Currently, VR is considered as a promising method for the formation of new motor opportunities with the integration of virtual limbs into the patient's body scheme, as well as cognitive and multisensory stimulation of mental processes. The definition of virtual rehabilitation combines all methods of treatment (physical, cognitive, psychological, and occupational therapy) that are based in VR or include elements of VR, augmented reality, or computer technology in their structure.

Virtual rehabilitation gives a person a sense of presence in an environment that is different from the one in which they find themselves, and which allows them to interact with this environment. Distortion of information from the environment is the impact on the human sense organs with the help of special devices that change the sensory flow from the environment (augmented reality). When exposed to a stimulus from the environment, a response occurs, unconditioned or conditioned. Environmental stimuli are perceived by the senses and, accordingly, are divided into visual, auditory, vestibular, olfactory, gustatory, tactile, and proprioceptive. Unconditional responses of the body can be:

1. physiological (increased heart rate, increased sweating, changes in blood pressure and body temperature, changes in the electrical activity of the brain, skin-galvanic potentials, etc.)
2. emotional - positive (joy, pleasure, interest, etc.) and negative (guardian, disgust, indignation, etc.).

Conditioned responses include behavioral ones, which include both simple voluntary movements mediated by a task, and complex multistage behavioral acts with the analysis of sensory information, comparing it with previous experience, building an action program, making decisions, performing actions, analyzing the results of these actions.

When systematizing computer programs to rehabilitation, four main categories can be distinguished:

1. Simulating everyday activities to perform some action from the patient's usual life (for example, cooking, cleaning, shopping, etc.), which can be easily transferred into real practice.
2. Games with more entertaining and/or unusual purposes - exploring remote places, racing, sports, etc.
3. Passive virtual environments - multisensory stimulation, unconditioned emotional reactions to activate mental activity in neurodynamic disorders.
4. Group virtual environments where patients compete with other participants in the performance of a particular task.

From the point of view of the rehabilitation component, virtual programs are conventionally divided into training motor skills, cognitive functions, or correcting the emotional state of patients. This division is conditional since any BP program affects all these areas.

In rehabilitation, an important role is played by the patient's return to daily activity, which is associated not only with the restoration of specific movements but also with the training of higher nervous activity in general (cognitive and emotional functions), which makes it possible to adapt the disabilities to the environment. Thus, patients will be able to return safely to their usual activities in the Virtual Environment: shopping in a store (training of working memory), navigating in a shopping center (training in spatial orientation), finding people by their external characteristics (training of selective attention), looking for familiar places. on the street (training of recognition memory), to pay at the checkout (training of the account). VR exercises, both motor and cognitive, can be easily reproduced the required number of times with an adjustable intensity level depending on the patient's capabilities.

In virtual rehabilitation systems, the patient usually receives information:

• about the movement itself in the form of its visualization;
• on the accuracy of the task performance through the system of reverse sensory stimulation;
• about changes in the surrounding virtual world.

Benefits of Virtual Rehabilitation:

1. Higher level of safety and control over the level and intensity of stimuli.
2. Better provision of patient confidentiality during treatment.
3. Significant reduction in the risk of trauma to patients during treatment.
4. Ability to adapt scenarios to the needs of a particular patient by his expectations and capabilities.
5. Ease of repeating specific virtual scenarios the required number of times with customizable incentives.
6. Possibility to reduce the number and duration of sessions due to the greater efficiency of the generated incentives.
7. Reducing the cost of treatment due to the inclusion of virtual scenarios in the program.
8. Attractiveness to patients: some patients see new technologies as more effective, which increases their adherence to therapy.

There are some difficulties in the use of Virtual Rehabilitation in clinical practice:

• Specialists will need certain guidelines for the effective and safe use of VR in their daily work.
• The cost of software and hardware for VR, limiting wider applications.
• The need for educational programs or courses to develop the skill of using VR.
• A skeptical attitude of some specialists to VR as to computer entertainment games.

VR is a computer technology that replaces or distorts information from the senses, alters and analyzes the response of the body, ensuring the interaction of the body with the generated VS.

Following from the definition, when mentioning VR technologies in rehabilitation, it is necessary to clarify:

• What kind of computer technologies:

• description of the program by genre, method of exposure, visual presentation, number of players, game platform;
• for additional devices - which helmet, platform, sensors;

• What level of substitution of sensory information - full or partial;
• What sensory modality is influenced by VR - visual, auditory, vestibular, proprioceptive, tactile and temperature, olfactory, gustatory;
• Methods for analyzing the body's responses - peripheral sensors, tracking systems, gyroscope, accelerometer, proximity sensor, sensor gloves, shoes or suits, face and emotion recognition system, etc .;
• What responses of the organism are corrected:

• emotional - positive / negative, desensitization;
• cognitive - attention, executive functions, memory (visual and verbal), spatial orientation, speed of reactions, and speech;
• behavioral - movements of the upper and/or lower limbs, walking, maintaining posture, activity from the patient's daily life, etc.

The presence of a systematic approach to the creation of virtual rehabilitation programs and a clear understanding of the body's reactions to which the impact is exerted will expand the arsenal of endpoints for future research using both clinical scales and objective neurophysiological methods.

There is also an objective fact that VR technologies are developing so rapidly, especially in the gaming segment, that scientists do not have time to introduce a new device into the field of medicine, and even more so to carry out a study of its effectiveness when other more advanced and accurate devices appear. Also, among specialists, the issue of creating common VR spaces for rehabilitation is being discussed, which will include a hospital site or alternative resources that unite both the patients themselves and their relatives and rehabilitation specialists.