BackgroundThe 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.MethodsParticipants 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.ResultsSignificant 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.ConclusionsThese 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.

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.

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We have shown before that subjects exposed to a changed gravitoinertial environment produce exaggerated manual forces. From the observed pattern of findings, we argued that initial forces were exaggerated because of abnormal vestibular activity and peak forces because of degraded proprioceptive feedback. If so, only peak but not initial forces should be affected by water immersion, an environment that influences proprioceptive feedback but not vestibular activity. The present study was undertaken to scrutinize this prediction. Twelve subjects sat in a chair once immersed in water and once on dry land, while producing pre-trained isometric forces with a joystick. In a control experiment, subjects performed a four-choice reaction-time task. During the joystick task, produced initial forces were comparable in water and on land, while peak (+24%) and end forces (+22%) were significantly higher in water, as was their reaction time (+6%). During the control task, reaction time was comparable in water and on land. Our findings corroborate the above notion that initial forces increase when the vestibular system is stimulated (gravitoinertial change, visual field motion, but not water immersion), while peak forces increase when proprioceptive feedback is degraded (probably all three scenarios) and are not corrected until response end. Our findings further confirm the absence of cognitive slowing in simple-choice reaction tasks under shallow-water immersion conditions.

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 postconcussion) 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.

Experimental data document that human cognition remains intact down to 6 m water immersion. This, however, is difficult to reconcile with introspective observations from experienced divers, who report cognitive impairments. We hypothesized that the discrepancy might be related to the fact that previous experiments assessed abstract cognitive skills, such as mental arithmetic, which might be less sensitive to immersion than performance-related cognitive skills, such as planning of behavior that is adequate for a given situation. Moreover, previous studies did not control for the effects of water viscosity on subjects' response times. To address these issues, the present study evaluated performance-related cognitive skills based on subjects' isometric responses. Forty-eight subjects were tested in 5 m under water and on dry land using multiple choice reaction tasks, a tracking task, and a combination of both. Sustained attention was also registered, and subjective workload was assessed by questionnaire. We found that a subject's cognitive performance was degraded under water by 9%, independent of task type and equally under single- and dual-task conditions. Sustained attention was reduced under water by 11% and tracking by 48%. The observed deficits were not correlated, which suggests multiple independent effects of immersion. Our findings support the hypothesis that performance-related cognitive skills are affected already by shallow-water immersion. Since no such deficits were observed in a companion study just below the water's surface, the present findings are probably due to increased ambient pressure.

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.

Proprioceptive feedback for active arm movements is enhanced under water, probably due to high water viscosity, which increases spindle afferents during active but not passive arm movements or isometric responses. We found no evidence that the reference frame for orientation judgments differ between Wet and Dry. Muscle tone of the relaxed arm was reduced under water, corroborating that water immersion degrades proprioception during isometric tasks and passive arm positioning. This is probably not relevant for active arm movements, which seem to increase rather than decrease muscle force to overcome water's viscosity.