1
|
Wen TC, Corkrum M, Carmel JB. Selective injury of thalamocortical tract in neonatal rats impairs forelimb use: model validation and behavioral effects. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.07.607003. [PMID: 39211132 PMCID: PMC11361120 DOI: 10.1101/2024.08.07.607003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Unilateral brain injury in neonates results in largely contralateral hand function in children. Most research investigating neurorehabilitation targets for movement recovery has focused on the effects of brain injury on descending motor systems, especially the corticospinal tract. However, a recent human study demonstrated that sensory tract injury may have larger effects on dexterity than motor tract injury. To validate that the sensory tract injury impairs dexterity, we modeled the most common site of sensory tract injury in neonates by targeting the thalamocortical tract. In the postnatal day 7 rats, we used three types of lesions to the thalamocortical tract: periventricular blood injection, photothrombotic lesion, and electrolytic lesion. To test the sensitivity and specificity of these techniques, viral tracers were injected into the primary sensory or motor cortex immediately after injury. Electrolytic lesions were the most specific and reproducible for inducing a lesion compared to the other two methods. Electrolytic lesions disrupted 63% of the thalamocortical tract, while sparing the adjacent corticospinal tract in the internal capsule. To measure the impact on dexterity, the cylinder exploration and pasta handling tests were used to test the changes of forelimb use at 8 weeks after injury when the rats reached maturity. Lesions to the thalamocortical tract were associated with a significant decrease in the use of the contralateral forelimb in the cylinder task, and the degree of impairment positively correlated with the degree of injury. Overall, specific sensory system lesions of the thalamocortical tract impair forelimb use, suggesting a key role for skilled movement.
Collapse
|
2
|
Jaekel F, Paino J, Engels E, Klein M, Barnes M, Häusermann D, Hall C, Zheng G, Wang H, Hildebrandt G, Lerch M, Schültke E. The Spinal Cord as Organ of Risk: Assessment for Acute and Subacute Neurological Adverse Effects after Microbeam Radiotherapy in a Rodent Model. Cancers (Basel) 2023; 15:cancers15092470. [PMID: 37173938 PMCID: PMC10177263 DOI: 10.3390/cancers15092470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/16/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
Microbeam radiotherapy (MRT), a high dose rate radiotherapy technique using spatial dose fractionation at the micrometre range, has shown a high therapeutic efficacy in vivo in different tumour entities, including lung cancer. We have conducted a toxicity study for the spinal cord as organ of risk during irradiation of a target in the thoracic cavity. In young adult rats, the lower thoracic spinal cord was irradiated over a length of 2 cm with an array of quasi-parallel microbeams of 50 µm width, spaced at a centre-to-centre distance of 400 µm, with MRT peak doses up to 800 Gy. No acute or subacute adverse effects were observed within the first week after irradiation up to MRT peak doses of 400 Gy. No significant differences were seen between irradiated animals and non-irradiated controls in motor function and sensitivity, open field test and somatosensory evoked potentials (SSEP). After irradiation with MRT peak doses of 450-800 Gy, dose-dependent neurologic signs occurred. Provided that long-term studies do not reveal significant morbidity due to late toxicity, an MRT dose of 400 Gy can be considered safe for the spinal cord in the tested beam geometry and field size.
Collapse
Affiliation(s)
- Felix Jaekel
- Department of Radiooncology, Rostock University Medical Center, 18059 Rostock, Germany
| | - Jason Paino
- Centre of Medical Radiation Physics, University of Wollongong, Wollongong 2522, Australia
| | - Elette Engels
- Centre of Medical Radiation Physics, University of Wollongong, Wollongong 2522, Australia
| | - Mitzi Klein
- Australian Synchrotron, ANSTO, Clayton 3168, Australia
| | - Micah Barnes
- Australian Synchrotron, ANSTO, Clayton 3168, Australia
| | | | | | - Gang Zheng
- Monash Biomedical Imaging, Clayton 3168, Australia
| | - Hongxin Wang
- Monash Biomedical Imaging, Clayton 3168, Australia
| | - Guido Hildebrandt
- Department of Radiooncology, Rostock University Medical Center, 18059 Rostock, Germany
| | - Michael Lerch
- Centre of Medical Radiation Physics, University of Wollongong, Wollongong 2522, Australia
| | - Elisabeth Schültke
- Department of Radiooncology, Rostock University Medical Center, 18059 Rostock, Germany
| |
Collapse
|
3
|
Liu W, He X, Lin H, Yang M, Dai Y, Chen L, Li C, Liang S, Tao J, Chen L. Ischemic stroke rehabilitation through optogenetic modulation of parvalbumin neurons in the contralateral motor cortex. Exp Neurol 2023; 360:114289. [PMID: 36471512 DOI: 10.1016/j.expneurol.2022.114289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/09/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Based on the theory of interhemispheric inhibition and the bimodal balance-recovery model in stroke, we explored the effects of excitation/inhibition (E/I) of parvalbumin (PV) neurons in the contralateral primary motor cortex (cM1) connecting the ipsilateral M1 (iM1) via the corpus callosum (cM1-CC-iM1) of ischemic stroke rats by optogenetic stimulation. METHODS We tested this by injecting anterograde and retrograde virus in rats with middle cerebral artery occlusion (MCAO), and evaluated the neurological scores, motor behavior, volume of cerebral infarction and the E/I balance of the bilateral M1 two weeks after employing optogenetic treatment. RESULTS We found that concentrations of Glu and GABA decreased and increased, respectively, in the iM1 of MCAO rats, and that the former increased in the cM1, suggesting E/I imbalance in bilateral M1 after ischemic stroke. Interestingly, optogenetic stimulation improved M1 E/I imbalance, as illustrated by the increase of Glu in the iM1 and the decrease of GABA in both iM1 and cM1, which were accompanied by an improvement in neurological deficit and motor dysfunction. In addition, we observed a reduced infarct volume, an increase in the expression of the NMDAR and AMPAR, and a decrease in GAD67 in the iM1 after intervention. CONCLUSIONS Optogenetic modulation of PV neurons of the iM1-CC-cM1 improve E/I balance, leading to reduced neurological deficit and improved motor dysfunction following ischemic stroke in rats.
Collapse
Affiliation(s)
- Weilin Liu
- Rehabilitation Industry institute, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Xiaojun He
- Rehabilitation Industry institute, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Huawei Lin
- Rehabilitation Industry institute, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Minguang Yang
- Rehabilitation Industry institute, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Yaling Dai
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Lewen Chen
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Chaohui Li
- General surgery, Anxi General Hospital of Traditional Chinese Medicine, Quanzhou, Fujian 362400, China
| | - Shengxiang Liang
- Rehabilitation Industry institute, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Jing Tao
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Lidian Chen
- Rehabilitation Industry institute, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China.
| |
Collapse
|
4
|
Sysoev YI, Prikhodko VA, Idiyatullin RD, Chernyakov RT, Karev VE, Okovityi SV. A Method for Chronic Registration of Brain Cortical Electrical Activity in Rats. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022010252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
5
|
Rapid and Bihemispheric Reorganization of Neuronal Activity in Premotor Cortex after Brain Injury. J Neurosci 2021; 41:9112-9128. [PMID: 34556488 PMCID: PMC8570830 DOI: 10.1523/jneurosci.0196-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 09/02/2021] [Accepted: 09/07/2021] [Indexed: 12/21/2022] Open
Abstract
Brain injuries cause hemodynamic changes in several distant, spared areas from the lesion. Our objective was to better understand the neuronal correlates of this reorganization in awake, behaving female monkeys. We used reversible inactivation techniques to “injure” the primary motor cortex, while continuously recording neuronal activity of the ventral premotor cortex in the two hemispheres, before and after the onset of behavioral impairments. Inactivation rapidly induced profound alterations of neuronal discharges that were heterogeneous within each and across the two hemispheres, occurred during movements of either the affected or nonaffected arm, and varied during different phases of grasping. Our results support that extensive, and much more complex than expected, neuronal reorganization takes place in spared areas of the bihemispheric cortical network involved in the control of hand movements. This broad pattern of reorganization offers potential targets that should be considered for the development of neuromodulation protocols applied early after brain injury. SIGNIFICANCE STATEMENT It is well known that brain injuries cause changes in several distant, spared areas of the network, often in the premotor cortex. This reorganization is greater early after the injury and the magnitude of early changes correlates with impairments. However, studies to date have used noninvasive brain imaging approaches or have been conducted in sedated animals. Therefore, we do not know how brain injuries specifically affect the activity of neurons during the generation of movements. Our study clearly shows how a lesion rapidly impacts neurons in the premotor cortex of both hemispheres. A better understanding of these complex changes can help formulate hypotheses for the development of new treatments that specifically target neuronal reorganization induced by lesions in the brain.
Collapse
|
6
|
Tai SH, Chao LC, Huang TY, Chang CC, Huang SY, Wu TS, Lee EJ. Short-term lithium treatment protects the brain against ischemia-reperfusion injury by enhancing the neuroplasticity of cortical neurons. Neurol Res 2021; 44:128-138. [PMID: 34396932 DOI: 10.1080/01616412.2021.1965427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVES Lithium exerts a broad neuroprotective effect on the brain. This study examined whether lithium exerts therapeutic effects on stroke by restoring neural connections at the ischemic core of cortices post brain insult. METHODS We treated rats with lithium or vehicle (saline) every 24 h for the first 72 h, starting at the beginning of reperfusion after inducing middle cerebral artery occlusion (MCAO) in rats. Somatosensory evoked potential (SSEP) recording and behavioral testing were employed to evaluate the beneficial effects of lithium treatment. To examine the effects of lithium-induced neuroplasticity, we evaluated the dendritic morphology in cortex pyramidal cells and the primary neuronal cell culture that underwent brain insults and oxygen and glucose deprivation (OGD), respectively. RESULTS The results demonstrated that rats subjected to MCAO had prolonged N1 latency and a decreased N1/P1 amplitude at the ipsilateral cortex. Four doses of lithium reduced the brain infarction volume and enhanced the SSEP amplitude. The results of neurobehavioral tests demonstrated that lithium treatment improved sensory function, as demonstrated by improved 28-point clinical scale scores. In vitro study results showed that lithium treatment increased the dendritic lengths and branches of cultured neurons and reversed the suppressive effects of OGD. The in vivo study results indicated that lithium treatment increased cortical spine density in various layers and resulted in the development of the dendritic structure in the contralateral hemisphere. CONCLUSION Our study confirmed that neuroplasticity in cortical neurons is crucial for lithium-induced brain function 50 recovery after brain ischemia.
Collapse
Affiliation(s)
- Shih-Huang Tai
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Neurophysiology Laboratory and Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Liang-Chun Chao
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Neurophysiology Laboratory and Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Tung-Yi Huang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Che-Chao Chang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Sheng-Yang Huang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Tian-Shung Wu
- School of Pharmacy, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - E-Jian Lee
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Neurophysiology Laboratory and Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| |
Collapse
|
7
|
Chornyy S, Das A, Borovicka JA, Patel D, Chan HH, Hermann JK, Jaramillo TC, Machado AG, Baker KB, Dana H. Cellular-resolution monitoring of ischemic stroke pathologies in the rat cortex. BIOMEDICAL OPTICS EXPRESS 2021; 12:4901-4919. [PMID: 34513232 PMCID: PMC8407830 DOI: 10.1364/boe.432688] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
Stroke is a leading cause of disability in the Western world. Current post-stroke rehabilitation treatments are only effective in approximately half of the patients. Therefore, there is a pressing clinical need for developing new rehabilitation approaches for enhancing the recovery process, which requires the use of appropriate animal models. Here, we demonstrate the use of nonlinear microscopy of calcium sensors in the rat brain to study the effects of ischemic stroke injury on cortical activity patterns. We longitudinally recorded from thousands of neurons labeled with a genetically-encoded calcium indicator before and after an ischemic stroke injury in the primary motor cortex. We show that this injury has an effect on the activity patterns of neurons not only in the motor and somatosensory cortices, but also in the more distant visual cortex, and that these changes include modified firing rates and kinetics of neuronal activity patterns in response to a sensory stimulus. Changes in neuronal population activity provided animal-specific, circuit-level information on the post-stroke cortical reorganization process, which may be essential for evaluating the efficacy of new approaches for enhancing the recovery process.
Collapse
Affiliation(s)
- Sergiy Chornyy
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Aniruddha Das
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Julie A. Borovicka
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Davina Patel
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Hugh H. Chan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - John K. Hermann
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Thomas C. Jaramillo
- Rodent Behavioral Core, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Andre G. Machado
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
- Department of Neurosurgery, Neurological Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Kenneth B. Baker
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Hod Dana
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| |
Collapse
|
8
|
Effects of Alpha-2 Adrenergic Agonist Mafedine on Brain Electrical Activity in Rats after Traumatic Brain Injury. Brain Sci 2021; 11:brainsci11080981. [PMID: 34439602 PMCID: PMC8392538 DOI: 10.3390/brainsci11080981] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 01/20/2023] Open
Abstract
The search for and development of new neuroprotective (or cerebroprotective) drugs, as well as suitable methods for their preclinical efficacy evaluation, are priorities for current biomedical research. Alpha-2 adrenergic agonists, such as mafedine and dexmedetomidine, are a highly appealing group of drugs capable of reducing neurological deficits which result from brain trauma and vascular events in both experimental animals and human patients. Thus, our aim was to assess the effects of mafedine and dexmedetomidine on the brain’s electrical activity in a controlled cortical-impact model of traumatic brain injury (TBI) in rats. The functional status of the animals was assessed by electrocorticography (ECoG), using ECoG electrodes which were chronically implanted in different cortical regions. The administration of intraperitoneal mafedine sodium at 2.5 mg∙kg−1 at 1 h after TBI induction, and daily for the following 6 days, restored interhemispheric connectivity in remote brain regions and intrahemispheric connections within the unaffected hemisphere at post-TBI day 7. Animals that had received mafedine sodium also demonstrated an improvement in cortical responses to photic and somatosensory stimulation. Dexmedetomidine at 25 μg∙kg−1 did not affect the brain’s electrical activity in brain-injured rats. Our results confirm the previously described neuroprotective effects of mafedine sodium and suggest that ECoG registration and analysis are a viable method evaluating drug efficacy in experimental animal models of TBI.
Collapse
|
9
|
Saito A, Wada K, Suzuki Y, Nakasono S. The response of the neuronal activity in the somatosensory cortex after high-intensity intermediate-frequency magnetic field exposure to the spinal cord in rats under anesthesia and waking states. Brain Res 2020; 1747:147063. [PMID: 32818531 DOI: 10.1016/j.brainres.2020.147063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 08/08/2020] [Accepted: 08/14/2020] [Indexed: 12/01/2022]
Abstract
Novel technologies using the intermediate-frequency magnetic field (IF-MF) in living environments are becoming popular with the advance in electricity utilization. However, the biological effects induced by the high-intensity and burst-type IF-MF exposure used in the wireless power transfer technologies for electric vehicles or medical devices, such as the magnetic stimulation techniques, are not well understood. Here, we developed an experimental platform using rats, that combined an 18 kHz, high-intensity (Max. 88 mT), Gaussian-shaped burst IF-MF exposure system with an in vivo extracellular recording system. In this paper, we aimed to report the qualitative differences in stimulus responses in the regions of the somatosensory cortex and peripheral nerve fibers that were induced by the IF-MF exposure to the rat spinal cord. We also report the modulation of the stimulus responses in the somatosensory cortex under anesthesia or waking states. Using this experimental platform, we succeeded in the detection of the motor evoked potentials or the neuronal activity in the somatosensory cortex that was induced by the IF-MF exposure to the spinal cord in rats. Compared to the state of anesthesia, the neuronal activities in the somatosensory cortex was enhanced during the waking state. On the other hand, these neuronal responses could not be confirmed by the IF-MF exposure-related coil sound only. Our experimental results indicated the basic knowledge of the biological responses and excitation mechanisms of the spinal cord stimulation by the IF-MF exposure.
Collapse
Affiliation(s)
- Atsushi Saito
- Biological Environment Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Abiko-shi, Chiba, Japan.
| | - Keiji Wada
- Department of Electrical Engineering and Computer Science, Graduate School of Systems Design, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo, Japan.
| | - Yukihisa Suzuki
- Department of Electrical Engineering and Computer Science, Graduate School of Systems Design, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo, Japan.
| | - Satoshi Nakasono
- Biological Environment Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Abiko-shi, Chiba, Japan.
| |
Collapse
|
10
|
Darrow DP, O'Brien P, Richner TJ, Netoff TI, Ebbini ES. Reversible neuroinhibition by focused ultrasound is mediated by a thermal mechanism. Brain Stimul 2019; 12:1439-1447. [PMID: 31377096 PMCID: PMC6851480 DOI: 10.1016/j.brs.2019.07.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/18/2019] [Accepted: 07/21/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Transcranial focused ultrasound (tFUS) at low intensities has been reported to directly evoke responses and reversibly inhibit function in the central nervous system. While some doubt has been cast on the ability of ultrasound to directly evoke neuronal responses, spatially-restricted transcranial ultrasound has demonstrated consistent, inhibitory effects, but the underlying mechanism of reversible suppression in the central nervous system is not well understood. OBJECTIVE/HYPOTHESIS In this study, we sought to characterize the effect of transcranial, low-intensity, focused ultrasound on the thalamus during somatosensory evoked potentials (SSEP) and investigate the mechanism by modulating the parameters of ultrasound. METHODS TFUS was applied to the ventral posterolateral nucleus of the thalamus of a rodent while electrically stimulating the tibial nerve to induce an SSEP. Thermal changes were also induced through an optical fiber that was image-guided to the same target. RESULTS Focused ultrasound reversibly suppressed SSEPs in a spatially and intensity-dependent manner while remaining independent of duty cycle, peak pressure, or modulation frequency. Suppression was highly correlated and temporally consistent with in vivo temperature changes while producing no pathological changes on histology. Furthermore, stereotactically-guided delivery of thermal energy through an optical fiber produced similar thermal effects and suppression. CONCLUSION We confirm that tFUS predominantly causes neuroinhibition and conclude that the most primary biophysical mechanism is the thermal effect of focused ultrasound.
Collapse
Affiliation(s)
- David P Darrow
- Department of Neurosurgery, University of Minnesota, MMC 96, Room D-429, 420 Delaware St SE, Minneapolis, MN, 55455, USA.
| | - Parker O'Brien
- Department of Electrical and Computer Engineering, University of Minnesota, 7-174 Keller Hall, 200 Union Street Se. Minneapolis, MN, 55455, USA.
| | - Thomas J Richner
- Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church St. SE, Minneapolis, MN, 55455, USA.
| | - Theoden I Netoff
- Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church St. SE, Minneapolis, MN, 55455, USA.
| | - Emad S Ebbini
- Department of Electrical and Computer Engineering, University of Minnesota, 7-174 Keller Hall, 200 Union Street Se. Minneapolis, MN, 55455, USA.
| |
Collapse
|
11
|
Brodnick SK, Ness JP, Richner TJ, Thongpang S, Novello J, Hayat M, Cheng KP, Krugner-Higby L, Suminski AJ, Ludwig KA, Williams JC. μECoG Recordings Through a Thinned Skull. Front Neurosci 2019; 13:1017. [PMID: 31632232 PMCID: PMC6779785 DOI: 10.3389/fnins.2019.01017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/06/2019] [Indexed: 12/12/2022] Open
Abstract
The studies described in this paper for the first time characterize the acute and chronic performance of optically transparent thin-film micro-electrocorticography (μECoG) grids implanted on a thinned skull as both an electrophysiological complement to existing thinned skull preparation for optical recordings/manipulations, and a less invasive alternative to epidural or subdurally placed μECoG arrays. In a longitudinal chronic study, μECoG grids placed on top of a thinned skull maintain impedances comparable to epidurally placed μECoG grids that are stable for periods of at least 1 month. Optogenetic activation of cortex is also reliably demonstrated through the optically transparent μECoG grids acutely placed on the thinned skull. Finally, spatially distinct electrophysiological recordings were evident on μECoG electrodes placed on a thinned skull separated by 500–750 μm, as assessed by stimulation evoked responses using optogenetic activation of cortex as well as invasive and epidermal stimulation of the sciatic and median nerve at chronic time points. Neural signals were collected through a thinned skull in mice and rats, demonstrating potential utility in neuroscience research applications such as in vivo imaging and optogenetics.
Collapse
Affiliation(s)
- Sarah K Brodnick
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Jared P Ness
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Thomas J Richner
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Sanitta Thongpang
- Department of Biomedical Engineering, Mahidol University, Salaya, Thailand
| | - Joseph Novello
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Mohammed Hayat
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Kevin P Cheng
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Lisa Krugner-Higby
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Aaron J Suminski
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States.,Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, United States
| | - Kip A Ludwig
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States.,Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, United States
| | - Justin C Williams
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States.,Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, United States
| |
Collapse
|
12
|
Somatosensory Evoked Potentials as a Stand-Alone Tool During Spine Surgery: An Egyptian Preliminary Report. J Clin Neurophysiol 2019; 36:161-165. [PMID: 30694942 DOI: 10.1097/wnp.0000000000000562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PURPOSE Monitoring of somatosensory evoked potentials (SSEPs) serves as an early warning system to detect spinal cord injury and is correlated with postoperative sensory findings. It is an indirect indicator of motor function. This study aimed to evaluate the usefulness of intraoperative SSEPs monitoring as a stand-alone tool during spinal surgeries when motor evoked potentials are not available, to prevent and predict new postoperative neurologic deficits. Motor evoked potentials were not used as the equipment needed to record them was not available at the time of this study. METHODS This study included 50 patients, aged 14 to 67 years, undergoing extramedullary manipulations, decompression of an epidural abscess or neoplasm, removal of intramedullary tumor, or arteriovenous malformation or spine correction procedures. Somatosensory evoked potentials were analyzed for latency and peak-to-peak amplitude. Critical SSEP changes were defined as a 50% decrease in amplitude or a 10% increase in latency. RESULTS Somatosensory evoked potentials had an overall sensitivity of 81.8%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 91.3%. CONCLUSIONS Intraoperative SSEPs have proved to be highly sensitive and specific for iatrogenic injury, mechanical stress caused by cord traction/compression, dural traction, lowered systemic blood pressure, and cord hypothermia. The reversibility of intraoperative SSEP changes showed a highly significant relation to the number of cases with new postoperative deficits as well as type and site of pathologic study (P = 0.00, P = 0.01, and P = 0.00, respectively) but not with the level of pathologic study (P = 0.49).
Collapse
|
13
|
Effect of Paired Associative Stimulation on Motor Cortex Excitability in Rats. Curr Med Sci 2018; 38:903-909. [PMID: 30341527 DOI: 10.1007/s11596-018-1960-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/10/2018] [Indexed: 10/28/2022]
Abstract
Paired associative stimulation (PAS), combining transcranial magnetic stimulation (TMS) with electrical peripheral nerve stimulation (PNS) in pairs with an optimal interstimulus interval (ISI) in between, has been shown to influence the excitability of the motor cortex (MC) in humans. However, the underlying mechanisms remain unclear. This study was designed to explore an optimal protocol of PAS, which can modulate the excitability of MC in rats, and to investigate the underlying mechanisms. The resting motor thresholds (RMTs) of TMS-elicited motor evoked potentials (MEPs) recorded from the gastrocnemius muscle and the latency of P1 component of somatosensory evoked potentials (SEPs) induced by electrical tibial nerve stimulation were determined in male Sprague-Dawley rats (n=10). Sixty rats were then randomly divided into 3 groups: a PAS group (further divided into 10 subgroups at various ISIs calculated by using the latency of P1, n=5, respectively), a TMS (only) group (n=5) and a PNS (only) group (n=5). Ninety repetitions of PAS, TMS and PNS were administered to the rats in the 3 groups, respectively, at the frequency of 0.05 Hz and the intensity of TMS at 120% RMT and that of PNS at 6 mA. RMTs and motor evoked potentials' amplitude (MEPamp) were recorded before and immediately after the interventions. It was found that the MEPamp significantly decreased after PAS at ISI of 5 ms (P<0.05), while the MEPamp significantly increased after PAS at ISI of 15 ms, as compared with those before the intervention (P<0.05). However, the RMT did not change significantly after PAS at ISI of 5 ms or 15 ms (P>0.05). PAS at other ISIs as well as the sole use of TMS and PNS induced no remarkable changes in MEPamp and RMT. In conclusion, PAS can influence motor cortex excitability in rats. Neither TMS alone nor PNS alone shows significant effect.
Collapse
|
14
|
Huang SY, Chang CH, Hung HY, Lin YW, Lee EJ. Neuroanatomical and electrophysiological recovery in the contralateral intact cortex following transient focal cerebral ischemia in rats. Neurol Res 2018; 40:130-138. [PMID: 29262766 DOI: 10.1080/01616412.2017.1411454] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Objectives Focal cerebral ischemia may induce synaptic, electrophysiological, and metabolic dysfunction in remote areas. We have shown that the remote dendritic spine density changes and electrophysiological diaschisis in the acute and subacute stages after stroke previously. Here, we further evaluated electrophysiological outcomes and synapto-dendritic plasticity in long-term recovery in the contralateral cortex following focal cerebral ischemia. Methods Male Sprague-Dawley rats were subjected to intraluminal suture occlusion for 90 min or sham-occlusion. Somatosensory electrophysiological recordings (SSEPs) and neurobehavioral tests were recorded each day for 28 days. Postmortem brains were sectioned and subjected to Nissl staining and Golgi-Cox impregnation through a 28-day period following ischemic stroke. Results In the ipsilateral cortex, infarct size in the cortex and striatum was decreased after the subacute stage; the brains showed reduced swelling in the cortex and stratum 3 days after ischemic insults. Dendritic spine density and SSEP amplitude decreased significantly during a 28-day recovery period. In the contralateral cortex, dendritic spine density and SSEP amplitude decreased significantly for 21 days after ischemic stroke, but recovered to baseline by day 28. The deterioration of the dendritic spine (density reduction) in the ischemic cortex was observed; however, this increased neuroplasticity in the contralateral cortex in the subacute stage. Discussion Focal cerebral ischemia-reperfusion induces time-dependent reduction of dendritic spine density and electrophysiological depression in both the ipsilateral and contralateral cortices and intact brain. This neuroanatomical and electrophysiological evidence suggests that neuroplasticity and functional re-organization in the contralateral cortex is possible following focal cerebral ischemia.
Collapse
Affiliation(s)
- Sheng-Yang Huang
- a Institute of Biomedical Engineering , National Cheng Kung University , Tainan , Taiwan.,b Neurophysiology Laboratory, Department of Surgery , National Cheng Kung University Medical Center and Medical School , Tainan , Taiwan
| | - Chih-Han Chang
- a Institute of Biomedical Engineering , National Cheng Kung University , Tainan , Taiwan
| | - Hsin-Yi Hung
- c School of Pharmacy , National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University , Tainan , Taiwan
| | - Yu-Wen Lin
- b Neurophysiology Laboratory, Department of Surgery , National Cheng Kung University Medical Center and Medical School , Tainan , Taiwan
| | - E-Jian Lee
- b Neurophysiology Laboratory, Department of Surgery , National Cheng Kung University Medical Center and Medical School , Tainan , Taiwan
| |
Collapse
|
15
|
Liu YH, Chan SJ, Pan HC, Bandla A, King NKK, Wong PTH, Chen YY, Ng WH, Thakor NV, Liao LD. Integrated treatment modality of cathodal-transcranial direct current stimulation with peripheral sensory stimulation affords neuroprotection in a rat stroke model. NEUROPHOTONICS 2017; 4:045002. [PMID: 29021986 PMCID: PMC5627795 DOI: 10.1117/1.nph.4.4.045002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/12/2017] [Indexed: 05/03/2023]
Abstract
Cathodal-transcranial direct current stimulation induces therapeutic effects in animal ischemia models by preventing the expansion of ischemic injury during the hyperacute phase of ischemia. However, its efficacy is limited by an accompanying decrease in cerebral blood flow. On the other hand, peripheral sensory stimulation can increase blood flow to specific brain areas resulting in rescue of neurovascular functions from ischemic damage. Therefore, the two modalities appear to complement each other to form an integrated treatment modality. Our results showed that hemodynamics was improved in a photothrombotic ischemia model, as cerebral blood volume and hemoglobin oxygen saturation ([Formula: see text]) recovered to 71% and 76% of the baseline values, respectively. Furthermore, neural activities, including somatosensory-evoked potentials (110% increase), the alpha-to-delta ratio (27% increase), and the [Formula: see text] ratio (27% decrease), were also restored. Infarct volume was reduced by 50% with a 2-fold preservation in the number of neurons and a 6-fold reduction in the number of active microglia in the infarct region compared with the untreated group. Grip strength was also better preserved (28% higher) compared with the untreated group. Overall, this nonpharmacological, nonintrusive approach could be prospectively developed into a clinical treatment modality.
Collapse
Affiliation(s)
- Yu-Hang Liu
- National University of Singapore, Singapore Institute for Neurotechnology (SINAPSE), Singapore, Singapore
- National University of Singapore, Department of Electrical and Computer Engineering, Singapore, Singapore
| | - Su Jing Chan
- Massachusetts General Hospital and Harvard Medical School, Department of Radiology, Boston, Massachusetts, United States
| | - Han-Chi Pan
- National Health Research Institutes, Institute of Biomedical Engineering and Nanomedicine, Miaoli, Taiwan
| | - Aishwarya Bandla
- National University of Singapore, Singapore Institute for Neurotechnology (SINAPSE), Singapore, Singapore
| | - Nicolas K. K. King
- National Neuroscience Institute (NNI), Department of Neurosurgery, Singapore, Singapore
- National Neuroscience Institute (NNI), SingHealth Duke-NUS Neuroscience Academic Clinical Program, Singapore, Singapore
| | - Peter Tsun Hon Wong
- National University of Singapore, Department of Pharmacology, Singapore, Singapore
| | - You-Yin Chen
- National Yang Ming University, Department of Biomedical Engineering, Taipei, Taiwan
| | - Wai Hoe Ng
- National Neuroscience Institute (NNI), Department of Neurosurgery, Singapore, Singapore
- National Neuroscience Institute (NNI), SingHealth Duke-NUS Neuroscience Academic Clinical Program, Singapore, Singapore
| | - Nitish V. Thakor
- National University of Singapore, Singapore Institute for Neurotechnology (SINAPSE), Singapore, Singapore
- National University of Singapore, Department of Electrical and Computer Engineering, Singapore, Singapore
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States
| | - Lun-De Liao
- National University of Singapore, Singapore Institute for Neurotechnology (SINAPSE), Singapore, Singapore
- National Health Research Institutes, Institute of Biomedical Engineering and Nanomedicine, Miaoli, Taiwan
- Address all correspondence to: Lun-De Liao, E-mail:
| |
Collapse
|
16
|
Jang H, Huang S, Hammer DX, Wang L, Rafi H, Ye M, Welle CG, Fisher JAN. Alterations in neurovascular coupling following acute traumatic brain injury. NEUROPHOTONICS 2017; 4:045007. [PMID: 29296629 PMCID: PMC5741992 DOI: 10.1117/1.nph.4.4.045007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
Following acute traumatic brain injury (TBI), timely transport to a hospital can significantly improve the prognosis for recovery. There is, however, a dearth of quantitative biomarkers for brain injury that can be rapidly acquired and interpreted in active, field environments in which TBIs are frequently incurred. We explored potential functional indicators for TBI that can be noninvasively obtained through portable detection modalities, namely optical and electrophysiological approaches. By combining diffuse correlation spectroscopy with colocalized electrophysiological measurements in a mouse model of TBI, we observed concomitant alterations in sensory-evoked cerebral blood flow (CBF) and electrical potentials following controlled cortical impact. Injury acutely reduced the peak amplitude of both electrophysiological and CBF responses, which mostly recovered to baseline values within 30 min, and intertrial variability for these parameters was also acutely altered. Notably, the postinjury dynamics of the CBF overshoot and undershoot amplitudes differed significantly; whereas the amplitude of the initial peak of stimulus-evoked CBF recovered relatively rapidly, the ensuing undershoot did not appear to recover within 30 min of injury. Additionally, acute injury induced apparent low-frequency oscillatory behavior in CBF ([Formula: see text]). Histological assessment indicated that these physiological alterations were not associated with any major, persisting anatomical changes. Several time-domain features of the blood flow and electrophysiological responses showed strong correlations in recovery kinetics. Overall, our results reveal an array of stereotyped, injury-induced alterations in electrophysiological and hemodynamic responses that can be rapidly obtained using a combination of portable detection techniques.
Collapse
Affiliation(s)
- Hyounguk Jang
- New York Medical College, Department of Physiology, Valhalla, New York, United States
- U.S. Food and Drug Administration, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Stanley Huang
- U.S. Food and Drug Administration, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Daniel X. Hammer
- U.S. Food and Drug Administration, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Lin Wang
- New York Medical College, Department of Physiology, Valhalla, New York, United States
| | - Harmain Rafi
- New York Medical College, Department of Physiology, Valhalla, New York, United States
| | - Meijun Ye
- U.S. Food and Drug Administration, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Cristin G. Welle
- U.S. Food and Drug Administration, Division of Biomedical Physics, Silver Spring, Maryland, United States
- University of Colorado Denver, Departments of Neurosurgery and Bioengineering, Aurora, Colorado, United States
| | - Jonathan A. N. Fisher
- New York Medical College, Department of Physiology, Valhalla, New York, United States
- U.S. Food and Drug Administration, Division of Biomedical Physics, Silver Spring, Maryland, United States
| |
Collapse
|
17
|
He X, Jiang L, Dan QQ, Lv Q, Hu Y, Liu J, Wang SF, Wang TH. Bone marrow stromal cells promote neuroplasticity of cerebral ischemic rats via a phosphorylated CRMP2-mediated mechanism. Behav Brain Res 2017; 320:494-503. [DOI: 10.1016/j.bbr.2016.10.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/14/2016] [Accepted: 10/15/2016] [Indexed: 11/30/2022]
|
18
|
Ramos E, Patiño P, Reiter RJ, Gil-Martín E, Marco-Contelles J, Parada E, de Los Rios C, Romero A, Egea J. Ischemic brain injury: New insights on the protective role of melatonin. Free Radic Biol Med 2017; 104:32-53. [PMID: 28065781 DOI: 10.1016/j.freeradbiomed.2017.01.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 12/20/2016] [Accepted: 01/04/2017] [Indexed: 12/15/2022]
Abstract
Stroke represents one of the most common causes of brain's vulnerability for many millions of people worldwide. The plethora of physiopathological events associated with brain ischemia are regulate through multiple signaling pathways leading to the activation of oxidative stress process, Ca2+ dyshomeostasis, mitochondrial dysfunction, proinflammatory mediators, excitotoxicity and/or programmed neuronal cell death. Understanding this cascade of molecular events is mandatory in order to develop new therapeutic strategies for stroke. In this review article, we have highlighted the pleiotropic effects of melatonin to counteract the multiple processes of the ischemic cascade. Additionally, experimental evidence supports its actions to ameliorate ischemic long-term behavioural and neuronal deficits, preserving the functional integrity of the blood-brain barrier, inducing neurogenesis and cell proliferation through receptor-dependent mechanism, as well as improving synaptic transmission. Consequently, the synthesis of melatonin derivatives designed as new multitarget-directed products has focused a great interest in this area. This latter has been reinforced by the low cost of melatonin and its reduced toxicity. Furthermore, its spectrum of usages seems to be wide and with the potential for improving human health. Nevertheless, the molecular and cellular mechanisms underlying melatonin´s actions need to be further exploration and accordingly, new clinical studies should be conducted in human patients with ischemic brain pathologies.
Collapse
Affiliation(s)
- Eva Ramos
- Department of Toxicology & Pharmacology, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain
| | - Paloma Patiño
- Paediatric Unit, La Paz University Hospital, Paseo de la Castellana 261, 28046 Madrid, Spain
| | - Russel J Reiter
- Department of Cellular and Structural Biology. University of Texas Health Science Center at San Antonio, USA
| | - Emilio Gil-Martín
- Department of Biochemistry, Genetics and Immunology, Faculty of Biology, University of Vigo, Vigo, Spain
| | - José Marco-Contelles
- Medicinal Chemistry Laboratory, Institute of General Organic Chemistry (CSIC), Juan de la Cierva, 3, 28006 Madrid, Spain
| | - Esther Parada
- Instituto de Investigación Sanitaria, Servicio de Farmacología Clínica, Hospital Universitario de la Princesa, 28006 Madrid, Spain; Instituto de I+D del Medicamento Teófilo Hernando (ITH), Facultad de Medicina, Universidad Autónoma de Madrid, Spain
| | - Cristobal de Los Rios
- Instituto de Investigación Sanitaria, Servicio de Farmacología Clínica, Hospital Universitario de la Princesa, 28006 Madrid, Spain; Instituto de I+D del Medicamento Teófilo Hernando (ITH), Facultad de Medicina, Universidad Autónoma de Madrid, Spain
| | - Alejandro Romero
- Department of Toxicology & Pharmacology, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Javier Egea
- Instituto de Investigación Sanitaria, Servicio de Farmacología Clínica, Hospital Universitario de la Princesa, 28006 Madrid, Spain; Instituto de I+D del Medicamento Teófilo Hernando (ITH), Facultad de Medicina, Universidad Autónoma de Madrid, Spain.
| |
Collapse
|
19
|
Transneuronal Degeneration of Thalamic Nuclei following Middle Cerebral Artery Occlusion in Rats. BIOMED RESEARCH INTERNATIONAL 2016; 2016:3819052. [PMID: 27597962 PMCID: PMC4997075 DOI: 10.1155/2016/3819052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 06/22/2016] [Accepted: 07/08/2016] [Indexed: 12/11/2022]
Abstract
Objective. Postinfarction transneuronal degeneration refers to secondary neuronal death that occurs within a few days to weeks following the disruption of input or output to synapsed neurons sustaining ischemic insults. The thalamus receives its blood supply from the posterior circulation; however, infarctions of the middle cerebral arterial may cause secondary transneuronal degeneration in the thalamus. In this study, we presented the areas of ischemia and associated transneuronal degeneration following MCAo in a rat model. Materials and Methods. Eighteen 12-week-old male Sprague-Dawley rats were randomly assigned to receive middle cerebral artery occlusion surgery for 1, 7, and 14 days. Cerebral atrophy was assessed by 2,3,5-triphenyltetrazolium hydrochloride staining. Postural reflex and open field tests were performed prior to animal sacrifice to assess the effects of occlusion on behavior. Results. Myelin loss was observed at the lesion site following ischemia. Gliosis was also observed in thalamic regions 14 days following occlusion. Differential degrees of increased vascular endothelial growth factor expression were observed at each stage of infarction. Increases in myelin basic protein levels were also observed in the 14-day group. Conclusion. The present rat model of ischemia provides evidence of transneuronal degeneration within the first 14 days of occlusion. The observed changes in protein expression may be associated with self-repair mechanisms in the damaged brain.
Collapse
|
20
|
Competition with Primary Sensory Afferents Drives Remodeling of Corticospinal Axons in Mature Spinal Motor Circuits. J Neurosci 2016; 36:193-203. [PMID: 26740661 DOI: 10.1523/jneurosci.3441-15.2016] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Injury to the mature motor system drives significant spontaneous axonal sprouting instead of axon regeneration. Knowing the circuit-level determinants of axonal sprouting is important for repairing motor circuits after injury to achieve functional rehabilitation. Competitive interactions are known to shape corticospinal tract axon outgrowth and withdrawal during development. Whether and how competition contributes to reorganization of mature spinal motor circuits is unclear. To study this question, we examined plastic changes in corticospinal axons in response to two complementary proprioceptive afferent manipulations: (1) enhancing proprioceptive afferents activity by electrical stimulation; or (2) diminishing their input by dorsal rootlet rhizotomy. Experiments were conducted in adult rats. Electrical stimulation produced proprioceptive afferent sprouting that was accompanied by significant corticospinal axon withdrawal and a decrease in corticospinal connections on cholinergic interneurons in the medial intermediate zone and C boutons on motoneurons. In contrast, dorsal rootlet rhizotomy led to a significant increase in corticospinal connections, including those on cholinergic interneurons; C bouton density increased correspondingly. Motor cortex-evoked muscle potentials showed parallel changes to those of corticospinal axons, suggesting that reciprocal corticospinal axon changes are functional. Using the two complementary models, we showed that competitive interactions between proprioceptive and corticospinal axons are an important determinant in the organization of mature corticospinal axons and spinal motor circuits. The activity- and synaptic space-dependent properties of the competition enables prediction of the remodeling of spared corticospinal connection and spinal motor circuits after injury and informs the target-specific control of corticospinal connections to promote functional recovery. SIGNIFICANCE STATEMENT Neuroplasticity is limited in maturity, but it is promoted after injury. Axons of the major descending motor pathway for motor skills, the corticospinal tract (CST), sprout after brain or spinal cord injury. This contributes to spontaneous spinal motor circuit repair and partial motor recovery. Knowing the determinants that enhance this plasticity is critical for functional rehabilitation. Here we examine the remodeling of CST axons directed by sensory fibers. We found that the CST projection is regulated dynamically in maturity by the competitive, activity-dependent actions of sensory fibers. Knowledge of the properties of this competition enables prediction of the remodeling of CST connections and spinal circuits after injury and informs ways to engineer target-specific control of CST connections to promote recovery.
Collapse
|
21
|
Barios JA, Pisarchyk L, Fernandez-Garcia L, Barrio LC, Ramos M, Martinez-Murillo R, Gonzalez-Nieto D. Long-term dynamics of somatosensory activity in a stroke model of distal middle cerebral artery oclussion. J Cereb Blood Flow Metab 2016; 36:606-20. [PMID: 26661150 PMCID: PMC4794092 DOI: 10.1177/0271678x15606139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 07/28/2015] [Indexed: 11/17/2022]
Abstract
A constant challenge in experimental stroke is the use of appropriate tests to identify signs of recovery and adverse effects linked to a particular therapy. In this study, we used a long-term longitudinal approach to examine the functional brain changes associated with cortical infarction in a mouse model induced by permanent ligation of the middle cerebral artery (MCA). Sensorimotor function and somatosensory cortical activity were evaluated with fault-foot and forelimb asymmetry tests in combination with somatosensory evoked potentials. The stroke mice exhibited both long-term deficits in the functional tests and impaired responses in the infarcted and intact hemispheres after contralateral and ipsilateral forepaw stimulation. In the infarcted hemisphere, reductions in the amplitudes of evoked responses were detected after contralateral and ipsilateral stimulation. In the intact hemisphere, and similar to cortical stroke patients, a gradual hyperexcitability was observed after contralateral stimulation but no parallel evidence of a response was detected after ipsilateral stimulation. Our results suggest the existence of profound and persistent changes in the somatosensory cortex in this specific mouse cortical stroke model. The study of evoked potentials constitutes a feasible and excellent tool for evaluating the fitness of the somatosensory cortex in relation to functional recovery after preclinical therapeutic intervention.
Collapse
Affiliation(s)
- Juan A Barios
- Unit of Cellular and Animal models, Experimental Neurology Laboratory, Center for Biomedical Technology, Universidad Politécnica, Madrid, Spain
| | - Liudmila Pisarchyk
- Unit of Cellular and Animal models, Experimental Neurology Laboratory, Center for Biomedical Technology, Universidad Politécnica, Madrid, Spain
| | - Laura Fernandez-Garcia
- Unit of Cellular and Animal models, Experimental Neurology Laboratory, Center for Biomedical Technology, Universidad Politécnica, Madrid, Spain
| | - Luis C Barrio
- Unit of Experimental Neurology, Hospital Universitario Ramón y Cajal-IRYCIS, Madrid, Spain
| | - Milagros Ramos
- Unit of Cellular and Animal models, Experimental Neurology Laboratory, Center for Biomedical Technology, Universidad Politécnica, Madrid, Spain Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain
| | - Ricardo Martinez-Murillo
- Department of Molecular, Cellular and Developmental Neurobiology, Instituto Cajal (CSIC), Madrid, Spain
| | - Daniel Gonzalez-Nieto
- Unit of Cellular and Animal models, Experimental Neurology Laboratory, Center for Biomedical Technology, Universidad Politécnica, Madrid, Spain Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain
| |
Collapse
|
22
|
Fisher JAN, Huang S, Ye M, Nabili M, Wilent WB, Krauthamer V, Myers MR, Welle CG. Real-Time Detection and Monitoring of Acute Brain Injury Utilizing Evoked Electroencephalographic Potentials. IEEE Trans Neural Syst Rehabil Eng 2016; 24:1003-1012. [PMID: 26955039 DOI: 10.1109/tnsre.2016.2529663] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Rapid detection and diagnosis of a traumatic brain injury (TBI) can significantly improve the prognosis for recovery. Helmet-mounted sensors that detect impact severity based on measurements of acceleration or pressure show promise for aiding triage and transport decisions in active, field environments such as professional sports or military combat. The detected signals, however, report on the mechanics of an impact rather than directly indicating the presence and severity of an injury. We explored the use of cortical somatosensory evoked electroencephalographic potentials (SSEPs) to detect and track, in real-time, neural electrophysiological abnormalities within the first hour following head injury in an animal model. To study the immediate electrophysiological effects of injury in vivo, we developed an experimental paradigm involving focused ultrasound that permits continuous, real-time measurements and minimizes mechanical artifact. Injury was associated with a dramatic reduction of amplitude over the damaged hemisphere directly after the injury. The amplitude systematically improved over time but remained significantly decreased at one hour, compared with baseline. In contrast, at one hour there was a concomitant enhancement of the cortical SSEP amplitude evoked from the uninjured hemisphere. Analysis of the inter-trial electroencephalogram (EEG) also revealed significant changes in low-frequency components and an increase in EEG entropy up to 30 minutes after injury, likely reflecting altered EEG reactivity to somatosensory stimuli. Injury-induced alterations in SSEPs were also observed using noninvasive epidermal electrodes, demonstrating viability of practical implementation. These results suggest cortical SSEPs recorded at just a few locations by head-mounted sensors and associated multiparametric analyses could potentially be used to rapidly detect and monitor brain injury in settings that normally present significant levels of mechanical and electrical noise.
Collapse
|
23
|
Liu TC, Chuang MC, Chu CY, Huang WC, Lai HY, Wang CT, Chu WL, Chen SY, Chen YY. Implantable Graphene-based Neural Electrode Interfaces for Electrophysiology and Neurochemistry in In Vivo Hyperacute Stroke Model. ACS APPLIED MATERIALS & INTERFACES 2016; 8:187-196. [PMID: 26653098 DOI: 10.1021/acsami.5b08327] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Implantable microelectrode arrays have attracted considerable interest due to their high temporal and spatial resolution recording of neuronal activity in tissues. We herein presented an implantable multichannel neural probe with multiple real-time monitoring of neural-chemical and neural-electrical signals by a nonenzymatic neural-chemical interface, which was designed by creating the newly developed reduced graphene oxide-gold oxide (rGO/Au2O3) nanocomposite electrode. The modified electrode on the neural probe was prepared by a facile one-step cyclic voltammetry (CV) electrochemical method with simultaneous occurrence of gold oxidation and GOs reduction to induce the intimate attachment by electrostatic interaction using chloride ions (Cl(-)). The rGO/Au2O3-modified electrode at a low deposition scan rate of 10 mVs(-1) displayed significantly improved electrocatalytic activity due to large active areas and well-dispersive attached rGO sheets. The in vitro amperometric response to H2O2 demonstrated a fast response of less than 5 s and a very low detection limit of 0.63 μM. In in vivo hyperacute stroke model, the concentration of H2O2 was measured as 100.48 ± 4.52 μM for rGO/Au2O3 electrode within 1 h photothrombotic stroke, which was much higher than that (71.92 μM ± 2.52 μM) for noncoated electrode via in vitro calibration. Simultaneously, the somatosensory-evoked potentials (SSEPs) test provided reliable and precise validation for detecting functional changes of neuronal activities. This newly developed implantable probe with localized rGO/Au2O3 nanocomposite electrode can serve as a rapid and reliable sensing platform for practical H2O2 detection in the brain or for other neural-chemical molecules in vivo.
Collapse
Affiliation(s)
- Ta-Chung Liu
- Department of Materials Science and Engineering, National Chiao Tung University , No. 1001, Ta-Hsueh Rd., Hsinchu, Taiwan 300, Republic of China
| | - Min-Chieh Chuang
- Department of Chemistry, Tunghai University , No. 181, Sec. 3, Taichung Port Rd., Taichung, Taiwan 407, Republic of China
| | - Chao-Yi Chu
- Department of Materials Science and Engineering, National Chiao Tung University , No. 1001, Ta-Hsueh Rd., Hsinchu, Taiwan 300, Republic of China
| | - Wei-Chen Huang
- Department of Materials Science and Engineering, Carnegie Mellon University , No.5000 Forbes Avenue, Wean Hall 3325, Pittsburgh, Pennsylvania 15213, United States
| | - Hsin-Yi Lai
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University , No.866 Yuhangtang Rd., Hangzhou, Zhejiang Province 310058, China
| | - Chao-Ting Wang
- Department of Biomedical Engineering, National Yang Ming University , No.155, Sec. 2, Linong St., Taipei, Taiwan 112, Republic of China
| | - Wei-Lin Chu
- Department of Biomedical Engineering, University of Michigan , No.2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099, United States
| | - San-Yuan Chen
- Department of Materials Science and Engineering, National Chiao Tung University , No. 1001, Ta-Hsueh Rd., Hsinchu, Taiwan 300, Republic of China
| | - You-Yin Chen
- Department of Biomedical Engineering, National Yang Ming University , No.155, Sec. 2, Linong St., Taipei, Taiwan 112, Republic of China
| |
Collapse
|
24
|
Assessment of neurovascular dynamics during transient ischemic attack by the novel integration of micro-electrocorticography electrode array with functional photoacoustic microscopy. Neurobiol Dis 2015; 82:455-465. [DOI: 10.1016/j.nbd.2015.06.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/11/2015] [Accepted: 06/24/2015] [Indexed: 01/18/2023] Open
|
25
|
Liao LD, Liu YH, Lai HY, Bandla A, Shih YYI, Chen YY, Thakor NV. Rescue of cortical neurovascular functions during the hyperacute phase of ischemia by peripheral sensory stimulation. Neurobiol Dis 2015; 75:53-63. [DOI: 10.1016/j.nbd.2014.12.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 12/07/2014] [Accepted: 12/23/2014] [Indexed: 10/24/2022] Open
|
26
|
Dancause N, Touvykine B, Mansoori BK. Inhibition of the contralesional hemisphere after stroke. PROGRESS IN BRAIN RESEARCH 2015; 218:361-87. [DOI: 10.1016/bs.pbr.2015.01.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
27
|
Interplay between intra- and interhemispheric remodeling of neural networks as a substrate of functional recovery after stroke: Adaptive versus maladaptive reorganization. Neuroscience 2014; 283:178-201. [DOI: 10.1016/j.neuroscience.2014.06.066] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 06/27/2014] [Accepted: 06/27/2014] [Indexed: 11/18/2022]
|
28
|
Mansoori BK, Jean-Charles L, Touvykine B, Liu A, Quessy S, Dancause N. Acute inactivation of the contralesional hemisphere for longer durations improves recovery after cortical injury. Exp Neurol 2014; 254:18-28. [DOI: 10.1016/j.expneurol.2014.01.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/07/2014] [Accepted: 01/11/2014] [Indexed: 10/25/2022]
|
29
|
Neuronal mechanisms underlying transhemispheric diaschisis following focal cortical injuries. Brain Struct Funct 2014; 220:1649-64. [DOI: 10.1007/s00429-014-0750-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Accepted: 03/03/2014] [Indexed: 12/18/2022]
|
30
|
Uncoupling PSD-95 interactions leads to rapid recovery of cortical function after focal stroke. J Cereb Blood Flow Metab 2013; 33:1937-43. [PMID: 24022623 PMCID: PMC3851903 DOI: 10.1038/jcbfm.2013.153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 11/08/2022]
Abstract
Since the most significant ischemic sequelae occur within hours of stroke, it is necessary to understand how neuronal function changes during this time. While histologic and behavioral models show the extent of stroke-related damage, only in vivo recordings can illustrate changes in brain activity during stroke and validate effectiveness of neuroprotective compounds. Spontaneous and evoked field potentials (fEPs) were recorded in the deep layers of the cortex with a linear microelectrode array for 3 hours after focal stroke in anesthetized rats. Tat-NR2B9c peptide, which confers neuroprotection by uncoupling the PSD-95 protein from N-methyl-D-aspartate receptor (NMDAR), was administered 5 minutes before ischemia. Evoked field potentials were completely suppressed within 3 minutes of infarct in all ischemic groups. Evoked field potential recovery after stroke in rats treated with Tat-NR2B9c (83% of baseline) was greater compared with stroke-only (61% of baseline) or control peptide (Tat-NR2B-AA; 67% of baseline) groups (P<0.001). Electroencephalography (EEG) power was higher in Tat-NR2B9c-treated animals at both 20 minutes and 1 hour (50% and 73% of baseline, respectively) compared with stroke-only and Tat-NR2B-AA-treated rats (P<0.05). Tat-NR2B9c significantly reduces stroke-related cortical dysfunction as evidenced by greater recovery of fEPs and EEG power; illustrating the immediate effects of the compound on poststroke brain function.
Collapse
|
31
|
Wang M, Li ZY, Xu WD, Hua XY, Xu JG, Gu YD. Sensory restoration in cortical level after a contralateral C7 nerve transfer to an injured arm in rats. Neurosurgery 2013; 67:136-43; discussion 143. [PMID: 20559101 DOI: 10.1227/01.neu.0000370603.45342.6b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The restoration of sensory and motor function in brachial plexus root avulsion patients is a difficult challenge. The central nervous system plays an important role in sensory recovery after peripheral nerve injury and repair. OBJECTIVE To investigate the sensory restoration process after surgery at the cortical level in rodent models with a contralateral C7 nerve transfer. METHODS Thirty-five male Sprague-Dawley rats were used in this experiment, and both behavioral tests and somatosensory evoked potentials were used to investigate the sensory function recovery of the injured forepaws and the cortical reorganization in the rats postoperatively. RESULTS The results demonstrated a dynamic change in the ipsilateral somatosensory cortex, both in the shape and location, where overlapping sensory cortical representations of the healthy and injured forepaws were observed consistently. Behavioral tests show that the sensation first occurred only in the healthy forepaw and later in both when stimulating the injured one, which suggested a tendency of the sensation function to recover in the injured forepaws of the rats as time progressed. CONCLUSION The cortical reorganization occurred only in the ipsilateral hemisphere, which is different from the motor cortex reorganization using the same model as that described in a previous study. This reorganization pattern offers an interpretation of the unique sensory recovery process after the transfer of the C7 nerve to the contralateral median nerve, but also provides the basis for further sensory restoration in clinical practice.
Collapse
Affiliation(s)
- Meng Wang
- Department of Hand Surgery, Huashan Hospital, Shanghai Medical College of Fudan University, Shanghai, People's Republic of China
| | | | | | | | | | | |
Collapse
|
32
|
Hung YC, Chou YS, Chang CH, Lin HW, Chen HY, Chen TY, Tai SH, Lee EJ. Early reperfusion improves the recovery of contralateral electrophysiological diaschisis following focal cerebral ischemia in rats. Neurol Res 2013; 32:828-34. [DOI: 10.1179/016164109x12581096870032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
33
|
Joo HW, Hyun JK, Kim TU, Chae SH, Lee YI, Lee SJ. Influence of constraint-induced movement therapy upon evoked potentials in rats with cerebral infarction. Eur J Neurosci 2012; 36:3691-7. [PMID: 23043504 DOI: 10.1111/ejn.12014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 09/02/2012] [Accepted: 09/06/2012] [Indexed: 11/28/2022]
Abstract
Constraint-induced movement therapy (CIMT) is an effective treatment promoting motor recovery of upper extremity function in stroke patients. The objective of the present study was to determine the effect of CIMT on the evoked potentials in rats with focal cerebral cortical ischemia induced by endothelin-1 (ET-1). Thirty rats were randomly assigned to the sham, infarct or CIMT groups. ET-1 was injected stereotaxically into the forelimb area of the cerebral cortex in the dominant hemisphere. Custom-made constraint jackets were applied to limit movement of the unaffected forelimb in the CIMT group. Motor and sensory function of the forelimb was evaluated by a pellet retrieval task and forearm asymmetry test. Electrophysiologic changes were evaluated by motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SEPs). The location and extent of cerebral ischemia were confirmed and compared histologically. The CIMT group showed better recovery in the pellet retrieval task. Forelimb use was more symmetrical in the CIMT group. The waveform of the SEP was reversed and delayed in the infarct group, but it was preserved in the CIMT group with amplitude decrease only. The estimated volume of infarction was smaller in the CIMT group, although statistically not significant. The results demonstrate that CIMT can promote recovery of motor function in focal cerebral cortical infarcts, and that recovery may be related to reorganization of the cerebral neuronal network in the somatosensory pathway.
Collapse
Affiliation(s)
- Hyung W Joo
- Department of Rehabilitation Medicine, Dankook University College of Medicine, Anseo-dong, Cheonan, Chungnam, 330-715, Korea
| | | | | | | | | | | |
Collapse
|
34
|
Motor-evoked potential confirmation of functional improvement by transplanted bone marrow mesenchymal stem cell in the ischemic rat brain. J Biomed Biotechnol 2011; 2011:238409. [PMID: 21772790 PMCID: PMC3134108 DOI: 10.1155/2011/238409] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 03/21/2011] [Accepted: 03/25/2011] [Indexed: 11/26/2022] Open
Abstract
This study investigated the effect of bone marrow mesenchymal stem cells (BMSCs) on the motor pathway in the transient ischemic rat brain that were transplanted through the carotid artery, measuring motor-evoked potential (MEP) in the four limbs muscle and the atlantooccipital membrane, which was elicited after monopolar and bipolar transcortical stimulation. After monopolar stimulation, the latency of MEP was significantly prolonged, and the amplitude was less reduced in the BMSC group in comparison with the control group (P < .05). MEPs induced by bipolar stimulation in the left forelimb could be measured in 40% of the BMSC group and the I wave that was not detected in the control group was also detected in 40% of the BMSC group. Our preliminary results imply that BMSCs transplanted to the ischemic rat brain mediate effects on the functional recovery of the cerebral motor cortex and the motor pathway.
Collapse
|
35
|
Imbrosci B, Mittmann T. Functional consequences of the disturbances in the GABA-mediated inhibition induced by injuries in the cerebral cortex. Neural Plast 2011; 2011:614329. [PMID: 21766043 PMCID: PMC3135051 DOI: 10.1155/2011/614329] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Accepted: 04/05/2011] [Indexed: 11/18/2022] Open
Abstract
Cortical injuries are often reported to induce a suppression of the intracortical GABAergic inhibition in the surviving, neighbouring neuronal networks. Since GABAergic transmission provides the main source of inhibition in the mammalian brain, this condition may lead to hyperexcitability and epileptiform activity of cortical networks. However, inhibition plays also a crucial role in limiting the plastic properties of neuronal circuits, and as a consequence, interventions aiming to reestablish a normal level of inhibition might constrain the plastic capacity of the cortical tissue. A promising strategy to minimize the deleterious consequences of a modified inhibitory transmission without preventing the potential beneficial effects on cortical plasticity may be to unravel distinct GABAergic signaling pathways separately mediating these positive and negative events. Here, gathering data from several recent studies, we provide new insights to better face with this "double coin" condition in the attempt to optimize the functional recovery of patients.
Collapse
Affiliation(s)
- Barbara Imbrosci
- Institute of Physiology and Pathophysiology, Medical Center of the Johannes Gutenberg University, Duesbergweg 6, 55128 Mainz, Germany.
| | | |
Collapse
|
36
|
Abstract
The past decade of neuroscience research has provided considerable evidence that the adult brain can undergo substantial reorganization following injury. For example, following an ischemic lesion, such as occurs following a stroke, there is a cascade of molecular, genetic, physiological and anatomical events that allows the remaining structures in the brain to reorganize. Often, these events are associated with recovery, suggesting that they contribute to it. Indeed, the term plasticity in stroke research has had a positive connotation historically. But more recently, efforts have been made to differentiate beneficial from detrimental changes. These notions are timely now that neurorehabilitative research is developing novel treatments to modulate, increase, or inhibit plasticity in targeted brain regions. We will review basic principles of plasticity and some of the new and exciting approaches that are currently being investigated to shape plasticity following injury in the central nervous system.
Collapse
Affiliation(s)
- Numa Dancause
- Département de Physiologie, Université de Montréal, Montréal, Québec, Canada.
| | | |
Collapse
|
37
|
Breschi GL, Librizzi L, Pastori C, Zucca I, Mastropietro A, Cattalini A, de Curtis M. Functional and structural correlates of magnetic resonance patterns in a new in vitro model of cerebral ischemia by transient occlusion of the medial cerebral artery. Neurobiol Dis 2010; 39:181-91. [DOI: 10.1016/j.nbd.2010.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 03/25/2010] [Accepted: 04/05/2010] [Indexed: 12/01/2022] Open
|
38
|
Samaniego EA, Stuckert E, Fischbein N, Wijman CAC. Crossed Cerebellar Diaschisis in Status Epilepticus. Neurocrit Care 2009; 12:88-90. [DOI: 10.1007/s12028-009-9312-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
39
|
Wang H, Sorenson EJ, Spinner RJ, Windebank AJ. Electrophysiologic findings and grip strength after nerve injuries in the rat forelimb. Muscle Nerve 2008; 38:1254-65. [PMID: 18671290 DOI: 10.1002/mus.20971] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We developed electrophysiologic methods for testing the three major forelimb nerves as a tool to evaluate motor and sensory recovery in rats. Median, ulnar, or radial nerves were transected and repaired in Sprague-Dawley rats. Compound muscle action potentials (CMAPs) and somatosensory evoked potentials (SSEPs) were recorded preoperatively and at various postoperative intervals. Correlation between grip strength and CMAPs was investigated. Reliable CMAPs were recorded for all three nerves. Median- or ulnar-nerve-derived SSEPs were reliably recorded; radial SSEPs could not be recorded. CMAPs followed typical regeneration patterns after nerve repair. SSEPs showed a consistent peak latency but fluctuating amplitude. Grip strength and median CMAP amplitude correlated positively. We conclude that it is possible to conduct minimally invasive electrophysiologic testing in rat forelimbs. The CMAP is a valid parameter that shows the typical time course of nerve regeneration and reinnervation.
Collapse
Affiliation(s)
- Huan Wang
- Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | | | | | | |
Collapse
|
40
|
Weber R, Ramos-Cabrer P, Justicia C, Wiedermann D, Strecker C, Sprenger C, Hoehn M. Early prediction of functional recovery after experimental stroke: functional magnetic resonance imaging, electrophysiology, and behavioral testing in rats. J Neurosci 2008; 28:1022-9. [PMID: 18234880 PMCID: PMC6671421 DOI: 10.1523/jneurosci.4147-07.2008] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 11/07/2007] [Accepted: 11/15/2007] [Indexed: 11/21/2022] Open
Abstract
Therapeutic success of treatment of cerebral diseases must be assessed in terms of functional outcome. In experimental stroke studies, this has been limited to behavioral studies combined with morphological evaluations and single time point functional magnetic resonance imaging (fMRI) measurements but lacking the access to understanding underlying mechanisms for alterations in brain activation. Using a recently developed blood oxygenation level-dependent fMRI protocol to study longitudinal and intraindividual profiles of functional brain activation in the somatosensory system, we have demonstrated activation reemergence in the original representation field as the basic principle of functional recovery from experimental stroke. No plastic reorganization has been observed at any time point during 7 weeks after stroke induction. Applying combined recording of fMRI and somatosensory evoked potentials, we observed a tight coupling of electrical brain activity and hemodynamic response at all times, indicating persistent preservation of neurovascular coupling. Identification of functional brain recovery mechanisms has important implications for the understanding of brain plasticity after cerebral lesions, whereas preservation of neurovascular coupling is important for the clinical translation of fMRI.
Collapse
Affiliation(s)
- Ralph Weber
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
- Department of Neurology, University Duisburg-Essen, 45122 Essen, Germany
| | - Pedro Ramos-Cabrer
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
- Clinical Neurosciences Research Laboratory, Hospital Clínico Universitario, 15706 Santiago de Compostela, Spain, and
| | - Carlos Justicia
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
- Farmacologia i Toxicologia, Institut d'Investigacions Biomèdiques de Barcelona/Consejo Superior de Investigaciones Científicas, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain
| | - Dirk Wiedermann
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
| | - Cordula Strecker
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
| | - Christiane Sprenger
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
| | - Mathias Hoehn
- In Vivo NMR Laboratory, Max-Planck-Institute for Neurological Research, 50931 Cologne, Germany
| |
Collapse
|
41
|
Zhang YP, Shields LBE, Zhang Y, Pei J, Xu XM, Hoskins R, Cai J, Qiu MS, Magnuson DSK, Burke DA, Shields CB. Use of magnetic stimulation to elicit motor evoked potentials, somatosensory evoked potentials, and H-reflexes in non-sedated rodents. J Neurosci Methods 2007; 165:9-17. [PMID: 17628688 DOI: 10.1016/j.jneumeth.2007.05.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 05/14/2007] [Accepted: 05/17/2007] [Indexed: 11/21/2022]
Abstract
Assessment of locomotor function of rodents may be supplemented using electrophysiological tests which monitor the integrity of ascending and descending tracts as well as the focal circuitry of the spinal cord in non-sedated rodents. Magnetically induced SSEPs (M-SSEPs) were elicited in rats by activating the hindpaw using magnetic stimulation (MS). M-SSEP response latencies were slightly longer than those elicited by electrical stimulation. M-SSEPs were eliminated following selective dorsal column lacerations of the spinal cord, indicating that they were transmitted via this tract. Magnetically induced motor evoked potentials (M-MEPs) were elicited in mice following transcranial MS and recorded from the gastrocnemius muscles. M-MEPs performed on myelin deficient mice demonstrated longer onset latencies and smaller amplitudes than in wild-type mice. Magnetically induced H-reflexes (MH-reflexes) which assess local circuitry in the lumbosacral area of the spinal cord were performed in rats. This response disappeared following an L3 contusion spinal cord injury, however, kainic acid (KA) injection at L3, known to selectively destroy interneurons, caused a shorter latency and an increase in the amplitude of the MH-reflex. M-SSEPs and MH-reflexes in rats and M-MEPs in mice compliment locomotor evaluation in assessing the functional integrity of the spinal cord under normal and pathological conditions in the non-sedated animal.
Collapse
Affiliation(s)
- Yi Ping Zhang
- Kentucky Spinal Cord Injury Research Center, 511 South Floyd Street, Louisville, KY 40202, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Henninger N, Heimann A, Kempski O. Electrophysiology and neuronal integrity following systemic arterial hypotension in a rat model of unilateral carotid artery occlusion. Brain Res 2007; 1163:119-29. [PMID: 17632088 DOI: 10.1016/j.brainres.2007.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 05/31/2007] [Accepted: 06/01/2007] [Indexed: 10/23/2022]
Abstract
Patients with carotid artery stenosis may be particularly susceptible to hypotension-associated cerebral ischemia and subsequent neurological sequelae. Measuring somatosensory evoked potentials (SEP), electroencephalogram (EEG), direct current (DC) potential, and histology, we compared the temporal evolution of cortical functional perturbations as well as neuronal integrity in a model of unilateral carotid artery occlusion and systemic hypobaric hypotension (HH) at the lower limit of cerebral blood flow autoregulation (50 mm Hg). Serial measurements of EEG power spectra as well as SEP-amplitudes and latencies of N10.3 were performed before, during, and up to 60 min after 30 min-HH (n=7) or the control condition (n=7) in male Wistar rats. In two additional groups (with [n=7] or without [n=7] HH), cortical spreading depressions (CSD) were elicited to ascertain their contribution to brain injury. Hematoxilin-Eosin (H&E) staining was used to assess neuronal cell death at 5 days after surgery. Relative to baseline, HH attenuated ipsilateral EEG power spectrum (by maximally 62%), increased SEP-latencies (by approximately 6-10%) and amplitudes (by approximately 57-70%), and induced selective neuronal cell death in the cerebral cortex and hippocampus (P<0.05 vs. contralateral). Spontaneous CSD occurred in approximately 30% of HH-animals. Repolarization of the DC-potential during HH was significantly prolonged relative to normotensive conditions (10.3+/-11.5 min, P<0.001). Our model may help to understand underlying pathophysiology and improve outcome in a clinical subset of patients with carotid artery stenosis and transient systemic hypotension.
Collapse
Affiliation(s)
- Nils Henninger
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
| | | | | |
Collapse
|
43
|
Brauna JC, Hanley DF, Thakor NV. Detection of neurological injury using time-frequency analysis of the somatosensory evoked potential. ACTA ACUST UNITED AC 2007; 100:310-8. [PMID: 17441301 DOI: 10.1016/0168-5597(96)95115-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Somatosensory evoked potentials (SEPs) can be monitored during critical surgery to help detect or possibly prevent post-operative injury to the brain. This paper presents the application of time-frequency analysis to detect both temporal and spectral changes in the SEP waveform that may occur due to injury. Time-frequency distributions, which provide a measure of signal energy at both a specific time and frequency, were computed for averaged SEPs acquired from anesthetized cats during various stages of hypoxic injury and then recovery. Wigner distributions of SEP waveforms were found to contain a peak of signal energy at a specific time and frequency, a peak that is altered during injury. Four characteristics of the distribution peak that demonstrate changes due to injury were computed: peak time, peak frequency, peak power, and peak sharpness. Peak time was found to increase while peak frequency, peak power, and peak sharpness were found to decrease during injury. Furthermore, the total signal power in a time-frequency space around the normal peak location was monitored by developing a time-frequency window filter (TFWF) method. For all cases, onset of hypoxia was detected an average of 2.75 min earlier by the TFWF method than by the conventional amplitude measurement method. Time-frequency analysis of EP signals may therefore be useful as a monitoring tool for early detection of brain injury.
Collapse
Affiliation(s)
- J C Brauna
- Department of Biomedical Engineering, Johns Hopkins University, 720 Rutland Avenue, Baltimore, MD 21205, USA
| | | | | |
Collapse
|
44
|
Oinuma M, Suzuki K, Honda T, Matsumoto M, Sasaki T, Kodama N. High-frequency monopolar electrical stimulation of the rat cerebral cortex. Neurosurgery 2007; 60:189-96; discussion 196-7. [PMID: 17228268 DOI: 10.1227/01.neu.0000249204.81472.88] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Intraoperative monitoring of the motor-evoked potential has been widely used in patients undergoing neurosurgery. Direct stimulation of the brain with high-frequency monopolar stimulation (HFMS) is one of the most common methods to produce motor-evoked potential. We studied the influence of HFMS on the rat cerebral cortex. METHODS We applied 1.5, 15, 30, 40, or 50 mA of HFMS to the rat sensorimotor cortex by a short sequence of five monopolar, monophasic, anodal rectangular 500-Hz pulses. We delivered one short five-pulse train 100 times every 5 seconds and examined pre- and post-stimulation electroencephalograms and histological changes at the stimulation site. RESULTS We observed no spike waves after HFMS in any of the rats. There was no change in the power spectrum or frequency content in any of the rats exposed to HFMS. Histologically, there was significant swelling of the dendrites in rats sacrificed immediately after exposure to 40- and 50-mA stimulation; the 50-mA stimulation group also exhibited slight swelling of the mitochondria. These findings were not obtained in any of the rats sacrificed 30 days after stimulation. CONCLUSION In rats exposed to a stimulation intensity of 30-mA or less, no morphological or electrophysiological changes were observed. However, the possibility that HFMS may affect neural tissue cannot be ruled out.
Collapse
Affiliation(s)
- Masahiro Oinuma
- Department of Neurosurgery, Fukushima Medical University, Fukushima, Japan.
| | | | | | | | | | | |
Collapse
|
45
|
Enager P, Gold L, Lauritzen M. Impaired neurovascular coupling by transhemispheric diaschisis in rat cerebral cortex. J Cereb Blood Flow Metab 2004; 24:713-9. [PMID: 15241179 DOI: 10.1097/01.wcb.0000121233.63924.41] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In acute brain disorders, elimination of the excitatory output from an injured brain region reduces activity in connecting brain regions remote from the lesion site (i.e., diaschisis). The authors examined the effect of functional ablation of the left cerebral cortex by cortical spreading depression (CSD) or topical application of tetrodotoxin on single cell spiking activity, baseline CBF, and neurovascular coupling in the right rat sensory cortex. CSD or tetrodotoxin in left cortex reduced the right cortical spontaneous spike rate by 36% and 45%, respectively. Baseline CBF in the right cortex was unaffected by a left-sided CSD, but decreased by 12% for left cortical application of tetrodotoxin. This suggested dissociation between spontaneous spiking activity and basal CBF. Left in-fraorbital nerve stimulation evoked local field potentials in right cerebral cortex that were reduced in amplitude by 19% for left CSD and by 23% for left tetrodotoxin application. The corresponding declines in the evoked CBF responses were 42% for CSD and 23% for tetrodotoxin. Vascular reactivity to adenosine remained unchanged in right cortex. Thus, transhemispheric diaschisis produced a pronounced decrease in the spontaneous spike rate accompanied by no reduction or a small reduction in basal CBF, and an attenuation in amplitudes of evoked synaptic responses and corresponding rises in CBF. The findings suggest that disturbed neurovascular coupling may contribute to the disturbance in brain function in acute transhemispheric diaschisis.
Collapse
Affiliation(s)
- Pia Enager
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | | | | |
Collapse
|
46
|
Nishio S, Kawauchi M, Tamiya T, Ohmoto T. Effects of hypothermia and rewarming on evoked potentials during transient focal cerebral ischemia in cats. Neurol Res 2002; 24:621-6. [PMID: 12238632 DOI: 10.1179/016164102101200465] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
We examined the effects of mild to moderate hypothermia and the influence of rewarming on electrophysiological function using somatosensory evoked potentials (SEPs) in transient focal ischemia in the brain. Nineteen cats underwent 60 min of left middle cerebral artery occlusion under normothermic (36 degrees-37 degrees C, n = 6) or hypothermic (30 degrees -31 degrees C, n = 13) conditions followed by 300 min of reperfusion with slow (120 min, n = 6) or rapid (30 min, n = 7) rewarming. Whole-body hypothermia was induced during ischemia and the first 180 min of reperfusion. SEPs and regional cerebral blood flow were measured before and during ischemia and during reperfusion. The specific gravity of gray and white matter was examined as the indicator of edema. During rewarming, SEP amplitudes recovered gradually. After rewarming, SEPs in the normothermic and rapid rewarming groups remained depressed (20%-40% of pre-occlusion values); however, recovery of SEPs was significantly enhanced in the slow rewarming group (p < 0.05). Hypothermia followed by slow rewarming reduced edema in gray and white matter. Rapid rewarming did not reduce edema in the white matter. The recovery of SEPs correlated with the extent of brain edema in transient focal ischemia. Rapid rewarming reduced the protective effect of hypothermia.
Collapse
Affiliation(s)
- Shinsaku Nishio
- Department of Neurological Surgery, Okayama University Medical School, Japan.
| | | | | | | |
Collapse
|
47
|
Gold L, Lauritzen M. Neuronal deactivation explains decreased cerebellar blood flow in response to focal cerebral ischemia or suppressed neocortical function. Proc Natl Acad Sci U S A 2002; 99:7699-704. [PMID: 12032346 PMCID: PMC124326 DOI: 10.1073/pnas.112012499] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2002] [Indexed: 11/18/2022] Open
Abstract
Functional neuroimaging in humans with acute brain damage often reveals decreases in blood flow and metabolism in areas unaffected by the lesion. This phenomenon, termed diaschisis, is presumably caused by disruption of afferent excitatory input from the lesioned area to other brain regions. By characterizing its neurophysiological basis, we used cerebellar diaschisis to study the relationship between electrical activity and blood flow during decreased neuronal activity. Here we show that focal cerebral ischemia in rats causes diaschisis in the cerebellar cortex characterized by pronounced decreases in Purkinje cell spiking activity and small decreases in cerebellar blood flow. The findings were explained by decreased excitatory input to the cerebellar cortex, i.e., deactivation, as cerebellar neuronal excitability and vascular reactivity were preserved. Functional ablation of the cerebral cortex by either spreading depression or tetrodotoxin reproduced the changes in cerebellar function with complete recovery of Purkinje cell activity and cerebellar blood flow concomitant with recovery of neocortical function. Decreases of activity involving the contralateral frontal cortex produced the largest decrease in cerebellar electrical activity and blood flow. Our data suggest that deactivation explains the decreases in blood flow and metabolism in cerebellar diaschisis observed in human neuroimaging studies. Decreases in spiking activity were 3-7 times larger than the respective decreases in flow. Therefore, under pathological conditions, neuroimaging methods based on hemodynamic signals may only show small changes, although the underlying decrease in neuronal activity is much larger.
Collapse
Affiliation(s)
- Lorenz Gold
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark.
| | | |
Collapse
|
48
|
Hu Y, Luk KD, Lu WW, Leong JC. Comparison of time-frequency analysis techniques in intraoperative somatosensory evoked potential (SEP) monitoring. Comput Biol Med 2002; 32:13-23. [PMID: 11738637 DOI: 10.1016/s0010-4825(01)00026-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Somatosensory evoked potentials (SEPs) can be monitored during spinal surgery to prevent possible spinal cord injury. In order to improve the reliability of SEP monitoring, an investigation of the application of various time-frequency analysis (TFA) techniques to detect both temporal and spectral changes in SEP waveforms was conducted. SEP signals from 15 scoliosis patients were analysed using various methods. The time-frequency distributions (TFDs) computed using these methods were assessed and compared. The most appropriate TFA technique may depend on the type of SEP signal, Short term Fourier transform (STFT) with a 20 point length Hanning window probably provides the best result for SEP signals.
Collapse
Affiliation(s)
- Yong Hu
- Department of Orthopaedic Surgery, The University of Hong Kong, Duchess of Kent Children's Hospital, 12 Sandy Bay Road, Hong Kong.
| | | | | | | |
Collapse
|
49
|
Bolay H, Gürsoy-Ozdemir Y, Unal I, Dalkara T. Altered mechanisms of motor-evoked potential generation after transient focal cerebral ischemia in the rat: implications for transcranial magnetic stimulation. Brain Res 2000; 873:26-33. [PMID: 10915807 DOI: 10.1016/s0006-8993(00)02466-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We recently demonstrated that a long-lasting transmission defect in cortical synapses caused motor dysfunction after brief middle cerebral artery (MCA) occlusion in the rat despite rapid recovery of axons. In this experimental study, we have examined the impact of differential recovery of synapses and axons on generation of motor-evoked potentials (MEP) recorded from contralateral paralyzed and ipsilateral unaffected muscles, to gain insight into mechanisms of MEPs recorded from stroke patients by transcranial magnetic stimulation (TMS). MEPs generated by focal electrical stimulation of the forelimb area of motor cortex were simultaneously recorded from the brain stem, contra- and ipsilateral forelimb and contralateral hindlimb muscles in rats subjected to transient MCA occlusion. The effect of ischemia on cortical activity and axonal conduction was differentially studied by proximal or distal occlusion of the MCA. Regional cerebral blood flow changes in the forelimb area were monitored by laser-Doppler flowmetry during ischemia and reperfusion. In addition, synaptic transmission within the forelimb area of motor cortex was examined by intracellular and extracellular recording of potentials generated by stimulation of the premotor area. No MEP response was recorded during ischemia. Upon reperfusion: (i) motor axons readily regained their excitability and cortical stimulation caused successive pyramidal volleys (recorded as D waves from the brain stem) and a MEP from contralateral paralytic muscles although synaptic activation of motor pathways was not feasible; (ii) the amplitude of pyramidal volley was increased; (iii) MEPs with a longer latency were recorded from the ipsilateral forelimb. In conclusion, differential recovery of synapses and axons after ischemia may account for some previously unexplained findings (such as preserved MEPs in paralysed muscles) observed in cortical stimulation studies of stroke patients.
Collapse
Affiliation(s)
- H Bolay
- Department of Neurology, Faculty of Medicine and Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | | | | | | |
Collapse
|
50
|
Abstract
This review is directed at understanding how neuronal death occurs in two distinct insults, global ischemia and focal ischemia. These are the two principal rodent models for human disease. Cell death occurs by a necrotic pathway characterized by either ischemic/homogenizing cell change or edematous cell change. Death also occurs via an apoptotic-like pathway that is characterized, minimally, by DNA laddering and a dependence on caspase activity and, optimally, by those properties, additional characteristic protein and phospholipid changes, and morphological attributes of apoptosis. Death may also occur by autophagocytosis. The cell death process has four major stages. The first, the induction stage, includes several changes initiated by ischemia and reperfusion that are very likely to play major roles in cell death. These include inhibition (and subsequent reactivation) of electron transport, decreased ATP, decreased pH, increased cell Ca(2+), release of glutamate, increased arachidonic acid, and also gene activation leading to cytokine synthesis, synthesis of enzymes involved in free radical production, and accumulation of leukocytes. These changes lead to the activation of five damaging events, termed perpetrators. These are the damaging actions of free radicals and their product peroxynitrite, the actions of the Ca(2+)-dependent protease calpain, the activity of phospholipases, the activity of poly-ADPribose polymerase (PARP), and the activation of the apoptotic pathway. The second stage of cell death involves the long-term changes in macromolecules or key metabolites that are caused by the perpetrators. The third stage of cell death involves long-term damaging effects of these macromolecular and metabolite changes, and of some of the induction processes, on critical cell functions and structures that lead to the defined end stages of cell damage. These targeted functions and structures include the plasmalemma, the mitochondria, the cytoskeleton, protein synthesis, and kinase activities. The fourth stage is the progression to the morphological and biochemical end stages of cell death. Of these four stages, the last two are the least well understood. Quite little is known of how the perpetrators affect the structures and functions and whether and how each of these changes contribute to cell death. According to this description, the key step in ischemic cell death is adequate activation of the perpetrators, and thus a major unifying thread of the review is a consideration of how the changes occurring during and after ischemia, including gene activation and synthesis of new proteins, conspire to produce damaging levels of free radicals and peroxynitrite, to activate calpain and other Ca(2+)-driven processes that are damaging, and to initiate the apoptotic process. Although it is not fully established for all cases, the major driving force for the necrotic cell death process, and very possibly the other processes, appears to be the generation of free radicals and peroxynitrite. Effects of a large number of damaging changes can be explained on the basis of their ability to generate free radicals in early or late stages of damage. Several important issues are defined for future study. These include determining the triggers for apoptosis and autophagocytosis and establishing greater confidence in most of the cellular changes that are hypothesized to be involved in cell death. A very important outstanding issue is identifying the critical functional and structural changes caused by the perpetrators of cell death. These changes are responsible for cell death, and their identity and mechanisms of action are almost completely unknown.
Collapse
Affiliation(s)
- P Lipton
- Department of Physiology, University of Wisconsin School of Medicine, Madison, Wisconsin, USA
| |
Collapse
|