Task-dependent changes of corticospinal excitability during observation and motor imagery of balance tasks

Abstract

Non-physical balance training has demonstrated to be efficient to improve postural control in young people. However, little is known about the potential to increase corticospinal excitability by mental simulation in lower leg muscles. Mental simulation of isolated, voluntary contractions of limb muscles increase corticospinal excitability but more automated tasks like walking seem to have no or only minor effects on motor-evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS). This may be related to the way of performing the mental simulation or the task itself. Therefore, the present study aimed to clarify how corticospinal excitability is modulated during AO+MI, MI and action observation (AO) of balance tasks. For this purpose, MEPs and H-reflexes were elicited during three different mental simulations (a) AO+MI, (b) MI and (c) passive AO. For each condition, two balance tasks were evaluated: (1) quiet upright stance (static) and (2) compensating a medio-lateral perturbation while standing on a free-swinging platform (dynamic). AO+MI resulted in the largest facilitation of MEPs followed by MI and passive AO. MEP facilitation was significantly larger in the dynamic perturbation than in the static standing task. Interestingly, passive observation resulted in hardly any facilitation independent of the task. H-reflex amplitudes were not modulated. The current results demonstrate that corticospinal excitability during mental simulation of balance tasks is influenced by both the type of mental simulation and the task difficulty. As H-reflexes and background EMG were not modulated, it may be argued that changes in excitability of the primary motor cortex were responsible for the MEP modulation. From a functional point of view, our findings suggest best training/rehabilitation effects when combining MI with AO during challenging postural tasks.

Age-Related Differences in Corticospinal Excitability during Observation and Motor Imagery of Balance Tasks

“…Brain activation patterns depend on the kind of mental simulation (i.e., AO + MI, MI and AO) and on the postural task (i.e., static vs. dynamic). In line with this, we found that corticospinal excitability was also modulated depending on the postural task and the kind of mental simulation performed by young subjects (Mouthon et al, 2015). To date, however, it is unknown whether the internal mental representation of balance tasks undergoes age-related changes.…”

“…All participants gave written consent, in accordance with the Declaration of Helsinki, before participating in this study which was approved by the local ethics committee of the canton Fribourg (014-CER-FR). Their data was compared with the results of a group of healthy young adults (aged 27 ± 4.6, five females) from a previous study (Mouthon et al, 2015). …”

Motor Imagery during Action Observation: A Brief Review of Evidence, Theory and Future Research Opportunities

“…First, corticospinal excitability, measured through the amplitudes of motor evoked potentials, during both AO and MI of hand gestures is reliably higher than control conditions (e.g., Clark et al, 2004; Williams et al, 2012; see Naish et al, 2014; Grosprêtre et al, 2016 for reviews). Second, AO+MI produces significantly greater facilitation of corticospinal excitability compared to AO (Ohno et al, 2011; Wright et al, 2014, 2016) and, in some cases, MI as well (Sakamoto et al, 2009; Tsukazaki et al, 2012; Mouthon et al, 2015). These effects have been demonstrated across a variety of tasks, including simple and sequential finger movements (Wright et al, 2014, 2016), gross and fine motor tasks (Sakamoto et al, 2009; Ohno et al, 2011) and coordination tasks (Tsukazaki et al, 2012; Mouthon et al, 2015).…”

“…Several studies have filmed the AO component from a first-person visual perspective (e.g., Villiger et al, 2013; Wright et al, 2014, 2016), while other studies have filmed the action from a third-person visual perspective (e.g., Eaves et al, 2014, 2016; Mouthon et al, 2015; Taube et al, 2015). In some cases, participants are instructed to explicitly image from a first person perspective, while in other cases they are only told to imagine themselves performing the observed movement, which may result in participants adopting either a first- or third-person imagery perspective, depending on their imagery perspective preference.…”

The Effects of Functional Knee Brace on Postural Control in Patients Who Underwent Anterior Cruciate Ligament Reconstruction

“…The more balance demanding tasks need considerable motor activity (16). Increased sensory motor activity demand in the more challenging balance tasks is not compensated with functional knee brace (9).…”