###### Abstract
According to [PERSON] and colleagues, patients with cognitive impairment who participated in 32 VR training sessions had no or negligible declines in their basic cognitive function, verbal memory, executive functions, and mental flexibility [23]. In another study, 12 weeks of VR rehabilitation were compared to conventional physical therapy for patients with Parkinson's disease. VR training contributed to a major improvement in the balance and gait of the patients as compared to the conventional physical therapy [24]. A systematic review by [PERSON] and colleagues showed that VR training is one of the most advanced motor rehabilitation methods for stroke patients [25]. The trainings were mainly aimed at improving balance and mobility of the limbs and demonstrated their effectiveness. The research on the impact of virtual reality on cognitive function recovery following cardiac surgery is still in its infancy. The studies mentioned above were not focused on POCD in patients who have ischemic brain damage or have undergone cardiac surgery. In order to successfully perform cognitive recovery in cardiac surgery patients, innovative techniques and approaches are necessary. Multitasking can be used in VR as one of these approaches. It should be noted that the physiological reserves in cardiac surgery patients are very limited, so it is important to take this into consideration when choosing VR as a rehabilitation procedure. Immersion in a virtual information environment can lead to a number of negative consequences that depend on such factors as the individual characteristics of the users of VR systems, technical characteristics of the system, and specificity of the tasks performed [26]. The research on the effects of VR on the human brain has not produced conclusive results. It was demonstrated that presence in VR is often accompanied by the observation of subjects moving, with their position being immobile, which creates the illusion of human body movement in space (vection) [27]. This produces a set of adverse effects, such as dizziness and disorientation in space [28]. To search for new approaches to the recovery of cognitive functions, it is necessary to understand the neurophysiological changes associated with VR cognitive rehabilitation. Digital electroencephalography (EEG) is widely used to control brain activity without invasive intervention and to study the fundamental mechanisms of brain functioning [29; 30]. The neurophysiological effects of VR training were studied by [PERSON] and colleagues in patients with ischemic stroke. The authors showed a significant increase in both the alpha band power in the occipital areas and the beta band power in the frontal areas. There were no significant changes in the theta band power [31]. In another study, it was demonstrated that VR-based rehabilitation in patients with chronic stroke caused the mirror neuron system to be involved, which resulted in enhanced motor performance [32]. Therefore, our literature review suggests that multitasking in virtual reality will be the most productive approach for cognitive rehabilitation of cardiac patients. However, it is necessary to consider the negative effects of VR on brain and cognitive functioning, which consequently affect the effectiveness of multitasking CT. Thus, the aim of our study is to investigate the neurophysiological effects of VR during multitasking CT in healthy subjects and evaluate the acceptability and feasibility of the original protocol VR multitasking CT in both a healthy group and cardiac surgery patients.