Motor Imagery

Abstract

Background and Purpose-Understanding brain plasticity after stroke is important in developing rehabilitation strategies.Active movement therapies show considerable promise but depend on motor performance, excluding many otherwise eligible patients. Motor imagery is widely used in sport to improve performance, which raises the possibility of applying it both as a rehabilitation method and to access the motor network independently of recovery. Specifically, whether the primary motor cortex (M1), considered a prime target of poststroke rehabilitation, is involved in motor imagery is unresolved. Summary of Review-We review methodological considerations when applying motor imagery to healthy subjects and in patients with stroke, which may disrupt the motor imagery network. We then review firstly the motor imagery training literature focusing on upper-limb recovery, and secondly the functional imaging literature in healthy subjects and in patients with stroke. Conclusions-The review highlights the difficulty in addressing cognitive screening and compliance in motor imagery studies, particularly with regards to patients with stroke. Despite this, the literature suggests the encouraging effect of motor imagery training on motor recovery after stroke. Based on the available literature in healthy volunteers, robust activation of the nonprimary motor structures, but only weak and inconsistent activation of M1, occurs during motor imagery. In patients with stroke, the cortical activation patterns are essentially unexplored as is the underlying mechanism of motor imagery training. Provided appropriate methodology is implemented, motor imagery may provide a valuable tool to access the motor network and improve outcome after stroke.

Cortical activation during executed, imagined, observed, and passive wrist movements in healthy volunteers and stroke patients

“…Mainly due to this difference, motor imagery resembles motor execution best in patients, but only second-best in HVs. While the reasons for this difference are unclear, it is interesting to note that while the involvement of the primary motor cortex in motor imagery is highly variable and debated in HVs (Dechent et al, 2004;Jackson et al, 2001;Sharma et al, 2006Sharma et al, , 2008, patient studies seem to show primary motor cortex involvement more consistently (Lehericy et al, 2004;Kimberley et al, 2006;Sharma et al, 2009aSharma et al, , 2009b. A reason for this may be that motor imagery is more difficult for patients so that additional neural resources are recruited for task performance.…”

“…This question was motivated from a clinical perspective, as we followed the suggestion that motor system activation is beneficial for motor recovery (Johnson-Frey, 2004;Munzert et al, 2009;Sharma et al, 2006). In this section, we will focus more on the scientist's perspective and scrutinize in more detail the potential underlying processes giving rise to the observed activation patterns.…”

“…the mental simulation of a motor act. It has been suggested that kinesthetic motor imagery involves the same neural network as motor planning (Jeannerod, 1994;Jeannerod and Frak, 1999), which in turn is thought to rely on the same motor structures as motor execution (Johnson-Frey, 2004;Munzert et al, 2009;Sharma et al, 2006). In support of this view, motor imagery shares a number of similarities with overt movement execution, such as behavioral (Decety and Jeannerod, 1995) and physiological parameters (Kranczioch et al, 2008(Kranczioch et al, , 2009, and, importantly, the functional neuroanatomical correlates (Decety, 1996;Lotze and Halsband, 2006;Porro et al, 1996;Szameitat et al, 2007aSzameitat et al, , 2007b.…”

Brain Activation Patterns Characterizing Different Phases of Motor Action: Execution, Choice and Ideation

“…Several studies have investigated the brain substrates of motor imagery, i.e. mental rehearsal in one's mind's eye of a movement, and have found that motor imagery activates to a large extent the same brain networks involved in motor execution, including parts of the SMA, the dorsal premotor cortex, the posterior parietal cortex, the cerebellum and M1 in certain conditions (Lui et al, 2008;Gao et al, 2011;Raffin et al, 2012), showing the potential role of motor imagery in motor rehabilitation (Sharma et al, 2006). Recent functional neuroimaging studies, using region of interest analyses, however, have shown a specific pattern associated with motor execution and imagery (Raffin et al, 2012).…”

Transcranial direct current stimulation of the motor cortex in waking resting state induces motor imagery

“…Studies revealing the strong relationship between motor simulations and motor system activation, functioning independently of motor performance (Abbruzzese et al, 1999, Bonnet et al, 1997, Decety, 1996, Fadiga et al, 1999, Jeannerod, 1995, Jeannerod, 2001, Porro et al, 1996and Schnitzler et al, 1997 have given rise to the hope that motor imagery will provide a backdoor to the motor system after impairments (Jackson et al, 2001, Lehéricy et al, 2004and Sharma et al, 2006. To this end, motor imagery has been shown in neurofeedback task paradigms to increase regional cortical activation: long-term effects of increased activation of motor areas involving neural circuitries associated with motor skill learning can last up to several days (Kober et al, 2014 andYoo et al, 2008).…”