Neurointerface improved limb function after stroke

Elizaveta Ivtushok, N+1

The results showed that such training for nine weeks can improve motor function by 36 percent. The article with the research is published in the journal Open Science.

One of the most common consequences of stroke is hemiparesis – partial loss of motor functions (paresis) of the extremities of one side of the body. The rehabilitation methods used (for example, physiotherapy) are able to partially restore lost functions, but their effectiveness is estimated at 70 percent. The development of technologies in the field of using neurocomputer interfaces (also known as brain-computer interfaces) can help in restoring motor functions even after the most serious damage caused by a stroke.

The authors of the new work used an EEG neurointerface, through which the movement of the hand presented by the patient is transformed into an electrical signal, which is then sent to the electrodes on the muscles of the affected limb in the form of a sensory signal using a computer. Muscle movements are read using electromyography, and palm pads were used for feedback, which allowed the patient to simultaneously see and feel the movement of the limb.

According to the authors, for the effective operation of such an interface, it is necessary to choose the optimal time required for the computer to process the signal from the EEG and send a return signal to the muscles. Previous studies of similar technologies have used time in the range from 200 to 300 milliseconds. Scientists have tested whether the quality of the interface will improve if the time that the computer uses to return the signal is in the range from 0 to 100 milliseconds.

For nine weeks, they conducted an experiment involving one patient who had suffered a stroke six months before the start of the study. During the experiment, the patient was connected to the interface and asked to imagine how he moves his left hand (affected by a stroke). After that, the sensory signal was sent to the limb after 16, 24, 28 or 96 milliseconds (in random order). During the study, the scientists conducted 10 attempts, each of which lasted 30 minutes.

Experimental conditions. a) an EEG cap; b) a device recording EEG and EMG signals; c) a computer; d) a damaged arm; e) a handstand (Darvishi et al. / Open Science 2017).

At the end of each week of training, the researchers measured changes in limb performance using the arm activity test (English: action research arm test, abbreviated ARAT), designed to study the effectiveness of rehabilitation of patients after stroke. The test results showed that training using the interface improved motor functions by 36 percent.

ARAT indicators for each week of the experiment

Scientists note that in order to confirm their results, it is necessary to increase the number of participants in the study, however, reducing the return time of the sensory signal, in their opinion, can significantly improve the known methods of rehabilitation using neurocomputer interfaces.

Neurointerfaces have recently been increasingly used as a means of rehabilitation of limb dysfunction after various injuries. Examples include systems that allow you to control individual fingers of the prosthesis, eat independently, move and touch an artificial arm with limb paralysis, as well as partially restore the spinal cord after injury and communicate with "locked" people. To date, the data transfer rate using a non-invasive neural interface has been increased to one character per second.

Portal "Eternal youth" http://vechnayamolodost.ru  01.09.2017