The system provides stimulation at the same time the SVM detects the motor command; thus, the stimulation occurs after the motor command is produced, but before it reaches the spine.
In this approach, each motor command is represented as a linear combination of prefixed basis patterns, and the command for a given task is designed by minimizing a two-termed criterion consisting of a task optimization term and a parameter preference (i.e., sparseness) term.
Sensory attenuation is normally explained in terms of sensory predictions based on the motor command being compared to actual sensory feedback.
However, an efferent copy of the motor command is still available for the CNS for sensorimotor prediction and physiological preparation of the organism (ANS activation).
Thus, the mere preparation of action has a structuring effect on somatosensory perception, even when the motor command is not actually executed.
During motor imagery, the inverse internal model prepares the appropriate motor command but no overt movement occurs because the motor command is inhibited, probably at the spinal cord or brainstem level.
The movement is prepared from the visual information of the target (motor planning) and the feedforward motor command is subsequently generated from the desired movement via an internal model of the arm and the environment (feedforward control) [11], [13], [14].
At the same time as the motor command is sent from M1 to the periphery, an efference copy (or corollary discharge) is created in brain structures also involved in the generation of the movement.
After the hand movement is initiated, the feedback motor command is generated using the sensory (e.g., visual) feedback signal associated with the ongoing movement in order to adjust the movement in mid-flight (feedback control) [9], [10], [13].
During a covert arm reaching movement, although the motor command is blocked at a certain level in the CNS, the efference copy is still available for the forward model which can thus predict the future state of the arm.
