Visual Feedforward Control in Human Locomotion During Avoidance of Obstacles that Change Size

Santos, Luiz; Moraes, Renato; Patla, Aftab E.

doi:10.1123/mcj.14.4.424

Cited by 10 publications

(7 citation statements)

References 15 publications

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“…This ability to use visual information for trailing limb control has already been suggested for a static obstacle avoidance situation when vision was manipulated during planning and approach [6]. In addition, Santos et al [11] showed this in a more dynamic situation for changing obstacle heights at a trailing limb foot contact (similar timing to T1 in the present study). However, previous studies involved only modifying an already planned trailing limb strategy.…”

Section: Discussionsupporting

confidence: 86%

“…This further supports independent control between limbs [6,8,12]. It appears that the previously suggested feedforward influence of leading limb function on trailing limb control [11] is thus context specific and likely only true when both limbs perform the same ALA (i.e., both stepping over an obstacle).…”

Section: Discussionsupporting

confidence: 70%

“…However, Santos et al [11] suggested that the hypothesis of independence between leading and trailing limbs could have been observed because of the predictability of the static environments used. By changing obstacle dimension one step before clearance, the authors showed that the trailing limb can use visual information from the leading limb's obstacle crossing.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Switching of Trailing Limb Anticipatory Locomotor Adjustments is Uninfluenced by what the Leading Limb Does, but General Time Constraints Remain

Fiset

McFadyen

2020

Applied Sciences

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Research shows a blend of bilateral influence and independence between leading and trailing limbs during obstacle avoidance. Recent research also shows time constraints in switching leading limb strategies. The present study aimed to understand the ability to switch anticipatory locomotor adjustments (ALAs) in the trailing limb. Ten healthy young adults (24 ± 3 years) were immersed in a virtual environment requiring them to plan and step over an obstacle that, for the trailing limb, could change to a platform, requiring a switch in locomotor strategies to become a leading limb to step onto a new surface. Such perturbations were provoked at either late planning or early execution of the initial trailing limb obstacle avoidance. Sagittal plane trailing limb kinematics, joint kinetics and energetics were measured along with electromyographic activity of key lower limb muscles. Repeated measures ANOVAs compared dependent variables across conditions. To adjust to the new environment, knee flexor power around toe-off decreased (p < 0.001) and hip flexor power increased (p < 0.001) for late planning phase perturbations, while there was only an increase in mid-swing hip flexor power (p < 0.05) during perturbations at execution. Findings showed no influence of the leading limb function on the ability to switch trailing limb ALAs during late planning. However, the trailing limb was also constrained for modifying ALAs once execution began, but on-going limb control strategies could be exploited in a reactive mode.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Switching of Trailing Limb Anticipatory Locomotor Adjustments is Uninfluenced by what the Leading Limb Does, but General Time Constraints Remain

Fiset

McFadyen

2020

Applied Sciences

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“…No changes in foot placement were observed, suggesting that the position cue provided salient online information to guide foot placement. This finding agrees with previous research that reported that humans control the obstacle crossing task guiding the leading limb on a feedforward manner using visual information (Moraes, Lewis, & Patla, 2004;Santos, Moraes, & Patla, 2010).…”

Section: Research Articlesupporting

confidence: 93%

Obstacle Crossing Differences Between Blind and Blindfolded Subjects After Haptic Exploration

Forner-Cordero

Garcia

Rodrigues

et al. 2016

Journal of Motor Behavior

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Little is known about the ability of blind people to cross obstacles after they have explored haptically their size and position. Long-term absence of vision may affect spatial cognition in the blind while their extensive experience with the use of haptic information for guidance may lead to compensation strategies. Seven blind and 7 sighted participants (with vision available and blindfolded) walked along a flat pathway and crossed an obstacle after a haptic exploration. Blind and blindfolded subjects used different strategies to cross the obstacle. After the first 20 trials the blindfolded subjects reduced the distance between the foot and the obstacle at the toe-off instant, while the blind behaved as the subjects with full vision. Blind and blindfolded participants showed larger foot clearance than participants with vision. At foot landing the hip was more behind the foot in the blindfolded condition, while there were no differences between the blind and the vision conditions. For several parameters of the obstacle crossing task, blind people were more similar to subjects with full vision indicating that the blind subjects were able to compensate for the lack of vision.

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“…In numerous studies a large variety of configurations of obstacles, their locations, and timings of their presentation during walking on walkways and treadmill belts have been used to analyze how humans avoid obstacles (Bauby and Kuo 2000;Berard and Vallis 2006;Chen et al 1991Chen et al , 1994Chou et al 2001;Mohagheghi et al 2004;Moraes et al 2004Moraes et al , 2007Owings and Grabiner 2004;Patla et al 1989Patla et al , 1999Patla and Rietdyk 1993;Santos et al 2010;Warren et al 1986;Weerdesteyn et al 2005;Zijlstra et al 1995). These studies showed that humans adapt their strategies for avoiding obstacles according to the context of the experimental task.…”

mentioning

confidence: 99%

Strategies for obstacle avoidance during walking in the cat

Chu

Seto

Beloozerova

et al. 2017

Journal of Neurophysiology

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Avoiding obstacles is essential for successful navigation through complex environments. This study aimed to clarify what strategies are used by a typical quadruped, the cat, to avoid obstacles during walking. Four cats walked along a corridor 2.5 m long and 25 or 15 cm wide. Obstacles, small round objects 2.5 cm in diameter and 1 cm in height, were placed on the floor in various locations. Movements of the paw were recorded with a motion capture and analysis system (Visualeyez, PTI). During walking in the wide corridor, cats' preferred strategy for avoiding a single obstacle was circumvention, during which the stride direction changed while stride duration and swing-to-stride duration ratio were preserved. Another strategy, stepping over the obstacle, was used during walking in the narrow corridor, when lateral deviations of walking trajectory were restricted. Stepping over the obstacle involved changes in two consecutive strides. The stride preceding the obstacle was shortened, and swing-to-stride ratio was reduced. The obstacle was negotiated in the next stride of increased height and normal duration and swing-to-stride ratio. During walking on a surface with multiple obstacles, both strategies were used. To avoid contact with the obstacle, cats placed the paw away from the object at a distance roughly equal to the diameter of the paw. During obstacle avoidance cats prefer to alter muscle activities without altering the locomotor rhythm. We hypothesize that a choice of the strategy for obstacle avoidance is determined by minimizing the complexity of neuro-motor processes required to achieve the behavioral goal. In a study of feline locomotor behavior we found that the preferred strategy to avoid a small obstacle is circumvention. During circumvention, stride direction changes but length and temporal structure are preserved. Another strategy, stepping over the obstacle, is used in narrow walkways. During overstepping, two strides adjust. A stride preceding the obstacle decreases in length and duration. The following stride negotiating the obstacle increases in height while retaining normal temporal structure and nearly normal length.

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Visual Feedforward Control in Human Locomotion During Avoidance of Obstacles that Change Size

Cited by 10 publications

References 15 publications

The Switching of Trailing Limb Anticipatory Locomotor Adjustments is Uninfluenced by what the Leading Limb Does, but General Time Constraints Remain

The Switching of Trailing Limb Anticipatory Locomotor Adjustments is Uninfluenced by what the Leading Limb Does, but General Time Constraints Remain

Obstacle Crossing Differences Between Blind and Blindfolded Subjects After Haptic Exploration

Strategies for obstacle avoidance during walking in the cat

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