Posts Tagged motor cortex

[ARTICLE] Large-scale changes in cortical dynamics triggered by repetitive somatosensory electrical stimulation – Full Text

Abstract

Background

Repetitive somatosensory electrical stimulation (SES) of forelimb peripheral nerves is a promising therapy; studies have shown that SES can improve motor function in stroke subjects with chronic deficits. However, little is known about how SES can directly modulate neural dynamics. Past studies using SES have primarily used noninvasive methods in human subjects. Here we used electrophysiological recordings from the rodent primary motor cortex (M1) to assess how SES affects neural dynamics at the level of single neurons as well as at the level of mesoscale dynamics.

Methods

We performed acute extracellular recordings in 7 intact adult Long Evans rats under ketamine-xylazine anesthesia while they received transcutaneous SES. We recorded single unit spiking and local field potentials (LFP) in the M1 contralateral to the stimulated arm. We then compared neural firing rate, spike-field coherence (SFC), and power spectral density (PSD) before and after stimulation.

Results

Following SES, the firing rate of a majority of neurons changed significantly from their respective baseline values. There was, however, a diversity of responses; some neurons increased while others decreased their firing rates. Interestingly, SFC, a measure of how a neuron’s firing is coupled to mesoscale oscillatory dynamics, increased specifically in the δ-band, also known as the low frequency band (0.3- 4 Hz). This increase appeared to be driven by a change in the phase-locking of broad-spiking, putative pyramidal neurons. These changes in the low frequency range occurred without a significant change in the overall PSD.

Conclusions

Repetitive SES significantly and persistently altered the local cortical dynamics of M1 neurons, changing both firing rates as well as the SFC magnitude in the δ-band. Thus, SES altered the neural firing and coupling to ongoing mesoscale dynamics. Our study provides evidence that SES can directly modulate cortical dynamics.

Background

Somatosensory input is essential for skilled movements [1,2,3]; this is particularly true for dexterous movements [14,5,6]. Interestingly, the somatosensory system has been shown to experience relatively rapid bidirectional changes in organization as a result of repetitive manipulations of peripheral inputs. Consistent with this notion are seminal studies in both animals and humans which demonstrated that reductions in sensory feedback, either by denervation or ischemic nerve block, induced changes in motor representations [78].

Studies have also shown that increases in afferent input by stimulating peripheral pathways (i.e. repetitive somatosensory electrical stimulation or SES) can alter sensorimotor representations of the stimulated body part [910]. One of the first studies examining this neuromodulation method found that sensory stimulation of oral structures resulted in prolonged changes in excitability as well as an increase in the area of representation determined using functional imaging [11]. Consistent with these results are studies demonstrating that altered patterns of physical contacts to the fingers can also persistently reorganize sensory maps [1213]. Importantly, repetitive SES has also proven to be a promising therapeutic tool for motor rehabilitation [1014,15,16].

In both humans and rodents, SES can increase excitability as measured by responses to transcranial magnetic stimulation (TMS) pulses [917]. Past studies have used non-invasive measures to examine cortical excitability such as motor evoked potentials (MEPs) with TMS [917] and cortical reorganization using blood oxygenation signals [11]. It remains unclear what are the precise mechanisms underlying these changes. For example, the observed change in the evoked MEPs following SES may occur without changes in brainstem electrical stimulation-evoked potentials or spinal reflexes [91819]. This suggests the possibility that the cortex may be an important site of plasticity. While our recent study showed that SES can also modify low-frequency dynamics as measured using electroencephalogram (EEG) [20], it remains unclear if these changes are local to cortex. Invasive electrophysiology offers one method to assess if SES can directly alter local motor cortical dynamics.

While the body of literature summarized above has provided important mechanistic insight, little is known about how SES interacts with ongoing cortical dynamics at the level of single neurons and groups of neurons, or neural ensembles. Single neurons are a fundamental unit of the nervous system. The coordinated firing of neural ensembles, e.g. co-firing of neurons in a temporally coupled manner, is now also recognized as an important module for information processing [21,22,23,24,25,26]. In addition, oscillations may provide a mechanism for dynamic coordination of ensembles across motor and sensory areas [21,22,23,24,2527]. Oscillations likely reflect synchronized rhythmic excitability linked to coordinated firing of neurons [28]. Our collective understanding of both single neuron and ensemble firing patterns has greatly improved our understanding of how neural activity patterns underlie complex sensory and motor behaviors. Similarly, it is likely that such activity may play an important role in driving neural plasticity after injury and during neuromodulation using methods such as SES.

The goal of this study was to develop a model of the cortical effects of SES using high-resolution, invasive recording of neurons. We were particularly interested in understanding the diversity of single neuron responses to SES. It is unlikely that all neurons respond identically to a given perturbation. This may be, in part, the result of the multiple cell-types in a given region and the diversity of network connectivity for single neurons [29]. We also wanted to compare changes in neural activity related to larger scale network oscillatory activity. More specifically, we examined the effects of SES on primary motor cortex (M1) at the level of single neuron firing rates as well as the neural coupling to ongoing spontaneous oscillations. We found that SES could independently change both the firing rate and the phase locking, i.e. the consistency of the neural firing relative to oscillatory dynamics. Together, our results provide evidence that SES can directly modulate neural dynamics in M1.

Methods

Animal and surgery preparation

All animal procedures were in accordance with protocols approved by the Institutional Animal Care and Use Committee at the San Francisco Veterans Affairs Medical Center. Adult male Long Evans rats (n = 8, 250-400 g, ~ 8 weeks old, Charles River Laboratories) were housed in a 12 h light:12 h dark cycle with lights out at 6:00 AM and were kept under controlled temperature. One animal was excluded from the study due to significant recording drift and electrical noise in the recording, thus n = 7 animals were used for the analysis shown. Animals were initially anesthetized using a ketamine/xylazine cocktail (85 mg/kg ketamine, and 10 mg/kg xylazine), with supplemental ketamine (at half of the induction dose) given every 40–60 min as needed to maintain a stable anesthetic level, and also to maintain anesthesia at stage III characterized by predominantly slow oscillations. Moreover, 0.05 mg/kg of atropine was given separately to counter respiratory and cardiac depression, and decrease secretion. Animals were sacrificed at the end of the recordings.

Somatosensory electrical stimulation and electrophysiology

After anesthesia induction, transcutaneous stimulation electrodes were clipped near forelimb peripheral nerves (medial, ulnar, and radial nerve), in the configuration noted in Fig. 1a. These copper metal clips were wrapped around the forelimb and then connected to a Multi-Channel Systems Stimulus Generator (MCS STG4000 series) to deliver transcutaneous stimulation. SES current parameters were set by determining the maximum amount of current where no evoked movement in the forelimb was seen (typically 300–750 μA currents).

 

figure1

Fig. 1 Schematic of the Experiment. a, Somatosensory electrical stimulation was applied directly to the distal forelimb while neural activity was recorded under anesthesia. b, Schematic of the stimulation paradigm. c, Averaged evoked potential in the local field potential during SES

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Continue —>  Large-scale changes in cortical dynamics triggered by repetitive somatosensory electrical stimulation | Journal of NeuroEngineering and Rehabilitation | Full Text

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[Abstract] Differential Poststroke Motor Recovery in an Arm Versus Hand Muscle in the Absence of Motor Evoked Potentials

Background. After stroke, recovery of movement in proximal and distal upper extremity (UE) muscles appears to follow different time courses, suggesting differences in their neural substrates.

Objective. We sought to determine if presence or absence of motor evoked potentials (MEPs) differentially influences recovery of volitional contraction and strength in an arm muscle versus an intrinsic hand muscle. We also related MEP status to recovery of proximal and distal interjoint coordination and movement fractionation, as measured by the Fugl-Meyer Assessment (FMA).

Methods. In 45 subjects in the year following ischemic stroke, we tracked the relationship between corticospinal tract (CST) integrity and behavioral recovery in the biceps (BIC) and first dorsal interosseous (FDI) muscle. We used transcranial magnetic stimulation to probe CST integrity, indicated by MEPs, in BIC and FDI. We used electromyography, dynamometry, and UE FMA subscores to assess muscle-specific contraction, strength, and inter-joint coordination, respectively.

Results. Presence of MEPs resulted in higher likelihood of muscle contraction, greater strength, and higher FMA scores. Without MEPs, BICs could more often volitionally contract, were less weak, and had steeper strength recovery curves than FDIs; in contrast, FMA recovery curves plateaued below normal levels for both the arm and hand.

Conclusions. There are shared and separate substrates for paretic UE recovery. CST integrity is necessary for interjoint coordination in both segments and for overall recovery. In its absence, alternative pathways may assist recovery of volitional contraction and strength, particularly in BIC. These findings suggest that more targeted approaches might be needed to optimize UE recovery.

 

via Differential Poststroke Motor Recovery in an Arm Versus Hand Muscle in the Absence of Motor Evoked Potentials – Heidi M. Schambra, Jing Xu, Meret Branscheidt, Martin Lindquist, Jasim Uddin, Levke Steiner, Benjamin Hertler, Nathan Kim, Jessica Berard, Michelle D. Harran, Juan C. Cortes, Tomoko Kitago, Andreas Luft, John W. Krakauer, Pablo A. Celnik, 2019

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[WEB SITE] Transcranial Magnetic Stimulation for the Recovery of Gait and Balance in Stroke Patients – BrainPost

Post by Thomas Brown

What’s the science?

The permanent brain damage which occurs following ischemic stroke makes functional recovery difficult. While physiotherapy can result in improved voluntary motor recovery, the improvement of balance and gait can be harder. Issues with balance pose a safety risk for stroke patients, who may be more likely to fall. Ultimately, problems with balance can mean reduced independence for patients. The cerebellum, a structure located at the back of the brain, is known to regulate movement, gait and balance. Deficits to the cerebellum often result in ataxia and widened gaits, making this area a prime target for functional recovery analysis. This week in JAMA Neurology Koch and colleagues demonstrate in a phase IIa clinical trial, an increase in gait and balance in hemiparetic stroke patients, up to three weeks after physiotherapy supplemented with transcranial magnetic stimulation of the cerebellum.

How did they do it?

A group of 36 hemiparetic (one side affected) stroke patients were randomly assigned to one of two age-matched groups; control or experimental. The experimental group was treated with intermittent theta-burst magnetic stimulation (TBS) of the cerebellar region ipsilateral (same side) to their motor issues. Intermittent TBS is a process by which bursts of magnetic energy are applied to the scalp over an area of interest. TBS was administered in conjunction with physiotherapy to the experimental group for three weeks. The control group still received physiotherapy, but received sham (fake) TBS. Patients were assessed using a wide range of balance and gait analysis tests to determine the degree of recovery. The authors relied primarily on the Berg Balance Scale, which is a series of 14 tests that determine the ability of an individual to balance without aid. Gait analysis was also performed, in which patients were asked to walk while a machine measured their gait (the space between each foot while walking). Neural activity was measured with electroencephalography while transcranial magnetic stimulation was applied simultaneously (EEG-TMS). This technique was used to measure neural activity changes in motor regions of the brain following activation of the motor cortex using a different TMS paradigm than the one used for treatment.

What did they find?

The authors found that after three weeks of the last treatment with either sham or cerebellar TBS, there was an average increase in the Berg Balance Scale score in those treated with TBS compared to controls. They also showed a reduction in gait width; a wide gait is often associated with the body’s attempt to compensate for problems with balance. This finding was supported by correlational analysis which found that a reduction is step width was associated with an improvement in Berg Balance Scale score. Interestingly, three weeks after treatment there was also an increase in neural activity in the motor (M1) region of the brain in the hemispheres affected by the stoke, in treated patients compared to controls. This area of the cortex is associated with the movement execution. Altogether these findings suggest that there were significant balance, gait and motor cortex activity improvements following treatment with TBS. Critically, no adverse effects were observed following treatment with TBS during the clinical trial.

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What’s the impact?

These findings suggest that theta-burst stimulation may be an effective way of supplementing physiotherapy in those suffering with balance and gait deficits following stroke. Theta-burst stimulation in conjunction with physiotherapy, was able to improve both balance and gait in stroke patients. Treatment with theta-burst stimulation could reduce the chance of falling and improve independence in stroke patients.

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Koch et al. Effect of Cerebellar Stimulation on Gait and Balance Recovery
in Patients With Hemiparetic Stroke. JAMA Neurology (2018).Access the original scientific publication here

 

via Weekly BrainPost — BrainPost

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[Abstract] Vagus nerve stimulation intensity influences motor cortex plasticity

Highlights

Recovery after neurological injury is thought to be dependent on plasticity.

Moderate intensity VNS paired with motor training enhances motor cortex plasticity.

Low and high intensity VNS paired with motor training fail to enhance plasticity.

The intensity of stimulation is a critical factor in VNS-dependent plasticity.

Optimizing stimulation paradigms may enhance VNS efficacy in clinical populations.

Abstract

Background

Vagus nerve stimulation (VNS) paired with forelimb motor training enhances reorganization of movement representations in the motor cortex. Previous studies have shown an inverted-U relationship between VNS intensity and plasticity in other brain areas, such that moderate intensity VNS yields greater cortical plasticity than low or high intensity VNS. However, the relationship between VNS intensity and plasticity in the motor cortex is unknown.

Objective

In this study we sought to test the hypothesis that VNS intensity exhibits an inverted-U relationship with the degree of motor cortex plasticity in rats.

Methods

Rats were taught to perform a lever pressing task emphasizing use of the proximal forelimb musculature. Once proficient, rats underwent five additional days of behavioral training in which low intensity VNS (0.4 mA), moderate intensity VNS (0.8 mA), high intensity VNS (1.6 mA), or sham stimulation was paired with forelimb movement. 24 h after the completion of behavioral training, intracortical microstimulation (ICMS) was used to document movement representations in the motor cortex.

Results

VNS delivered at 0.8 mA caused a significant increase in motor cortex proximal forelimb representation compared to training alone. VNS delivered at 0.4 mA and 1.6 mA failed to cause a significant expansion of proximal forelimb representation.

Conclusion

Moderate intensity 0.8 mA VNS optimally enhances motor cortex plasticity while low intensity 0.4 mA and high intensity 1.6 mA VNS fail to enhance plasticity. Plasticity in the motor cortex exhibits an inverted-U function of VNS intensity similar to previous findings in auditory cortex.

via Vagus nerve stimulation intensity influences motor cortex plasticity – Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation

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[ARTICLE] Vagus Nerve Stimulation Paired With Upper Limb Rehabilitation After Chronic Stroke – Full Text PDF

A Blinded Randomized Pilot Study

Background and Purpose

We assessed safety, feasibility, and potential effects of vagus nerve stimulation (VNS) paired with rehabilitation for improving arm function after chronic stroke.

Methods

We performed a randomized, multisite, double-blinded, sham-controlled pilot study. All participants were implanted with a VNS device and received 6-week in-clinic rehabilitation followed by a home exercise program. Randomization was to active VNS (n=8) or control VNS (n=9) paired with rehabilitation. Outcomes were assessed at days 1, 30, and 90 post-completion of in-clinic therapy.

Results

All participants completed the course of therapy. There were 3 serious adverse events related to surgery. Average FMA-UE scores increased 7.6 with active VNS and 5.3 points with control at day 1 post–in-clinic therapy (difference, 2.3 points; CI, −1.8 to 6.4; P=0.20). At day 90, mean scores increased 9.5 points from baseline with active VNS, and the control scores improved by 3.8 (difference, 5.7 points; CI, −1.4 to 11.5; P=0.055). The clinically meaningful response rate of FMA-UE at day 90 was 88% with active VNS and 33% with control VNS (P<0.05).

Conclusions

VNS paired with rehabilitation was acceptably safe and feasible in participants with upper limb motor deficit after chronic ischemic stroke. A pivotal study of this therapy is justified.

 

Full Text PDF

via Vagus Nerve Stimulation Paired With Upper Limb Rehabilitation After Chronic Stroke | Stroke

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[ARTICLE] Effects of 8-week sensory electrical stimulation combined with motor training on EEG-EMG coherence and motor function in individuals with stroke – Full Text

Abstract

The peripheral sensory system is critical to regulating motor plasticity and motor recovery. Peripheral electrical stimulation (ES) can generate constant and adequate sensory input to influence the excitability of the motor cortex. The aim of this proof of concept study was to assess whether ES prior to each hand function training session for eight weeks can better improve neuromuscular control and hand function in chronic stroke individuals and change electroencephalography-electromyography (EEG-EMG) coherence, as compared to the control (sham ES). We recruited twelve subjects and randomly assigned them into ES and control groups. Both groups received 20-minute hand function training twice a week, and the ES group received 40-minute ES on the median nerve of the affected side before each training session. The control group received sham ES. EEG, EMG and Fugl-Meyer Assessment (FMA) were collected at four different time points. The corticomuscular coherence (CMC) in the ES group at fourth weeks was significantly higher (p = 0.004) as compared to the control group. The notable increment of FMA at eight weeks and follow-up was found only in the ES group. The eight-week rehabilitation program that implemented peripheral ES sessions prior to function training has a potential to improve neuromuscular control and hand function in chronic stroke individuals.

Introduction

Stroke is one of the leading contributing factors to the loss of functional abilities and independence in daily life in adults1. The most common and widely observed impairment following stroke is motor impairment, which can be regarded as a loss or limitation of function in muscle control or movement25. Most stroke survivors later regain the ability to walk independently, but only fewer than 50% of them will have fully recovered upper extremity functions6,7. From a review focusing on motor recovery after stroke, it has been indicated that the recovery of both arm and hand function among subacute and chronic stroke survivors is limited in current neural rehabilitation settings4; therefore, additional management with activating plasticity before or during performing motor training is necessary for better motor recovery.

The fundamental principle of stroke rehabilitation is inducing brain plasticity by sensory or proprioceptive input in order to facilitate motor functions8,9. It has been demonstrated that strong sensory input can induce plastic changes in the motor cortex via direct or indirect pathways1017. In this case, electrical stimulation (ES) that provides steady and adequate somatosensory input can be an ideal method of stimulating the motor cortex.

Recent studies using functional magnetic resonance imaging (fMRI) or transcranial magnetic stimulation (TMS) suggest that ES on peripheral nerves can increase motor-evoked potential (MEP)1820, increase the active voxel count in the corresponding motor cortex13, and increase blood-oxygen-level dependent (BOLD) signals in fMRI, suggesting peripheral ES induced higher excitability and activation level of cortical neurons21. Since the expansion of the motor cortical area or increase in the excitability of neural circuits is associated with learning new motor skills2226, clinicians should take advantage and assist patients with stroke on motor tasks training during this period of time. Celnik and colleagues27found that the hand function of chronic stroke subjects improved immediately after two-hour peripheral nerve stimulation combined with functional training, and the effect lasted for one day. Based on previous studies, the ES that increases corticomuscular excitability may turn out to be an ideal intervention added prior to traditional motor training to “activate” the neural circuit, so that patients may get the most out of the training. According to a recent study that applied single session peripheral ES on post-stroke individuals, the corticomuscular coherence (CMC), which is the synchronization level between EEG and EMG, increased significantly and was accompanied by improvement in the steadiness of force output28.

To our knowledge, however, there is no study investigating the long-term effect of ES combined with functional training on both motor performance and cortical excitability. We targeted the median nerve because its distribution covered the dorsal side of index, middle, and half of ring finger and the palmar side of the first three fingers and half of the ring finger. Besides, median nerve is in charge of the flexion of the first three fingers, which combined they accounts for most of the functional tasks of hand. Therefore, the purpose of this pilot study was to preliminarily evaluate the effect of eight-week ES-combined hand functional training among chronic stroke patients based on CMC and motor performance. We followed up for four weeks after the intervention ceased and examined the lasting effect. We hypothesized that those who received intervention with ES would have better hand function and higher CMC than those who received intervention with sham ES. We also hypothesized that the effect would last for at least four weeks during our follow-up.[…]

 

Continue —>  Effects of 8-week sensory electrical stimulation combined with motor training on EEG-EMG coherence and motor function in individuals with stroke

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[Abstract] Transcranial Direct Current Stimulation Enhances Motor Skill Learning but Not Generalization in Chronic Stroke

Background. Motor training alone or combined with transcranial direct current stimulation (tDCS) positioned over the motor cortex (M1) improves motor function in chronic stroke. Currently, understanding of how tDCS influences the process of motor skill learning after stroke is lacking.

Objective. To assess the effects of tDCS on the stages of motor skill learning and on generalization to untrained motor function.

Methods. In this randomized, sham-controlled, blinded study of 56 mildly impaired chronic stroke patients, tDCS (anode over the ipsilesional M1 and cathode on the contralesional forehead) was applied during 5 days of training on an unfamiliar, challenging fine motor skill task (sequential visual isometric pinch force task). We assessed online and offline learning during the training period and retention over the following 4 months. We additionally assessed the generalization to untrained tasks.

Results. With training alone (sham tDCS group), patients acquired a novel motor skill. This skill improved online, remained stable during the offline periods and was largely retained at follow-up. When tDCS was added to training (real tDCS group), motor skill significantly increased relative to sham, mostly in the online stage. Long-term retention was not affected by tDCS. Training effects generalized to untrained tasks, but those performance gains were not enhanced further by tDCS.

Conclusions. Training of an unfamiliar skill task represents a strategy to improve fine motor function in chronic stroke. tDCS augments motor skill learning, but its additive effect is restricted to the trained skill.

 

via Transcranial Direct Current Stimulation Enhances Motor Skill Learning but Not Generalization in Chronic Stroke – Manuela Hamoudi, Heidi M. Schambra, Brita Fritsch, Annika Schoechlin-Marx, Cornelius Weiller, Leonardo G. Cohen, Janine Reis, 2018

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[Abstract] Long-lasting effects of transcranial static magnetic field stimulation on motor cortex excitability

Abstract

Background

Transcranial static magnetic field stimulation (tSMS) was recently added to the family of inhibitory non-invasive brain stimulation techniques. However, the application of tSMS for 10–20 min over the motor cortex (M1) induces only short-lasting effects that revert within few minutes.

Objective

We examined whether increasing the duration of tSMS to 30 min leads to long-lasting changes in cortical excitability, which is critical for translating tSMS toward clinical applications.

Methods

The study comprised 5 experiments in 45 healthy subjects. We assessed the impact of 30-min-tSMS over M1 on corticospinal excitability, as measured by the amplitude of motor evoked potentials (MEPs) and resting motor thresholds (RMTs) to single-pulse transcranial magnetic stimulation (TMS) (experiments 1–2). We then assessed the impact of 30-min-tSMS on intracortical excitability, as measured by short-interval intracortical facilitation (SICF) and short-interval intracortical inhibition (SICI) using paired-pulse TMS protocols (experiments 2–4). We finally assessed the impact of 10-min-tSMS on SICF and SICI.

Results

30-min-tSMS decreased MEP amplitude compared to sham for at least 30 min after the end of the stimulation. This long-lasting effect was associated with increased SICF and reduced SICI. 10-min-tSMS –previously reported to induce a short-lasting decrease in MEP amplitude– produced the opposite changes in intracortical excitability, decreasing SICF while increasing SICI.

Conclusions

These results suggest a dissociation of intracortical changes in the consolidation from short-lasting to long-lasting decrease of corticospinal excitability induced by tSMS. The long-lasting effects of 30-min-tSMS open the way to the translation of this simple, portable and low-cost technique toward clinical trials.

via Long-lasting effects of transcranial static magnetic field stimulation on motor cortex excitability – Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation

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[BLOG] The Importance of Cortical Plasticity in Stroke Rehabilitation – Saebo

the-importance-of-cortical-plasticity-in-stroke-rehabilitation-blog

Those who have survived a stroke may experience neurological damage that leads to deficiencies in their sensory and motor systems, such as limited use in their hands and/or arms. This damage also affects the sensory communication to the brain and impairs the ability to touch, feel, or be aware of joint movement. The combination of motor and sensory impairments significantly impacts stroke patients’ capacity to perform daily activities.

The Motor Cortex

Located in the frontal lobe of the brain is the area known as the motor cortex. There are three areas that comprise this important part of the cerebellum: the primary motor cortex, the premotor cortex, and the supplementary motor area. The motor cortex controls the higher levels of movement, such as voluntary action. When the neurons experience electrical stimulation in this part of the brain, associated body parts move. It is a complex process that involves making decisions and coordinating movements appropriately to perform an intended action.

How Strokes Affect the Motor Cortex

Human body with a head ache of the brain with a migrain and stroke accident caused by poor circulation representing neurology with heart blood health problems.

When the motor cortex becomes damaged from head injuries, including strokes or other accidents, it affects the ability of the brain to control the body’s movement.

The brain is divided into two halves, the right and the left hemispheres. Each hemisphere controls the voluntary movement of the half of the body opposite it, which is known as crossed control (e.g., the right half of the brain controls the left side of the body). Because of this, when one hemisphere of the brain experiences damage, the movement of the opposite side of the body is affected. When the damage is severe enough to completely destroy the system, paralysis occurs.

Any damage impacts a person’s ability to control movement. For example, when a patient whose motor cortex is injured from a stroke tries to hold an object, the communication between the brain and rest of the body is delayed. This might cause the patient to have unsteady hands, stop prior to the target, move past it, or simply move too late.

Physical Conditions Resulting From Stroke

Common physical conditions after a stroke include:

  • Weakness, paralysis, and problems with balance or coordination
  • Pain, numbness, or burning and tingling sensations
  • Fatigue
  • Inattention to one side of the body, also known as neglect. In extreme cases, the patient may not be aware of their arm or leg
  • Urinary or bowel incontinence
  • Speech problems or difficulty understanding speech, reading, or writing
  • Difficulty swallowing
  • Memory problems, poor attention span, or difficulty solving problems
  • Visual problems
  • Depression, anxiety, or mood swings with emotional outbursts
  • Difficulty recognizing limitations caused by the stroke

How the Motor Cortex is Repaired

How the motor cortex is repaired

Damage to the brain does not have to be permanent; the brain has the capability to repair itself thanks to cortical plasticity (neuroplasticity). Upon experiencing damage or injury, the brain builds new neural connections using cues from the environment and individual experiences.

Neuroplasticity and Neurorehabilitation

A certain amount of neuroplasticity occurs throughout a person’s life, as it is part of learning to respond to a particular activity or behavior. This can be seen in brain scans  when a person learns a new motor skill and corresponding regions in larger cortical territories light up.

Neurorehabilitation has been shown to support the brain’s efforts to rebuild and reprogram itself. It requires task-orientated arm training and extensive practice to re-teach the brain. The surrounding tissue that remains healthy takes over some of the work of the damaged tissue. By conducting task training, this healthy tissue is stimulated, which facilitates the building of new connections between the healthy, intact neurons.

For these changes to occur in the motor cortex, it is important to conduct skill-dependent activities rather than use-dependent. For an activity to be considered skill-dependent, it requires a challenge rather than simple repetition. Training using tasks that require problem solving, or some other meaningful challenge, has greater success. Neural remodeling might occur anytime during the weeks to months after an injury, based on the experiences of an individual.

How Quickly Do Changes in the Motor Cortex Begin?

The old saying, “if you don’t use it, you lose it,” is very apt for the motor cortex. Upon immobilization of a limb, there is a window of just nine days before the potential for recovery decreases. After not using the affected limb, the tissue around the cortical lesion or other damage in the brain starts to experience problems, which leads to further loss of function.

Thus, the sooner a patient begins therapy, the better. Starting a program with occupational therapists that stimulates and retrains the limb as soon as five days after the injury has the potential to minimize cortical loss and enhance the brain’s reorganizing capabilities. The brain constantly conducts neuroplastic changes through a variety of mechanisms, such as motor learning and peripheral deafferentation. Most likely, this plasticity leads to spontaneous recovery. However, it is best to stimulate reorganization in the damaged hemisphere to increase chances of recovery.

Effective Ways to Retrain Limb Use

Effective Ways to Retrain Limb Use

There are several factors that affect stroke recovery: the amount of brain damage, the location of the damage, and the presence of healthy areas of the brain. Less damage tends to correspond with less disability, which translates to the greatest chance for recovery. And rehabilitation plays an important role in healing.

You will typically be in stage 1 or 2 of stroke recovery right after a stroke.

Treatments for Stage 1 of Stroke Recovery

For stage 1, follow the exercises and treatments laid out here. Treatments include:

  • supporting affected limbs
  • passive range of motion
  • muscle facilitation
  • movement exercises
  • mirror-box therapy
  • mental visualization

Treatments for Stage 2 of Stroke Recovery

For stage 2, follow exercises and treatments laid out here. Treatments include:

Exercises Based on Stroke Severity

It is important to remember that motor cortex deficits will differ depending on how severe the stroke is. For the patient with severe motor, sensory, and functional deficits, ensure that the arm and hand are in the proper position, mobile, and comfortable with no pain. There should be support during rest, and the upper limb should be handled carefully during the activities. Then, practice self range-of-motion exercises. You can use some of the same means of external support for the upper limb from stages 1 or 2.

For patients with moderate impairments who demonstrate high motivation and potential for functional motor gains, it is important to use repetitive, novel tasks that truly challenge the person. This helps to build the necessary neural networks to increase functional ability. Motor-learning training using imagery is very beneficial as well.

Rehabilitation is Key to Recovery

Stroke recovery is possible for many occupational therapists’ patients. Although it ultimately depends on the severity of the brain injury and the area affected, rehabilitation plays a key role in chances of success. Starting as soon as possible is key, since after nine days any repair becomes increasingly difficult. During rehab, a therapist may recommend products such as the SaeboGlove and other items that are made to improve motor functions.


All content provided on this blog is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by the Saebo website is solely at your own risk.

via The Importance of Cortical Plasticity in Stroke Rehabilitation

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[WEB SITE] Brain-Machine Interface Shows Potential for Hand Paralysis – Rehab Managment

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The use of a brain-machine interface shows potential for helping to restore function in stroke patients with hand paralysis, according to a study of healthy adults published in the Journal of Neuroscience.

According to the study, researchers note that the brain-machine interface, which is designed to combine brain stimulation with a robotic device that controls hand movement, increases the output of pathways connecting the brain and spinal cord.

Researchers Alireza Gharabaghi and colleagues asked participants to imagine opening their hand without actually making any movement while their hand was placed in a device that passively opened and closed their fingers as it received the necessary input from their brain activity. Stimulating the hand area of the motor cortex at the same time, but not after, the robotic device initiated hand movement increased the strength of the neural signal, most likely by harnessing the processing power of additional neurons in the corticospinal tract, explains a media release from the Society for Neuroscience.

However, the signal decreased when participants were not required to imagine moving their hand. Delivering brain stimulation and robotic motor feedback simultaneously during rehabilitation may therefore be beneficial for patients who have lost voluntary muscle control, the release continues.

[Source(s): Society for Neuroscience]

via Brain-Machine Interface Shows Potential for Hand Paralysis – Rehab Managment

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