Brain functional impairment after stroke is common;however,the molecular mechanisms of post-stroke recovery remain unclear.It is well-recognized that age is the most important independent predictor of poor outcomes af...Brain functional impairment after stroke is common;however,the molecular mechanisms of post-stroke recovery remain unclear.It is well-recognized that age is the most important independent predictor of poor outcomes after stroke as older patients show poorer functional outcomes following stroke.Mounting evidence suggests that axonal regeneration and angiogenesis,the major forms of brain plasticity responsible for post-stroke recovery,diminished with advanced age.Previous studies suggest that Ras-related C3 botulinum toxin substrate(Rac)1 enhances stroke recovery as activation of Rac1 improved behavior recovery in a young mice stroke model.Here,we investigated the role of Rac1 signaling in long-term functional recovery and brain plasticity in an aged(male,18 to 22 months old C57BL/6J)brain after ischemic stroke.We found that as mice aged,Rac1 expression declined in the brain.Delayed overexpression of Rac1,using lentivirus encoding Rac1 injected day 1 after ischemic stroke,promoted cognitive(assessed using novel object recognition test)and sensorimotor(assessed using adhesive removal tests)recovery on days 14–28.This was accompanied by the increase of neurite and proliferative endothelial cells in the periinfarct zone assessed by immunostaining.In a reverse approach,pharmacological inhibition of Rac1 by intraperitoneal injection of Rac1 inhibitor NSC23766 for 14 successive days after ischemic stroke worsened the outcome with the reduction of neurite and proliferative endothelial cells.Furthermore,Rac1 inhibition reduced the activation of p21-activated kinase 1,the protein level of brain-derived neurotrophic factor,and increased the protein level of glial fibrillary acidic protein in the ischemic brain on day 28 after stroke.Our work provided insight into the mechanisms behind the diminished plasticity after cerebral ischemia in aged brains and identified Rac1 as a potential therapeutic target for improving functional recovery in the older adults after stroke.展开更多
Very little is known about the effects of transcranial magnetic stimulation and rehabilitation training on pyramidal cell dendrites and synapses of the contralateral, unaffected sensorimotor cortex in a rat model of f...Very little is known about the effects of transcranial magnetic stimulation and rehabilitation training on pyramidal cell dendrites and synapses of the contralateral, unaffected sensorimotor cortex in a rat model of focal cerebral infarct. The present study was designed to explore the mechanisms underlying improved motor function via transcranial magnetic stimulation and rehabilitation training following cerebral infarction. Results showed that rehabilitation training or transcranial magnetic stimulation alone reduced neurological impairment in rats following cerebral infarction, as well as significantly increased synaptic curvatures and post-synaptic density in the non-injured cerebral hemisphere sensorimotor cortex and narrowed the synapse cleft width. In addition, the percentage of perforated synapses increased. The combination of transcranial magnetic stimulation and rehabilitation resulted in significantly increased total dendritic length, dendritic branching points, and dendritic density in layer V pyramidal cells of the non-injured cerebral hemisphere motor cortex. These results demonstrated that transcranial magnetic stimulation and rehabilitation training altered structural parameters of pyramidal cell dendrites and synapses in the non-injured cerebral hemisphere sensorimotor cortex, thereby improving the ability to compensate for neurological functions in rats following cerebral infarction.展开更多
Brain plasticity, including anatomical changes and functional reorganization, is the physiological basis of functional recovery after spinal cord injury(SCI). The correlation between brain anatomical changes and fun...Brain plasticity, including anatomical changes and functional reorganization, is the physiological basis of functional recovery after spinal cord injury(SCI). The correlation between brain anatomical changes and functional reorganization after SCI is unclear. This study aimed to explore whether alterations of cortical structure and network function are concomitant in sensorimotor areas after incomplete SCI. Eighteen patients with incomplete SCI(mean age 40.94 ± 14.10 years old; male:female, 7:11) and 18 healthy subjects(37.33 ± 11.79 years old; male:female, 7:11) were studied by resting state functional magnetic resonance imaging. Gray matter volume(GMV) and functional connectivity were used to evaluate cortical structure and network function, respectively. There was no significant alteration of GMV in sensorimotor areas in patients with incomplete SCI compared with healthy subjects. Intra-hemispheric functional connectivity between left primary somatosensory cortex(BA1) and left primary motor cortex(BA4), and left BA1 and left somatosensory association cortex(BA5) was decreased, as well as inter-hemispheric functional connectivity between left BA1 and right BA4, left BA1 and right BA5, and left BA4 and right BA5 in patients with SCI. Functional connectivity between both BA4 areas was also decreased. The decreased functional connectivity between the left BA1 and the right BA4 positively correlated with American Spinal Injury Association sensory score in SCI patients. The results indicate that alterations of cortical anatomical structure and network functional connectivity in sensorimotor areas were non-concomitant in patients with incomplete SCI, indicating the network functional changes in sensorimotor areas may not be dependent on anatomic structure. The strength of functional connectivity within sensorimotor areas could serve as a potential imaging biomarker for assessment and prediction of sensory function in patients with incomplete SCI. This trial was registered with the Chinese Clinical Trial Registry(registration number: Chi CTR-ROC-17013566).展开更多
The study aims to confirm the neuroregenerative effects of bacterial melanin (BM) on central nervous system injury using a special staining method based on the detection of Ca^2+-dependent acid phosphatase activity...The study aims to confirm the neuroregenerative effects of bacterial melanin (BM) on central nervous system injury using a special staining method based on the detection of Ca^2+-dependent acid phosphatase activity. Twenty-four rats were randomly assigned to undergo either unilateral destruction of sensorimotor cortex (group I; n = 12) or unilateral rubrospinal tract transection at the cervical level (C3-4) (group II; n = 12). In each group, six rats were randomly selected after surgery to undergo intramuscular injection of BM solution (BM subgroup) and the remaining six rats were intramuscularly in)ected with saline (saline subgroup). Neurological testing confirmed that BM accelerated the recovery of motor function in rats from both BM and saline subgroups. Two months after surgery, Ca^2+-dependent acid phosphatase activity detection in combination with Chilingarian's calcium adenoside triphosphate method revealed that BM stimulated the sprouting of fibers and dilated the capillaries in the brain and spinal cord. These results suggest that BM can promote the recovery of motor function of rats with central nervous system injury; and detection of Ca^2+-dependent acid phosphatase activity is a fast and easy method used to study the regeneration-promoting effects of BM on the injured central nervous system.展开更多
Perceiving pitch is a central function of the human auditory system;congenital amusia is a disorder of pitch perception.The underlying neural mechanisms of congenital amusia have been actively discussed.However,little...Perceiving pitch is a central function of the human auditory system;congenital amusia is a disorder of pitch perception.The underlying neural mechanisms of congenital amusia have been actively discussed.However,little attention has been paid to the changes in the motor rain within congenital amusia.In this case-control study,17 participants with congenital amusia and 14 healthy controls underwent functional magnetic resonance imaging while resting with their eyes closed.A voxel-based degree centrality method was used to identify abnormal functional network centrality by comparing degree centrality values between the congenital amusia group and the healthy control group.We found decreased degree centrality values in the right primary sensorimotor areas in participants with congenital amusia relative to controls,indicating potentially decreased centrality of the corresponding brain regions in the auditory-sensory motor feedback network.We found a significant positive correlation between the degree centrality values and the Montreal Battery of Evaluation of Amusia scores.In conclusion,our study identified novel,hitherto undiscussed candidate brain regions that may partly contribute to or be modulated by congenital amusia.Our evidence supports the view that sensorimotor coupling plays an important role in memory and musical discrimination.The study was approved by the Ethics Committee of the Second Xiangya Hospital,Central South University,China(No.WDX20180101GZ01)on February 9,2019.展开更多
Mice subjected to an irregular light-dark cycle are known to lose their capacity to synchronize their behavioral rhythm to environmental light, and to show endophenotypes related to depressive disorders. Here we obser...Mice subjected to an irregular light-dark cycle are known to lose their capacity to synchronize their behavioral rhythm to environmental light, and to show endophenotypes related to depressive disorders. Here we observed that a susceptible strain of mice (C3H/HeJ) subjected to an irregular 3.5 hr:3.5 hr light-dark cycle showed an enhanced acoustic startle reflex and deficits in prepulse inhibition. As impaired sensorimotor gating is associated with the onset of a variety of mental disorders such as schizophrenia and major depressive disorder, irregular environmental light without circadian photo-entrainment may cause stress that has the potential to be involved in humans’ susceptibility to neuropsychiatric abnormalities.展开更多
Background:Warm acupuncture,or warm-needle acupuncture,is a traditional external treatment widely used in China for thousands of years.However,the effects of different treatment times on limb spasticity post-stroke ha...Background:Warm acupuncture,or warm-needle acupuncture,is a traditional external treatment widely used in China for thousands of years.However,the effects of different treatment times on limb spasticity post-stroke have not been evaluated.Methods:We searched PubMed,Embase,the Cochrane Library,the Web of Science,the China National Knowledge Infrastructure,the Chinese Scientific and Journal Database,the Wanfang database,and the Chinese Biomedical Literature Database from inception to May 21st,2020,to seek information regarding randomized controlled trials studying warm-needle acupuncture for limb spasticity post-stroke.Two authors selected 24 studies fitting the eligibility criteria and developed this systematic review and meta-analysis.Results:Warm-needle acupuncture is shown to be more effective than other treatments used in the control groups(odds ratio(OR)=3.61,95%confidence intervals(CI)(2.51,5.19),P<0.001).This treatment decreased limb spasticity as assessed with the Modified Ashworth Scale(mean differences(MD)=−0.78,95%CI(−1.00,−0.56),P<0.001)and the Clinic Spasticity Index(MD=1.06,95%CI(0.51,1.60),P=0.0002),improved sensorimotor impairments according to the Fugl-Meyer Assessment(MD=9.51,95%CI(6.99,12.03),P<0.001),and improved activities of daily living according to the Barthel Index(MD=9.70,95%CI(6.27,13.12),P<0.001).Subgroup analysis based on the length of the treatment using the Modified Ashworth Scale,Fugl-Meyer Assessment,and Barthel Index showed better outcomes for patients who received more than 20 days of treatments(P<0.001).Conclusion:Warm-needle acupuncture is an effective treatment for limb spasticity post-stroke.A treatment frequency of more than 20 days appears to have better effectiveness than that of less than 20 days.展开更多
Norepinephrine plays an important role in motor functional recovery after a brain injury caused by ferrous chloride.Inhibition of norepinephrine release by clonidine is correlated with motor deficits after motor corte...Norepinephrine plays an important role in motor functional recovery after a brain injury caused by ferrous chloride.Inhibition of norepinephrine release by clonidine is correlated with motor deficits after motor cortex injury.The aim of this study was to analyze the role ofα-adrenergic receptors in the restoration of motor deficits in recovering rats after brain damage.The rats were randomly assigned to the sham and injury groups and then treated with the following pharmacological agents at 3 hours before and 8 hours,3 days,and 20 days after ferrous chloride-induced cortical injury:saline,clonidine,efaroxan(a selective antagonist ofα-adrenergic receptors)and clonidine+efaroxan.The sensorimotor score,the immunohistochemical staining forα-adrenergic receptors,and norepinephrine levels were evaluated.Eight hours post-injury,the sensorimotor score and norepinephrine levels in the locus coeruleus of the injured rats decreased,and these effects were maintained 3 days post-injury.However,20 days later,clonidine administration diminished norepinephrine levels in the pons compared with the sham group.This effect was accompanied by sensorimotor deficits.These effects were blocked by efaroxan.In conclusion,an increase inα-adrenergic receptor levels was observed after injury.Clonidine restores motor deficits in rats recovering from cortical injury,an effect that was prevented by efaroxan.The underlying mechanisms involve the stimulation of hypersensitiveα-adrenergic receptors and inhibition of norepinephrine activity in the locus coeruleus.The results of this study suggest thatαreceptor agonists might restore deficits or impede rehabilitation in patients with brain injury,and therefore pharmacological therapies need to be prescribed cautiously to these patients.展开更多
Objectives:To examine the effects of 16-week Tai Chi(TC) training on postural stability and associated physiological factors in older subjects,forty elderly individuals(aged ≥ 60 years) living in the community were r...Objectives:To examine the effects of 16-week Tai Chi(TC) training on postural stability and associated physiological factors in older subjects,forty elderly individuals(aged ≥ 60 years) living in the community were randomly placed into either the TC intervention group(n=22) or the control group(n=18).The former underwent a supervised TC exercise program for 16 weeks,while the latter received general education for a comparable time period.Measurements:Postural stability was assessed by timed stance tests in single-leg stance with the eyes open(SLO) or closed(SLC),and tandem stance with the eyes closed(TSC).Proprioceptive function was evaluated by measuring ankle and knee kinesthesia.The maximum concentric strength of the knee flexors and extensors,ankle plantarflexors and dorsiflexors was measured by isokinetic dynamometer.Moreover,the reaction time of different muscles in the lower extremity was also examined by measuring the onset latency of the muscles to perturbations on the ankle joint using an electromyography system.Results:After the 16-week TC intervention,significant TC training effects were gained on knee kinesthesia,knee flexor strength,latency of semitendinous muscle,and postural stability in SLO.For the other measures,no significant training effects were found.Conclusions:The 16-week TC intervention was found to be beneficial for the improvement of postural stability and associated physiological factors.However,there are discrepancies in TC training effects on different factors in the sensorimotor system.展开更多
Objective of the study: This study aimed at characterizing output features of the higher-order motor control centers (hoMCCs), including secondary (premotor cortex [Pre] and supplementary motor area [SMA]) and associa...Objective of the study: This study aimed at characterizing output features of the higher-order motor control centers (hoMCCs), including secondary (premotor cortex [Pre] and supplementary motor area [SMA]) and association (prefrontal cortex [PFC]) motor regions to the primary motor cortex (M1) during graded force tasks. It is well known that one of the major roles of the primary motor cortex (M1) is controlling motor output such as muscle force. However, it is unclear how the hoMCCs interact with M1 in regulating voluntary muscle contractions. Methods: fMRI data was acquired during graded force tasks and fMRI-based effective connectivity (EC) and muscle force analyses were performed to study the relationship between hoMCCs-M1 effective connectivity and voluntarily exerted handgrip force. Results: The results show that there is a consistent information flow from the hoMCCs to M1 under all force conditions, suggesting a hierarchical control mechanism in the brain in regulating voluntary muscle force. Only the premotor cortex exhibited a significant role in mediating the level of force production through its EC with M1 but that role diminished when the exerted force was high, suggesting perhaps a ceiling and/or fatigue effect on the EC. A flip in the direction of EC from the primary sensory cortex (S1) to the hoMCCs (PFC, SMA, and Pre) at lower force levels while at higher forces EC was observed from the hoMCCs to S1. Conclusion: The hoMCCs regulate M1 output to produce desired voluntary muscle force. Only the Pre-to-M1 connectivity strength directly correlates with the force level especially from low to moderate levels. The hoMCCs are involved in modulating higher force production likely by strengthening M1 output and downgrad<span style="font-size:12px;line-height:102%;font-family:Verdana;">ing</span><span style="font-size:12px;line-height:102%;font-family:Verdana;"> inhibition from S1 to M1.</span>展开更多
基金supported by NIH grants RF1 AG069466(to JL and LDM),R01 NS099628(to JL),and AG069466(to JL and LDM)the American Heart Association award 20POST35180172(to FB)。
文摘Brain functional impairment after stroke is common;however,the molecular mechanisms of post-stroke recovery remain unclear.It is well-recognized that age is the most important independent predictor of poor outcomes after stroke as older patients show poorer functional outcomes following stroke.Mounting evidence suggests that axonal regeneration and angiogenesis,the major forms of brain plasticity responsible for post-stroke recovery,diminished with advanced age.Previous studies suggest that Ras-related C3 botulinum toxin substrate(Rac)1 enhances stroke recovery as activation of Rac1 improved behavior recovery in a young mice stroke model.Here,we investigated the role of Rac1 signaling in long-term functional recovery and brain plasticity in an aged(male,18 to 22 months old C57BL/6J)brain after ischemic stroke.We found that as mice aged,Rac1 expression declined in the brain.Delayed overexpression of Rac1,using lentivirus encoding Rac1 injected day 1 after ischemic stroke,promoted cognitive(assessed using novel object recognition test)and sensorimotor(assessed using adhesive removal tests)recovery on days 14–28.This was accompanied by the increase of neurite and proliferative endothelial cells in the periinfarct zone assessed by immunostaining.In a reverse approach,pharmacological inhibition of Rac1 by intraperitoneal injection of Rac1 inhibitor NSC23766 for 14 successive days after ischemic stroke worsened the outcome with the reduction of neurite and proliferative endothelial cells.Furthermore,Rac1 inhibition reduced the activation of p21-activated kinase 1,the protein level of brain-derived neurotrophic factor,and increased the protein level of glial fibrillary acidic protein in the ischemic brain on day 28 after stroke.Our work provided insight into the mechanisms behind the diminished plasticity after cerebral ischemia in aged brains and identified Rac1 as a potential therapeutic target for improving functional recovery in the older adults after stroke.
基金Yantai Science and Technology Development Projects, No. 2008142-5
文摘Very little is known about the effects of transcranial magnetic stimulation and rehabilitation training on pyramidal cell dendrites and synapses of the contralateral, unaffected sensorimotor cortex in a rat model of focal cerebral infarct. The present study was designed to explore the mechanisms underlying improved motor function via transcranial magnetic stimulation and rehabilitation training following cerebral infarction. Results showed that rehabilitation training or transcranial magnetic stimulation alone reduced neurological impairment in rats following cerebral infarction, as well as significantly increased synaptic curvatures and post-synaptic density in the non-injured cerebral hemisphere sensorimotor cortex and narrowed the synapse cleft width. In addition, the percentage of perforated synapses increased. The combination of transcranial magnetic stimulation and rehabilitation resulted in significantly increased total dendritic length, dendritic branching points, and dendritic density in layer V pyramidal cells of the non-injured cerebral hemisphere motor cortex. These results demonstrated that transcranial magnetic stimulation and rehabilitation training altered structural parameters of pyramidal cell dendrites and synapses in the non-injured cerebral hemisphere sensorimotor cortex, thereby improving the ability to compensate for neurological functions in rats following cerebral infarction.
基金supported by a grant from Tsinghua University Initiative Scientific Research Program,No.2014081266,20131089382the National Natural Science Foundation of China,No.61171002,60372023
文摘Brain plasticity, including anatomical changes and functional reorganization, is the physiological basis of functional recovery after spinal cord injury(SCI). The correlation between brain anatomical changes and functional reorganization after SCI is unclear. This study aimed to explore whether alterations of cortical structure and network function are concomitant in sensorimotor areas after incomplete SCI. Eighteen patients with incomplete SCI(mean age 40.94 ± 14.10 years old; male:female, 7:11) and 18 healthy subjects(37.33 ± 11.79 years old; male:female, 7:11) were studied by resting state functional magnetic resonance imaging. Gray matter volume(GMV) and functional connectivity were used to evaluate cortical structure and network function, respectively. There was no significant alteration of GMV in sensorimotor areas in patients with incomplete SCI compared with healthy subjects. Intra-hemispheric functional connectivity between left primary somatosensory cortex(BA1) and left primary motor cortex(BA4), and left BA1 and left somatosensory association cortex(BA5) was decreased, as well as inter-hemispheric functional connectivity between left BA1 and right BA4, left BA1 and right BA5, and left BA4 and right BA5 in patients with SCI. Functional connectivity between both BA4 areas was also decreased. The decreased functional connectivity between the left BA1 and the right BA4 positively correlated with American Spinal Injury Association sensory score in SCI patients. The results indicate that alterations of cortical anatomical structure and network functional connectivity in sensorimotor areas were non-concomitant in patients with incomplete SCI, indicating the network functional changes in sensorimotor areas may not be dependent on anatomic structure. The strength of functional connectivity within sensorimotor areas could serve as a potential imaging biomarker for assessment and prediction of sensory function in patients with incomplete SCI. This trial was registered with the Chinese Clinical Trial Registry(registration number: Chi CTR-ROC-17013566).
基金supported by the Armenian National Science and Education Fund for Project in New York,USA(No.ANSEF biotech-4241)
文摘The study aims to confirm the neuroregenerative effects of bacterial melanin (BM) on central nervous system injury using a special staining method based on the detection of Ca^2+-dependent acid phosphatase activity. Twenty-four rats were randomly assigned to undergo either unilateral destruction of sensorimotor cortex (group I; n = 12) or unilateral rubrospinal tract transection at the cervical level (C3-4) (group II; n = 12). In each group, six rats were randomly selected after surgery to undergo intramuscular injection of BM solution (BM subgroup) and the remaining six rats were intramuscularly in)ected with saline (saline subgroup). Neurological testing confirmed that BM accelerated the recovery of motor function in rats from both BM and saline subgroups. Two months after surgery, Ca^2+-dependent acid phosphatase activity detection in combination with Chilingarian's calcium adenoside triphosphate method revealed that BM stimulated the sprouting of fibers and dilated the capillaries in the brain and spinal cord. These results suggest that BM can promote the recovery of motor function of rats with central nervous system injury; and detection of Ca^2+-dependent acid phosphatase activity is a fast and easy method used to study the regeneration-promoting effects of BM on the injured central nervous system.
基金supported by the National Natural Science Foundation of China,No.81771172(to DXW),81671671(to JL)the Second Xiangya Hospital Start-Up Fund,China。
文摘Perceiving pitch is a central function of the human auditory system;congenital amusia is a disorder of pitch perception.The underlying neural mechanisms of congenital amusia have been actively discussed.However,little attention has been paid to the changes in the motor rain within congenital amusia.In this case-control study,17 participants with congenital amusia and 14 healthy controls underwent functional magnetic resonance imaging while resting with their eyes closed.A voxel-based degree centrality method was used to identify abnormal functional network centrality by comparing degree centrality values between the congenital amusia group and the healthy control group.We found decreased degree centrality values in the right primary sensorimotor areas in participants with congenital amusia relative to controls,indicating potentially decreased centrality of the corresponding brain regions in the auditory-sensory motor feedback network.We found a significant positive correlation between the degree centrality values and the Montreal Battery of Evaluation of Amusia scores.In conclusion,our study identified novel,hitherto undiscussed candidate brain regions that may partly contribute to or be modulated by congenital amusia.Our evidence supports the view that sensorimotor coupling plays an important role in memory and musical discrimination.The study was approved by the Ethics Committee of the Second Xiangya Hospital,Central South University,China(No.WDX20180101GZ01)on February 9,2019.
文摘Mice subjected to an irregular light-dark cycle are known to lose their capacity to synchronize their behavioral rhythm to environmental light, and to show endophenotypes related to depressive disorders. Here we observed that a susceptible strain of mice (C3H/HeJ) subjected to an irregular 3.5 hr:3.5 hr light-dark cycle showed an enhanced acoustic startle reflex and deficits in prepulse inhibition. As impaired sensorimotor gating is associated with the onset of a variety of mental disorders such as schizophrenia and major depressive disorder, irregular environmental light without circadian photo-entrainment may cause stress that has the potential to be involved in humans’ susceptibility to neuropsychiatric abnormalities.
文摘Background:Warm acupuncture,or warm-needle acupuncture,is a traditional external treatment widely used in China for thousands of years.However,the effects of different treatment times on limb spasticity post-stroke have not been evaluated.Methods:We searched PubMed,Embase,the Cochrane Library,the Web of Science,the China National Knowledge Infrastructure,the Chinese Scientific and Journal Database,the Wanfang database,and the Chinese Biomedical Literature Database from inception to May 21st,2020,to seek information regarding randomized controlled trials studying warm-needle acupuncture for limb spasticity post-stroke.Two authors selected 24 studies fitting the eligibility criteria and developed this systematic review and meta-analysis.Results:Warm-needle acupuncture is shown to be more effective than other treatments used in the control groups(odds ratio(OR)=3.61,95%confidence intervals(CI)(2.51,5.19),P<0.001).This treatment decreased limb spasticity as assessed with the Modified Ashworth Scale(mean differences(MD)=−0.78,95%CI(−1.00,−0.56),P<0.001)and the Clinic Spasticity Index(MD=1.06,95%CI(0.51,1.60),P=0.0002),improved sensorimotor impairments according to the Fugl-Meyer Assessment(MD=9.51,95%CI(6.99,12.03),P<0.001),and improved activities of daily living according to the Barthel Index(MD=9.70,95%CI(6.27,13.12),P<0.001).Subgroup analysis based on the length of the treatment using the Modified Ashworth Scale,Fugl-Meyer Assessment,and Barthel Index showed better outcomes for patients who received more than 20 days of treatments(P<0.001).Conclusion:Warm-needle acupuncture is an effective treatment for limb spasticity post-stroke.A treatment frequency of more than 20 days appears to have better effectiveness than that of less than 20 days.
基金supported by Consejo Nacional de Ciencia y Tecnología(CONACy T)project CB 2016-287614(to RGP and ABN)by Scholarship Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica de la Universidad Nacional Autónoma de México(PAPIIT-UNAM)IA203319 and PAPIIT-UNAM IN216221 to(LERL)。
文摘Norepinephrine plays an important role in motor functional recovery after a brain injury caused by ferrous chloride.Inhibition of norepinephrine release by clonidine is correlated with motor deficits after motor cortex injury.The aim of this study was to analyze the role ofα-adrenergic receptors in the restoration of motor deficits in recovering rats after brain damage.The rats were randomly assigned to the sham and injury groups and then treated with the following pharmacological agents at 3 hours before and 8 hours,3 days,and 20 days after ferrous chloride-induced cortical injury:saline,clonidine,efaroxan(a selective antagonist ofα-adrenergic receptors)and clonidine+efaroxan.The sensorimotor score,the immunohistochemical staining forα-adrenergic receptors,and norepinephrine levels were evaluated.Eight hours post-injury,the sensorimotor score and norepinephrine levels in the locus coeruleus of the injured rats decreased,and these effects were maintained 3 days post-injury.However,20 days later,clonidine administration diminished norepinephrine levels in the pons compared with the sham group.This effect was accompanied by sensorimotor deficits.These effects were blocked by efaroxan.In conclusion,an increase inα-adrenergic receptor levels was observed after injury.Clonidine restores motor deficits in rats recovering from cortical injury,an effect that was prevented by efaroxan.The underlying mechanisms involve the stimulation of hypersensitiveα-adrenergic receptors and inhibition of norepinephrine activity in the locus coeruleus.The results of this study suggest thatαreceptor agonists might restore deficits or impede rehabilitation in patients with brain injury,and therefore pharmacological therapies need to be prescribed cautiously to these patients.
文摘Objectives:To examine the effects of 16-week Tai Chi(TC) training on postural stability and associated physiological factors in older subjects,forty elderly individuals(aged ≥ 60 years) living in the community were randomly placed into either the TC intervention group(n=22) or the control group(n=18).The former underwent a supervised TC exercise program for 16 weeks,while the latter received general education for a comparable time period.Measurements:Postural stability was assessed by timed stance tests in single-leg stance with the eyes open(SLO) or closed(SLC),and tandem stance with the eyes closed(TSC).Proprioceptive function was evaluated by measuring ankle and knee kinesthesia.The maximum concentric strength of the knee flexors and extensors,ankle plantarflexors and dorsiflexors was measured by isokinetic dynamometer.Moreover,the reaction time of different muscles in the lower extremity was also examined by measuring the onset latency of the muscles to perturbations on the ankle joint using an electromyography system.Results:After the 16-week TC intervention,significant TC training effects were gained on knee kinesthesia,knee flexor strength,latency of semitendinous muscle,and postural stability in SLO.For the other measures,no significant training effects were found.Conclusions:The 16-week TC intervention was found to be beneficial for the improvement of postural stability and associated physiological factors.However,there are discrepancies in TC training effects on different factors in the sensorimotor system.
文摘Objective of the study: This study aimed at characterizing output features of the higher-order motor control centers (hoMCCs), including secondary (premotor cortex [Pre] and supplementary motor area [SMA]) and association (prefrontal cortex [PFC]) motor regions to the primary motor cortex (M1) during graded force tasks. It is well known that one of the major roles of the primary motor cortex (M1) is controlling motor output such as muscle force. However, it is unclear how the hoMCCs interact with M1 in regulating voluntary muscle contractions. Methods: fMRI data was acquired during graded force tasks and fMRI-based effective connectivity (EC) and muscle force analyses were performed to study the relationship between hoMCCs-M1 effective connectivity and voluntarily exerted handgrip force. Results: The results show that there is a consistent information flow from the hoMCCs to M1 under all force conditions, suggesting a hierarchical control mechanism in the brain in regulating voluntary muscle force. Only the premotor cortex exhibited a significant role in mediating the level of force production through its EC with M1 but that role diminished when the exerted force was high, suggesting perhaps a ceiling and/or fatigue effect on the EC. A flip in the direction of EC from the primary sensory cortex (S1) to the hoMCCs (PFC, SMA, and Pre) at lower force levels while at higher forces EC was observed from the hoMCCs to S1. Conclusion: The hoMCCs regulate M1 output to produce desired voluntary muscle force. Only the Pre-to-M1 connectivity strength directly correlates with the force level especially from low to moderate levels. The hoMCCs are involved in modulating higher force production likely by strengthening M1 output and downgrad<span style="font-size:12px;line-height:102%;font-family:Verdana;">ing</span><span style="font-size:12px;line-height:102%;font-family:Verdana;"> inhibition from S1 to M1.</span>