EYE-HEAD COORDINATION FOR THE STEERING OF LOCOMOTION IN HUMANS - AN ANTICIPATORY SYNERGY

We investigated head and gaze orientation in six healthy volunteers wa lking along 90 degrees corner trajectories, both at light and with eye s closed. We found that head and eyes systematically deviated toward t he future direction of the curved trajectory. Anticipation lead was ab out 1 s, Strikingly, the same behaviour was observed in darkness. In b ackward (BW) locomotion along the trajectory (from end- to start-point ), gaze deviated toward the opposite direction, such that the forward locomotor pattern did not appear time-reversed, Orienting movements di splayed higher amplitude, reproducibility and time lead in the forward (FW) direction at light. We suggest that anticipatory orienting syner gies belong to the behavioural repertoire of human navigation and may reflect the need to prepare a stable reference frame for intended acti on. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.