Posts Tagged Nervous system

[WEB SITE] Study investigates plasticity of motor representations in patients with brain tumors

Winner of the Brainlab Community Neurosurgery Award, Sandro Krieg, MD, presented his research, Plasticity of Motor Representations in Patients with Brain Lesions: a Navigated TMS Study, during the 2017 American Association of Neurological Surgeons (AANS) Annual Scientific Meeting.

This study investigated the spatial distributions of motor representations in terms of tumor-induced brain plasticity by analyzing navigated transcranial magnetic stimulation (nTMS) motor maps derived from 100 patients with motor eloquently located brain tumors in or adjacent to the precentral gyrus (PrG).

The research evoked 8,774 motor potentials (MEPs) that were elicited in six muscles of the upper and lower extremity by stimulating four gyri in patients with five possible tumor locations. Regarding the MEP frequency of each muscle-gyrus subdivision per patient, the expected frequency was 3.53 (8,774 divided by 100 patients, further divided by six muscles and four gyri). Accordingly, the patient ratio for each subdivision was calculated by defining the per-patient minimum data points as three.

The tumor-location specific patient ratios were higher for frontal tumors in both gyri than for other tumor locations. This suggests that the finger representation reorganization in these frontal gyri, which corresponds to location of dorsal premotor areas, might be due to within-premotor reorganization rather than relocation of motor function from PrG into premotor areas one might expect from the Rolandic tumors. The research indicates that reorganization of the finger motor representations might be limited along the middle-to-dorsal dimension of the dorsal premotor areas (posterior MFG and SFG) and might not cross rostrally from the primary motor cortex (PrG) to the dorsal premotor cortex.

Source: Study investigates plasticity of motor representations in patients with brain tumors

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[VIDEO] Why Can’t WE Reverse Nerve Damage ? – Reversing Nerve Damage: Central Nervous System Inhibits Cell Regeneration, But Stem Cell Treatment May Help

 

Our nervous system is involved in everything our body does, from maintaining our breath to controlling our muscles. Our nerves are vital to all we do; therefore, nerve pain and damage can heavily influence our quality of life. In Discovery News’ latest video, “Why Can’t We Reverse Nerve Damage?” host Lissette Padilla explains the central nervous system (CNS) has certain proteins that inhibit cell regeneration, because each cell in the nervous system has a unique function on the pathway, like a circuit, and can’t be replaced.

The nervous system can be divided into two sections, with the brain and spinal cord making up the CNS. Nerves are made up of sensory fibers and motor neurons, which comprise the peripheral nervous system. Nerve cells are made up of many parts, but they send signals through threads covered in a protective sheet of myelin. These threads are called axons.

Axons are the long part of the cell that reaches out to neighboring cells to send information down the line. Schwann cells, found only in the peripheral nervous system, are glial cells that produce protective myelin. Schwann cells could potentially clean up damaged nerves, which could make way for healing process to take place and new nerves to be formed.

The problem is these Schwann cells are missing from the CNS. The CNS is comprised of myelin-producing cells called oligodendrocytes. And these cells don’t clean up damaged nerve cells at all, hence the damage problem.

However, research is currently underway to examine the potential success of system cell treatment, where stem cells are injected directly at the injury site. It will still take a few years to see the results of such trials, but since the peripheral nervous system doesn’t have the same blocking proteins that the CNS has, the idea is Schwann cells could help heal the damage.

So it is possible to regrow nerves, albeit slowly. For instance, if you cut a nerve into your shoulder, it could take a year to regrow. By that time, the muscles in your arms could become atrophied. Researchers are working on helping the body heal faster.

Source: Reversing Nerve Damage: Central Nervous System Inhibits Cell Regeneration, But Stem Cell Treatment May Help

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[WEB SITE] Study shows continuous electrical stimulation suppresses seizures in patients with epilepsy.

When surgery and medication don’t help people with epilepsy, electrical stimulation of the brain has been a treatment of last resort. Unfortunately, typical approaches, such as vagal nerve stimulation or responsive nerve stimulation, rarely stop seizures altogether. But a new Mayo Clinic study in JAMA Neurology shows that seizures were suppressed in patients treated with continuous electrical stimulation.

Epilepsy is a central nervous system disorder in which nerve cell activity in the brain becomes disrupted. In the study, 13 patients with drug-resistant epilepsy were deemed unsuitable for resective surgery, which removes a portion of the brain — usually about the size of a golf ball — that was causing seizures. When patients are evaluated for surgery, a grid of electrical contacts is placed on the brain to record seizures and interictal epileptiform discharges (IEDs). IEDs are electrical discharges that occur intermittently during normal brain function, and have been used as markers to locate portions of brain affected by epilepsy.

In the study, the grid of electrical contacts was used for stimulation at levels the patient would not notice. If the stimulation provided clinical benefit to the patient, this temporary grid was replaced with more permanent contacts that could offer continuous stimulation.

Ten of the 13 patients, 77 percent, reported improvement for both epilepsy severity and life satisfaction. The majority of patients experienced more than 50 percent reduction in seizures, and 44 percent were free of disabling seizures. The reduction in IED rate occurred within minutes of initiating stimulation.

“This study suggests that subthreshold cortical stimulation is both effective clinically and reduces interictal epileptiform discharges,” says lead author Brian Lundstrom, M.D., Ph.D., a neurology epilepsy fellow at Mayo Clinic. “We think this approach not only provides an effective treatment for those with focal epilepsy but will allow us to develop ways of assessing seizure likelihood for all epilepsy patients. It would be of enormous clinical benefit if we could personalize treatment regimens for individual patients without waiting for seizures to happen.”

During seizures, abnormal electrical activity in the brain sometimes results in loss of consciousness. For people with epilepsy, seizures severely limit their ability to perform tasks where even a momentary loss of consciousness could prove disastrous — driving a car, swimming or holding an infant, for example. Approximately 50 million people worldwide have epilepsy, according to the World Health Organization.

Seizures sometimes have been compared to electrical storms in the brain. Seizure signs and symptoms may include:

•Temporary confusion
•A staring spell
•Uncontrollable jerking movements of the arms and legs
•Loss of consciousness or awareness

Treatment with medications or surgery can control seizures for about two-thirds of people with epilepsy. However, when drug-resistant focal epilepsy occurs in an area of the brain that controls speech, language, vision, sensation or movement, resective surgery is not an option.

“For people who have epilepsy that can’t be treated with surgery or medication, effective neurostimulation could be a wonderful treatment option,” Dr. Lundstrom says.

The risks of subthreshold cortical stimulation are relatively minimal and include typical infection and bleeding risks as well as the possibility that the stimulation would not be subthreshold and would be noticed by the patient, Dr. Lundstrom says. The authors note that further investigation is needed to quantify treatment effect and examine the effect mechanism. The authors plan to examine the efficacy of this approach in a prospective clinical trial.

This study represents ongoing efforts to restore normal function to epileptic brain tissue by using neurostimulation. Other efforts are aimed at understanding the physiologic changes that chronic stimulation produces in brain tissue.

Source: Study shows continuous electrical stimulation suppresses seizures in patients with epilepsy

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[WEB SITE] Research could pave way for more effective and safer anti-epilepsy drugs

Columbia University Medical Center (CUMC) researchers have discovered how a new epilepsy drug works, which may lead the way to even more effective and safer medications.

The findings were published today in Neuron.

The most commonly used anti-epilepsy drugs are ineffective for about 30 percent of people with seizure disorders.

A new direction in the treatment of epilepsy is aimed at inhibiting AMPA receptors, which help transmit electrical signals in the brain and play a key role in propagating seizures. Currently, perampanel is the only FDA-approved drug that targets AMPA receptors. But because perampanel is associated with significant side effects, its clinical use has been limited.

“The problem is that AMPA receptors are heavily involved in the central nervous system, so if you inhibit their function, you cause an array of unwanted effects,” said study leader Alexander I. Sobolevsky, PhD, professor of biochemistry and molecular biophysics at CUMC. “If we hope to design better drugs for epilepsy, we need to learn more about the structure and function of these receptors.”

In this study, Dr. Sobolevsky employed a technique called crystallography to determine how perampanel and two other inhibitors interact with the AMPA receptors to stop transmission of electrical signals. The study was conducted using rat AMPA receptors, which are almost identical to human receptors.

In the new study, the researchers were able to pinpoint exactly where the drugs bind to AMPA receptors.

“Our data suggest that the inhibitors wedge themselves into the AMPA receptor, which prevents the opening of a channel within the receptor,” said Dr. Sobolevsky. When that channel is closed, ions cannot pass into the cell to trigger an electrical signal.

According to the researchers, these findings may allow drug makers to develop medications that are highly selective for the AMPA receptors, which could be safer and more effective than currently available anti-epilepsy drugs.

Source: Research could pave way for more effective and safer anti-epilepsy drugs

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[WEB SITE] Small device detects initial signal of epileptic attack and provides effective relief.

Published on August 23, 2016 

The results, from the Laboratory for Organic Electronics at LiU’s Campus Norrköping, have been published in the prestigious journal Proceedings of the National Academy of Sciences (PNAS), with Asst. Prof. Daniel Simon as main author.

According to a recently produced estimate, no less than six percent of the Earth’s population suffers from some type of neurological illness such as epilepsy or Parkinson’s. Some medicines are available, but when these are taken orally or injected into the bloodstream, they also end up where they aren’t needed and may cause serious problems. All medicines have more or less severe side effects, and no fully satisfactory treatment for neurological illnesses is available.

Neurons, or nerve cells, are the cells in the body that both transmit and receive nerve impulses. The small 20×20 µm device developed by the scientists can both capture signals and stop them in the exact area of nerve cells where they arise. No other part of the body needs to be involved.

“Our technology makes it possible to interact with both healthy and sick neurons. We can now start investigating opportunities for finding therapies for neurological illnesses that arise so rapidly and so locally that the patient doesn’t notice them,” says Daniel Simon.

The experiments were conducted in the laboratory on slices of brains from mice. The device consists of a sensor that detects nerve signals, and a small ion pump that doses an exact amount of the neurotransmitter GABA, a substance the body itself uses to inhibit stimuli in the central nervous system.

“The same electrode that registers the activity in the cell can also deliver the transmitter. We call it a bioelectronic ‘neural pixel’, since it imitates the functions of biological neurons,” says Daniel Simon.

“Signalling in biological systems is based on chemical signals in the form of cations, which are passed between transmitters and receptors, which consist of proteins. When a signal is transferred to another cell, the identification of the signal and the triggering of a new one occur within a very small distance – only a few nanometers. In certain cases, it happens at the same point. That’s why being able to combine electronic detection and release in the same electrode is a major advance,” says Professor Magnus Berggren.

The small ion pump, which was developed at the Laboratory for Organic Electronics, attracted a great deal of attention when it´s first application as a therapeutic device was published a year ago. The sensor that captures the nerve signal has subsequently been developed by the LiU researchers’ collaborators at the école Nationale Supérieure des Mines in Gardanne, France. The mouse experiments were performed at Aix-Marseille University. The entire device is manufactured from conductive, biocompatible plastic.

Source: Small device detects initial signal of epileptic attack and provides effective relief

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[Abstract] Deficits in motor abilities for multi-finger force control in hemiparetic stroke survivors.

Abstract

The ability to control redundant motor effectors is one of hallmarks in human motor control, and the topic has been studied extensively over several decades since the initial inquiries proposed by Nicholi Bernstein. However, our understanding of the influence of stroke on the control of redundant motor systems is very limited.

This study aimed to investigate the effect of stroke-related constraints on multi-finger force control abilities in a visuomotor task. Impaired (IH) and less-impaired hands (LH) of 19 hemiparetic stroke survivors and 19 age-matched control subjects were examined. Each hand repeatedly produced isometric forces to match a target force of 5 N shown on a computer screen using all four fingers. The hierarchical variability decomposition (HVD) model was used to separate force-matching errors (motor performance) into task-relevant measures (accuracy, steadiness, and reproducibility). Task-irrelevant sources of variability in individual finger force profiles within and between trials (flexibility and multiformity) were also quantified. The IH in the stroke survivors showed deficits in motor performance attributed mainly to lower accuracy and reproducibility as compared to control hands (p < 0.05). The LH in stroke survivors showed lower reproducibility and both hands in stroke also had higher multiformity than the control hands (p < 0.05).

The findings from our HVD model suggest that accuracy, reproducibility, and multiformity were mainly impaired during force-matching task in the stroke survivors. The specific motor deficits identified through the HVD model with the new conceptual framework may be considered as critical factors for scientific investigation on stroke and evidence-based rehabilitation of this population.

Source: Deficits in motor abilities for multi-finger force control in hemiparetic stroke survivors – Online First – Springer

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[BOOK] Occupational Therapy and Neurological Conditions – Google Books

An introductory, comprehensive textbook covering all aspects of the occupational needs of clients with neurological conditions. Written from an occupational perspective and for the needs of occupational therapists and their clients Ideal for students and newly qualified practitioners to provide them with an overview of this key area of practice Includes case studies to place material within the context of practice Officially endorsed by the College of Occupational Therapists

Source: Occupational Therapy and Neurological Conditions – Judi Edmans, Jenny Preston – Google Books

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[BOOK] Hellier: The Brain, the Nervous System, and Their Deseases – Google Books

Front Cover

JL Hellier – 2014 – books.google.com

Written to be accessible to high school and college students and general readers, this three-

volume encyclopedia provides a sweeping overview of the brain, nervous system, and their

diseases. Bringing together contributions from leading neuroscientists, neurologists, …

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via Hellier: The Brain, the Nervous System, and Their… – Google Scholar.

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