Effects Of Attention On The Anticipatory And Complimentary Postural Control

Background:During sudden internally or externally triggered postural perturbation, the brain integrades sensory informations from visual, proprioceptive and vestibular systems. Through subconscious feedforward and feedback control as well as conscious voluntary control leading by central nervous system(CNS), the brain coordinates sequential movements of postural and focal muscles to deal with the impact on center of body weight and posture caused by postural perturbations quickly and effectively. It was found that as an important mechanism in human cognition and information processing, attention regulates the occurance and control of voluntary movement. However, the effects of attention on feedforward and feedback control of postural and focal muscles are not completely clear yet. Objective:Using the classic ball hitting test(BHT) and balance control test combined with the surface electromyography(sEMG) and the displacements of center of pressure(COP) to observe the effects of perceptual cues, attentional strategies and cognitive load on subconsciously anticipatory and complementary postural adjustments and the displacements of COP, and to investigate the effects of attention on the subconsciously neuromuscular feedforward and feedback control, which provides a theoretical basis for further improving control theories of neuromuscular cognitive neuroscience. Methods: To study the effects of vision and cognitive load on stance posture control, Prokin platform was used to record the changes of COP indices in different vision and cognitive load conditions. To study the effects of perceptual cues, attentional strategies and cognitive load on APAs and CPAs, self-made ball-hitting equipment and plat form as well as sEMG were used to investigate the effects of perceptual cues, attentional strategies and cognitive load on the latancy and the response intensity of postural and focal muscles during APAs and CPAs. Result:Posture stability increased with vision and cognitive load during quite stance. In the condition of externally triggered postural perturbation, the effects of optic and temporal cues on CNS motor control of postural and focal muscles are different. The internal focus of attention facilitates balance to a certain extent during postural perturbation through earlier pre-activation. With intentive attention muscles activate earilier to keep posture stability, and the effect of the internal focus of attention on the focal muscles just existed with vision. There was no effect of cognitive load on postural and focal muscles during APAs and CPAs of sudden arm loading. However, it increased posture stability during CPAs. But this occured without vision, which suggests that cognitive load benefits posture stability in the condition out of vision. Conclusion:Vision and cognitive load can reduce postural sway and improve posture stability during both quite stance and externally triggered postural perturbation. Optic cues are better than temporal cues in both latency and response intensity of APAs, which suggests a superiority for optic cues. External focus of attention is not advantaged when the coordination of the movement is investigated. Instead, internal focus of attention facilitates balance to a certain extent during postural perturbation through earlier pre-activation, and this attentional strategy may be more effective for postural muscles. The spotlight model can be transferred to the internal focus of attention strategy of postural control. The results showed a focus effect of internal focus of attention during externally triggered postural perturbation, and this effect on focal muscles just exists with vision. The recent study is with great significance in further revealing mechanisms of falling of old people and age-related movement disorders to achieve interventions and protections as well as improvement of athletes’performance.