Rapid visuo-motor processes drive the leg regardless of balance constraints

Reynolds, Raymond F.; Day, Brian L.

doi:10.1016/j.cub.2004.12.051

Cited by 77 publications

(98 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To our knowledge, the only other study of double-step perturbations during stance investigated differences in reaction time or MT with the likelihood of a double-step perturbation (Martin et al 2000). Other recent studies have investigated online corrections of the foot during walking or a single step (Reynolds and Day 2005b;2005a). The foot online correction onset has been reported to be between 239 and 402 ms after the foot off the ground for a step (Reynolds and Day 2005a), whereas during swing phase of locomotion the foot online correction onset has been reported to be more similar to that for the arm, 114 -151 ms (Reynolds and Day 2005b).…”

Section: Discussionmentioning

confidence: 99%

“…Other recent studies have investigated online corrections of the foot during walking or a single step (Reynolds and Day 2005b;2005a). The foot online correction onset has been reported to be between 239 and 402 ms after the foot off the ground for a step (Reynolds and Day 2005a), whereas during swing phase of locomotion the foot online correction onset has been reported to be more similar to that for the arm, 114 -151 ms (Reynolds and Day 2005b). This suggests that the delayed onset of foot online correction during a step and, possibly, the delayed onsets of online correction observed in this study are attributable to the increased information processing of equilibrium constraints, which may be simplified during a predictive shift of CoM thought to occur during locomotion (Day et al 1997).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Postural adjustments for online corrections of arm movements in standing humans

Leonard

Gritsenko

Ouckama

et al. 2011

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Postural adjustments for online corrections of arm movements in standing humans

Leonard

Gritsenko

Ouckama

et al. 2011

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…The appropriate execution of stepping adjustments (either to acquire a shifted target or to avoid an obstacle) depends on adjustments in the stance leg as well as the stepping leg. 8 The resulting bilateral muscle activation pattern probably engages both hemispheres. Any disruption of the coupled activity of the 2 hemispheres might therefore result in reduced accuracy for either leg.…”

Section: Foot Placement Errormentioning

confidence: 99%

Deficits Underlying Impaired Visually Triggered Step Adjustments in Mildly Affected Stroke Patients

Nonnekes

Talelli²,

Niet

et al. 2009

Neurorehabil Neural Repair

View full text Add to dashboard Cite

Background. The ability to make step adjustments while walking is often impaired following a stroke, but the basic sensorimotor control deficits responsible have not been established. Objective. To identify these deficits in Patients who have recovered from stroke leaving only mild lower limb impairment. Methods. Ten stroke and 10 age-matched control patients stepped onto an illuminated rectangle. In 40% of trials it jumped 140 mm either medially or laterally when the stepping foot left the ground, thus provoking a mid-step adjustment. In a separate block, patients performed the same task but with the body supported by a frame to eliminate balance responses. Results. Irrespective of support condition stroke patients produced short-latency foot trajectory adjustments compatible with a fast-acting, possibly subcortical, visuomotor process. However, the latency was slightly but significantly longer for the contralesional leg (148 ms) than the ipsilesional leg (141 ms) and longer than for controls (129 ms). Stroke patients' foot adjustments were executed slower and undershot the target more than controls. These deficits were most pronounced in the medial direction when the body was unsupported. The pattern of undershooting was the same for ipsilesional and contralesional legs. Conclusions. Mildly impaired stroke patients have deficits in initiating and executing visually triggered step adjustments but more profound difficulties with balance control during the adjustment, which caused them to suppress mid-step adjustments of foot placement in the medial direction where balance demands were greatest. Paradoxically, such suppression outside the laboratory may also threaten balance if it leads to unsafe foot placement or obstacle collision.

show abstract

“…The visuo-motor processing delay between the visual stimulus and the motor response (as reXected in the onset of the ipsilateral biceps femoris muscle) in our task was approximately 130 ms, which closely resembles that of other studies. For example, the processing delay for pointing movements ranges from approximately 114 to 201 ms (change in kinematics; Day and Lyon 2000;Whitney et al 2003) and from 100 to 120 ms for stepping movements (change in kinematics, onset of muscle activity, and foot acceleration, respectively; Patla et al 1991;Reynolds and Day 2005a;Weerdesteyn et al 2004). …”

Section: Bfimentioning

confidence: 99%

“…Behaviorally, obstacle avoidance reactions to a suddenly appearing obstacle during locomotion on a treadmill elicit rapid responses of approximately 120 ms as reXected in changes in foot acceleration proWles (Weerdesteyn et al 2004). In addition, recent experiments on a stepping task where the step target is displaced on toe-oV suggest that the nervous system can rapidly alter lower limb trajectory in response to a visual stimulus without sacriWcing balance (Reynolds and Day 2005a) and online monitoring of the limb is important for accurate foot placement (Reynolds and Day 2005b).…”

Section: Introductionmentioning

confidence: 99%

Keep looking ahead? Re-direction of visual fixation does not always occur during an unpredictable obstacle avoidance task

et al. 2006

View full text Add to dashboard Cite

Visual information about the environment, especially Wxation of key objects such as obstacles, is critical for safe locomotion. However, in unpredictable situations where an obstacle suddenly appears it is not known whether central vision of the obstacle and/or landing area is required or if peripheral vision is suYcient. We examined whether there is a re-direction of visual Wxation from an object Wxated ahead to a suddenly appearing obstacle during treadmill walking. Furthermore, we investigated the temporal relationship between the onset of muscle activity to avoid the obstacle and saccadic eye and head movements to shift Wxation. Eight females (mean § SD; age = 24.8 § 2.3 years) participated in this experiment. There were two visual conditions: a central vision condition where participants Wxated on two obstacles attached to a bridge on the treadmill and a peripheral vision condition where participants Wxated an object two steps ahead. There were two obstacle release conditions: only an obstacle in front of the left foot was released or an obstacle in front of either foot could be released. Only trials when the obstacle was released in front of the left foot were analyzed such that the diVerence in the two obstacle conditions was whether there was a choice of which foot to step over the obstacle. Obstacles were released randomly in one of three phases during the step cycle corresponding to available response times between 219 and 462 ms. We monitored eye and head movements along with muscle activity and spatial foot parameters. Performance on the task was not diVerent between vision conditions. The results indicated that saccades are rarely made (< 18% of trials) and, when present, are initiated » 350 ms after muscle activity for limb elevation, often accompanied by a downward head movement, and always directed to the landing area. Therefore, peripheral vision of a suddenly appearing obstacle in the travel path is suYcient for successful obstacle avoidance during locomotion: visual Wxation is generally not re-directed to either the obstacle or landing area.

show abstract

Rapid visuo-motor processes drive the leg regardless of balance constraints

Cited by 77 publications

References 9 publications

Postural adjustments for online corrections of arm movements in standing humans

Postural adjustments for online corrections of arm movements in standing humans

Deficits Underlying Impaired Visually Triggered Step Adjustments in Mildly Affected Stroke Patients

Keep looking ahead? Re-direction of visual fixation does not always occur during an unpredictable obstacle avoidance task

Contact Info

Product

Resources

About