Plasticity

Nudo, Randolph J.

doi:10.1016/j.nurx.2006.07.006

Cited by 158 publications

(109 citation statements)

References 61 publications

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“…In primates and humans, the somatotopic map for the hand and fingers has expanded considerably compared to lower animals in keeping with the importance of refined hand movements in these species compared with rodents. Nudo et al [1996] showed that retraining of hand skill in an experimental primate model after a focal infarct in motor cortex prevented the shrinkage of the hand area that normally occurred adjacent to the infarct following the injury [Nudo, 2006]. They also found that the hand area sometimes expanded into the area generally occupied by the shoulder and elbow.…”

Section: Structural Changes In Brain Circuitry Caused By Experiencementioning

confidence: 98%

Plasticity in the developing brain: Implications for rehabilitation

Johnston

2009

Dev Disabil Res Revs

417

273

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Neuronal plasticity allows the central nervous system to learn skills and remember information, to reorganize neuronal networks in response to environmental stimulation, and to recover from brain and spinal cord injuries. Neuronal plasticity is enhanced in the developing brain and it is usually adaptive and beneficial but can also be maladaptive and responsible for neurological disorders in some situations. Basic mechanisms that are involved in plasticity include neurogenesis, programmed cell death, and activity-dependent synaptic plasticity. Repetitive stimulation of synapses can cause long-term potentiation or long-term depression of neurotransmission. These changes are associated with physical changes in dendritic spines and neuronal circuits. Overproduction of synapses during postnatal development in children contributes to enhanced plasticity by providing an excess of synapses that are pruned during early adolescence. Clinical examples of adaptive neuronal plasticity include reorganization of cortical maps of the fingers in response to practice playing a stringed instrument and constraint-induced movement therapy to improve hemiparesis caused by stroke or cerebral palsy. These forms of plasticity are associated with structural and functional changes in the brain that can be detected with magnetic resonance imaging, positron emission tomography, or transcranial magnetic stimulation (TMS). TMS and other forms of brain stimulation are also being used experimentally to enhance brain plasticity and recovery of function. Plasticity is also influenced by genetic factors such as mutations in brain-derived neuronal growth factor. Understanding brain plasticity provides a basis for developing better therapies to improve outcome from acquired brain injuries. ' 2009 Wiley-Liss, Inc. Dev Disabil Res Rev 200915:94-101.

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Section: Structural Changes In Brain Circuitry Caused By Experiencementioning

confidence: 98%

Plasticity in the developing brain: Implications for rehabilitation

Johnston

2009

Dev Disabil Res Revs

417

273

View full text Add to dashboard Cite

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“…Although the stimulation protocol is similar to the principles used by Penfield, it is important to recognize that the maps created using this technique do not compare in precision to maps created using intracortical microstimulation 46,48 . Animal studies have demonstrated that individual corticospinal neurons innervate several motor neuron pools and thus different muscles and corticospinal neurons that innervate a particular muscle are distributed among other corticospinal neurons projecting to different muscle combinations 50,51 . This mosaic somatotopy of the cortex and the overlapping spinal cord projections in combination with the lack of stimulus precision with TMS means that multiple muscles will respond to a single TMS pulse delivered at one point on the scalp matrix 46 .…”

Section: Interhemispheric Facilitation and Inhibitionmentioning

confidence: 99%

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Goss

Hoffman

Clark

2012

JoVE

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Transcranial magnetic stimulation (TMS) has been in use for more than 20 years 1 , and has grown exponentially in popularity over the past decade. While the use of TMS has expanded to the study of many systems and processes during this time, the original application and perhaps one of the most common uses of TMS involves studying the physiology, plasticity and function of the human neuromuscular system. Single pulse TMS applied to the motor cortex excites pyramidal neurons transsynaptically 2 ( Figure 1) and results in a measurable electromyographic response that can be used to study and evaluate the integrity and excitability of the corticospinal tract in humans 3 . Additionally, recent advances in magnetic stimulation now allows for partitioning of cortical versus spinal excitability 4,5 . For example, paired-pulse TMS can be used to assess intracortical facilitatory and inhibitory properties by combining a conditioning stimulus and a test stimulus at different interstimulus intervals 3,4,[6][7][8] . In this video article we will demonstrate the methodological and technical aspects of these techniques. Specifically, we will demonstrate singlepulse and paired-pulse TMS techniques as applied to the flexor carpi radialis (FCR) muscle as well as the erector spinae (ES) musculature. Our laboratory studies the FCR muscle as it is of interest to our research on the effects of wrist-hand cast immobilization on reduced muscle performance 6,9 , and we study the ES muscles due to these muscles clinical relevance as it relates to low back pain 8 . With this stated, we should note that TMS has been used to study many muscles of the hand, arm and legs, and should iterate that our demonstrations in the FCR and ES muscle groups are only selected examples of TMS being used to study the human neuromuscular system. Video LinkThe video component of this article can be found at http://www.jove.com/video/3387/ Protocol 1. Single and Paired-Pulse TMS of the FCR and ES Muscles 1. Basic Safety Precautions: Prior to performing TMS on a human subject it is necessary to first screen them for basic safety precautions as it pertains to exposure to a magnetic field. In our laboratory we follow the screening guidelines set forth by the Institute for Magnetic Resonance Safety, Education and Research 10 . In our laboratory we also routinely exclude individuals with a family history of epilepsy seizures. We also require subjects undergoing TMS of the ES muscles to wear earplugs and a mouth guard due to the less focal and stronger stimulation intensities. Electrical Recordings:To examine TMS responses in the motor system it is necessary to record electromyographic (EMG) signals from skeletal muscles. For the FCR muscle we place surface electrodes on the forearm using a bipolar electrode arrangement located longitudinally over the muscle on shaved and abraded skin as we have previously described 7,11 . For the erector spinae muscles we use a similar electrode arrangement located longitudinally over the muscles at the L3-L5 vertebral level...

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“…VSD imaging, which detects subthreshold and suprathreshold membrane potential changes of the superficial cortical layers, likewise revealed stronger activation of the forelimb sensory cortcex after contralesional forepaw stimulation 12 weeks after C3 hemisection. These alterations may be driven by acquisitions of new movements or movement strategies after injury, and not just repetitive use (Nudo, 2006).…”

Section: Increase In Size Of Sensory Activation Map Of the Unimpairedmentioning

confidence: 99%

Functional and Anatomical Reorganization of the Sensory-Motor Cortex after Incomplete Spinal Cord Injury in Adult Rats

Ghosh¹,

Sydekum²,

Haiss³

et al. 2009

J. Neurosci.

155

112

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A lateral hemisection injury of the cervical spinal cord results in Brown-Séquard syndrome in humans and rats. The hands/forelimbs on the injured side are rendered permanently impaired, but the legs/hindlimbs recover locomotor functions. This is accompanied by increased use of the forelimb on the uninjured side. Nothing is known about the cortical circuits that correspond to these behavioral adaptations. In this study, on adult rats with cervical spinal cord lateral hemisection lesions (at segment C3/4), we explored the sensory representation and corticospinal projection of the intact (ipsilesional) cortex. Using blood oxygenation level-dependent functional magnetic resonance imaging and voltage-sensitive dye (VSD) imaging, we found that the cortex develops an enhanced representation of the unimpaired forepaw by 12 weeks after injury. VSD imaging also revealed the cortical spatio-temporal dynamics in response to electrical stimulation of the ipsilateral forepaw or hindpaw. Interestingly, stimulation of the ipsilesional hindpaw at 12 weeks showed a distinct activation of the hindlimb area in the intact, ipsilateral cortex, probably via the injury-spared spinothalamic pathway. Anterograde tracing of corticospinal axons from the intact cortex showed sprouting to recross the midline, innervating the spinal segments below the injury in both cervical and lumbar segments. Retrograde tracing of these midline-crossing axons from the cervical spinal cord (at segment C6/7) revealed the formation of a new ipsilateral forelimb representation in the cortex. Our results demonstrate profound reorganizations of the intact sensory-motor cortex after unilateral spinal cord injury. These changes may contribute to the behavioral adaptations, notably for the recovery of the ipsilesional hindlimb.

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Plasticity

Cited by 158 publications

References 61 publications

Plasticity in the developing brain: Implications for rehabilitation

Plasticity in the developing brain: Implications for rehabilitation

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Functional and Anatomical Reorganization of the Sensory-Motor Cortex after Incomplete Spinal Cord Injury in Adult Rats

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