Internally Simulated Movement Sensations during Motor Imagery Activate Cortical Motor Areas and the Cerebellum

Abstract

It has been proposed that motor imagery contains an element of sensory experiences (kinesthetic sensations), which is a substitute for the sensory feedback that would normally arise from the overt action. No evidence has been provided about whether kinesthetic sensation is centrally simulated during motor imagery. We psychophysically tested whether motor imagery of palmar flexion or dorsiflexion of the right wrist would influence the sensation of illusory palmar flexion elicited by tendon vibration. We also tested whether motor imagery of wrist movement shared the same neural substrates involving the illusory sensation elicited by the peripheral stimuli. Regional cerebral blood flow was measured with H215O and positron emission tomography in 10 right-handed subjects. The right tendon of the wrist extensor was vibrated at 83 Hz ("illusion") or at 12.5 Hz with no illusion ("vibration"). Subjects imagined doing wrist movements of alternating palmar and dorsiflexion at the same speed with the experienced illusory movements ("imagery"). A "rest" condition with eyes closed was included. We identified common active fields between the contrasts of imagery versus rest and illusion versus vibration. Motor imagery of palmar flexion psychophysically enhanced the experienced illusory angles of plamar flexion, whereas dorsiflexion imagery reduced it in the absence of overt movement. Motor imagery and the illusory sensation commonly activated the contralateral cingulate motor areas, supplementary motor area, dorsal premotor cortex, and ipsilateral cerebellum. We conclude that kinesthetic sensation associated with imagined movement is internally simulated during motor imagery by recruiting multiple motor areas.

The Cortical Timeline for Deciding on Reach Motor Goals

“…In visuomotor tasks, movement planning then would equal the process of analyzing the difference between the current sensory state and the prospective sensory state, which is predicted to result from the currently imagined movement in the future, once it is executed (Salinas, 2004;Shadmehr and Wise, 2005). This view is consistent with our data and previous studies, which showed activation of PPC during motor imagery (Decety et al, 1994;Stephan et al, 1995;Sirigu et al, 1996;Gerardin et al, 2000;Naito et al, 2002), and the fact that parietal electrical stimulation can trigger subjective movement intentions without actual movements being performed (Desmurget et al, 2009). …”

Somatic Sensation of Hand-Object Interactive Movement Is Associated with Activity in the Left Inferior Parietal Cortex

“…From the flexor muscle (the FCU), we found no robust EMG activity during the illusions. These EMG results confirmed those in our previous studies (Naito et al, 2002a(Naito et al, ,b, 2005.…”

“…a protoractor [see methods in the study by Naito et al (2002a)]. The subjects were also requested to rate the vividness of illusions on an analog scale from 1 to 10.…”

Mentally represented motor actions in normal agingI. Age effects on the temporal features of overt and covert execution of actions

“…For instance, brain's neuroimaging exploration provided evidences that similar neural structures, including the parietal and prefrontal cortices, the supplementary motor area, the premotor and primary motor cortices, the basal ganglia, the cerebellum, and for some motor tasks the spinal cord, are engaged during both movement execution and internal simulation (for a review see [11,15,21]). Specifically, this overlap has been reported for hand movements [25,31], finger-to-thumb movements [38], toe and tongue movements [14] as well as during walking [29]. It has also been shown that muscular force is enhanced by an 'imagined' training [39,51] and that autonomic activation is increased, compared to rest, when subjects imagine motor actions with large physical effort [8,9,33].…”