Abstract
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.
Highlights
Research on motor imagery has identified many similarities between imagined and executed actions at the behavioral, physiological and neural levels, supporting their “functional equivalence”
Neuroimaging studies further showed that motor imagery activates a set of frontal motor areas, parietal areas, and cerebellar regions that partially overlaps with the brain network that is activated during motor execution[13,14], and that motor imagery of different effectors activates the corresponding sections of the somatotopically organized motor cortex[17]
No previous study has directly tested this hypothesis of computational equivalence between motor imagery and motor execution; we do not know whether imagined movements engage the same central sensorimotor mechanisms as overt movements do
Summary
Research on motor imagery has identified many similarities between imagined and executed actions at the behavioral, physiological and neural levels, supporting their “functional equivalence”. Little is known about their possible “computational equivalence”— whether the brain’s internal forward models predict the sensory consequences of imagined movements as they do for overt movements We address this question by assessing whether imagined self-generated touch produces an attenuation of real tactile sensations. The classical example of this phenomenon is that when we touch one hand with the other, the touch feels weaker compared with a touch of identical intensity that is applied by another person or a robot This occurs because the self-generated touch has been predicted by the forward models based on the efference copy; the somatosensory feedback is attenuated[31,32]. We conclude that during motor imagery, the forward models predict the sensory consequences of the imagined movement
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