[Abstract Title]. - Society for Neuroscience

data of the head and whole body were recorded using a 12-camera Vicon motion capture system.
Movements of the head were tracked in real-time via three markers placed on the HMD. Head
position data was computed and fed to the CAREN-2 (MOTEK) system, allowing for real-time
movements of the head to be synchronized and displayed in the HMD. Subjects were instructed
to either use optic flow information and walk straight with respect to the scene in the HMD
(virtual environment: VE) or ignore visual information and walk straight with respect to the
physical environment (PE). For both conditions, the flow could either be presented as rotational
(FOE rotated along the anterioposterior axis) or translational (FOE shifted linearly with respect
to the subject). For each type of flow presented, the FOE could be displaced by either 0°, 40° to
the left, or 40° to the right. Results showed that participants kept their head aligned with the
desired heading direction. When asked to walk straight with respect to the PE, the head was
aligned with the physical neutral direction and the centre of mass (CoM) showed little
mediolateral deviations in the PE. When asked to walk straight with respect to the VE, the head
was aligned towards the virtual neutral and CoM showed small deviations in the VE. However,
the strategy to maintain a straight heading differed between rotational and translational flows.
With a rotational flow, subjects reoriented their body by rotating their head and trunk in the yaw
direction. In contrast, with translational flows, reorientation was achieved using a side-stepping
strategy. This study suggests that the head is consistently aligned with the heading direction, that
locomotor reorienting strategies are specific to the type of optic flow presented and that healthy
young individuals have the ability to reweight sensory information in a task-dependent manner.
Disclosures: J.R. Berard , Canadiant Institutes of Health Research, B. Research Grant
(principal investigator, collaborator or consultant and pending grants as well as grants already
received); Heart and Stroke Foundation of Canada, B. Research Grant (principal investigator,
collaborator or consultant and pending grants as well as grants already received); J. Fung,
Canadian Institutes of Health Research, B. Research Grant (principal investigator, collaborator or
consultant and pending grants as well as grants already received); Heart and Stroke Foundation,
B. Research Grant (principal investigator, collaborator or consultant and pending grants as well
as grants already received); A. Lamontagne, Canadian Institutes of Health Research, B.
Research Grant (principal investigator, collaborator or consultant and pending grants as well as
grants already received); Heart and Stroke Foundation, B. Research Grant (principal investigator,
collaborator or consultant and pending grants as well as grants already received).
Poster
275. Posture: Kinematics and Muscle Activity
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 275.16/JJ31
Topic: D.16.d. Kinematics and Muscle Activity