Today, unfortunately, more and more people fall into a situation when the brain loses control over the body. It is the stroke that is the cause. Stroke is a severe disturbance of blood circulation in the brain, which leads to cell death. The disease enters the group of todays most deadly (the world average) cardiovascular diseases, it annually affects about 400 thousand of our compatriots. However, a stroke is not a death sentence. If person is provided with timely medical assistance, his or her life could be saved, but he or she will have to go a long way to recover health.
When the stroke strikes, paralysis occurs due to partial damage areas of the cerebral cortex responsible for movement. Not every patient is able mentally play sports for days to restore neurons.
For a full recovery of the body mobility it is necessary for the brain not only to send commands but also receive a "report" on the work done.
Recent studies give scientists an opportunity to come closer to solving the puzzle of mobility recovery of patients who have suffered strokes, but the best solution is yet to be found.
Already there are many interface options, allowing to convey the brain command on the exoskeleton, which in turn controls for example index finger of right hand, and sends a response signal in such a way, training the arm and restoring the lost connection between brain and finger. But in order to work with the majority of interfaces, you need a long period of training, and for the people who suffered strokes this can be a daunting task.
Young scientists from the laboratory of brain-computer interface headed by professor Alexander Kaplan at Moscow State University are currently conducting a series of studies in which they test a relatively easy to manage neurointerface, easy but very necessary for post-stroke patients. I decided to take part in one of the experiments.
I had to master the management techniques robotic arm, which scientists affectionately called "Senator".
Movement of our limbs is managed by specific areas of the brain - motor centers. But robotic "hand" responds to the visual cortex activity. To stimulate it, the participants watch the lamps located on the fingers of the robot and concentrates on one of them. The purpose of the experiment - to see if the motor centers of the brain are activated.
During system operation, these light bulbs light up one by one on each finger robotic hand. My task was to hold the flash bulb on the "target finger" (there were only 10 flashes), imagining at each flash that I bend a finger, but do not bend it in fact. If I did everything right, "target" finger robot hand bends.
For the study, neither the movement of the robot and even nor the way he gets the command but the reaction of the participant is indeed important. When observing the movement activity of motor areas of the brain can be increased, and to cut off the unwanted impulses, scientists are trying to minimize the arbitrary stresses of hands of the participants during the experiment. It is much easier to make, if his hand and tested smart "prostheses" are fully separated. To this end, my "target" right hand was equipped with electrodes, which recorded the muscle activity and I could perform exercise only if my hand was completely relaxed.
"Previously, in order to activate the motor cortical areas in patients with stroke, people used interfaces that operated using imagining the movement. The subjects (or patients) did not make the movement itself but imagined it and thus could randomly activated motor areas of brain cortex, due to which these areas would practice attempts to restore motor function, - told me t Nikolay Syrov, graduate student, having put electrodes on my hand (the ones that hold the muscle tone), while I wiggled his fingers. - The problem is that the precision of imagination of the patients varies greatly, and one needs a long time to train, to imagine movement. But even after such training it is impossible for every patient to do this quite accurately. "
"In the interface of movement imagining number of commands is not high, - added Daria Zhigulskaya, also graduate student of biological faculty, filling gel for electrodes on my head.
Our interface generates 5 commands - one for each finger bending, and may provide further commands if necessary. For the interface of motion imagining, that is, without external photostimulation, there are only 2-3 commands".
Indeed, to cope with lamp interface was easy. By the end of the session we will watch with the "Senator" accustomed to each other, and I could move mechanical fingers with high accuracy. Laboratory of Kaplan patented this innovation.
When I got used to the interface, the most important moments began. After each attempt ten seconds long, which was supposed to lead to a single movement of "Senator", Nicholas brought to my neck to the left (because the robot was the deputy of my right hand) electromagnetic coil that with weak stimuli tested the excitability of the motor area of my brain. The purpose of the experiment, for which you need at least 20 volunteers, is precisely to see whether the interface allows you to activate the motor centers of the brain. In other words, the aim is to understand whether it is suitable for those who cannot activate them in a common way.
If the experiment proves successful, the program will be connected to the exoskeleton hand. The patient will be able to wear the device as a kind of glove that will bend his fingers on a right moment.
"It is very important for these patients. With such training, firstly the limbs are mechanically developed, and secondly additional paths are formed in the brain that can compensate for the loss of motor function "- Daria explained.
Now only people perform this function in rehabilitation centers. On paramedics command the patient imagines that he is about to makes this or that movement, and the former accordingly moves his hand, sending a "report" to the brain. The trick is that this response should arrive with a slight delay after the brain commands and to correctly synchronize the patient's thought and the answer of "muscle" is not easy for man, but is an elementary thing for neurointerface.
"It is somewhat similar to experiments that Ivan Pavlov made on dogs - said Nikolai. - When you bend your finger, and you just want it, there is a positive feedback, positive reinforcement. If we did not tell you what is going to occur at the time of the experiment, you would just have looked at the bulb, I would have lost your motivation for some time, and the accuracy of the classification (selecting the desired finger) also would decrease. "
In fact, now scientists neither know any route of these pulses, nor how they are formed, and to find out how it works - one of the most important tasks to resolve a wide range of medical problems. Laboratory of Alexander Kaplan plans to test other types of non-invasive neurointerface (if it is possible to return the mobility of the patient's own muscles, preference is given to such interim measures). For example, in the simulator approach, where the focus is not visual (looking at the light bulb) but tactile (due to the vibration motor is attached to the fingers). Standing frame, a device for moving patients to the upright state is already in operation by brain commands.
Scientists have a lot of tasks and plans of solutions,too. But for myself, I decided that it is necessary to better monitor the health and work with technology for regenerative medicine as a volunteer without being a patient. Do not be ill!