Posts Tagged Neurobiology

[NEWS] Brain-controlled, non-invasive muscle stimulation allows chronic paraplegics to walk

Brain-controlled, non-invasive muscle stimulation allows chronic paraplegics to walk again and exhibit partial motor recovery

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IMAGE: THE NON-INVASIVE CLOSED-LOOP NEUROREHABILITATION PROTOCOL: I) EEG: ELECTROENCEPHALOGRAPHY, NON-INVASIVE BRAIN-RECORDING. II) BRAIN-MACHINE INTERFACE: REAL-TIME DECODING OF MOTOR INTENTIONS. III) THE LEFT OR RIGHT LEG MUSCLES ARE STIMULATED TO TRIGGER THE… view more 
CREDIT: WALK AGAIN PROJECT – ASSOCIAÇÃO ALBERTO SANTOS DUMONT PARA APOIO À PESQUISA

In another major clinical breakthrough of the Walk Again Project, a non-profit international consortium aimed at developing new neuro-rehabilitation protocols, technologies and therapies for spinal cord injury, two patients with paraplegia regained the ability to walk with minimal assistance, through the employment of a fully non-invasive brain-machine interface that does not require the use of any invasive spinal cord surgical procedure. The results of this study appeared on the May 1 issue of the journal Scientific Reports.

The two patients with paraplegia (AIS C) used their own brain activity to control the non-invasive delivery of electrical pulses to a total of 16 muscles (eight in each leg), allowing them to produce a more physiological walk than previously reported, requiring only a conventional walker and a body weight support system as assistive devices. Overall, the two patients were able to produce more than 4,500 steps using this new technology, which combines a non-invasive brain-machine interface, based on a 16-channel EEG, to control a multi-channel functional electrical stimulation system (FES), tailored to produce a much smoother gait pattern than the state of the art of this technique.

“What surprised us was that, in addition to allowing these patients to walk with little help, one of them displayed a clear motor improvement by practicing with this new approach. Patients required approximatively 25 sessions to master the training before they were able to walk using this apparatus,” said Solaiman Shokur one of the authors of the study.

The two patients that used this new rehabilitation approach had previously participated in the long-term neurorehabilitation study carried out using the Walk Again Project Neurorehabilitation (WANR) protocol. As reported in a recent publication from the same team (Shokur et al., PLoS One, Nov. 2018), all seven patients who participated in that protocol for a period of 28 months improved their clinical status, from complete paraplegia (AIS A or B, meaning no motor functions below the level of the injury, according to the ASIA classification) to partial paraplegia (AIS C, meaning partial recovery of sensory and motor function below the injury level). This significant neurological recovery included major clinical improvements in sensory discrimination (tactile, nociception, vibration, and pressure), voluntary motor control of abdomen and leg muscles, and important gains in autonomic control, such as bladder, bowel, and sexual functions.

“The last two studies published by the Walk Again Project clearly indicate that partial neurological and functional recovery can be induced in chronic spinal cord injury patients by combining multiple non-invasive technologies that are based around the concept of using a brain-machine interface to control different types of actuators, like virtual avatars, robotic walkers, or muscle stimulating devices, to allow the total involvement of patients in their own rehabilitation routine,” said Miguel Nicolelis, scientific director of the Walk Again Project and one of the authors of the study.

In a recent report by another group, one AIS C and two AIS D patients were able to walk thanks to the employment of an invasive method for spinal cord electrical stimulation, which required a spinal surgical procedure. In contrast, in the present study two AIS C patients – which originally were AIS A (see Supplemental Material below)- and a third AIS B subject, who recently achieved similar results, were able to regain a significant degree of autonomous walking without the need for such invasive treatments. Instead, these patients only received electrical stimulation patterns delivered to the skin surface of their legs, so that a total of eight muscles in each limb could be electrically stimulated in a physiologically accurate sequence. This was done in order to produce a smoother and more natural pattern of locomotion.

“Crucial for this implementation was the development of a closed-loop controller that allowed real-time correction of the patients’ walking pattern, taking into account muscle fatigue and external perturbations, in order to produce a predefined gait trajectory. Another major component of our approach was the use of a wearable haptic display to deliver tactile feedback to the patients´ forearms in order to provide them with a continuous source of proprioceptive feedback related to their walking,” said Solaiman Shokur.

To control the pattern of electrical muscle stimulation in each leg, these patients utilized an EEG-based brain-machine interface. In this setup, patients learned to alternate the generation of “stepping motor imagery” activity in their right and left motor cortices, in order to create alternated movements of their left and right legs.

According to the authors, the patients exhibited not only “less dependency on walking assistance, but also partial neurological recovery, with substantial rates of motor improvement in one of them.” The improvement in motor control in this last AIS C patient was 9 points in the lower extremity motor score (LEMS), which was comparable with that observed using invasive spinal cord stimulation.

Based on the results obtained over the past 5 years, the WAP now intends to combine all its neurorehabilitation tools into a single integrated, non-invasive platform to treat spinal cord injury patients. This platform will allow patients to begin training soon after the injury occurs. It will also allow the employment of a multi-dimensional integrated brain-machine interface capable of simultaneously controlling virtual and robotic actuators (like a lowerlimb exoskeleton), a multi-channel non-invasive electrical muscle stimulation system (like the FES used in the present study), and a novel non-invasive spinal cord stimulation approach. In this final configuration, this WAP platform will incorporate all these technologies together in order to maximize neurological and functional recovery in the shortest possible time, without the need of any invasive procedure.

According to Dr. Nicolelis, “there is no silver bullet to treat spinal cord injuries. More and more, it looks like we need to implement multiple techniques simultaneously to achieve the best neurorehabilitation results. In this context, it is also imperative to consider the occurrence of cortical plasticity as a major component in the planning of our rehabilitation approach.”

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The other authors of this paper are Aurelie Selfslagh, Debora S.F. Campos, Ana R. C. Donati, Sabrina Almeida, Seidi Y. Yamauti, Daniel B. Coelho and Mohamed Bouri. This project was developed through a collaboration between the Neurorehabilitation Laboratory of the Associação Alberto Santos Dumont para Apoio à Pesquisa (AASDAP), the headquarters of the Walk Again Project, the Biomechanics and Motor Control Laboratory at the Federal University of ABC (UFABC), and the Laboratory of Robotic System at the Swiss Institute of Technology of Lausanne (EPFL). It was funded by a grant from the Brazilian Financing Agency for Studies and Projects (FINEP) 01.12.0514.00, Ministry of Science, Technology, Innovation and Communications (MCTIC), to AASDAP.

Supplemental Material:

https://www.youtube.com/watch?v=AZbQeuJiSOI

Supporting Research Studies:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0206464

https://www.nature.com/articles/s41598-019-43041-9

 

via Brain-controlled, non-invasive muscle stimulation allows chronic paraplegics to walk | EurekAlert! Science News

 

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[ARTICLE] Arm Ability Training (AAT) Promotes Dexterity Recovery After a Stroke—a Review of Its Design, Clinical Effectiveness, and the Neurobiology of the Actions – Full Text

Arm Ability Training (AAT) has been specifically designed to promote manual dexterity recovery for stroke patients who have mild to moderate arm paresis. The motor control problems that these patients suffer from relate to a lack of efficiency in terms of the sensorimotor integration needed for dexterity. Various sensorimotor arm and hand abilities such as speed of selective movements, the capacity to make precise goal-directed arm movements, coordinated visually guided movements, steadiness, and finger dexterity all contribute to our “dexterity” in daily life. All these abilities are deficient in stroke patients who have mild to moderate paresis causing focal disability. The AAT explicitly and repetitively trains all these sensorimotor abilities at the individual’s performance limit with eight different tasks; it further implements various task difficulty levels and integrates augmented feedback in the form of intermittent knowledge of results. The evidence from two randomized controlled trials indicates the clinical effectiveness of the AAT with regard to the promotion of “dexterity” recovery and the reduction of focal disability in stroke patients with mild to moderate arm paresis. In addition, the effects have been shown to be superior to time-equivalent “best conventional therapy.” Further, studies in healthy subjects showed that the AAT induced substantial sensorimotor learning. The observed learning dynamics indicate that different underlying sensorimotor arm and hand abilities are trained. Capacities strengthened by the training can, in part, be used by both arms. Non-invasive brain stimulation experiments and functional magnetic resonance imaging data documented that at an early stage in the training cortical sensorimotor network areas are involved in learning induced by the AAT, yet differentially for the tasks trained. With prolonged training over 2 to 3 weeks, subcortical structures seem to take over. While behavioral similarities in training responses have been observed in healthy volunteers and patients, training-induced functional re-organization in survivors of a subcortical stroke uniquely involved the ipsilesional premotor cortex as an adaptive recruitment of this secondary motor area. Thus, training-induced plasticity in healthy and brain-damaged subjects are not necessarily the same.

Motor Deficits of Stroke Survivors With Mild to Moderate Arm Paresis

Arm paresis post stroke shows a bi-modal distribution. Many stroke survivors have either severe arm paresis and are only able to use their arms functionally in everyday life to a very limited extent, if at all, or mild to moderate arm paresis with the ability to use their paretic arm for functional tasks, yet with a lack of dexterity (12). Thus, the motor control deficits of these subgroups are quite different and hence so too are their therapeutic needs.

Clinically, stroke survivors with mild to moderate arm paresis have reduced strength and endurance of their paretic arm and are functionally limited by a lack of speed, accuracy and co-ordination of arm, hand, and finger movements and a lack of dexterity when handling objects. Key to understanding any functional deficits and the need and opportunities to improve function by training is a focused analysis of the specific motor control deficits involved in this clinical syndrome. A way to do this is to test various domains of sensorimotor control that have been shown to be independent by factorial analysis (34).

When motor performance of healthy people across various tasks has been analyzed by factorial analysis certain independent arm motor abilities have been documented. These are different independent sensorimotor capacities that together contribute to our skilfulness in everyday life. What are these abilities? They are our ability to make fast selective wrist and finger movements (wrist-finger speed), to manipulate small objects (finger dexterity) or larger objects (manual dexterity) efficiently, our ability to keep our arm steady (steadiness), to move our arm quickly and precisely to an intended target (aiming), or to move it under constant visual control along a line (tracking) (5).

When tested among stroke survivors with mild to moderate arm paresis all these abilities are deficient, indicating the complex nature of sensorimotor control deficits in this clinical condition (67).

The Arm Ability Training as a “Tailor-Made training” to Meet Specific Rehabilitation Demands

The Arm Ability Training (AAT) was designed to train all these sensorimotor abilities and thus to meet the specific rehabilitation demands of this subgroup of stroke survivors (89). The eight training tasks collectively cover these affordances (Figure 1).

Figure 1. Training tasks of the Arm Ability Training. Description of the eight training tasks of the Arm Ability Training (AAT) that are repetitively exercised daily. Together they train various independent arm and hand sensorimotor abilities. During the AAT sensorimotor performance is trained at its individual limit. Further aspects thought to promote motor learning are a high repetition rate of trained tasks, variation in the difficulty of training tasks, and the augmented feedback provided in the form of intermittent knowledge of the results.

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Continue —->  Frontiers | Arm Ability Training (AAT) Promotes Dexterity Recovery After a Stroke—a Review of Its Design, Clinical Effectiveness, and the Neurobiology of the Actions | Neurology

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