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Obstacle crossing during locomotion: Visual exproprioceptive information is used in an online mode to update foot placement before the obstacle but not swing trajectory over it
Timmis, Matthew A.
Timmis, Matthew A.
Publication Date
2012-05, 2012-05
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© 2012 Elsevier. Full-text reproduced in accordance with the publisher’s self-archiving policy. This article is distributed under the Creative Commons CC-BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/2.0/uk/)
Peer-Reviewed
Yes
Open Access status
Accepted for publication
2012-02-13
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Additional title
Abstract
Although gaze during adaptive gait involving obstacle crossing is typically directed two or more steps
ahead, visual information of the swinging lower-limb and its relative position in the environment
(termed visual exproprioception) is available in the lower visual field (lvf). This study determined exactly
when lvf exproprioceptive information is utilised to control/update lead-limb swing trajectory during
obstacle negotiation. 12 young participants negotiated an obstacle wearing smart-glass goggles which
unpredictably occluded the lvf for certain periods during obstacle approach and crossing. Trials were also
completed with lvf occluded for the entirety of the trial. When lvf was occluded throughout, footplacement
distance and toe-clearance became significantly increased; which is consistent with previous
work that likewise used continuous lvf occlusion. Both variables were similarly affected by lvf occlusion
from instant of penultimate-step contact, but both were unaffected when lvf was occluded from instant
of final-step contact. These findings suggest that lvf (exproprioceptive) input is typically used in an
online manner to control/update final foot-placement, and that without such control, uncertainty
regarding foot placement causes toe-clearance to be increased. Also that lvf input is not normally
exploited in an online manner to update toe-clearance during crossing: which is contrary to what
previous research has suggested.
Version
Accepted manuscript
Citation
Timmis MA and Buckley JG (2012) Obstacle crossing during locomotion: Visual exproprioceptive information is used
in an online mode to update foot placement before the obstacle but not swing trajectory over it. Gait and Posture. 36(1): 160-162.
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Article