lecture 5 Flashcards
Difference in COP-COM are ______ correlated to the linear acceleration of COM
Negatively
What does COP Displacement reflect in terms of static posturography
Generation of stabilizing ankle torques (A-P) and lateral weight shifts (M-L)
Direction-independent amplitude changes during measures of COP/COM (stabilogram/time series)
Total sway path
areas of sway (circle, elliptical)
Direction-dependant amplitude changes during measures of COP/COM (Stabilogram/time series)
Range (ignore extremes)
standard deviation
RMS (with bias removed) = SD
Frequency domain measures of COP/COM
Mean/median power frequency
Area within certain bins
- Most power in COP lies below 0.05Hz
Slow oscillations of COM displacement usually LARGER in amplitude
True or false: COP displacement is smaller in the A-P vs M-L directions. (Winter et. al., 2005)
False, COP displacement is LARGER in the A-P vs M-L directions
COP displacements are ___ amplitude and ____ frequency than COM
Larger, higher
Why does Carpenter et. al. suggest that testing durations of COP/COM should be at least 60s be used?
Increases possibility of discovering subtle differences
Largest signals are seen in the lower frequency, which take longer to occur
What is EMG (lmao)
Electromyography
records muscle activity during posture
records amplitude, timing, co-contraction
What are balance-relevant senses?
Vision
Vestibular and hearing
Muscle spindles
skin/cutaneous receptors
Golgi tendon organs
what can visual information be used to control?
sway
sway toward target, details larger on retina
away from target, smaller details
SWAY is INCREASED IF
vision
- Vision is removed
- vision is references to sway
- distance to the visual target is too large (eg. standing on a cliff, postural vertigo)
- visual illusion
If you stand inside a moving visual scene…
you will sway with the same frequency as the moving scene
