Head control strategies during whole-body turns

Abstract

Recent reports have described the motion of individual body segments during turns toward visual targets. During a whole-body turn, the head's trajectory in space is determined by both body-in-space rotation and head-on-body rotation. To inform subsequent investigations of head control strategies during turns, we provide a kinematic description of head and pelvis rotation in 20 healthy human subjects as they performed step turns toward a visible target or in the direction of a previously seen target. At the time of peak head velocity in space, the head was moving faster than the pelvis by approximately 54 degrees s(-1) when turning toward a visible target, and approximately 25 degrees s(-1) when turning in a remembered direction. Peak head velocities were slower in the absence of a visual target, but pelvis velocities were not significantly different. The pattern of relative motion between the head and pelvis followed a temporal sequence. Early in the turn, the head rotated with respect to the pelvis in the same direction as the pelvis was rotating in space. During the mid portions of the turn, en bloc rotation of the head and pelvis predominated. Later in the turn, head-in-space velocity was lower than pelvis-in-space velocity, and was thus relatively stabilized. This pattern of head movement during turns is quite similar to eye-in-head movements during large eye-head gaze shifts. This suggests that in addition to saccadic and stabilization mechanisms, a specific control strategy to move segments together should be incorporated into models of gaze reorienting behavior.

Walking along curved paths of different angles: the relationship between head and trunk turning

“…4, the results from our study correspond well with studies that used heading as a reference (Grasso et al 1998;Imai et al 2001;Prévost et al 2002) as well as with those that used the trunk/pelvis (Hicheur et al 2007;Solomon et al 2006). A similar trend of increasing relative yaw for turns of higher angles was also reported in a recent study by Hicheur et al (2007) although their task and setup were very diVerent from those in our study.…”

“…Courtine and Schieppati 2003;Grasso et al 1996Grasso et al , 1998Hicheur et al 2005aHicheur et al , 2007Imai et al 2001;Prévost et al 2002). The second reference is the orientation of the trunk/pelvis (Hicheur et al 2007;Solomon et al 2006). Maximum relative yaw of the head was determined relative to these references for the period between trunk turn start and trunk turn end (Fig.…”

Spontaneous whole body rotations and classical dance expertise: How shoulder–hip coordination influences supporting leg displacements

“…Indeed, the spot technique could be used only by expert dancers to stop the nystagmus vestibular reflex source of vertigo when they had to perform several turns (Tokita et al, 1972). These instructions did not modify the shoulder-hip interaction regardless the mental imagery styles because, unlike head turns, pelvic self-paced velocities were not significantly different with or without a visual target as described for a 90°step turn (Solomon et al, 2006).…”

“…Dancers displaced their supporting leg less than untrained participants. Then, at the beginning as well as at the end of a turn, the en bloc trunk would be an expert behavior performed during preferred direction or professionnal dance and would be a specific control strategy to move segments together as described for head control strategies during step turns (Solomon et al, 2006). Furthermore, Thullier and Moufti (2004) showed the ability of dancers' nervous system to integrate multiple degrees of freedom to master body balance while producing complex circular leg movements.…”

Vestibular and proprioceptive estimation of imposed rotation and spatial updating in standing subjects

“…Is rotation perception affected differently by the rotation velocity and by the duration? Considering that vestibular/proprioceptive information differs between active and passive movements, because during active rotation the head and trunk anticipate the movement [15], do the active movements influence the perception of rotation?…”