Motor imagery reinforces brain compensation of reach-to-grasp movement after cervical spinal cord injury

Abstract

Individuals with cervical spinal cord injury (SCI) that causes tetraplegia are challenged with dramatic sensorimotor deficits. However, certain rehabilitation techniques may significantly enhance their autonomy by restoring reach-to-grasp movements. Among others, evidence of motor imagery (MI) benefits for neurological rehabilitation of upper limb movements is growing. This literature review addresses MI effectiveness during reach-to-grasp rehabilitation after tetraplegia. Among articles from MEDLINE published between 1966 and 2015, we selected ten studies including 34 participants with C4 to C7 tetraplegia and 22 healthy controls published during the last 15 years. We found that MI of possible non-paralyzed movements improved reach-to-grasp performance by: (i) increasing both tenodesis grasp capabilities and muscle strength; (ii) decreasing movement time (MT), and trajectory variability; and (iii) reducing the abnormally increased brain activity. MI can also strengthen motor commands by potentiating recruitment and synchronization of motoneurons, which leads to improved recovery. These improvements reflect brain adaptations induced by MI. Furthermore, MI can be used to control brain-computer interfaces (BCI) that successfully restore grasp capabilities. These results highlight the growing interest for MI and its potential to recover functional grasping in individuals with tetraplegia, and motivate the need for further studies to substantiate it.

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

“…MI is a type of mental practice involving the internal generation of visual and kinesthetic aspects of movement, and a large body of research has recommended that practitioners working in motor learning and rehabilitation settings should use MI to improve motor abilities (see Schuster et al, 2011). This can either be as an accompaniment to physical practice to improve behavioral outcomes (e.g., Rozand et al, 2014; Di Rienzo et al, 2015; Ingram et al, 2016), or as a replacement when movement is restricted due to either neurological impairment or injury (e.g., Szameitat et al, 2012; Hoyek et al, 2014; Mateo et al, 2015). It is also well-documented that AO evokes an internal motor representation of the observed movement (also termed “motor resonance”; see Rizzolatti and Sinigaglia, 2010).…”

Motor Imagery Practice and Cognitive Processes

“…A popular and widely investigated application of MI is "motor imagery practice" (MIP; also known as "mental practice") which is a mental simulation process that involves the systematic use of imagery to covertly rehearse a movement without actually executing it (Di Rienzo et al, 2016). Research shows that MIP is effective in enhancing skilled performance both in healthy populations (Driskell et al, 1994) and in clinical groups (e.g., Mateo et al, 2015). It not only improves motor learning (e.g., Kraeutner et al, 2016) but also induces "neural plasticity" (e.g., Debarnot et al, 2014) or the capacity of the brain to reshape its physical structure as a direct result of repeated experience.…”

Effect of motor imagery and actual practice on learning professional medical skills

“…[28] MI can adequately plan the needed actions before their execution and complete the usual way to learn medical techniques by memorizing mental references for real practice. [14,26,29] Training through mixed practice of actual and MI of suturing a pig's foot led to perform as well as actual practice alone. [25] MI thus provided the same performance as real repetitions, after initial training with actual practice.…”

“…speed, amplitude, force, pressure. [12,14] MI has extensively been used in sports, music or medicine [15] with various goals, in particular learning motor skill and recovering motor ability after injury. [4,5,16] MI duration shares similar constraints to those of actual action and took the same time as that needed for actual execution.…”

“…[10,[21][22][23][24][25] MI improved the seizure-grasping abilities of C6-C7 quadriplegic patients through decreased of both movement time and trajectory variability thus revealing brain adaptations. [14] It is particularly effective in cognitively demanding tasks e.g. in surgical techniques.…”