Dynamic motor imagery mentally simulates uncommon real locomotion better than static motor imagery both in young adults and elderly.

Augusto Fusco,Livia Tucci,Gabriella Antonucci,Luigi Iasevoli,Laura Guidetti,Maria Chiara Gallotta,Luca Padua,Marco Iosa,Carlo Baldari,Richard James Keegan

doi:10.1371/journal.pone.0218378

Abstract

A new form of Motor Imagery (MI), called dynamic Motor Imagery (dMI) has recently been proposed. The dMI adds to conventional static Motor Imagery (sMI) the presence of simultaneous actual movements partially replicating those mentally represented. In a previous research conducted on young participants, dMI showed to be temporally closer than sMI in replicating the real performance for some specific locomotor conditions. In this study, we evaluated if there is any influence of the ageing on dMI. Thirty healthy participants were enrolled: 15 young adults (27.1±3.8 y.o.) and 15 older adults (65.9±9.6y.o.). The performance time and the number of steps needed to either walk to a target (placed at 10m from participants) or to imagine walking to it, were assessed. Parameters were measured for sMI, dMI and real locomotion (RL) in three different locomotor conditions: forward walking (FW), backward walking (BW), and lateral walking (LW). Temporal performances of sMI and dMI did not differ between RL in the FW, even if significantly different to each other (p = 0.0002). No significant differences were found for dMI with respect to RL for LW (p = 0.140) and BW (p = 0.438), while sMI was significantly lower than RL in LW (p<0.001). The p-value of main effect of age on participants’ temporal performances was p = 0.055. The interaction between age and other factors such as the type of locomotion (p = 0.358) or the motor condition (p = 0.614) or third level interaction (p = 0.349) were not statistically significant. Despite a slight slowdown in the performance of elderly compared to young participants, the temporal and spatial accuracy was better in dMI than sMI in both groups. Motor imagery processes may be strengthened by the feedback generated through dMI, and this effect appears to be unaffected by age.

Highlights

Motor Imagery (MI) is a mental process during which the motor action is simulated without any overt motor output [1,2]
These results showed that the differences between dynamic and static motor imagery performances resulted statistically significant only in specific locomotor conditions
The mixed-ANOVA performed on the Imagery Perfomance Index (IPI) computed on the absolute difference between motor imagery and actual performances did not show any significant effect

Summary

Introduction

Motor Imagery (MI) is a mental process during which the motor action is simulated without any overt motor output [1,2]. Imagery allows analysis of the processes of motor planning and motor execution both for simple and complex movements [3] and investigations of the mechanisms of motor control both in healthy participants and in patients with different diseases [4]. The imagery of movements shares many features with the actual executed actions, such as timing of actions, activations of neural substrates in several cortical and subcortical brain areas and neurophysiological autonomic responses [7,8,9,10]. The primary motor cortex is not consistently activated, the MI network includes several regions known as playing a role during actual motor execution [11]. MI, as well as movement observation, may elicit physiological responses from the autonomic nervous system at the peripheral level; and in turn, these peripheral physiological responses may be analysed to provide objective evidences that MI is performed [12]

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Conclusion