Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: 1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and 2) treadmill obstacles are visible for a shorter time compared to runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in 8 hindlimb muscles of the guinea fowl (Numida meleagris, n=6) during treadmill locomotion at two speeds (0.7ms−1 and 1.3ms−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5cm low contrast obstacles (<10% contrast, black/black), and (iii) repeated 5cm high contrast obstacles (>90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for 1) high contrast obstacles, and 2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies.
ACCEPTED MANUSCRIPT
RESEARCH ARTICLE|
01 January 2015
How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?
Joanne C. Gordon,
Joanne C. Gordon
*
Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire
, UK
*Author for correspondence: jcgordon@rvc.ac.uk
Search for other works by this author on:
Jeffery W. Rankin,
Jeffery W. Rankin
Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire
, UK
Search for other works by this author on:
Monica A. Daley
Monica A. Daley
Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire
, UK
Search for other works by this author on:
Joanne C. Gordon
*
Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire
, UK
Jeffery W. Rankin
Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire
, UK
Monica A. Daley
Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire
, UK
*Author for correspondence: jcgordon@rvc.ac.uk
Received:
23 Mar 2015
Accepted:
21 Jul 2015
Online ISSN: 1477-9145
Print ISSN: 0022-0949
© 2015. Published by The Company of Biologists Ltd
2015
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
J Exp Biol jeb.104646.
Article history
Received:
23 Mar 2015
Accepted:
21 Jul 2015
Currently Viewing Accepted Manuscript - Newer Version Available
01 Oct 2015
Citation
Joanne C. Gordon, Jeffery W. Rankin, Monica A. Daley; How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?. J Exp Biol 2015; jeb.104646. doi: https://doi.org/10.1242/jeb.104646
Download citation file: