Spatial constraints and cognitive fatigue affect motor imagery of walking in people with multiple sclerosis

Jessica Podda,Ludovico Pedullà,Margherita Monti Bragadin,Andrea Tacchino,Giampaolo Brichetto,Elisa Piccardo,Mario Alberto Battaglia,Marco Bove

doi:10.1038/s41598-020-79095-3

Abstract

Motor imagery (MI) is the mental simulation of an action without any overt motor execution. Interestingly, a temporal coupling between durations of real and imagined movements, i.e., the so-called isochrony principle, has been demonstrated in healthy adults. On the contrary, anisochrony has frequently been reported in elderly subjects or those with neurological disease such as Parkinson disease or multiple sclerosis (MS). Here, we tested whether people with MS (PwMS) may have impaired MI when they imagined themselves walking on paths with different widths. When required to mentally simulate a walking movement along a constrained pathway, PwMS tended to overestimate mental movement duration with respect to actual movement duration. Interestingly, in line with previous evidence, cognitive fatigue was found to play a role in the MI of PwMS. These results suggest that investigating the relationship between cognitive fatigue and MI performances could be key to shedding new light on the motor representation of PwMS and providing critical insights into effective and tailored rehabilitative treatments.

Highlights

Motor imagery (MI) is the mental simulation of an action without any overt motor execution
We investigate if people with MS (PwMS) show anisochrony in a task involving lower limbs and if the dependency on spatial constraints was present
Fifteen PwMS with mild disability and 15 age-matched healthy subjects (HS) were required to either walk or imagine themselves walking on three paths of the same length, but different widths

Summary

Introduction

Motor imagery (MI) is the mental simulation of an action without any overt motor execution. Anisochrony, i.e., a temporal discrepancy between actual and mental movements, has been frequently reported in populations of neurological patients, as people after stroke[10], with Parkinson disease (PD)[11,12] and with multiple sclerosis (MS)[13,14,15], gaining increasing attention as a promising additional clinical investigation tool[16]. Walking is interesting for a broader understanding of MI This represents a unique window into the study of MI because subjects are requested to simulate full-body movements and simultaneously update environmental spatial information[5]. Findings indicate that healthy good imagers usually preserve temporal congruence[31,32,33] as well as recruiting very similar cerebral networks (e.g. fronto-parietal areas, basal ganglia, brainstem, cerebellum)[34,35] when they are asked to and mentally execute tasks involving locomotion. More contradictory results have been found in patients with PD, mainly due to differences in testing procedures and task instructions[27,39,40]

Objectives

Methods

Results

Conclusion