Visual control of locomotion: Strategies for changing direction and for going over obstacles.

Patla, Aftab E.; Prentice, Stephen D.; Robinson, C.; Neufeld, J.

doi:10.1037/0096-1523.17.3.603

Cited by 329 publications

(287 citation statements)

References 20 publications

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“…The onsets of these changes precede the change in walking direction. The body center of mass is displaced in the new direction of travel through appropriate foot placement (Courtine and Schieppati 2003;Patla et al 1991Patla et al , 1999Xu et al 2004). This is accompanied by turning the head in the direction of the upcoming turn.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2008

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Walking along a curved path requires coordinated motor actions of the entire body. Here, we investigate the relationship between head and trunk movements during walking. Previous studies have found that the head systematically turns into turns before the trunk does. This has been found to occur at a constant distance rather than at a constant time before a turn. We tested whether this anticipatory head behavior is spatially invariant for turns of diVerent angles. Head and trunk positions and orientations were measured while participants walked around obstacles in 45°, 90°, 135° or 180° turns. The radius of the turns was either imposed or left free. We found that the head started to turn into the direction of the turn at a constant distance before the obstacle (»1.1 m) for turn angles up to 135°. During turns, the head was consistently oriented more into the direction of the turn than the trunk. This diVerence increased for larger turning angles and reached its maximum later in the turn for larger turns. Walking speeds decreased monotonically for increasing turn angles. Imposing Wxed turn radii only aVected the point at which the trunk started to turn into a turn. Our results support the view that anticipatory head movements during turns occur in order to gather advance visual information about the trajectory and potential obstacles.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2008

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“…This pattern can adapt easily to different speeds, 15,17 inclines, [30][31] surfaces such as overground versus treadmill [32][33][34][35] and uneven surfaces. 36 The main objective of the present study was to measure how SCI subjects adapt to changes in the walking speed. Studies of hindlimb locomotion in spinalized cats [37][38][39] have shown that adaptation to increasing treadmill speed was possible, but that this adaptation was limited to a maximal speed varying between 0.8 and 1.0 m/s.…”

Section: Discussionmentioning

confidence: 99%

Treadmill walking in incomplete spinal-cord-injured subjects: 1. Adaptation to changes in speed

2003

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Walking in spinal-cord-injured (SCI) subjects is usually achieved at a lower speed than in normal subjects. Study design/methods: Time and distance parameters, angular displacements of lower limbs and electromyographic (EMG) activity were measured for seven normal and seven SCI subjects at several walking speeds. Analyses of variance were used for comparing groups and speeds. Objectives: First, to measure the adaptability of SCI subjects' walking pattern to different speeds (0.1-1.0 m/s), and to compare it to that of normal subjects. Second, to characterize SCI subjects' walking pattern as compared to that of normal subjects at a matched treadmill speed (0.3 m/s). Setting: University-Based Human Gait Laboratory, Montreal, Canada. Results: SCI subjects' pattern adapted to a limited range of speeds. Longer cycle duration, flexed knee at foot contact, increased hip joint flexion at foot contact and during swing, and altered coordination of hip and knee joints were found for the SCI group. At all speeds, duration of muscle activity was longer in the SCI group and the increase in amplitude of soleus EMG activity at higher speeds was not specific to push-off. The importance of matching the walking speed of SCI and normal subjects in order to differentiate the features that are a consequence of SCI subjects' reduced walking speed rather than a direct consequence of the injury is demonstrated. Conclusions: All SCI subjects could adapt to a narrow range of speeds and only three could reach the maximal tested speed. This limited maximal speed seems to be a consequence of SCI subjects having reached their limit in increasing stride length and not being able to increase stride frequency further. This limitation in increasing stride frequency is likely because of the altered neural drive. Sponsorship: Neuroscience Network of the Canadian Centre of Excellence.

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“…This kind of visual guidance has been examined in anterior-posterior and mediolateral directions (Lyon & Day, 1997), as well as stepping upwards over an obstacle (Patla et al, 1991). However much less is known about the control of stepping down.…”

Section: Introductionmentioning

confidence: 99%

Visual control of action in step descent

2008

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractVisual guidance of forwards, sideways, and upwards stepping has been investigated, but there is little knowledge about the visuomotor processes underlying stepping down actions. In this study we investigated the visual control of a single vertical step. We measured which aspects of the stepping down movement scaled with visual information about step height, and how this visual control varied with binocular vs monocular vision.Subjects stepped down a single step of variable and unpredictable height. Several kinematic measures were extracted including a new measure, 'kneedrop'. This describes a transition in the movement of the lower leg, which occurs at a point proportional to step height. In a within-subjects design measurements were made with either full vision, monocular vision, or no vision. Subjects scaled kneedrop relative to step height with vision, but this scaling was significantly impaired in monocular and no vision conditions.The study establishes a kinematic marker of visually controlled scaling in single-step locomotion which will allow further study of the visuomotor control processes involved in stepping down.

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Visual control of locomotion: Strategies for changing direction and for going over obstacles.

Cited by 329 publications

References 20 publications

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

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

Treadmill walking in incomplete spinal-cord-injured subjects: 1. Adaptation to changes in speed

Visual control of action in step descent

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