A single exposure to 100% normo-baric oxygen therapy appears to improve sequence learning processes by increasing prefrontal cortex oxygen saturation.

Previously, we showed that a normo-baric 100 % oxygen treatment (NbOxTr) enhances motor learning processes, e.g., visuomotor adaptation (VMA) and sequence learning (SL). However, this work was limited to behavioral outcomes and did not identify the physiological mechanistic underpinnings of these improvements. Here, we expand on this research to investigate the effects of a NbOxTr on the oxygen tissue saturation index (TSI) level of the prefrontal cortex (PFC) when performing a SL task and whether potential SL improvements relate to increased TSI levels in the PFC. Twenty four right-handed young, healthy adults were randomly assigned to a NbOxTr group (normo-baric 100 % oxygen, n = 12) or a control group (normal air, n = 12). They received their respective treatments via a nasal cannula during the experiment. Oxygen TSI levels of the right and left PFC were measured via near-infrared spectroscopy (NIRS) throughout different SL task phases (Baseline, Training, Testing). The NbOxTr increased the TSI of the PFC in the Training phase (p < 0.01) and positively affected SL retention in the Testing phase (p < 0.05). We also found a positive correlation between TSI changes in the right PFC during the gas treatment phase (3.4 % increase) and response time (RT) improvements in the SL task training and retention phase (all p < 0.05). Our results suggest that a simple NbOxTr increases the oxygenated hemoglobin availability in the PFC, which appears to mediate the retention of acquired SL improvements in healthy young adults. Future studies should examine treatment-related oxygenation changes in other brain areas involved and their relation to enhanced learning processes. Whether this NbOxTr improves SL in neurologically impaired populations should also be examined.

A simple 100% normobaric oxygen treatment can substantially enhance sequence learning processes.

Motor learning processes are crucial for our everyday life, and improving skills by tailored interventions is of great clinical interest and value. Our previous work revealed a positive effect of normo-baric oxygen treatment on visuomotor adaptation. Here, we investigate whether it could positively affect sequence learning (SL) processes as well. Sixty-four healthy young adults were divided into a 100% oxygen treatment (NbOxTr; N = 32, M=20.7 ± 1.63 yrs.) and a normal air treatment (AirTr; N = 32, M=20.8 ± 0.95 yrs.) group. Participants performed a standardized SL task by pressing the spatial-compatible key on a keyboard according to four visual stimuli with two pre-determined 8-item sequences with different training depths. Following a baseline session (10 trials), both groups received a gas treatment (5 L/min, via nasal cannula) during the next training session (4 blocks, 45 trials each block), followed by a testing session (30 trials) without gas treatment. On day two, participants completed another 30 trials, similar to the first-day testing session, also without gas treatment. ANOVA revealed no significant group differences during baseline (p > 0.05) but a significantly faster response time (+45.5%) in the NbOxTr than AirTr group in the training session with gas treatment for all training depths (p < 0.05). The positive NbOxTr effect consolidated into the following testing session without gas treatment for deeply trained sequences (+17%; p < 0.05), and for all training depth on day-two testing (+45.2%; p < 0.05). Results suggest that the NbOxTr substantially improved participants' SL processing speed. Notably, improvements consolidated after an overnight sleep. The present work confirms a beneficial effect of a single, simple NbOxTr on fundamental motor learning processes. This treatment approach may provide promising implications for practice in neurological rehabilitation and other motor learning-related scenarios and should be further investigated in future research.

Boost your brain: a simple 100% normobaric oxygen treatment improves human motor learning processes.

Introduction: Human motor learning processes are a fundamental part of our daily lives and can be adversely affected by neurologic conditions. Motor learning largely depends on successfully integrating cognitive and motor-related sensory information, and a simple, easily accessible treatment that could enhance such processes would be exciting and clinically impactful. Normobaric 100% oxygen treatment (NbOxTr) is often used as a first-line intervention to improve survival rates of brain cells in neurological trauma, and recent work indicates that improvements in elements crucial for cognitive-motor-related functions can occur during NbOxTr. However, whether NbOxTr can enhance the motor learning processes of healthy human brains is unknown. Here, we investigated whether a brief NbOxTr administered via nasal cannula improves motor learning processes during a visuomotor adaptation task where participants adapt to a visual distortion between visual feedback and hand movements. Methods: 40 healthy young adults (M = 21 years) were randomly assigned to a NbOxTr (N = 20; 100% oxygen) or air (N = 20; regular air) group and went through four typical visuomotor adaptation phases (Baseline, Adaptation, After-Effect, Refresher). Gas treatment (flow rate 5 L/min) was only administered during the Adaptation phase of the visuomotor experiment, in both groups. Results: The NbOxTr provided during the Adaptation phase led to significantly faster and about 30% improved learning (p < 0.05). Notably, these motor learning improvements consolidated into the subsequent experiment phases, i.e., after the gas treatment was terminated (p < 0.05). Discussion: We conclude that this simple and brief NbOxTr dramatically improved fundamental human motor learning processes and may provide promising potential for neurorehabilitation and skill-learning approaches. Further studies should investigate whether similar improvements exist in elderly and neurologically impaired individuals, other motor learning tasks, and also long-lasting effects.

Prolonged eye-hand decoupling deficits in young adults with a history of concussion from adolescence.

Previous studies reported that adolescents with a sport-related concussion history showed prolonged visuomotor deficits during an eye-hand decoupling task until around 1.5-2 years post-event. The present study expands this work, examining whether such deficits do or do not emerge when testing individuals in young adulthood, i.e. later post-event. Twenty-one non-athlete college students with sport-related concussion history from adolescence (CH; M = 21 yrs.; M = 46 months post-concussion, range 10-90 months) and twenty controls with no history of concussion (NoH; M = 21 yrs.) performed two touchscreen-based visuomotor tasks. It included a coupled task where eyes and hand moved in similar directions, and decoupled-task with eyes and hand going to different directions. Movement planning (e.g. reaction time, initial direction error) and execution (e.g. movement time, path length) related variables were analyzed in both groups and conditions. Movement execution measures were similar for both groups and conditions (all p > 0.05). However, movement planning was impaired in the CH participants in the eye-hand decoupling condition (p < 0.05). CH's initial direction error was larger (i.e. worse spatial movement planning) than in the NoH group. Although movement execution deficits shown in earlier work in youth were not present in young adults, the present results suggest that a sport-related concussion sustained in adolescence can lead to prolonged deficits with spatial movement planning processes while performing eye-hand decoupling tasks about four years post-injury. Further research should investigate whether these deficits continue into adulthood and expand control on time since concussion and number of concussion metrics.Highlights Young adult college students with a history of a sport-related concussion from adolescence, tested about four years post-incident, showed spatial movement preparation deficits during an eye-hand decoupling visuomotor task.Eye-hand reversal decoupling errors also correlated with time since concussion in those with concussion history.These prolonged eye-hand decoupling deficits may emerge with ongoing time post-event, as comparable deficits were absent in previous work where youth were tested sooner post-injury.Our current findings point towards long-lasting performance impairments in young adult non-athletes after a sport-related concussion from adolescence.

Rapid Dual-Task Decrements After a Brief Period of Manual Tracking in Simulated Weightlessness by Water Submersion.

OBJECTIVE: Investigating dual-task (DT) performance during simulated weightlessness by water submersion, using a manual tracking and a choice reaction task. In contrast to previous work, we focus on performance changes over time. BACKGROUND: Previous research showed motor tracking and choice reaction impairments under DT and single-task (ST) conditions in shallow water submersion. Recent research analyzed performance as average across task time, neglecting potential time-related changes or fluctuations of task-performance. METHOD: An unstable tracking and a choice reaction task was performed for one minute under ST and DT conditions in 5 m water submersion and on dry land in 43 participants. Tracking and choice reaction time performance for both tasks were analyzed in blocks of 10 seconds. RESULTS: Tracking performance deteriorated underwater compared to dry land conditions during the second half while performing one minute in DT conditions. Choice reaction time increased underwater as well, but independent of task time and type. CONCLUSION: Tracking error increased over time when performing unstable tracking and choice reaction together. Potentially, physiological and psychological alterations under shallow submersion further strain the human system during DT operations, exceeding available recourse capacities such that DT performance deteriorated over time. APPLICATION: Humans operating in simulated weightlessness underwater should be aware of substantial performance declines that can occur within a short amount of time during DT situations that include continuous tracking.

Eye-hand decoupling deficits in young adults with concussion history from adolescence: Issues with task novelty or task demand?

The present study expands previous work that reported eye-hand decoupling (EHD) deficits in young adults with concussion history from adolescence. Here, we examine whether these deficits in movement planning (i.e., larger initial direction error) can be linked to difficulties with adapting to new task constraints or meeting ongoing task demands. Data from 21 young adults with concussion history from adolescence (CH) and 20 no history controls (NoH) were analyzed. All participants (Mean = 21 yrs.) performed two eye-hand coordination tasks, a standard task with vision and motor action in alignment, and an EHD task with eye- and hand movement direction spatially decoupled, with twenty trials per task condition. The re-analysis focused on the EHD condition as deficits were found for this task only in prior work. Trials were split into 5 blocks (trial 1-4, 5-8, 9-12, 13-16, 17-20), which included one movement to each of four target directions, and were analyzed across blocks and groups. The CH group had a larger initial direction error during blocks 1-2 but not in blocks 3-5. Our findings suggest that young adults with concussion history from adolescence can have difficulty with adapting to new task constraints associated with complex skill performance during a short series of trials.

Evidence of residual cognitive deficits in young adults with a concussion history from adolescence.

The present study investigated executive function and sustained attention of non-athlete, young adults (ages 18-23) with a history of concussion beyond ten months post incident. Cognitive functioning was examined in 24 non-athletic, college students with a concussion history (mean age 21 yrs.; mean time and range post-injury: 4 years, 10-90 months) and 24 non-athletic controls with no history (NH) of concussion. Computerized versions of two cognitive assessment techniques were utilized to examine executive functioning (Stroop) and sustained attention capacity (D2). Primary dependent variables were response time, error score, and sustained attention score. Relationships between dependent variables and concussion metrics were also analyzed. ANOVA's revealed a significantly higher error rate in concussion history (CH) participants when performing the Stroop task (p < 0.05), including a trend for greater errors in the incongruent task condition (p < 0.05). Group measures did not differ in the sustained attention test (all p > 0.05). Nevertheless, there was a significant relationship between D2 error rate and time since concussion (p < 0.01), showing that D2 error rate was greater for participants with more time since concussion sustainment. Our findings indicate the potential for prolonged cognitive dysfunction linked to decision-making, but not to processing speed, in young adult non-athletes with a CH averaging four years post-injury. These findings may provide evidence of residual cognitive deficits in young adults with a concussion history over time.

Eye movement influences on coupled and decoupled eye-hand coordination tasks.

Visually guided reaching precision and accuracy depend on the level of coupling between movements of the eyes and hand. In the present study, participants performed central fixations and either saccadic or smooth pursuit eye movements during fast and accurate reaching tasks involving eye-hand coupling and decoupling to better understand type of eye movement influence over upper limb control. Some eye-hand coupling and decoupling tasks also included hand reversals, where the hand moves away from the target to direct a cursor toward the target to account for various levels of hand-cursor and eye-cursor coupling. Regardless of eye-movement type, eye-hand-cursor coupling produced an endpoint accuracy advantage over decoupling. Use of hand reversal decreased peak speed and increased response time of the hand, whether considering fixation or a given eye movement. Use of smooth pursuit slowed hand movements relative to saccades, yet improved endpoint accuracy. Compared to central fixations, using smooth pursuit also slowed hand movements, while using saccades decreased, thus improved, hand reaction times. Data suggest an advantage, when using smooth pursuit to track the hand movement for the greatest endpoint accuracy, an advantage when using saccades for the fastest movements, and an eye-hand coupling advantage when using saccades for the shortest reactions. Researchers should provide clear eye-movement instructions for participants and/or monitor the eyes when assessing similar upper limb control to account for possible differences in eye movements used. Moreover, the type of eye movement chosen for participants should correspond to the primary goal of the task.

Eye-hand decoupling decreases visually guided reaching independently of posture but reduces sway while standing: Evidence for supra-postural control.

We investigated whether visually guided reaching differs for sitting and standing postures while the eyes and hand are coupled to move in the same direction or decoupled to move in opposite directions. We also investigated how coupled and decoupled reaching tasks influenced standing postural control. Eighteen healthy young adults (M = 21 years) moved a cursor using finger movements along a vertical touchscreen while sitting or standing. In an eye-hand coupling (EH) task, participants moved their finger/cursor from a central target to a peripheral target located either up, down, left, or right. In an eye-hand decoupling (EHD) task, participant's finger movement moved the cursor in the opposite direction. Sway measures during the standing condition and kinematic variables for the cursor offered insight into whole-body control. Performances in EH revealed smaller errors and faster movements than EHD regardless of postural condition. Similar hand movements existed between sitting and standing when accounting for task, while greater variability in absolute endpoint errors existed for standing than sitting when task was ignored. Less postural sway existed for EHD than EH when standing. These data provide evidence that when participants decoupled the eyes and hand movement direction while standing, they attenuated sway to support control of this complex, cognitively demanding, visuomotor task.

Physical Exercise Intensity During Submersion Selectively Affects Executive Functions.

OBJECTIVE: The intact cognitive processing capacity in highly demanding and dynamically changing situations (e.g., in extreme environmental conditions) is of central relevance for personal safety. This study therefore investigated whether underwater physical exercise (PE) affected cognitive performance by comparing these effects during underwater fin-swimming as opposed to inactivity under normal environmental conditions. BACKGROUND: Although acute bouts of PE can modulate cognitive performance under highly controlled and standardized laboratory conditions, no previous study has determined whether PE acutely modulates cognitive performance in non-laboratory testing conditions involving extreme environments (e.g., underwater). METHOD: A total of 27 healthy volunteers (16 males and 11 females; 28.9 ± 7.4 years of age) participated in two experiments involving either moderate or high PE intensity. A PRE/POST crossover design was employed among participants while performing cognitive tests in a counterbalanced order (i.e., before and after 20 min of PE in submersion [WET] and once before and after inactivity [DRY] while in the laboratory). Cognitive performance was measured as a combination of executive functions through the Eriksen Flanker (inhibition) and Two-Back (working memory) Tasks using an underwater tablet computer. RESULTS: ANOVAs revealed enhanced reaction times only in the Flanker test after moderate PE for the WET condition. No other effects were detected. CONCLUSION: These findings indicate that cognitive performance is exercise-intensity-dependent with enhanced effects during moderate PE, even in extreme environments (i.e., underwater). APPLICATION: These results should be relevant in recreational and occupational contexts involving underwater activity and may also apply to microgravity (e.g., during extra-vehicular activities). DESCRIPTION: This study compared the acute effects of physical exercise (PE) on cognitive performance in an underwater environment while participants fin-swam with SCUBA (self-contained underwater breathing apparatus) gear. Findings revealed that 20 min of moderate PE positively affected cognitive performance (i.e., inhibitory control ability). However, no changes were observed after high-intensity exercise.

Does Hand-Dominance Matter in Non-Standard Visuomotor Transformations?

Previous nonstandard visuomotor transformation studies using variations of eye-hand coupling and decoupling tasks focused on dominant hand use. The present study expanded this work by including the non-dominant hand. Twenty-four right-hand dominant adults (M = 21 yrs.; 12 females) slid their index finger along a vertical or horizontal touchscreen to move a cursor that was always displayed in the vertical plane. In four different action-perception conditions, the finger and cursor moved either in the same plane and direction or in the other plane and/or opposite direction. Performance differed between the hands only for movement trajectory related variables but not for endpoint related measures. Across conditions the initial direction error was larger when performing with the non-dominant hand (p < 0.001). A significant hand × cursor direction × cursor plane interaction for path length (p < 0.05) revealed longer movement trajectories for the non-dominant hand compared to the dominant hand in conditions with none or one level of eye-hand decoupling, and similar hand performance when movements were made in the horizontal plane with reversed cursor direction, i.e., two eye-hand decoupling levels. Our findings suggest a non-dominant hand overall eye-hand coordination deficit for spatial planning and an inversely related deficit to the eye-hand decoupling level for trajectory execution.

Motor Deficits in Youth with Concussion History: Issues with Task Novelty or Task Demand?

The present study expands previous work on eye-hand decoupling deficits in youth with concussion history. It examines whether deficits can be linked to difficulties adapting to new task constraints or meeting ongoing task demands. Data from 59 youth with concussion history (M=11 months post-concussion) and 55 no history controls were analyzed. All 114 participants (M=12.5 yrs.) performed two touchscreen-based eye-hand coordination tasks: A standard task with vision and motor action in alignment, and an eye-hand decoupling task with both spatially decoupled, with twenty trials per task condition. First (trial 1-4), middle (trial 9-12), and last (trial 17-20) trial blocks were analyzed in each condition across groups, as well as first and last blocks only. The latter analysis showed in the first block longer response times in the concussion history group in the eye-hand decoupling condition due to a general slowdown of the reaction times across blocks and a trend for higher movement times. Our findings suggest that youth with concussion history have difficulty to adapt to new task constraints associated with complex skill performance during a short series of trials. These results are relevant for athletic trainers, therapists and coaches who work with youth with concussion history.

Sport experience is correlated with complex motor skill recovery in youth following concussion.

A previous study showed prolonged cognitive-motor integration (CMI) deficits in youth with a history of concussion who were classified as asymptomatic by current return-to-play protocols, highlighting potential differences between clinical symptom recovery and skill recovery. The present study examines factors that may influence skilled performance recovery (defined as matching the skill level of no-concussion history peers) post-concussion in a similar cohort. Sixty-four asymptomatic youth (M = 13 yrs.) soccer, hockey, and lacrosse players with a concussion history (M = 14 months post-concussion) who returned to play and sixty-two age-matched team members with no previous concussion participated in this study. They performed two touchscreen-based eye-hand coordination tasks, including a direct interaction and a CMI task. We analysed the relationship between CMI performance and concussion history, and whether age, sex, number of concussions, and years of sport experience in their sport affected skill recovery. Individuals with concussion history and higher amounts of sport experience (7-12 years) reached a performance level matching their no-history peers quicker (after 12 months) than those with concussion history and lower sport experience (1-6 years; recovery after 30 months). This effect was independent of the number of concussions, age, and sex. The present results point towards an important role of eye-limb coordination-related sport experience in functional CMI recovery post-concussion. Youth with a concussion history but greater sport experience may have more skill-related motor "reserve". This reserve may directly aid in behavioural recovery post-concussion, or the greater neurological efficiency associated with athletic experience provides a compensatory mechanism that provides faster functional recovery.

Development of rule-based eye-hand-decoupling in children and adolescents.

In the present study, we characterize how the ability to decouple guiding visual information from a motor action emerges during childhood and adolescence. Sixty-two participants (age range 8-15 yrs.) completed two eye-hand coordination tasks. In a direct interaction task, vision and motor action were in alignment, and participants slid their finger along a vertical touch screen to move a cursor from a central target to one of four peripheral targets. In an eye-hand-decoupled task, eye and hand movements were made in different planes and cursor feedback was 180° reversed. We analyzed whether movement planning, timing and trajectory variables differed across age in both task conditions. There were no significant relationships between age and any movement planning, timing, or execution variables in the direct interaction task. In contrast, in the eye-hand-decoupled task, we found a relationship between age and several movement planning and timing variables. In adolescents (13-15 yrs.), movement planning and timing was significantly shorter than that of young children (8-10 yrs.). Eye-hand-decoupled maturation emerged mainly during late childhood (11-12 yrs.). Notably, we detected performance differences between young children and adolescents exclusively during the eye-hand decoupling task which required the integration of rule-based cognitive information into the motor action. Differences were not observed during the direct interaction task. Our results quantify an important milestone for eye-hand-decoupling development in late childhood, leading to improved rule-based motor performance in early adolescence. This eye-hand-decoupling development may be due to frontal lobe development linked to rule-based behavior and the strengthening of fronto-parietal networks.

Gaze Behavior While Operating a Complex Instrument Control Task.

INTRODUCTION: The recent developments of technology in almost all areas of industrial processing, workplace, smart homes, mobility, media, and communication change humans' everyday life environment and behavioral responses in numerous ways. Our main objective in this study was to determine whether subjects' operator performance in a complex sensorimotor task is associated with their gaze behavior. METHODS: In two experiments subjects operated a complex control task. To this end they watched multiple displays, made strategic decisions, and used multiple actuators to maximize their virtual earnings from operating a virtual power plant. In Experiment 1 we compared gaze behavior during the tasks with respect to operator performance in two different age groups (young vs. old), and in Experiment 2 in two different gravity conditions (normal vs. microgravity). RESULTS: We found gaze pattern changed in older subjects as well as in microgravity. Older adults and subjects in microgravity looked longer at areas that are less relevant for task success. Most importantly, these changes in gaze pattern accounted for the effects of age and microgravity and on total earnings in the instrument-control task. DISCUSSION: In conclusion, age- and gravity-related changes of gaze behavior show a similar pattern. Gaze behavior seems to play an important role in complex control tasks and might predict alterations of operational performance. Kalicinski M, Steinberg F, Dalecki M, Bock O. Gaze behavior while operating a complex instrument control task. Aerosp Med Hum Perform. 2016; 87(7):646-651.

Prolonged cognitive-motor impairments in children and adolescents with a history of concussion.

AIM: We investigated whether children and adolescents with concussion history show cognitive-motor integration (CMI) deficits. METHOD: Asymptomatic children and adolescents with concussion history (n = 50; mean 12.84 years) and no history (n = 49; mean: 11.63 years) slid a cursor to targets using their finger on a dual-touch-screen laptop; target location and motor action were not aligned in the CMI task. RESULTS: Children and adolescents with concussion history showed prolonged CMI deficits, in that their performance did not match that of no history controls until nearly 2 years postevent. CONCLUSION: These CMI deficits may be due to disruptions in fronto-parietal networks, contributing to an increased vulnerability to further injury. Current return-to-play assessments that do not test CMI may not fully capture functional abilities postconcussion.

Cognitive-motor integration deficits in young adult athletes following concussion.

BACKGROUND: The ability to perform visually-guided motor tasks requires the transformation of visual information into programmed motor outputs. When the guiding visual information does not align spatially with the motor output, the brain processes rules to integrate the information for an appropriate motor response. Here, we look at how performance on such tasks is affected in young adult athletes with concussion history. METHODS: Participants displaced a cursor from a central to peripheral targets on a vertical display by sliding their finger along a touch sensitive screen in one of two spatial planes. The addition of a memory component, along with variations in cursor feedback increased task complexity across conditions. RESULTS: Significant main effects between participants with concussion history and healthy controls without concussion history were observed in timing and accuracy measures. Importantly, the deficits were distinctly more pronounced for participants with concussion history compared to healthy controls, especially when the brain had to control movements having two levels of decoupling between vision and action. A discriminant analysis correctly classified athletes with a history of concussion based on task performance with an accuracy of 94 %, despite the majority of these athletes being rated asymptomatic by current standards. CONCLUSIONS: These findings correspond to our previous work with adults at risk of developing dementia, and support the use of cognitive motor integration as an enhanced assessment tool for those who may have mild brain dysfunction. Such a task may provide a more sensitive metric of performance relevant to daily function than what is currently in use, to assist in return to play/work/learn decisions.

Human Performance in a Realistic Instrument-Control Task during Short-Term Microgravity.

Previous studies have documented the detrimental effects of microgravity on human sensorimotor skills. While that work dealt with simple, laboratory-type skills, we now evaluate the effects of microgravity on a complex, realistic instrument-control skill. Twelve participants controlled a simulated power plant during the short-term microgravity intervals of parabolic flight as well as during level flight. To this end they watched multiple displays, made strategic decisions and used multiple actuators to maximize their virtual earnings from the power plant. We quantified control efficiency as the participants' net earnings (revenue minus expenses), motor performance as hand kinematics and dynamics, and stress as cortisol level, self-assessed mood and self-assessed workload. We found that compared to normal gravity, control efficiency substantially decreased in microgravity, hand velocity slowed down, and cortisol level and perceived physical strain increased, but other stress and motor scores didn't change. Furthermore, control efficiency was not correlated with motor and stress scores. From this we conclude that realistic instrument control was degraded in short-term microgravity. This degradation can't be explained by the motor and/or stress indicators under study, and microgravity affected motor performance differently in our complex, realistic skill than in the simple, laboratory-type skills of earlier studies.

Mental rotation of letters, body parts and scenes during whole-body tilt: role of a body-centered versus a gravitational reference frame.

It is known that in mental-rotation tasks, subjects mentally transform the displayed material until it appears "upright" and then make a judgment. Here we evaluate, by using three typical mental rotation tasks with different degrees of embodiment, whether "upright" is coded to a gravitational or egocentric reference frame, or a combination of both. Observers stood erect or were whole-body tilted by 60°, with their left ear down. In either posture, they saw stimuli presented at different orientation angles in their frontal plane: in condition LETTER, they judged whether the stimuli were normal or mirror-reversed letters, in condition HAND whether they represented a left or a right hand, and in condition SCENE whether a weapon laid left or right in front of a displayed person. Data confirm that reaction times are modulated by stimulus orientation angle, and the modulation curve in LETTER and HAND differs from that in SCENE. More importantly, during 60° body tilt, the modulation curve shifted 12° away from the gravitational towards the egocentric vertical reference; this shift was comparable in all three conditions and independent of the degree of embodiment. We conclude that mental rotation in all conditions relied on a similar spatial reference, which seems to be a weighted average of the gravitational and the egocentric vertical, with a higher weight given to the former.

When neuroscience gets wet and hardcore: neurocognitive markers obtained during whole body water immersion.

Neutral buoyancy facilities are used to prepare astronauts and cosmonauts for extra vehicular activities e.g. on-board of the International Space Station. While previous studies indicated a decrease in cognitive performance in an under water setting, they have only provided behavioural data. This study aimed to review whether recording of electro cortical activity by the use of electroencephalography (EEG) is possible in an under water setting and if so, to identify the influence of water immersion at a depth of 4 m on neurocognitive markers. Ten male subjects performed a cognitive choice-reaction times (RT) task that progressed through five levels of increasing difficulty on land and when submerged 4 m under water. N200 latency and amplitude in the occipital and frontal areas were measured, and baseline cortical activity was measured during rest in both conditions. Neither RT nor amplitude or latency of the N200 showed any significant changes between the land and the under water conditions. Also theta, alpha and beta frequencies showed no differences between the two conditions. The data provided in this study demonstrate the possibility of recording EEG even under the extreme conditions of full body water immersion. The lack of cognitive impairment in RT and N200 in the under water condition may be explained by the fact that only experienced divers participated in the study. As a proof of principle, this study generates many new experimental possibilities that will improve our understanding of cognitive processes under water.