Unintentional modulations of human gait by optical flow

Pailhous, Jean; Ferrandez, Anne-Marie; Flückiger, Michelangelo; Baumberger, Bernard

doi:10.1016/0166-4328(90)90181-d

Cited by 84 publications

(58 citation statements)

References 14 publications

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“…The monkeys blink during head yaw rotations in both treadmill walks and gallops. Blinks temporarily eliminate optic flow input, the presence of which in humans is known to have an impact on postural maintenance (Bronstein and Buckwell, 1997;Dietz et al, 1994;Gielen and van Asten, 1990;Stoffregen, 1985;Wolsley et al, 1996) and locomotor heading (Bardy et al, 1996;Pailhous et al, 1990;Patla and Vickers, 2003;Prokop et al, 1997;Schubert et al, 2003;Warren and Kay, 1997;Warren et al, 2001). Changes in optic flow rate induced by head and eye rotations elicit lateral body sway, especially when optic flow is artificially increased by 2-4 times the normally experienced flow rate to create an incongruity with somatosensory inputs (Schubert et al, 2003).…”

Section: Blinks and Optic Flowmentioning

confidence: 99%

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

Dunbar

2004

Journal of Experimental Biology

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The brain requires internal or external reference frames to determine body orientation in space. These frames may change, however, to meet changing conditions. During quadrupedal overground locomotion by monkeys, the head rotates on a stabilized trunk during walking, but the trunk rotates on a stabilized head during galloping. Do the same movement patterns occur during in-place locomotion? Head and trunk pitch rotations were measured, and yaw and roll rotations estimated from cine films of three adult vervet monkeys (Cercopithecus aethiops L. 1758) walking and galloping quadrupedally on a treadmill. Head and trunk rotational patterns during treadmill walks were comparable to the patterns found during overground walks. The rotational velocities of these segments during both treadmill walks and gallops were also comparable to the velocities found during natural locomotion. By contrast, whereas head and trunk rotational patterns during treadmill gallops did occur that were comparable to the patterns practiced during overground gallops, a significantly different pattern involving large and simultaneous head and trunk rotations was more commonly observed. Simultaneous head and trunk rotations may be possible during treadmill gallops because the fixed visual surround is providing an adequate spatial reference frame. Alternatively, or in addition to this visual information, a re-weighting in other sensory modalities may be occurring. Specifically, the vestibular inputs used during overground locomotion to reference gravity or a gravity-derived vector may become less important than proprioceptive inputs that are using the treadmill belt surface as a reference. Regardless, the spatial reference frame being used, blinks that occur at specific times during the largest head yaw rotations may be necessary to avoid the initiation of unwanted and potentially destabilizing lateral sway brought on by sudden increases in optic flow velocity.

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Section: Blinks and Optic Flowmentioning

confidence: 99%

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

Dunbar

2004

Journal of Experimental Biology

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“…Our first experiment on locomotion in our texture flow generator (see Method, below, and Flückiger & Baumberger, 1988) examined which modifications in gait parameters can be observed in subjects actively walking in an approaching optical flow (Pailhous, Ferrandez, Flückiger, & Baumberger, 1990). This experiment, carried out with adult subjects, showed that the directional information of the optical flow actually induces modifications in the velocity of locomotion, as walkers slow down in an approaching optical flow.…”

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confidence: 99%

Walking in an environment of moving ground texture

2000

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The visual control of global body movements has mainly been studied in terms of the maintenance of balance. The present experiment examined the effect of moving visual surroundings on the speed of locomotion. A virtually boundless optical environment was generated by the projection of a dotted texture on the ground that was reflected on large vertical mirrors fixed along the walls of the room. Subjects' head velocity was recorded over a walking path of about 10 m along the projection surface. In the experimental sessions, the texture was animated and moved at different speeds in the same direction as the subject or in the opposite direction. In the control condition, the projected texture remained motionless and therefore appeared to pass by at the subjects' walking speed. The subjects' task was to maintain a constant walking speed as far as possible over the different conditions. Changes in walking speed give indications of how the processing of optical flow modulates locomotor activity.

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“…Given Pailhous et al [10], the subject maintained consistent step patterns through the small standard deviations of their step lengths (about 0.04 m on average). But according to Lee et al [7] in the long jumping task and Cornus et al [4] in the stepping across task, the standard deviation of step lengths increased during the last steps.…”

Section: Standard Deviation (M)mentioning

confidence: 68%

Perception of a Stepping-across Affordance when Approaching an Obstacle

Cornus

2011

BIO Web of Conferences

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Affordances are behavior opportunities that delineate a phase transition beyond which a change in behavior requiring muscular reorganization. In the stepping across task, this muscular reorganization enables subjects to put the tip of the shoe as close as possible to the obstacle. But subjects modify step lengths when approaching an obstacle to secure these adequate foot placements. What is the relationship between the perception of the phase transition and the modification of step lengths?This experiment consisted of two different tasks. The first involved subjects physically stepping across an obstacle, the second involved subjects judging the step-acrossability of an obstacle when moving towards the given obstacle. The results showed that subjects seemed to perceive the step-acrossability of the obstacle before the initiation of regulation.

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Unintentional modulations of human gait by optical flow

Cited by 84 publications

References 14 publications

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

Walking in an environment of moving ground texture

Perception of a Stepping-across Affordance when Approaching an Obstacle

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