Effect of motor imagery on excitability of spinal neural function and its impact on the accuracy of movement-considering the point at which subjects subjectively determine the 50%MVC point

Abstract

[Purpose] This study aimed to examine the effect of motor imagery on the accuracy of motion and the excitability of spinal neural function. [Subjects and Methods] Thirty healthy volunteers (males, 15; females, 15; mean age, 20.3 ± 1.0 years) were recruited. F-waves was recorded at rest, while holding a sensor, and while using motor imagery. Next, subjects learned 50% maximum voluntary contraction. The pinch force was measured without visual feedback before and after motor imagery. F-waves were analyzed with respect to persistence and the F/M amplitude ratio. Correction time and coefficient of variation were calculated from the pinch force. [Results] Persistence and F/M amplitude ratio ware significantly higher in the holding sensor and motor imagery conditions than in the resting condition. In addition, persistence under motor imagery was significantly higher than that in the holding sensor condition. No significant differences were observed in relative values of correction time and coefficient of variation between the two pinch action conditions. The pinch force in task 2 approximated a more authentic 50%MVC than that in task 1. [Conclusion] Motor imagery increases the excitability of spinal neural function, suggesting that it also affects accurate control of muscle force.

Differences in motor imagery strategy change behavioral outcome

“…However, this report did not provide an explanation of how spinal motor neuron excitability controls movement because it only focused on spinal motor neuron excitability. In our previous study, the excitability of spinal motor neurons was increased during MI, while precision pinch force control skills did not improve 27 . Additionally, increased excitability of spinal motor neurons during MI was not always associated with improved precision pinch force control skills.…”

“…Therefore, 21 healthy participants (13 men and 8 women; mean age: 24.8 ± 5.5 years) were included to ensure that the actual sample size was greater than the calculated sample size. We did not exclude any participants due to an error of more than 5% (error [%] = [exerting pinch force – 50% MVC] / 50% MVC × 100) from the 50% MVC to examine the time required for accurate adjustment 27 . The participants were determined to be right-handed using the Edinburgh Handedness Inventory to control the condition of hand dominance (Table 1 ).…”

“…While checking the pinch meter, the subject exerts 10 kgf, but if the adjustment does not go smoothly and the subject exerts a pinch force of 10.4 kgf, the error is 0.4 kgf. Since there are individual differences in pinch force for 50% MVC, it was expressed as a ratio, which in this example is 4% error (error [%] = [exerting pinch force – 50% MVC] / 50% MVC × 100) 27 . However, this index was not a performance study item, but rather a precision item for skill assurance and was used to classify the recruited participants.…”

Effect of Motor Imagery After Motor Learning for 30 sec on Excitability of Spinal Neural Function and its Impact on Accurate Control of Muscle Force

“…Therefore, persistence and the F/M amplitude ratio are regarded as indices of the swimmer. Moreover, Dickstein et al [14] reported gait speed to be improved using motor imagery in hemiparesis patients with Cardio Vascular Disease. Thus, motor imagery may improve muscle strength, motor function, muscle ductility, gait speed, and so forth.…”

Neural activity during simple visual imagery compared with mental rotation imagery in young adults with smartphone overuse

“…Mental rotation makes the brain move objects in order to help understand what they are and where they belong. The aim is to rotate the image without requiring the use of higher cognitive function and attention and to think of simple visual images to further promote the activation of the brain [7][8][9][10][11].…”