Cortical motor areas and their properties: Implications for neuroprosthetics

Pd, Cheney; Hill-Karrer, J; Belhaj-Saïf, Abderraouf; Bj, McKiernan; Mc, Park; Jk, Marcario

doi:10.1016/s0079-6123(00)28013-8

Cited by 15 publications

(8 citation statements)

References 143 publications

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“…Several changes occur in the neuron after axotomy, including those related to metabolism, gene regulation, and neurotrophic factor production 1. Cheney and colleagues78 have emphasized that, whereas corticospinal cells survive severing of axons at the subcortical level, the functional properties of these cells requires further study. This study is a useful step toward this goal.…”

Section: Discussionmentioning

confidence: 99%

Motor cortex activation is preserved in patients with chronic hemiplegic stroke

Cramer¹,

Mark²,

Barquist³

et al. 2002

Annals of Neurology

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Many central nervous system conditions that cause weakness, including many strokes, injure corticospinal tract but leave motor cortex intact. Little is known about the functional properties of surviving cortical regions in this setting, in part because many studies have used probes reliant on the corticospinal tract. We hypothesized that many features of motor cortex function would be preserved when assessed independent of the stroke-affected corticospinal tract. Functional MRI was used to study 11 patients with chronic hemiplegia after unilateral stroke that spared regions of motor cortex. Activation in stroke-affected hemisphere was evaluated using 3 probes independent of affected corticospinal tract: passive finger movement, a hand-related visuomotor stimulus, and tapping by the nonstroke index finger. The site and magnitude of cortical activation were similar when comparing the stroke hemisphere to findings in 19 control subjects. Patients activated each of 8 cortical regions with similar frequency as compared to controls, generally with a smaller activation volume. In some cases, clinical measures correlated with the size or the site of stroke hemisphere activation. The results suggest that, despite stroke producing contralateral hemiplegia, surviving regions of motor cortex actively participate in the same proprioceptive, visuomotor, and bilateral movement control processes seen in control subjects.

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Section: Discussionmentioning

confidence: 99%

Motor cortex activation is preserved in patients with chronic hemiplegic stroke

Cramer¹,

Mark²,

Barquist³

et al. 2002

Annals of Neurology

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“…Each animal received a calibrated contusion injury to the thoracic spinal cord at the Ohio State University as previously described (Stokes, 1992;. Briefly, the animal was anesthetized with an intraperitoneal injection of ketamine HC1 (80 mg/kg) and xylazine (10 mg/kg). A partial dorsal laminectomy was performed at the T8-T9 vertebral junction, and over a 23-msec period the dorsal surface of the cord was compressed either 0.7 mm (mild contusion, 10 rats) or 0.9 mm (medium contusion, four rats).…”

Section: Methodsmentioning

confidence: 99%

Operant Conditioning of H-Reflex Increase in Spinal Cord–Injured Rats

Chen

Wolpaw²,

Jakeman³

et al. 1999

Journal of Neurotrauma

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Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of long-term supraspinal control over spinal cord function. Primates and rats can gradually increase (HRup conditioning mode) or decrease (HRdown conditioning mode) the H-reflex when reward is based on H-reflex amplitude. An earlier study indicated that HRdown conditioning of the soleus H-reflex in rats is impaired following contusion injury to thoracic spinal cord. The extent of impairment was correlated with the percent of white matter lost at the injury site. The present study investigated the effects of spinal cord injury on HRup conditioning. Soleus H-reflexes were elicited and recorded with chronically implanted electrodes from 14 rats that had been subjected to calibrated contusion injuries to the spinal cord at T8. At the lesion epicenter, 12-39% of the white matter remained. After control-mode data were collected, each rat was exposed to the HRup conditioning mode for 50 days. Final H-reflex amplitudes after HRup conditioning averaged 112% (+/-22% SD) of control. This value was significantly smaller than that for 13 normal rats exposed to HRup conditioning, in which final amplitude averaged 153% (+/-51%) SD of control. As previously reported for HRdown conditioning after spinal cord injury, success was inversely correlated with the severity of the injury as assessed by white matter preservation and by time to return of bladder function. HRup and HRdown conditioning are similarly sensitive to injury. These results further demonstrate that H-reflex conditioning is a sensitive measure of the long-term effects of injury on supraspinal control over spinal cord functions and could prove a valuable measure of therapeutic efficacy.

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“…For example, the macaque's L-6-S-1 neurons, which contribute to hindlimb stepping, receive descending corticospinal tract projections from about 24,000 neurons in M1, 6000 from SMA, 6200 from dorsal and ventral cingulate, 5000 from dorsal premotor, and 10 from ventral premotor cortices. 4 Each of these cortical regions interacts with visual, vestibular, aural, proprioceptive, cutaneous and other inputs to help plan, select, initiate, and maintain unilateral and bilateral skilled movements. Thus, the corticospinal tract, which includes some uncrossed fibers within the lateral and ventral funiculi, draws from neurons that are distributed and separated by somewhat different vascular territories.…”

Section: Cerebral Sensorimotor Systemmentioning

confidence: 99%

Neurobiology of Rehabilitation

Dobkin

2004

Annals of the New York Academy of Sciences

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Rehabilitation aims to lessen the physical and cognitive impairments and disabilities of patients with stroke, multiple sclerosis, spinal cord or brain injury, and other neurologic diseases. Conventional approaches beyond compensatory adjustments to disability may be augmented by applying some of the myriad experimental results about mechanisms of intrinsic biological changes after injury and the effects of extrinsic manipulations on spared neuronal assemblies. The organization and inherent adaptability of the anatomical nodes within distributed pathways of the central nervous system offer a flexible substrate for treatment strategies that drive activity-dependent plasticity. Opportunities for a new generation of approaches are manifested by rodent and non-human primate studies that reveal morphologic and physiologic adaptations induced by injury, by learning-associated practice, by the effects of pharmacologic neuromodulators, by the behavioral and molecular bases for enhancing activity-dependent synaptic plasticity, and by cell replacement, gene therapy, and regenerative biologic strategies. Techniques such as functional magnetic resonance imaging and transcranial magnetic stimulation will help determine the most optimal physiologic effects of interventions in patients as the cortical representations for skilled movements and cognitive processes are modified by the combination of conventional and biologic therapies. As clinicians digest the finer details of the neurobiology of rehabilitation, they will translate laboratory data into controlled clinical trials. By determining how much they can influence neural reorganization, clinicians will extend the opportunities for neurorestoration.

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Cortical motor areas and their properties: Implications for neuroprosthetics

Cited by 15 publications

References 143 publications

Motor cortex activation is preserved in patients with chronic hemiplegic stroke

Motor cortex activation is preserved in patients with chronic hemiplegic stroke

Operant Conditioning of H-Reflex Increase in Spinal Cord–Injured Rats

Neurobiology of Rehabilitation

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