Functional Activity of the Retina and Visual Evoked Cortical Potentials in Simulation the Factors of Space Flight in Conditions of Four Month Isolation in a Hermetic Object with Artificial Habitat

Background. The artificial environment of confined space causes a decrease in the functional reserve of the central nervous system and can affect human health and the success of space missions. In solving this problem, the urgent task is to study adaptation mechanisms that adapt the functioning of the visual sensory system to the conditions of the extreme environment. Purpose to obtain new objective data on the alterations in the functional activity of the visual system during prolonged stay of a person in extreme environmental conditions. Methods. Before and after a 4-month isolation experiment simulating a flight to the moon, an electrophysiological study was conducted of six practically healthy crew members with registration of a set of electroretinograms (ERG) and pattern-reversal visual evoked cortical potentials (VEP) according to the ISCEV standards. In dynamics, corrected monocular visual acuity (MVA) was assessed on board. Results. After the end of the experiment, on average for the group, there were no statistically significant changes in the MVA and functional activity of the retina and visual cortex compared with the initial data. However, individual changes on the part of the flicker ERG and reduction of VEP to small patterns stimulating the parvocellular channel of the visual system were revealed in three testers. These changes were associated with higher visually intense work and physical activity of these crew members, and with an individual reaction to sleep deprivation of pilots with increased responsibility. Conclusion. Four-month isolation with imitation of a space mission did not cause significant changes in the functional activity of the retina and visual pathways in healthy crew members. Individual differences of VEP-responses of the parvocellular visual system were revealed, which can reflect a high level of psychophysiological adaptation and stress resistance in physically active crew members.

Movement-Related Cortical Potentials in Embodied Virtual Mirror Visual Feedback

Background: Mirror therapy is thought to drive interhemispheric communication, resulting in a balanced activation. We hypothesized that embodied virtual mirror visual feedback (VR-MVF) presented on a computer screen may produce a similar activation. In this proof-of-concept study, we investigated differences in movement-related cortical potentials (MRCPs) in the electroencephalogram (EEG) from different visual feedback of user movements in 1 stroke patient and 13 age-matched adults.Methods: A 60-year-old right-handed (Edinburgh score >95) male ischemic stroke [left paramedian pontine, National Institutes of Health Stroke Scale (NIHSS) = 6] patient and 13 age-matched right-handed (Edinburgh score >80) healthy adults (58 ± 9 years; six female) participated in the study. We recorded 16-electrode electroencephalogram (EEG), while participants performed planar center-out movements in two embodied visual feedback conditions: (i) direct (movements translated to the avatar's ipsilateral side) and (ii) mirror (movements translated to the avatar's contralateral side) with left (direct left/mirror left) or right (direct right/mirror right) arms.Results: As hypothesized, we observed more balanced MRCP hemispheric negativity in the mirror right compared to the direct right condition [statistically significant at the FC4 electrode; 99.9% CI, (0.81, 13)]. MRCPs in the stroke participant showed reduced lateralized negativity in the direct left (non-paretic) situation compared to healthy participants. Interestingly, the potentials were stronger in the mirror left (non-paretic) compared to direct left case, with significantly more bilateral negativity at FC3 [95% CI (0.758 13.2)] and C2 [95% CI (0.04 9.52)].Conclusions: Embodied mirror visual feedback is likely to influence bilateral sensorimotor cortical subthreshold activity during movement preparation and execution observed in MRCPs in both healthy participants and a stroke patient.

The Neural Blending of Words and Movement: Event-Related Potential Signatures of Semantic and Action Processes during Motor–Language Coupling

Behavioral embodied research shows that words evoking limb-specific meanings can affect responses performed with the corresponding body part. However, no study has explored this phenomenon's neural dynamics under implicit processing conditions, let alone by disentangling its conceptual and motoric stages. Here, we examined whether the blending of hand actions and manual action verbs, relative to nonmanual action verbs and nonaction verbs, modulates electrophysiological markers of semantic integration (N400) and motor-related cortical potentials during a lexical decision task. Relative to both other categories, manual action verbs involved reduced posterior N400 amplitude and greater modulations of frontal motor-related cortical potentials. Such effects overlapped in a window of ∼380–440 msec after word presentation and ∼180 msec before response execution, revealing the possible time span in which both semantic and action-related stages reach maximal convergence. These results allow refining current models of motor–language coupling while affording new insights on embodied dynamics at large.