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

IntroductionHuman 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.Methods40 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.ResultsThe 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).DiscussionWe 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

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

<div><p>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 <i>control efficiency</i> as the participants’ net earnings (revenue minus expenses), <i>motor performance</i> as hand kinematics and dynamics, and <i>stress</i> 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.</p></div

Summary and description of all test variables^*.

<p>Summary and description of all test variables^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128992#t001fn001" target="_blank">*</a>}.</p

ANOVA of motor parameters.

<p>ANOVA of motor parameters.</p

Control efficiency.

<p>Shown is the parameter control efficiency in normal (1G) and in microgravity (μG). 1G score is the total earned money across all 26 episodes of the control task performed in normal gravity; accordingly μG score represents the earnings of all 26 episodes of the control task in microgravity. Data are presented as means ± standard errors divided by 1000. *** = <i>p</i> < .001.</p

Motor performance.

<p>Shown are the interaction plots of grasping parameters subdivided by their values of the three knobs (large, rotary and small knob) in normal (1G) and in microgravity (μG). PHV represents peak hand velocity, PGA the peak grip aperture, CT the knob contact time, F the maximum force applied to the knobs and KC the number of grasping movements performed in each condition and for each knob. Mean KC values for all knobs were above 50, which were acceptable for calculating means of motor performance. For all parameters, significant effects were found between the large, rotary and small knob (all <i>p</i> < .001). Significant interaction (<i>p</i> < .05) emerged between Knob x Gravity for PHV with speed reduction of the small (<i>p</i> < .05) and rotary knob (<i>p</i> < .05) in microgravity, and no change for the big knob (<i>p</i> > .05). All other ANOVA factors were not significant (<i>p</i> > .05). Data are presented as means ± standard errors, additional statistics are summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128992#pone.0128992.t002" target="_blank">Table 2</a>.</p

Experimental setup, control task and experimental timeline.

<p><b>a:</b> Experimental setup for the use in parabolic flights. Shown is a participant sitting in a chair in front of the Eye tracker (incorporated in the screen) and the control panel within the metal frame, which serves as the construction for assembly into the parabolic flight plane. Four Bonita Vicon cameras for 3D hand motion capturing surround the participant. <b>b:</b> Screen of the simulated power plant with feedback displays regarding the requested power (top left), level of fuel rods (middle left), light button (top middle), temperature (bottom left), cooling tank (bottom middle) and earnings (right). The top left display element presents the inset for power requests. <b>c</b>: Enlargement of the control panel as shown in “a” with the small and big rotatable knobs, the rotary switch and the flip switch. The small rotatable knob controls the display element on the bottom left, the rotary switch the middle-left, the flip switch the light button and the big rotatable knob controls the top left element. <b>d:</b> Experimental time line for a participant during one flight day; shown are the points in time where the measurements were taken with respect to the flight profile along with the blocks of the control task. Cortisol stands for collection of saliva sample, the MoodMeter for mood assessment and the TLX for the NASA task load index.</p

Multiple stepwise regression of motor and stress changes on control efficiency change.

<p>Multiple stepwise regression of motor and stress changes on control efficiency change.</p