(Image caption: This image shows an artificial connection that connects brain to spinal circuits. Credit: © Yukio Nishimura)

Bypass commands from the brain to legs through a computer

Gait disturbance in individuals with spinal cord injury is attributed to the interruption of neural pathways from brain to the spinal locomotor center, whereas neural circuits locate below and above the lesion maintain most of their functions. An artificial connection that bridges the lost pathway and connects brain to spinal circuits has potential to ameliorate the functional loss. A Japanese research group led by Shusaku Sasada, research fellow and Yukio Nishimura, associate professor of the National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS) has successfully made an artificial connection from the brain to the locomotion center in the spinal cord by bypassing with a computer interface. This allowed subjects to stimulate the spinal locomotion center using volitionally-controlled muscle activity and to control walking in legs. This result was published online in The Journal of Neuroscience on August 13, 2014.

Neural networks in the spinal cord, locomotion center are capable of producing rhythmic movements, such as swimming and walking, even when isolated from the brain. The brain controls spinal locomotion center by sending command to the spinal locomotion center to start, stop and change waking speed. In most cases of spinal cord injury, the loss of this link from the brain to the locomotion center causes problems with walking.

The research group came up with bypassing the functioning brain and locomotion center with the computer to compensate lost pathways as a way to enable individuals with spinal cord injury to regain walking ability.

Since the arm movement associate with leg movement when we walk they used muscle activity of arm to sarogate the brain activity. The computer interface allowed subjects to control magnetic stimulator that drive to the spinal locomotion center non-invassively using volitionally-controlled muscle activity and to control walking in legs. As a results of experiments in people who are neurologically intact, the subjects were asked to make own legs relaxed and passively controlled via computer interface that was controlled by arm muscle, walking behavior in legs was induced and subjects could control the step cycle volitionally as well. However without bypassing with the computer interface, the legs did not move even if the arms muscle was volitionally acivated.

"We hope that this technology would compensate for the interrupted pathways’ function by sending an intentionally encoded command to the preserved spinal locomotor center and regain volitionally-controlled walking in indviduals with paraplegia. However, the major challenge that this technology does not help them to dodge obstacles and to maintain posture. We are carefully working toward clinical application in near future", Nishimura said.

Gets stroke patients back on their feet

A robot is now being built to help stroke patients with training, motivation and walking.

In Europe, strokes are the most common cause of physical disability among the elderly. This often result in paralysis of one side of the body, and many patients suffer much reduced physical mobility and are often unable to walk on their own. These are the hard facts the EU project CORBYS has taken seriously. Researchers in six countries are currently developing a robotic system designed to help stroke patients re-train their bodies. The concept is based on helping the patient by constructing a system consisting of powered orthosis to help patient in moving his/her legs and a mobile platform providing patient mobility.

The CORBYS researchers are also working with the cognitive aspects. The aim is to enable the robot to interpret data from the patient and adapt the training programme to his or her capabilities and intention. This will bring rehabilitation robots to the next level.

Back to walking normally
It is vital to get stroke patients up on their feet as soon as possible. They must have frequent training exercises, and re-learn how to walk so that they can function as good as possible on their own.
Why a robot? “Absolutely, because it is difficult to meet these requirements using today’s work-intensive manual method where two therapists assisting the patient by lifting one leg after the other”, says ICT researcher Anders Liverud at SINTEF, which is one of the CORBYS project partners.

Robot-patient learning
CORBYS involves the use of physiological data such as heart rate, temperature and muscle activity measurements to provide feedback to the therapist and help control the robot. Do the patient’s legs always go where the patient want? Is the patient getting tired and stressed?

“The walking robot has several settings, and the therapist selects the correct mode based on how far the patient has come in his or her rehabilitation”, says Liverud. “The first step is to attach sensors to the patient’s body and let them walk on a treadmill. A therapist manually corrects the walking pattern and, with the help of the sensors, create a model of the patient’s walking pattern”, he says.

In the next mode, the system adjusts the walking pattern to the defined model. New adjustments are made and are used to improve optimisation of the walking pattern.

“The patient wears an EEG cap which measures brain activity”, says Liverud. “By using these signals combined with input from other physiological and system sensors, the robotic system registers whether the patient wants to stop, change speed or turn, and can adapt immediately”, he says. “The robot continues to correct any walking pattern errors. However, since it also allows the patient the freedom to decide where and how he or she walks, the patient experiences control and keeps motivation to continue with the training”, says Liverud.

Working with Europe
The European researchers have now completed specification of the system and its components, and construction of the robot is underway.
Construction involves a large team. The University of Bremen is heading the project and developing the architecture to integrate all system modules, and German wheelchair, orthosis and robotics experts are constructing the mechanical components, while two UK universities are working with cognitive aspects. Spanish specialists are addressing brain activity measurements and the University of Brussels is looking into robot control. SINTEF is working with the sensors and the final functional integration of the system. In a year’s time construction will be completed and the robot will be tested on stroke patients at rehabilitation institutes in Slovenia and Germany. The CORBYS project has a total budget of EUR 8.7 million.