Sensory Contributions Balance/Posture 24 Flashcards
Difference between balance and posture?
Balance is point of equilibrium the CNS is trying to maintain
- posture is more the “how”
Reasons why we study balance and posture?
Injury prevention
Old people falling
Etc
3 major sensory systems that contribute to posture and balance ?
Visual - interpret environment at a distance
Vestibular - accelerations of head in space and head relative to body
Somatosensory - Proprioception (exocentric - outside of body) and relative body segment orientation (egocentric - inside of body)
Difference between exocentric and egocentric somatosensory information?
Exocentric - outside of the body (Proprioception)
Egocentric - inside of the body (relative body segment orientation)
Examples of experimental techniques to test the 3 major sensory systems?
Vision - closed eyes increases sway, virtual reality for what visual cues cause what response
Vestibular - galvanic stimulation behind ears, tilt table
Somatosensory - augment vibration, ice/anesthetic
Somatosensory feedback involves information from?
Spindles
GTOs
Skin receptors - slip/stretch
Joint receptors
3 ways Ian Waterman changed his dynamic posture to be able to walk? (During gate)
Stiffened muscles/joints to reduce degrees of freedom
Wider base of support
Tilt head forward to visually monitor body orientation
Deafferented subjects provide support against what balance model?
Inverted pendulum model - stiffness control of balance
- model suggests no use of sensory information because there isn’t enough time to process time for reactions
Ian waterman exception to this - shows we are complicated system
Def. Visual gaze
Movement of our eyes as we fixate on one object to another
Def. Saccades
Quick active movements connecting fixations
Related to visual gaze
Def. Optic flow
The pattern of visual motion at the eye
Def. Visual flow
Rate of optic flow
Optic flow = the pattern of visual motion at the eye
Visual feedback provides: (3)
- Information about the environment at a distance
- Helps to determine the speed of locomotion (visual flow)
- Provides postural and movement information about the body segments relative to each other and the environment
Older adults rely more heavily on visual feedback
How vision info is used during obstacle avoidance ?
Do not need continuous info
Successful clearance requires accurate placement and movement of feet
Obsticle fixation highest 1-2 steps before obstacle
Visual info within step n-2 sufficient
What is vestibular feedback?
Provides linear and angular head accelerations
