Aging and saccade-stepping interactions in humans

Fabio, Richard P. Di; Zampieri, Cris; Greany, John

doi:10.1016/s0304-3940(03)00032-6

Cited by 43 publications

(43 citation statements)

References 19 publications

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“…3 It is also possible that the CNS uses eye movements toward the anticipated landing site to 4 help guide the foot trajectory and step placement, during the execution of the stepping reaction. 5 This would be consistent with findings from studies of targeted volitional stepping movements, 6 which suggest that a saccade toward the step target is used to guide feedforward control of the 7 foot movement (Hollands and Marple-Horvat, 2001; Di Fabio et al, 2003). Interestingly, the 8 timing of this saccade, which typically occurred prior to foot-off during these self-initiated 9 volitional movements (Hollands et al, 1995;Hollands and Marple-Horvat, 1996), appears to be 10 similar to the timing at which we have observed an apparent switching of attention during rapid 11 stepping reactions that are triggered by postural perturbation (Maki et al, 2001a).…”

supporting

confidence: 76%

“…The findings also indicate that the apparent switching of attention that follows onset of 11 postural perturbation is not related to redirection of gaze. Evidence of attention switching (i.e.…”

mentioning

confidence: 68%

“…error (|m-l distance| from great toe to target tape) improved by 2cm when downward gaze shift 11 did occur (21±20mm versus 41±39mm). "Practice" appeared to lead to some small improvements 12 in ability to land on the target.…”

mentioning

confidence: 98%

“…limited to six subjects, who each looked down in four or more of the twelve step-target trials. Of 10 the remaining subjects, four looked down in only one of these trials and two did not look down at 11 all. There was no evidence of substantive changes in gaze behavior due to increasing familiarity 12 or "practice" effects: subjects were equally likely to look downward in their first three trials 13 involving the step target as in their last three step-target trials (in each case: 12 of 36 trials).…”

mentioning

confidence: 99%

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Redirection of gaze and switching of attention during rapid stepping reactions evoked by unpredictable postural perturbation

et al. 2005

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1In many situations, successful execution of a balance-recovery reaction requires visual 2 information about the environment. In particular, reactions that involve rapid limb movements, 3 such as stepping, must be controlled to avoid obstacles and accommodate other constraints on 4 limb trajectory. However, it is unknown whether the CNS can acquire the necessary visuospatial 5 information prior to perturbation onset, or must instead redirect gaze at the floor during the 6 execution of the stepping reaction. To study this, we examined gaze behavior during rapid 7 forward-directed stepping reactions triggered by unpredictable platform perturbation, in 12 8 healthy young adults. We also monitored switching of attention, as inferred from onset of 9 significant error in performing a concurrent visuomotor tracking task. Obstacles and/or step 10 targets were used as constraints, to increase demands for accurate foot movement. Downward 11 gaze shifts toward the floor almost never occurred during stepping reactions when foot motion 12 was unconstrained, but did occur more frequently as the demands for accurate foot movement

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supporting

confidence: 76%

mentioning

confidence: 68%

mentioning

confidence: 98%

mentioning

confidence: 99%

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Redirection of gaze and switching of attention during rapid stepping reactions evoked by unpredictable postural perturbation

et al. 2005

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“…Di Fabio et al (2003b) argue stepping movements use this visual anchoring behavior, proposed by Johansson et al (2001) for object manipulation, and hence saccadic eye movements are linked to stepping. Studies on obstacle avoidance suggest that visual input is utilized during the approach phase, which is evident from visual Wxations directed to the obstacle (Patla and Vickers 1997) or downward saccades made to an area behind the obstacle following a cue as to which limb to initiate the step over the obstacle (Di Fabio et al 2003a).…”

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

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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.

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Saccade to stepping delays in elders at high risk for falling

Greany

Fabio

2008

Aging Clin Exp Res

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The timing of saccades and precise foot placement in older persons living in the community are associated with fall risk status and cognitive status. The prolonged time for saccade-footlift in H-R elderly may be attributed to greater central nervous system processing time necessary to plan precise foot placements or volitional processing delays in postural control due to fall risk status. In addition, age related changes in cognitive functions appear to be associated with saccade stepping interaction when performing a visually guided stepping pattern and may influence the ability to coordinate precise lower extremity movements.

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Aging and saccade-stepping interactions in humans

Cited by 43 publications

References 19 publications

Redirection of gaze and switching of attention during rapid stepping reactions evoked by unpredictable postural perturbation

Redirection of gaze and switching of attention during rapid stepping reactions evoked by unpredictable postural perturbation

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

Saccade to stepping delays in elders at high risk for falling

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