What are motor imagery and action observation?
Studies and modern neurorehabilitation approaches show that motor imagery, as well as action observation, improve motor performance and upper limb function after a stroke. These techniques are not only used in rehabilitation but also in sports. Based on research, they are an example of evidence-based clinical practice for the rehabilitation of movement-related disorders. (1,2)
But what happens during action observation and motor imagery?
Not only executing actions but also imagining and observing, activates certain motor-related regions, such as the premotor cortex and inferior parietal lobule. This means that thinking about and observing a movement activates the same areas in the brain as the actual movement. (3)Motor imagery requires the mental practice of movements without visible movement. This can happen implicitly, for example during mental rotation tasks, or explicitly through voluntary imagination of movements. (4 )While motor imagery has also been used for brain-machine/computer interfaces (BMI/BCI), both can be used to learn and relearn complex motor tasks. The complexity and level of performance influence the brain’s activity. At least in the early phases of motor learning, action observation overrules motor imagery as a strategy. (3,5) Both motor imagery and action observation are connected to the mirror neuron system.
What is the mirror neuron system?
The mirror neuron system is identified as the network for understanding actions performed by others. Using functional magnetic resonance (fMRI) the presence of mirror neuron systems during motor tasks was defined. These neurons discharge either when performing a motor task or watching as someone else performs a related action. This is called the action observation-action execution matching mechanism. Action observation and motor imagery use this mechanism for the recovery of motor impairment. (1,5,6,7) Studies describe the findings and knowledge of the mirror neuron system as a source of information to motor training after stroke. (8)
How can this be used?
The understanding of the basics of motor imagery and action observation can be applied in the rehabilitation of upper limb motor functions in chronic stroke patients. Although there are studies that explain typical sessions such as observing a daily action and afterward executing it in context, there is no information about timelines and overall therapy time. However, brain activity is influenced by task complexity. (1,3)
New approaches, new technologies
Technologies, for example, virtual reality (VR), use neurophysiology knowledge to bring rehabilitation to the next level. Studies have already shown that there is no difference in healthy people’s fMRI when watching real or virtual hands. These findings bring VR to the next level as a promising tool for neurorehabilitation. (9)Further promising technologies are Brain-Computer Interface (BCI) technologies or combining eye tracking and VR. These new approaches can lead the way to new methods in overcoming stroke-related motor limitations. (10,11)
How I use motor imagery and action observation every day in therapy
Harnessing this knowledge, through therapy methods such as mirror therapy or hand laterality judgment task, I have brought the awareness of neurophysiology into my daily therapies. Especially in the early rehabilitation phase of a stroke, but also years after a stroke, motor imagery and action observation are some of the tools that I always implement.Starting at an early phase, motor imagery is a skill that I like to work on with my patients on their way into independent day-to-day training.
What are your thoughts on motor imagery and action observation?Do you have a method of choice?
- Buccino, G. (2014). Action observation treatment: a novel tool in neurorehabilitation. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1644), 20130185–20130185. https://doi.org/10.1098/rstb.2013.0185
- Borges, L. R., Fernandes, A. B., Melo, L. P., Guerra, R. O., & Campos, T. F. (2018). Action observation for upper limb rehabilitation after stroke. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD011887.pub2
- Mizuguchi, N., & Kanosue, K. (2017). Changes in brain activity during action observation and motor imagery: Their relationship with motor learning (pp. 189–204). https://doi.org/10.1016/bs.pbr.2017.08.008
- Chong, B. W. X., & Stinear, C. M. (2017). Modulation of motor cortex inhibition during motor imagery. Journal of Neurophysiology, 117(4), 1776–1784. https://doi.org/10.1152/jn.00549.2016
- Gatti, R., Tettamanti, A., Gough, P. M., Riboldi, E., Marinoni, L., & Buccino, G. (2013). Action observation versus motor imagery in learning a complex motor task: A short review of literature and a kinematics study. Neuroscience Letters, 540, 37–42. https://doi.org/10.1016/j.neulet.2012.11.039
- Gatti, R., Rocca, M. A., Fumagalli, S., Cattrysse, E., Kerckhofs, E., Falini, A., & Filippi, M. (2017). The effect of action observation/execution on mirror neuron system recruitment: an fMRI study in healthy individuals. Brain Imaging and Behavior, 11(2), 565–576. https://doi.org/10.1007/s11682-016-9536-3
- Plata-Bello, J., Modroño, C., Hernández-Martín, E., Pérez-Martín, Y., Fariña, H., Castañón-Pérez, A., … González-Mora, J. L. (2017). The mirror neuron system also rests. Brain Structure and Function, 222(5), 2193–2202. https://doi.org/10.1007/s00429-016-1335-5
- Garrison, K. A., Winstein, C. J., & Aziz-Zadeh, L. (2010). The Mirror Neuron System: A Neural Substrate for Methods in Stroke Rehabilitation. Neurorehabilitation and Neural Repair, 24(5), 404–412. https://doi.org/10.1177/1545968309354536
- Brihmat, N., Tarri, M., Quidé, Y., Anglio, K., Pavard, B., Castel-Lacanal, E., … Loubinoux, I. (2018). Action, observation or imitation of virtual hand movement affect differently regions of the mirror neuron system and the default mode network. Brain Imaging and Behavior, 12(5), 1363–1378. https://doi.org/10.1007/s11682-017-9804-x
- Vourvopoulos, A., & Bermúdez i Badia, S. (2016). Motor priming in virtual reality can augment motor-imagery training efficacy in restorative brain-computer interaction: a within-subject analysis. Journal of NeuroEngineering and Rehabilitation, 13(1), 69. https://doi.org/10.1186/s12984-016-0173-2
- Alves, J., Vourvopoulos, A., Bernardino, A., & Badia, i B. (2016). Eye Gaze Correlates of Motor Impairment in VR Observation of Motor Actions. Methods of Information in Medicine, 55(01), 79–83. https://doi.org/10.3414/ME14-01-0125