Combined action observation and imagery facilitates corticospinal excitability

Abstract

Observation and imagery of movement both activate similar brain regions to those involved in movement execution. As such, both are recommended as techniques for aiding the recovery of motor function following stroke. Traditionally, action observation and movement imagery (MI) have been considered as independent intervention techniques. Researchers have however begun to consider the possibility of combining the two techniques into a single intervention strategy. This study investigated the effect of combined action observation and MI on corticospinal excitability, in comparison to either observation or imagery alone. Single-pulse transcranial magnetic stimulation (TMS) was delivered to the hand representation of the left motor cortex during combined action observation and MI, passive observation (PO), or MI of right index finger abduction-adduction movements or control conditions. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles of the right hand. The combined action observation and MI condition produced MEPs of larger amplitude than were obtained during PO and control conditions. This effect was only present in the FDI muscle, indicating the facilitation of corticospinal excitability during the combined condition was specific to the muscles involved in the observed/imagined task. These findings have implications for stroke rehabilitation, where combined action observation and MI interventions may prove to be more effective than observation or imagery alone.

The effect of action observation and motor imagery combinations on upper limb kinematics and EMG during dart‐throwing

“…Action observation (AO) training consists of observing an action conducted by others without any motor output . Both MI and AO have been shown to promote motor learning, demonstrating neurophysiological activation of the brain areas corresponding to motor planning and voluntary movement . Acute effects of AO and MI interventions filmed from the first‐person visual perspective have also been shown to optimize kinetic and kinematic variables and promote motor learning .…”

Combined Action Observation and Motor Imagery Neurofeedback for Modulation of Brain Activity

“…This is an unexpected result given previous findings that typically show a reduction in mu rhythm magnitude during tasks involving sensorimotor processes (Nedelko et al, 2012; Villiger et al, 2013; Kondo et al, 2015). Several studies of II have found it to be associated with increased motor cortex excitability (Sakamoto et al, 2009; Ohno et al, 2011; Tsukazaki et al, 2012; Wright et al, 2014), and increased activation of the motor network more broadly (Nedelko et al, 2012; Villiger et al, 2013), when compared to MI or AO alone. One explanation for the lack of ERD/S values <0 is that engaging with the present NFB system while performing II was too cognitively demanding, hindering subjects' performance of II.…”

“…Recently, researchers have used a combined MI/AO approach: here an individual watches a motor task being performed repetitively, while simultaneously imagining they are performing the movement themselves. This approach of “Imagined Imitation” (II) has been shown to facilitate corticospinal excitability to a greater degree than either AO or MI alone (Sakamoto et al, 2009; Ohno et al, 2011; Tsukazaki et al, 2012; Wright et al, 2014), and to increase brain activity in several regions critical for motor learning and performance over and above that seen in AO or MI (Macuga and Frey, 2012; Nedelko et al, 2012; Villiger et al, 2013; Kondo 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.…”