Functional Roles of Saccades for a Hand Movement

Abstract

An eye saccade provides appropriate visual information for motor control. The present study was aimed to reveal the role of saccades in hand movements. Two types of movements, i.e., hitting and circle-drawing movements, were adopted, and saccades during the movements were classified as either a leading saccade (LS) or catching saccade (CS) depending on the relative gaze position of the saccade to the hand position. The ratio of types of the saccades during the movements was heavily dependent on the skillfulness of the subjects. In the late phase of the movements in a less skillful subject, CS tended to occur in less precise movements, and precision of the movement tended to be improved in the subsequent movement in the hitting. While LS directing gaze to a target point was observed in both types of the movements regardless of skillfulness of the subjects, LS in between a start point and a target point, which led gaze to a local minimum variance point on a hand movement trajectory, was exclusively found in the drawing in a less skillful subject. These results suggest that LS and some types of CS may provide positional information of via-points in addition to a target point and visual information to improve precision of a feedforward controller in the brain, respectively.

Special Issue: Movement Biomechanics and Motor Control

“…The papers collected deal with anticipatory postural adjustments [2] and anticipatory locomotor adjustments [3], strategies to tackle obstacles [2][3][4], the effects of weight unloading on gait [5], posture control in special populations: ataxic children [6] and obese subjects [7], surface perturbation during posture [8], effects of sensory information and feedback on postural control [9,10], elderly behavior during a motor-motor double task [11], upper limb control [12,13], different aspects related to running: ankle joint dynamic stiffness [14] and fatigue [15]. There is also a flash on an ecologic condition where a pedestrian has to program its strategy to cross a road in between two moving vehicles [16], and a study on visual-manual control in monkeys [17].…”