Functional roles of the proprioceptive system in the control of goal-directed movement.

This article explored functional roles of the proprioceptive system during the control of goal-directed movements. Proprioceptive information contributes to the control of movement through both reflex and central connections. Spinal and transcortical reflex loops establish a servomechanism which provides automatic corrections of unexpected changes in muscle length and allows compensation for undesirable irregularities in the mechanical properties of muscles by modulating limb stiffness at the subconscious level. Central connections provide the control system with information about peripheral states which is used in voluntary components of movement control. Before the initiation of movement, proprioceptive information about initial limb orientation becomes a basis for the programming of motor commands. During a movement, proprioceptive input about velocities and angular displacements of a limb is used to regulate movement by triggering planned sequences of muscle activation and modulating motor commands. After movement, feedback produced by responses is compared with previously stored information, verifying the quality of the movement. Considering potential roles of the reflex and central connections, the proprioceptive system seems to constitute an important aspect of motor control mechanisms, providing the control system with efficiency and flexibility in the regulation of goal-directed movements.