Polikanova, I.S.

Background. There is a lack of research in the scientific literature regarding the functional reorganisation of spatial perception in individuals with lower limb amputations, while most attention has been focused on upper limb amputees. However, the characteristics of spatial perception restructuring differ between upper and lower limb amputations, which highlights the need for further research to better understand the changes taking place and develop methods to compensate for them.

Objective. The aim of this study is to identify the features of spatial perception in patients with lower limb amputations as compared to subjects with severe injuries but without complete amputation, as well as to healthy volunteers.

Study Participants. A total of 90 participants were divided into four groups: right (20 individuals) and left (12 individuals) lower limb amputees, patients with combat wounds, but without amputations (22 individuals), and a control group of healthy participants (36 individuals).

Methods. Spatial perception was modeled in virtual reality (VR) conditions, including 3 test series with measuring reaction times to the appearance of a stimulus (1 session), to the beginning of the stimulus movement (2 session), to determining the direction of the stimulus movement to the left or right (3 session). The subject completed each series in turn using a special keyboard. Stimuli appeared in each series in random order at a distance of either 9 or 18 meters with equal probability.

Results. The showed that the reaction time did not significantly differ between the groups of patients with amputation of the left and right lower limbs. The group with amputation of the left lower limb, in comparison with the control group, showed a slower reaction time, which was maximally expressed in the task of determining the direction of stimulus movement, especially to the left.

Conclusions. The study highlights the importance of considering the type of amputation when analysing visual and spatial perception in patients. Despite the absence of significant differences between the groups with amputations of the left and right lower limbs, the results indicate that amputation of the left limb has a more significant effect on reaction time and perception of space than amputation of the right one.

Background. Very scarce works are devoted to the study of hockey players' brain activity, which is connected, among other things, with the large amount of motor activity in athletes and the complexity of EEG registration.

Objective. The aim of the study was to investigate electroencephalographic markers (in alpha, beta, and theta EEG bands) during a puck kicking task of varying difficulty under virtual reality conditions in ice hockey players compared to freestyle wrestlers.

Methods. The previously developed VR-PACE technology was used for the study, which allows practicing puck reflection skills in hockey in a virtual scene. In the study, pucks were presented in blocks (five blocks in total), the difficulty increased from block 1 to block 4, in block 5 the subjects only observed the pucks. EEG recordings were made using a wireless electroencephalograph BrainScanner V3.1 (research edition) by “NeuroDrive” throughout the entire task, analyzed by 20-second segments in each block and in each of the backgrounds (before and after). Twenty-two male subjects (average age=20, SD=2.4 years) participated in the study.

Results. The results showed significant differences between the groups, as well as significant within-group differences between the “before” and “after” conditions of the experiment in terms of the Individual Alpha Frequency (IAF), as well as the average and total power of theta, alpha, and beta rhythms. The overall trend in both groups is similar (after the experiment, there is a decrease in IAF, an increase in alpha rhythm power in central and parietal electrodes, and a decrease in occipital electrodes; a decrease in theta rhythm power in frontal and occipital electrodes; and a decrease in beta rhythm across all electrodes). However, the hockey group exhibits significantly more pronounced shifts in EEG, indicating greater alertness and attention (higher powers of theta, alpha, and beta rhythms both before and after the experiment), as well as greater relaxation (higher power of mu rhythm after the experiment).

Conclusions. The study examined the electroencephalographic correlates (IAF, power in the alpha, beta, and theta frequency bands of EEG) in hockey players and freestyle wrestlers while performing a task of deflecting a puck in virtual reality (VR). The dynamics of the EEG indicators indicate more efficient brain function in hockey players when performing the puck reflection task in a virtual reality setting, confirming the hypothesis of neural efficiency.