippocampus after global cerebral ischemia in rats.

Early motor balance and coordination training increased synaptophysin in subcortical regions of the ischemic rat brain

The aim of this study was to evaluate the effect of early motor balance and coordination training on functional recovery and brain plasticity in an ischemic rat stroke model, compared with simple locomotor exercise. Adult male Sprague-Dawley rats with cortical infarcts were trained under one of four conditions: nontrained control, treadmill training, motor training on the Rota-rod, or both Rota-rod and treadmill training. All types of training were performed from post-operation day 1 to 14. Neurological and behavioral performance was evaluated by Menzies' scale, the prehensile test, and the limb placement test, at post-operation day 1, 7, and 14. Both Rota-rod and treadmill training increased the expression of synaptophysin in subcortical regions of the ischemic hemisphere including the hippocampus, dentate gyrus, and thalamus, but did not affect levels of brain-derived neurotrophic factor or tyrosin kinase receptor B. The Rota-rod training also improved Menzies' scale and limb placement test scores, whereas the simple treadmill training did neither. The control group showed significant change only in Menzies' scale score. This study suggests that early motor balance and coordination training may induce plastic changes in subcortical regions of the ischemic hemisphere after stroke accompanied with the recovery of sensorimotor performance.

Exercise pre-conditioning reduces brain inflammation in stroke via tumor necrosis factor-alpha, extracellular signal-regulated kinase 1/2 and matrix metalloproteinase-9 activity

OBJECTIVE

We sought to determine whether cerebral inflammation in ischemic rats was reduced by a neuroprotective action of pre-ischemic tumor necrosis factor-alpha up-regulation, which down-regulated matrix metalloproteinase-9 activity via extracellular signal-regulated kinase 1/2 phosphorylation.

MATERIAL AND METHODS

Adult male Sprague-Dawley rats were subjected to 30 minutes of exercise on a treadmill for 3 weeks. Stroke was induced by a 2 hour middle cerebral artery occlusion using an intraluminal filament. The exercised animals were treated with tumor necrosis factor-alpha antibody, UO126 (extracellular signal-regulated kinase 1/2 inhibitor), or both UO126 and doxycycline (matrix metalloproteinase-9 inhibitor). Brain infarct volume was assessed using Nissl staining. Leukocyte infiltration was evaluated using myeloperoxidase immunostaining. Intercellular adhesion molecule-1 and matrix metalloproteinase protein levels were determined by Western blot, and enzyme activity was evaluated using zymography.

RESULTS

There was a significant decrease in neurological deficits, brain infarct volume and leukocyte infiltration, in association with reduction in matrix metalloproteinase-9 and intercellular adhesion molecule-1 expression in exercised animals. Exercised animals treated with either tumor necrosis factor-alpha antibody or with UO126 showed a reversal of neurological outcome, infarct volume and leukocyte infiltration. Matrix metalloproteinase-9 activity was reversed, at least partially, but the intercellular adhesion molecule-1 expression was not. Neuroprotection remained when the exercised ischemic rats were treated with both UO126 and doxycycline.

CONCLUSION

These results suggest that exercise-induced up-regulation of tumor necrosis factor-alpha before stroke and extracellular signal-regulated kinase 1/2 phosphorylation play a role in decreasing brain inflammation by regulating matrix metalloproteinase-9 activity.

Translational research in aphasia: from neuroscience to neurorehabilitation

PURPOSE

In this article, the authors encapsulate discussions of the Language Work Group that took place as part of the Workshop in Plasticity/NeuroRehabilitation Research at the University of Florida in April 2005.

METHOD

In this narrative review, they define neuroplasticity and review studies that demonstrate neural changes associated with aphasia recovery and treatment. The authors then summarize basic science evidence from animals, human cognition, and computational neuroscience that is relevant to aphasia treatment research. They then turn to the aphasia treatment literature in which evidence exists to support several of the neuroscience principles.

CONCLUSION

Despite the extant aphasia treatment literature, many questions remain regarding how neuroscience principles can be manipulated to maximize aphasia recovery and treatment. They propose a framework, incorporating some of these principles, that may serve as a potential roadmap for future investigations of aphasia treatment and recovery. In addition to translational investigations from basic to clinical science, the authors propose several areas in which translation can occur from clinical to basic science to contribute to the fundamental knowledge base of neurorehabilitation. This article is intended to reinvigorate interest in delineating the factors influencing successful recovery from aphasia through basic, translational, and clinical research.

Long-term monitoring of post-stroke plasticity after transient cerebral ischemia in mice using in vivo and ex vivo diffusion tensor MRI

WE USED A MURINE MODEL OF TRANSIENT FOCAL CEREBRAL ISCHEMIA TO STUDY: 1) in vivo DTI long-term temporal evolution of the apparent diffusion coefficient (ADC) and diffusion fractional anisotropy (FA) at days 4, 10, 15 and 21 after stroke 2) ex vivo distribution of a plasticity-related protein (GAP-43) and its relationship with the ex vivo DTI characteristics of the striato-thalamic pathway (21 days). All animals recovered motor function. In vivo ADC within the infarct was significantly increased after stroke. In the stroke group, GAP-43 expression and FA values were significantly higher in the ipsilateral (IL) striatum and contralateral (CL) hippocampus compared to the shams. DTI tractography showed fiber trajectories connecting the CL striatum to the stroke region, where increased GAP43 and FA were observed and fiber tracts from the CL striatum terminating in the IL hippocampus.Our data demonstrate that DTI changes parallel histological remodeling and recovery of function.

Exercise pre-conditioning ameliorates blood-brain barrier dysfunction in stroke by enhancing basal lamina

OBJECTIVE

We investigated whether exercise pre-conditioning ameliorates stroke-induced blood-brain barrier (BBB) dysfunction by strengthening basal lamina.

METHODS

Adult male Sprague-Dawley rats were subjected to a 30 minute exercise program on a treadmill each day for 3 weeks. Stroke was induced by a 2 hour middle cerebral artery (MCA) occlusion using an intraluminal filament in the exercised and non-exercised groups. BBB dysfunction was then determined by brain edema. Expression of collagen IV, the major component of basal lamina essential for maintenance of the endothelial permeability barrier, was quantitatively detected by Western blot and immunocytochemistry. Ex vivo techniques were used to compare collagen IV-labeled vessels in response to ischemic insult.

RESULTS

Brain edema was significantly (p<0.05) reduced after stroke in the exercised group. Western blot analysis indicated that exercise pre-conditioning enhanced collagen IV expression and reduced the loss after stroke. Immunocytochemistry demonstrated that collagen IV-positive vessels were significantly (p<0.01) increased in exercised rats. In ex vivo study, after exercised brain was incubated with ischemic brain tissue, a significantly (p<0.01) higher expression of collagen IV in cortex and striatum was observed compared to non-exercised brain following the same treatment. The ex vivo study also revealed that matrix metalloproteinase (MMP)-9 plays a key role in exercise-strengthened collagen IV expression against ischemia/reperfusion injury.

DISCUSSION

Our results indicate that exercise pre-conditioning improved BBB function and enhanced basal lamina, which involved MMP-9.

Increased astrocyte proliferation in rats after running exercise

The aim in this study was to investigate whether physical exercise could induce astroglial proliferation in the frontoparietal cortex and dorsolateral striatum where extensive angiogenesis had been found after exercise in previous studies. Adult male Sprague Dawley rats (n=48) were used in four experimental groups. Animals were exercised 30 min each day on a treadmill on which repetitive locomotor movement was required, for 0 (n=12), 3 (n=12) or 6 (n=12) weeks, as well as 3-week exercise plus 3-week rest (n=12). Brain tissues of the exercised and non-exercised rats were processed for glial fibrillary acidic protein (GFAP) immunocytochemistry (n=6 x 4) and Western blotting (n=6 x 4) to evaluate regional astrocyte proliferation in the frontoparietal cortex and dorsolateral striatum. By using GFAP immunocytochemistry and stereological methods, we compared the density of astrocytes in the animals with or without exercise. In comparison to non-exercised animals, a significant (p<0.01) increase in the number of astrocytes was observed in both cortex and striatum of rats exercised for 3 or 6 weeks. Our data also indicated that astrocytic density continued to increase up to 6 weeks either with an additional 3 weeks of exercise (p<0.01) or 3 weeks of rest (p<0.01). In addition, Western blotting analysis showed an obvious increase in GFAP protein from cortex and striatum of exercised animals. Astrocytosis after exercise, coupled with angiogenesis, is thought to provide strength to the neurovascular unit (a construct consisting of microvascular endothelium, astroglia, neurons and the extracellular matrix). Strengthening of this unit by exercise may protect blood-brain-barrier function following brain injury, such as that occurring after stroke.

Local saline infusion into ischemic territory induces regional brain cooling and neuroprotection in rats with transient middle cerebral artery occlusion

OBJECTIVE

The neuroprotective effect of hypothermia has long been recognized. Use of hypothermia for stroke therapy, which is currently being induced by whole-body surface cooling, has been limited primarily because of management problems and severe side effects (e.g., pneumonia). The goal of this study was to determine whether local infusion of saline into ischemic territory could induce regional brain cooling and neuroprotection.

METHODS

A novel procedure was used to block the middle cerebral artery of rats for 3 hours with a hollow filament and locally infuse the middle cerebral artery-supplied territory with 6 ml cold saline (20 degrees C) for 10 minutes before reperfusion.

RESULTS

The cold saline infusion rapidly and significantly reduced temperature in cerebral cortex from 37.2 +/- 0.1 to 33.4 +/- 0.4 degrees C and in striatum from 37.5 +/- 0.2 to 33.9 +/- 0.4 degrees C. The significant hypothermia remained for up to 60 minutes after reperfusion. Significant (P < 0.01) reductions in infarct volume (approximately 90%) were evident after 48 hours of reperfusion. In ischemic rats that received the same amount of cold saline systemically through a femoral artery, a mild hypothermia was induced only in the cerebral cortex (35.3 +/- 0.2 degrees C) and returned to normal within 5 minutes. No significant reductions in infarct volume were observed in this group or in the ischemic group with local warm saline infusion or without infusion. Furthermore, brain-cooling infusion significantly (P < 0.01) improved motor behavior in ischemic rats after 14 days of reperfusion. This improvement continued for up to 28 days after reperfusion.

CONCLUSION

Local prereperfusion infusion effectively induced hypothermia and ameliorated brain injury from stroke. Clinically, this procedure could be used in acute stroke treatment, possibly in combination with intra-arterial thrombolysis or mechanical disruption of clot by means of a microcatheter.

Exercise pre-conditioning reduces brain damage in ischemic rats that may be associated with regional angiogenesis and cellular overexpression of neurotrophin

There is increasing evidence that physical activity is associated with a decreased stroke risk. The purpose of this study was to determine if exercise could also reduce brain damage in rats subjected to transient middle cerebral artery (MCA) occlusion, and if the reduced brain injury is associated with angiogenesis as well as cellular expression of the nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in regions supplied by the MCA. Adult male Sprague Dawley rats (n=36) exercised 30 min each day for 3 weeks on a treadmill on which repetitive locomotor movement was required. Then, stroke was induced by a 2-h MCA occlusion using an intraluminal filament, followed by 48 h of reperfusion. In addition to the two exercised groups of animals with or without MCA occlusion, there were two other groups of animals, with or without MCA occlusion, housed for the same duration and used as non-exercised controls. Brain damage in ischemic rats was evaluated by neurologic deficits and infarct volume. Exercise preconditioned and non-exercised brains were processed for immunocytochemistry to quantify the number of microvessels or NGF- and BDNF-labeled cells. Pre-ischemic motor activity significantly (P<0.01) reduced neurologic deficits and infarct volume in the frontoparietal cortex and dorsolateral striatum. Cellular expressions of NGF and BDNF were significantly (P<0.01) increased in cortex (neuron) and striatum (glia) of rats under the exercise condition. Significant (P<0.01) increases in microvessel density were found in striatum. Physical activity reduced stroke damage. The reduced brain damage may be attributable to angiogenesis and neurotrophin overexpression in brain regions supplied by the MCA following exercise.

Motor balance and coordination training enhances functional outcome in rat with transient middle cerebral artery occlusion

The goal of this study was to determine if relatively complex motor training on Rota-rod involving balance and coordination plays an essential role in improving motor function in ischemic rats, as compared with simple locomotor exercise on treadmill. Adult male Sprague-Dawley rats with (n=40) or without (n=40) ischemia were trained under each of three conditions: (1) motor balance and coordination training on Rota-rod; (2) simple exercise on treadmill; and (3) non-trained controls. Motor function was evaluated by a series of tests (foot fault placing, parallel bar crossing, rope and ladder climbing) before and at 14 or 28 days after training procedures in both ischemic and normal animals. Infarct volume in ischemic animals was determined with Nissl staining. Compared with both treadmill exercised and non-trained animals, Rota-rod-trained animals with or without ischemia significantly (P<0.01) improved motor performance of all tasks except for foot fault placing after 14 days of training, with normal rats having better performance. Animals trained for up to 28 days on the treadmill did not show significantly improved function. With regard to foot fault placing task, performance on foot placing was improved in ischemic rats across the three measurements at 0, 14 and 28 days regardless of training condition, while the normal group reached their best performance at the beginning of measurement. No significant differences in infarct volume were found in rats trained either with Rota-rod (47+/-4%; mean+/-S.E.), treadmill (45+/-5%) or non-exercised control (45+/-3%). In addition, no obvious difference could be detected in the location of the damage which included the dorso-lateral portion of the neostriatum and the frontoparietal cortex, the main regions supplied by the middle cerebral artery. The data suggest that complex motor training rather than simple exercise effectively improves functional outcome.