(XXIX.) Erect posture examination using stabilometry
Physiology II - practices
Dep. of Physiology, Fac. of Medicine, MU, 2016 © Michal Pásek
Control of erect posture by central nervous system is
manifested by permanent corrections of deviations of the
body from the vertical axis, which results in changes of
gravity-opposing muscle tone.
Simplified scheme of regulation of stability
spinal cord muscle tone
(to keep upright posture)
proprioreceptors
tactile receptors
vision
vestibular system
brainstem
(motor centers)
motor cortex
cerebellum
Deviation of the body from the vertical axis and following changes
in muscle tone are manifested by changes in the moments of
supporting forces that are registered by stabilometer.
COP (centre of pressure) is an imaginary point on the ground, where the
resultant ground reaction force (opposing the resultant gravity force) is
located.
COP displacement in the statokineziogram (a) and stabilogram (b, c)
L-R displacement
axisY[mm]
axis X [mm]
P-A displacement
[mm][mm]
• Mean COP X,Y (mm): the mean value of X coordinates and mean value
of Y coordinates of all points of statokinesigram. It depends not only on
the position of the subject on stabilometer plate but also on inclination
of his/her body.
Parameters of stabilometric test
• Mean distance from the centre (mm): the average deviation of COP
position from the mean COP X, Y in left-right (X) and front-back (Y)
directions. It is proportional to size of the area determined by COP
trajectory.
• Mean velocity (mm/s): represents the average speed achieved by
moving COP. It characterizes the extent of muscular effort in maintaining
the erect posture.
• X, Y-axis movement (mm): the total length of path that the COP
followed in the left-right (X) and front-back (Y) directions. It provides
information about prevailing direction of the movement.
• Romberg’s test I: Subject’s feet are 10 cm from each other, eyes open,
and the head is straight ahead.
Stabilometric tests
• Romberg’s test II: The experimental subject puts his/her feet together,
keeps eyes open and head straight ahead.
• Romberg’s test III: The subject closes his/her eyes and keeps feet
together and head straight ahead.
• Stimulation of the Achilles tendons with vibrators: The examined
subject keeps eyes closed, feet together and head straight ahead.
• Attenuation of tactile afferentation from feet: The subject steps on the
stabilometer equipped by soft pad, puts feet together, and after a short
adaptation closes his/her eyes.
(XLI.) Estimation of Reaction Time Using Computer
Physiology II - practices
Fyziologický ústav LF MU, 2015 © Michal Pásek
sensory organ
(detection)
CNS
(processing)
muscle system
(reaction)
stimulus
reaction time
Reaction time is a time from application of stimulus
(light, acoustic, touch, etc.) till the moment of reaction of
experimental subject.
Reaction time depends on:
•modality and intensity of the stimulus,
•complexity of task (different reaction on different stimulus),
•motivation, attention, fatigue and experience of the subject.
Tests or reaction time
• Visual and acoustic stimuli: The test consists of repeated random presentation of
visual (asterisk in the centre of the screen) and acoustic (simple sound of 1 kHz)
stimuli. The examined person responds to every stimulus by pressing ENTER on the
keyboard.
• Visual stimuli: The reaction to repeated random presentation of visual stimuli.
• Acoustic stimuli: The reaction to repeated random presentation of acoustic stimuli.
• Go/NoGo centre: The test consists of repeated random presentation of two different
visual stimuli (asterisk and symbol of dollar). Every stimulus is presented in the centre
of the screen. The examined person responds to every asterisk by pressing ENTER on
the keyboard. The symbol of dollar should be ignored.
• Go/NoGo periphery: The test consists of repeated random presentation of two
different visual stimuli (asterisk and symbol of dollar). Each stimulus is presented
anywhere on the screen. The examined person responds to every asterisk by pressing
ENTER on the keyboard. The symbol of dollar should be ignored.
Source of figures
Slide 2 – Physiology and neuroscience practicals, Masaryk University 2011