Summary: Researchers report imagined movements can alter our sense of perception in the same ways as real movements do. The study reveals our brains predict how we would feel sensations if the imagined movements were executed.
Source: Karolinska Institute.
A new study from Karolinska Institutet shows that imagined movements can change our perception in the same way as real, executed movements do. The research, which is presented in the scientific journal Nature Communications, contributes to an increased understanding of how mental training works and may be useful for patients with motor disabilities.
“Mental training is very beneficial if you want to improve your motor performance – this is something elite athletes and professional musicians know very well. We wanted to find out the mechanisms behind this phenomenon,” says Dr. Konstantina Kilteni, lead author of the study and researcher at Karolinska Institutet’s Department of Neuroscience.
Touch resulting from our voluntary movements, for example when we touch one hand with the other, feels less intense compared to when somebody else touches our hand with the exact same intensity. This is because our brain uses information about how we plan to move in order to predict how we will feel. These predictable sensations feel weaker.
The brain predicts how we would feel
“Our study shows that if we imagine the movement but we do not physically perform it, real touch will still feel less intense,” says Dr. Kilteni. “This implies that during imagining the movement the brain also predicts how we would feel if the imagined movements were executed. Taken together our findings suggest that imagined and real movements have very similar brain mechanisms, if not sharing the same one, which may explain the positive effects of mental training”.
The study consists of three series of experiments where 36 healthy individuals were asked to either perform or imagine performing a movement. The experimenters recorded muscular activity to ensure that the participants were not moving while imagining.
During imagination, the participants were told to imagine pressing their right index finger against the relaxed left index finger. At the same time, a touch was applied on their left index finger via specially designed equipment. Participants perceived this touch as less intense compared to when they were neither moving nor imagining suggesting that the brain had predicted how they would feel. In fact, their weakened perception during imagination was equivalent to that when they physically performed the movement.
May be useful for some patient groups
In addition to shedding new light on a classic question in psychology and neuroscience – whether the brain’s representation of imagined and executed movements are the same – the results can be useful for clinical research, especially for neurological patient groups with motor disabilities.
“For example, stroke patients imagining performing the movement that they cannot physically perform could benefit their motor rehabilitation,” says principal investigator Dr. H. Henrik Ehrsson, professor at Karolinska Institutet’s Department of Neuroscience. “Another area of application concerns paralysed or amputated patients that use brain-computer interfaces to control artificial limbs through imagining moving them.”
Funding: The study was funded by the European Commission, the Swedish Research Council, the Torsten Söderberg Foundation and Riksbankens Jubileumsfond.
Source: Karolinska Institute
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to Ulf Sirborn.
Original Research: Open access research for “Motor imagery involves predicting the sensory consequences of the imagined movement” by Konstantina Kilteni, Benjamin Jan Andersson, Christian Houborg & H. Henrik Ehrsson in Nature Communications. Published April 24 2018.
Motor imagery involves predicting the sensory consequences of the imagined movement
Research on motor imagery has identified many similarities between imagined and executed actions at the behavioral, physiological and neural levels, thus supporting their “functional equivalence”. In contrast, little is known about their possible “computational equivalence”—specifically, whether the brain’s internal forward models predict the sensory consequences of imagined movements as they do for overt movements. Here, we address this question by assessing whether imagined self-generated touch produces an attenuation of real tactile sensations. Previous studies have shown that self-touch feels less intense compared with touch of external origin because the forward models predict the tactile feedback based on a copy of the motor command. Our results demonstrate that imagined self-touch is attenuated just as real self-touch is and that the imagery-induced attenuation follows the same spatiotemporal principles as does the attenuation elicited by overt movements. We conclude that motor imagery recruits the forward models to predict the sensory consequences of imagined movements.