Horizontal and Vertical Eye Deviations
in Response to Linear Accelerations
by
Brenda Joyce Kitchen
Subikitted in Partial Fulfillment
of the Requirements for the
Degree of Bachelor of Science
at the
Mas sachusetts Institute of Technolo gy
May, 1983
Signature of Author.
Department of Electrical Engineering, Date
Certified by...
Thesis Supervisor
Certified by..-
.....
S.,...p...................
Thesis Supervisor
Accepted by.....................................................
Chairman, Departmental Committee on Theses
ABSTRACT
Horizontal and Vertical Eye Deviations
in Response to Linear Accelerations
Author:
Brenda Joyce Kitchen
Thesis Supervisors:
Dr. Charles M. Oman
Senior Research Engineer
Mr. Anthony P. Arrott
Ph.D. Candidate
Department of Aeronautics and Astronautics
In order to determine the effects of periodic, whole body, linear
accelerations on compensatory eye movements a series of experiments were
mounted linear acceleration
performed on 23 normal subjects using a rail
sled. Sub ects were accelerated sinusoidally at amplitudes between 0.06g
(60 cm/s ) and 0.9g (900 cm/s 2 ) at frequencies ranging from 0.1 Hz to
with respect to the
0.8 Hz. Subjects were tested in two orientations
direction of motion and the direction of gravity: i) Y-Z: lateral
longitudinal
Z-I:
acceleration in the upright position; and ii)
Eye movements were recorded using
acceleration in the supine position.
standard electro-oculography. Horizontal eye movements were recorded
for the Y-Z orientation and vertical eye movements were recorded for the
Z-X orientation.
All subjects from whom measurements were obtained showed consistent
evidence of horizontal compensatory eye movements in the Y-Z
orientation. Only two subjects exhibited distinct vertical compensatory
Vestibular nystagmus similar to that elicited by head
eye movements.
Lighting
rotation was observed under conditions of complete darkness.
conditions were significant in that even very dim, diffuse light caused
the distinctly nystagmic response of total darkness to be transformed
into lower amplitude smooth eye movements with few or no saccades.
Significant compensatory eye movements were obtained only for
Slow phase eye velocity was
stimulus amplitudes of 0.2g or greater.
by a sinusoid of the same
and fit
filtering
determined by digitial
frequency as the stimulus. The amplitude of slow phase eye velocity
The sensitivity was
appears to be linear with respect to acceleration.
determined to be 9.8 deg/sec/g for motion between 0.2g and 0.9g at 0.4
Hz.
The amplitude was found to increase with frequency over the range
0.28 Hz to 0.8 Hz. Phase tends to increasingly lag the stimulus motion
over this same range.
2
ACKNOWLEDGEMENTS
I would like to thank everyone
helped me with this thesis.
in the Man Vehicle Lab who has
A special thanks goes to my thesis supervisors, Dr. Charles M.
and Mr. Anthony P. Arrott, for their invaluable assistance.
Oman
An additional thanks to Anthony Arrott for his continuous guidance
and encouragement.
Without his help and support, this thesis would not
have been such a great learning experience.
A big thanks to Robert "MONTY"
Grimes,
for everything...
I would like to thank Mohammed Massoumnia, Bob Renshaw, and Joyce
Lee their valuable help. Also, thanks to Sherry Modestino and Margaret
Amour for helping with the final document.
I am very grateful to all
of the subjects who gave so freely of
their time and patience.
Without their cooperation this thesis would
not have been possible.
A very special thanks to my family for the enormous amount of
support, encouragement and love they have given me.
Without them I
could never made it through the "Institute," let alone this thesis.
3
TABLE OF CONTENTS
2
ABSTRACT .......................................
ACKNOWLEDGE14ENTS................................3
TABLE OF CONTENTS.............................................4
LIST OF FIGURES . ............................
5
LIST OF TABLES.................. ...........................
6
INTRODUCTION..................................7
BACKGROUND.........
0.8
..
Physiology....
. .8
Eye Movements.
Recording Eye Movements.
Vestibular Nomenclature.
Past Experimentation....
.12
.14
.14
.18
METHODS.....................
Equipment..............
.21
.21
.21
.24
.24
.25
.25
..
MIT Sled Facility.
Helmet............
EOG Amplifier.....
Light Array.......
Description of the Expe
.iments....
RESULTS..*...o..oo................
Preliminary Experiments...........
Protocol I........................
Protocol II.....................
Protocol III (Spacelab Crew Tests)
..a.
..
..
.
..
.
..........o S....
..
..
..
..
..
..
..
..
.. 41
DISCUSSION.............................
SUtmARY.................... .
0
.
30
30
30
32
34
45
................
SUGGESTIONS FOR FURTHER RESEARCH.............................46
BIBLIOGRAPHY....................................47
..
..
..
..
APPENDICES............................
A: Detailed Protocols............
B: Electrode Study...............
C: Individual Test Results.......
4
...
...
...
...
...
...
...
...
..
..
..
..
...
...
...
...
..
..
..
..
..
..
..
..
..... 49
..... 49
..... 54
...... 63
LIST OF FIGURES
-
*.........9
Figure 1:
The Ear................................
Figure 2:
Vestibular Apparatus................
Figure 3:
Otolith Macculae.......................
Figure 4:
Hixson Vestibular Nomenclature.........
16
Figure 5:
Sled Motion Nomenclature...............
.........17
Figure 6:
The M.I.T. Sled........................
22
Figure 7:
Example of Nystagmus Induced by Linear 0scillation
From Protocol I. ........
10
31
.....
Figure 8:
Example of Nystagmus From Protocol II..
33
Figure 9:
Example of'Smooth Response.............
35
Figure 10: Example of Z-X No Response.............
Figure 11:
Example of Z-X Smooth Response.........
37
Figure 12:
Bode Plot, Gain vs. Frequency..........
39
FIgure 13:
Linearity Plot, Protocol III...........
FIgure 14: Polar Plot,
Comparison of Niven,
40
Protocol 1, and
Protocol III.................... ............
5
.......
......
43
LIST OF TABLES
Table 1:
Protocol I
Table 2:
Protocol II
Table 3:
Protocol III
6
INTRODUCTION
The
objective
of
this
thesis
on
acceleration
periodic
linear
analyzing
these effects
it
is
to
determine
compensatory
the
eye
effects
of
By
movements.
that a better understanding of the
is hoped
otolith-ocular reflex can be gained.
There has been a great deal of experimental work done to determine
the role of
the semicircular
canals
in producing
compensatory
eye
movements.
However there is not much data on the behavior and role of
the otolith
organs.
contradictory.
nystagmus
Much of the evidence
Niven,
Hixson,
axis.
and Correia (1966)
could regularly be elicited,
nystagmus were found.
In parallel
cited in the literature
All of their
swing tests,
found that horizontal
while no
tests
signs of vertical
were conducted along the y-
Bles and Kapteyn (1973)
horizontal and vertical eye movements.
is
Thus,
found
both
one of the main purposes
of this thesis is to take a closer look at the response
of the otoliths.
The research contained in this thesis is part of a battery of tests
which are being conducted for NASA as
experiments.
understanding
weightlessness
The
of
and
part of the
aim of this series of tests
the
learn
adaptation
how space
of
the
1NS102 Spacelab
is
to
gain a better
vestibular
motion sickness
1
system
to
is related to this
adaptation.
The central aim of this thesis is to determine a set of conditions
under
be
which consistant manifestations
obtained.
From
this
an
of
indicator
obtained which can be used to moniter
the otolith-ocular
of otolith
reflex
function
might
be
the process of adaptation to
weightlessness and subsequent re-adaptation to the earth's Ig bias.
7
can
BACKGROUND
Physiology
The vestibular system, located
consists of two specialized
otoliths
(figure 1).
This
in the non-auditory inner ear,
portions,
the
semicircular
system has three
major
canals
functions.
is responsible for a great deal of the information we use
spatial orientation as well as sensation of motion.
stabilization
of the visual field
First
the
it
to determine
Secondly, the
canals and otoliths are very influential in the maintenance
Finally,
and
of posture.
is also controlled by the
vestibular system.
The semicircular canals are fluid-filled ducts which act as angular
accelerometers
(figure
2).
They
are
stimulated
by
angular
accelerations of the head normal to the plane of the given ring.
frequencies
between 0.1
Hz
and
5 Hz
Thus perception of rotation
velocity.
the
canals
transduce
For
angular
and stabilization of the visual
field on the retina are based on the interpretation of the canal signals
as representations of angular velocity.
relatively insensitive
The
utricular
The semicircular canals are
to linear inertial forces.
and
saccular
otoliths,
however,
do
perform
the
functions of detecting gravitational and linear inertial forces, but can
not
distinquish between
the
two.
The utricular
both consist of hair cells and supporting cells.
mechanical
endorgans.
energy
to initiate
Hair-like cilia
otolithic membrane.
nerve impulses
and saccular
macculae
Hair cells transduce
which emanate
from these
project into a gelatenous mass called the
On top of this membrane lies a dense layer of
8
cwricle or
--
,
---
=t~iclc
. elers
'4e
t
ole
=On
-
* - intc rme dicte
ow
-u
.
Figure 1.
the
=iddla,
rln.
evol-
-tympanie
Ec te
ub durcl sac
Inncr.
rnn II-Adle
Diagram of an ear,
showing the ralations of the external,
and t~he inner ear.(Addison:
ad. 1.3. Lippincott, Philadelphia)
9
Pie-4rsol's ',.ormal_. Histology,
ANTL0IOR ERTCAL
WSMICRCULAR CAMAL.
L.XTKRAL OR HCRUM"Al.
VEMTBUL.AR ME
$tE!CI.RCANAL.~
COCH4LUiA NZRV
<-
, SCWPtS GANUCON
souacu.ARCAMAt.
MACUL.A Of THE VMCIct
MACULA OF THE SACULE.
Figure 2,
medial
Labyrinth of .eft ear as viewed from the
aspect.
(Bioastronautic Da:ta Book,
10
NASA S?-3006)
.%.ANTIRCR
40..
A
Figure
3.
General orienzation and- distbution
of morPhological polarizavion vectors of (A)
ut-icular and (B)
saccular macul1ae.
1966)
11
(Spoendli.n,
calcite
called otoconia.
crystals
these
crystals
otolithic
to
"lag" behind
as
is
When the head
membrane.
they move
tilted,
across
they
tend
the dense
to "slide"
The threshold response is approximately 0.005g (Young and
downhill.
Meiry,
tend
During accelerations of the head
where g - 9.81 m/sec/sec.
1970),
The geometrical distribution of
sensory cells along the macculae provides sufficient information so that
both the magnitude and direction of the gravito-inertial
determined.
The utricles
are most sensitive
along
the
transverse
to
stimulus can be
gravitational
and
inertial
forces
saccules
are most sensitive to these forces along the sagital
plane
of
the
head
while
the
plane
(figure 3).
Eye Movements
Saccadic
eye
movements
are
characterized
by rapid
conjugate
movements whereby the eyes "jump" from one point of fixation to another.
The initial
acceleration as well as the final
saccadic eye movements
is very high
deceleration of these
(ranging up to 40,000
deg/sec/sec).
Both the peak velocity and duration are dependent on the magnitutde.
The amplitude of the peak velocity may be as high as 600 deg/sec,
while
the duration varies from 30 to 120 msec.
Smooth pursuit eye movements are used when tracking slow moving
visual
targets
(ranging
from
1
to 30 deg/sec.)
Apparently the purpose
of this type of conjugate eye movement is to maintain a moving image on
the fovea without the influence of saccades.
pursuit movements
seem
to be
limited
12
to
The velocity of smooth
less
than
40 deg/sec.
An
of this slow-tracking mechanism is that it
important characteristic
Attempts to track
requires the existence of an actual moving target.
conjugate
feedback,
eye movements.
in smooth
normallly do not result
"imaginary" slow moving targets,
found that,
however
(1978)
Nakayoma
with
subjects can be trained to make these smooth movements.
Compensatory eye movements are generally imooth movements which are
very much like pursuit movements,
target on the fovea,
except
compensatory eye movements attempt to stabilize the
The maximum velocity is faster than
entire visual field on the retina.
foveal
smooth
pursuit
movements,
Compensatory eye movements occur
entire visual field
that instead of maintaining a
in response
to coherent motion of the
well as in response
as
(optokinetic eye movements)
or neck (cervico-
to movements of the head (vestibulo-ocular reflex)
ocular reflex).
120 deg/sec.
high as
as
ranging
Vestibular eye movements are influenced by both the
semicircular canals and the otoliths.
is sufficiently
If the amplitude of the compensatory movement
great, nystagmus results.
phase.
image
Nystagmus consists of both a slow and fast
The slow phase corresponds to a smooth pursuit movement where an
is
movement
stabilized
on
the
retina.
The
fast
phase
where the eyes "jump" to pick up another image.
is then tracked during another slow phase component.
is
a
saccadic
This new image
Thus,
a saw-tooth
pattern emerges during this oscillatory motion.
R cording Eye Movements
A corneo-retinal potential difference between 0.2 and 1 my normally
exists
during steady state illumination.
13
This
is
the basis
for one of
the simplest,
most inexpensive
electro-oculaography
This bioelectric
(EOG).
Thus,
level of light adaptation.
60
minutes
prior
Realistically
to
5 to
the
level to be used during
adaptation should occur
(Young
experiment
15 minutes
the subject
for stable EOG recordings,
Ideally this
actual experiment.
should
with the
potential varies
should be allowed to adapt to the ambient light
the
movements -
of recording eye
techniques
prove
to
and
for 30
Sheena,
be
to
1975).
sufficient
(see
appendix C).
As the eye rotates or moves, the corneo-retinal dipole rotates with
it.
Therefore the potential difference
measured by electrodes
to the temples varies as the sine of the angle of deviation.
attached
For small
angles w < pi/4 (45 degrees) sin w = w is within 10%.
The major difficulties
encountered
with EOG are
muscle artifacts,
particularly interference of the eyelids during blinking, and variations
in the corneo-retinal potential.
factors such as light
electrode/skin
These variations are caused by several
adaptation and subject alertness. The recording
interface
is also
(see Appendix
a major source of drift
C).
Vestibular Nomenclature
When refering to these experiments
tent frame of reference.
well as Figure 5
3)
X-Z,
is helpful
to have a consis-
Using the nomenclature found in Figure 4 as
the four positions utilized
acceleration while seated upright;
lying supine;
it
2)
Y-X,
fore-aft acceleration
14
are:
1)
Y-Z,
lateral
acceleration
while
while seated upright;
and 4)
lateral
Z-X,
longitudinal acceleration while lying supine.
vector refers to the direction of motion relative
(Note,
to the head while the
second vector corresponds to the direction of gravity relative
head.)
15
the first
to the
VEST!6LtAR
NOMENCLATURE
&CrMTAN0ECUS RUM1AXNT LJAR
A
7A,
+
A,, +
ACE'RATCN OF TWE HEA0
UtS: bh/wne',"ba"Es d 9.s
iA2
VECTOR
C=MPONENTS
WNNgATICS PONW)
sAsIC
.T1MUu
UNEAR ANO ANGULAR ACCELRATION
NUTATION
WMTANWNEOUS RESL1WNT ANGULAR ACCEI.ERATION OF THE HEA
ft/90
i - Ias
+
j+a,
+
UNJTS.
;g
'qwnw.
seg. deqise.
VECTOR
COMPONENTS
(grabAiY
Fu)
+2
i,
AT.
a urtt voreom
awor m
o we a, y,Z GAUS
direved
A
-x
i Alt
*A1
A to wcUude
-2
+X
POLARITY
CONVENTiONS
wel
a
~VutwwW.
IWflal
-1
a
eee.n, .'
iawe
@C3Ier?gs
-z
POLARITY
CONVENTICNS
+2
SA
+
z
2
+YSWr -7
-"om
+
-Alt
ye
+AY
+AY+a
-2.
f
mpg wod
nft m~
-2
Figure 4. Vestibular nomenclature.
-?d
yaw
nett
-Z
(Hixs-on, Niven, and Correia, 1966)
16
-Y
+Y
-
Y-z
gravity
(-Z)
+z-Z
Z-Y
gravity C-Y)
+Z
-z
4
z-x
gravity (-X)
Figure 5. Nomenclature for sled motion stimulus conditions.
The direction of motion is given first, followed by the
direction of gravity.
(Arrott, 1982)
17
Past Experimentation
Previous experiments on both animals and humans have been conducted
to study the effects of linear acceleration on eye movements.
(1931)
found that vertical
using horizontal
eye movements could be elicited
linear accelerations.
responses in either dogs or humans.
experiments on a parallel
regular,
swing,
not nystagmic.
humans using vertical
Jongkees (1961)
McCabe (1964)
Kapteyn
(1972)
experiments
and Niven,
Hixson,
swing.
moved with the body.
the left
body
1)
(Z-X
vertical
obtained:
sinusoidal
the
2)
accelerations
Bles
conducted
by Bles and
Bles and Kapteyn
linear accelerations
lying on the right side;
3)
lying on
both
horizontal
and
However the patterns seen were
subjects
Lying on the back,
movements,
eyes
were along the lengthwise axis of the
and Kapteyn observed
the twenty-two
1)
and
They were placed in each of three
(right eye moving differently
For
were
and vertical
eye movements for each eye.
consistent.
chinchillas
The subjects were instructed to keep their
supine).
disconjugate
were
All
to be
The subject's head was suspended so that it
lying on the back;
side.
conducted human
He found that rhythmic
and Correia (1966).
closed and assume a reverie state.
positions:
reproduce these
nystagmus in all three.
on humans
generated a combination of horizontal
using a parallel
tested cats,
linear accelerations.
recent
in rabbits
but found the eye movements
vertical linear acceleration could elicit
Two more
He could
Sjoberg
for the left
tested,
six subjects
eye) and not
the following results
exhibited
horizontal
even though there was no acceleration stimulus in
horizontal direction.
Two
of
18
these
six
showed
disconjugate
sinusoidal movements
with double
subjects had vertical
disconjugate
side,
right
only one subject exhibited
vertical eye movements.
in six of these, it
subjects showed horizontal sinusoids,
int
the
Lying on the
3)
lower eye only;
Lying on the
2)
eye movements.
Fifteen
was present
they observed
side,
left
other
Two
swing frequency.
the
fourteen subjects with horizontal sinusoidal eye movements.
subjects exhibited vertical eye movements only in the lower
and Kapteyn claim that their head suspension
electrode
Bles
eye.
system eliminated the
due to
that the eye movement signals seen were artifacts
possibility
Eleven
and skin motion.
Niven, Hixson, and Correia conducted their
a device which is capable of producing
Acceleration Platform (CAP),
on a 45 foot track.
accelerations
horizontal linear
on the Coriolis
tests
The stimulus used
consisted of three sinusoidal oscillations, all with a peak acceleration
The frequencies
of 0.58g.
were 0.2,
the body
was secured
to
the
subject
position as
on
the
to
These orientations
of oscillation.
the
back
with
transverse
acceleration vector and
plane normal
xz
the sagital
acceleration vector;
in 1 except subject
Each of
2) Y-Z
sitting upright;
xy
four
orientations and exposed to all
lying on the back such that
perpendicular
In these experiments,
seat with straps.
subjects was placed in four different
three frequencies
0.8 Hz.
fixed in a custom-molded plaster cast,
the subject's head was rigidly
while
0.4,
head
plane
were:
head
1)
Y-X,
plane
was
subject in same
3) Z-X, subject lying
perpendicular
to
the
4) Subject sitting upright with frontal yz head
to the track motion.
"maintain a straight ahead gaze
The subjects
at all
19
were instructed
times" during
to
cab oscillations.
the cab was closed
After the subjects' eye movements had been calibrated
light-tight and the tests were conducted
in this configuration.
the recordings were made with eyes closed.
minutes with the first
run lasted
Each test
2
60 seconds being ignored due to transient effects
that supposedly take place during that time.
To increase the nystagmic
response mental arithmetic and verbal "chatter" were used.
experiments,
Some of
the subject's head was
rigidly
fixed
in place
In these
with a
custon-made plaster cast, while the body was secured to the seat with
straps.
For eyes open and eyes closed,
the 1st and 2nd orientations,
applied
to
the subject's
horizontal nystagmus was elicited in
in which the acceleration stimulus was
y-axis.
Horizontal nystagmus
was not observed
in orientations 3 and 4, in which the stimulus was in the z-axis planes.
Vertical nystagmus was never observed.
at
approximately
remained
constant
both Y-Z
and Y-Z axis stimuli.
0.4, and 0.8 were 20,
are relative to
31,
10
frequencies
for
lags for the frequencies
0.2,
deg/sec
The phase
and 38 degrees
The mean peak eye velocity
for all
respectively.
These phase lags
the negative acceleration vector.
Vidic (1976) investigated the role of the otoliths
fixation points during earth vertical displacements
fixation tests conducted
recorded.
very erratic
of the body.
eye
These movements were primarily saccadic,
smooth tracking movements.
straight
in the dark,
in tracking
During
movements
were
with very little
Normal subjects that were instructed to look
ahead exhibited no signs of vertical nystagmus.
20
METHODS
By
periodic linear accelerations,
Experiments
of development.
understanding
a better
exhibited
during
of the otolith-
were conducted on twenty-three subjects in four phases
Seven subjects were used in preliminary experiments
motion
profiles,
Results
instructions.
movements
can be gained.
ocular response
determine
eye
compensatory
the
studying
recording
conditions,
and
to
subject
were obtained from fourteen subjects using three
protocols.
distinct
Subjects were placed on a rail-mounted linear acceleration cart
which provides earth horizontal
to varying acceleration,
sinusoidal
accelerations.
In addition
a range of frequencies was also used.
Eye
movements were recorded using standard EOG techniques.
E quipment
The MIT Sled Facility
1979)
The MIT Sled (Lichtenberg,
along two circular rails
designed
chair
(Abramson,
bushings
on four ball
1983)
consists of a cart which runs
(figure 6).
is mounted on top of the cart which is
driven by a torque motor connected to a winch drum,
assembly.
Subjects
are
A newly
placed in
adjustable four point seat belt.
the
chair
cable,
and pulley
and restrained by an
The head is firmly restrained
special helmet which is attached to the frame of the cart.
in a
This helmet
is a prototype of the helmet to be used in the Spacelab experiments.
21
i4
Cart
Motor
rails
winch
cable ,
7-
FIgure 6.
The M.I.T.
motion.
Bled showing the components which achieve cart
The chair is not depicted.
(Lichtenberg, 1979)
rails
The aluminum cart is a simple box frame guided along the
by four pillow blocks with recirculating linear ball bearing bushings.
rails
are one inch in diameter and are made of hardened steel.
rails
are 5 meters long,
block walls.
1.7 meters apart and mounted on top of concrete
One rail is rigidly fixed to its concrete wall, thus
concrete wall.
is held more losely on top
The other rail
properly aligning the cart.
of its
The two
is aligned by the ball
Therefore it
bushing as
the cart moves along the track.
A cable is attached to both sides of the cart and is wound around a
pulley at one end of the track and a winch drum at the other.
600 pounds of tension to help improve the dynamic response of
is under
the cart.
magnet
driven by a 3.5 hp DC permanent
The winch drum is directly
torque
controller
motor
The cable
(GE
using
motor
(Inland
PWM Hi-Ac
pulse-width
TTB-5302-100c.)
Servo-drive
controller
and
modulation
controller also serves as a current
An
analog
Model 3A)
tachometer
velocity
controls the
feedback.
generator which allows
The
the velocity
of the cart to be proportional to low-current voltage signals applied to
the controller.
A ten-turn potentiometer
is mounted on the motor shaft,
while an accelerometer is mounted on the chair near the subject's head.
These sensors as well as the motor shaft tachometer are used to moniter
and control the motion profile of the sled.
The sled
Digital
CART,
of the
is
controlled
by
the DEC
An interactive
Lab Peripheral System (LPS).
written by A.P. Arrott (1980),
sled throughout
PDP-ll/34 minicomputer
FORTRAN program,
provides "real time" remote
the experiment.
control
The computer program generates
velocity commands for the analog controller which executes
23
and
the given
The
Position and velocity feedback are used to provide a
motion profile.
In addition,
safety interlock.
the computer records and stores the
The EOG calibration
physical and physiological signals of interest.
controlled by
also
the
which provides
computer
is
on-line diagnostics of
the EOG signal's, reporting any warnings or other messages which might be
useful to
the experimenter.
Helmet
Throughout
the
experiment
helmet by a contoured stiff
subject's
head is restrained
foam liner six inches deep,
in the
which extends
in
leaving on to two inches clearance for the horizontal
front of the ears,
To help eliminate
electrodes.
the
all
sources
of
light
leaks,
a shroud
is
placed around the subject's neck and securely attached to the helmet
Inside the helmet,
itself.
a light array is fixed,
(approximately five
inches from the subject's eyes) from which the EOG calibrations are
made.
The EOG amplifier is mounted on the side of the helmet.
addition,
In
a fan is mounted to the helmet in order to maintain proper
ventilation.
EOG Amplifier
The EOG amplifier consists of a differential isolation amplifier
(Analog Devices 284J) at the input followed by a stage of high gain low
pass amplifier.
The isolation amplifier prevents dangerous
from being passed through the subject.
amplifier
is 20 Hz,
and it
currents
The low pass frequency of the
has adjustable gain levels ranging from 10 to
3000.
24
Light Array
The light array found inside the helmet consists of five LED lights
subject fixate on a given light when it
Both the horizontal and
is lit.
light.
from a center
lights are 15 degrees
vertical
can be made by having the
Calibrations of eye movements
(figure 5).
Thus a horizontal
sequence,
is made by having the subject look at the light
calibration
left,
center,
"right,
measurement
this
type
[microvolts/degree]
sensitivity
of
From
center."
sensitivities ranged from 5 to 20 microvolts/degree
of
is
a
calibration
made.
Typical
for both horizontal
and vertical eye movements.
Description of the Experiments
The results presented
in this
thesis were obtained from three
In the first
distinct protocols, performed on different subjects.
protocol (protocol I) some initial
characteristics
all
profile
room
of these experiments
repeated
lateral (Y-Z)
2)
turned off;
lights
three times;
3)
tests
were performed.
were:
1)
they were
only three
profiles
All runs
were done
The major
conducted
were
run,
with
each
in the upright
position and only horizontal eye movements were recorded.
The second set of experiments (protocol II) were conducted under
the following conditions: 1)
all room lights were off; 2) eight separate
runs were made in two different orientations,
position,
and
the fore-aft
supine (Z-X)
25
the upright
position;
3)
lateral
(Y-Z)
in the upright
only horizontal
position
eye
crew
members
of
preflight/postflight
Spacelab
test
conditions for these
room lights on.
1
in
1)
conjunction
being
series
tests were:
only
was performed on the
group of experiments (protocol III)
A final
while
recorded,
in the supine positions.
vertical eye movements were recorded
six
were
movements
with
conducted
the
for
INS102
NASA.
The
the experiments were conducted with
The helmet and shroud were
to provide
total darkness.
However there were problems with light leaks. 2) Eight runs were made in
the Y-Z and Z-X orientations.
motor,
all
of
the
particular, there
0.8 Hz.
runs
were
were
However,
not
problems with
due
conducted
to overheating
on every
the 0.9g profiles
general
gaze at all
protocol
times,
Also,
by thirteens.
was
for
all
these
hoped
was
the
same.
to "maintain a straight ahead
was asked
to count backwards
from a thousand
This instruction was given for two specific reasons.
counting
would
increase
measure
to
keep
the
mental
of
the eye
subject's
description of the protocol
movements
alertness,
Secondly,
movements. Between each run, an EOG calibration
sensitivity
and 3.
being sure not to fixate on any real or imaginary
the subject
that
diversionary
2,
experiments
improving the quality of nystagmic response.
the
In
The orientations, motion profiles, and experiment conditions in
First, the subject was given instructions
point."
subject.
the
at both 0.4 and
each of the three protocols are summarized in tables 1,
The
of
being
mind
was
off
thereby
was used as a
of
made to
recorded.
is provided in Appendix A.
26
it
It
A
his
eye
determine
detailed
TABLE 1
PROTOCOL I
# of Cycles
Type
Parameters
1
Sine
0.06g 0.lHz
40sec
4
2
Sine
0.2g
0.2Hz
40sec
8
3
Sine
0.9g
0.4Hz
40sec
16
Profile #
Duration
Orientations:
Upright
Repetitions:
Each run performed three times.
Room Conditions
All room lights turned off.
# of Subjects:
Three.
Subject Codes:
XIC, X1J, and
Protocol File:
X1SB4.PCL
lateral Y-Z only.
IS.
27
TABLE 2
Protocol II
Type
Parameters
1
Sine
0.6g 0.28Hz
36sec
10
2
Sine
0.05g 0.09Hz
44sec
4
3
Sine
0.2g 0.18Hz
44sec
8
4
Sine
0.lg 0.13Hz
46sec
6
5
Sine
0.9g 0.4Hz
40sec
16
6
Sine
0.2g 0.4Hz
40sec
16
7
Sine
0.6g 0.8Hz
40sec
32
8
Sine
0.lg 0.4Hz
40sec
16
Prof ile
Duration
# of Cycles
Orientations:
Upright lateral (Y-Z), and fore-aft supine (Z-X).
Repetitions:
Each run was performed once
Room Conditions:
All room lights turned off.
# of Subjects:
Four.
Subject Codes:
Xl,
Protocol File:
XlSBSM.PCL
12, X13, and X14.
28
in each orientation.
TABLE 3
Protocol III
Profile #
Type
Parameters
1
Sine
0.6g 0.28Hz
43 sec
12
2
Sine
0.9g 0.4Hz
40sec
16
3
Sine
0.2g 0.2Hz
40sec
8
4
Sine
0.6g 0.4Hz
40sec
16
5
Sine
0.6g 0.56Hz
39sec
22
6
Sine
0.9g 0.8Hz
40sec
32
7
Sine
0.2g 0.4Hz
40sec
16
8
Sine
0.6g 0.8Hz
40sec
32
rientations:
Duration
# of Cycles
Upright lateral (Y-Z) and fore-aft supine (Z-X)
Repetitions:
Each profile was performed once in each orientation.
Room Conditions:
Room lights were on.
Darkness provided by helmet
and shroud.
# of Subjects:
Six.
Subject Codes:
NiB, N2B, N3B, N4B, N5B, and N6B.
Protocol File:
XlCBT.PCL
29
RESULTS
Preliminary Experiments
Preliminary experiments were performed on seven subjects.
Although
experiments did not yield any useful data for analysis,
they did
these
resolve several important issues.
subject
were
First,
the instructions given to
found to strongly influence the eye
movements
Initially,
the
that
subjects interpreted this to mean "look at a
most
Because
the
instructions were to gaze straight ahead.
room
lights
a
obtained.
It
appears
fixed
point."
were on and the helmet and. shroud
did
not
provide complete darkness, it was possible for subjects to look at dimly
lit features inside the helmet.
not
move
Under,
these conditions the eyes
much and no evidence of nystagmus or
very
compensatory
did
eye
movements was observed.
Instructions
to the subject were modified to include the statement,
"do not fixate on any point,
were
asked
subject
lighting
real or imaginary".
perform mental arithmetic.
to
In addition,
This helped
alert and kept his mind of his eye movements.
was
to
subjects
keep
The problem
resolved by reducing the light in the room to the
the
of
lowest
level compatible with safety considerations.
Results with Protocol I
Evidence of horizontal nystagmus was clearly exhibited in
during
the
0.9g
0.4 Hz profiles.
Figure 7 shows that
30
the
subjects
response
30
20
10
0
-10
-20
-30
10
15
20
30
3 05
140
0
30&
20
10
0
-10
-20
20
25
X1C109
0.9G
0.4H-z
Fig.
Horizontal eye position (in
velocity
YZ
ti re Csec)
7
degrees)
during linear motion.
Cart
is presented arbitrarily scaled to indicate phase.
31
becomes distinct at the highest acceleration
trend in the response,
is a definite
it
amplitude.
Although there
to assess
is difficult
the
of increasing frequency or acceleration since they are both
effects
coupled in this protocol.
The average
slow phase velocity for the 0.9g
0.4 Hz profiles was 20.4 deg/sec with an average phase lag of -139 deg.
in the following sections
(All phase lags discussed
are with respect
to
cart velocity.)
The major function of the tests conducted with this protocol was to
the conditions necessary to obtain horizontal nystagmus.
determine
The
major conclusions drawn from this protocol were:
1)
verified importance of
2)
verified need for complete darkness;
3)
demonstrated need for high acceleration to obtain
an adequate
Plots
of
selected
instructions;
stimulus.
runs
for
this
and
subsequent
protocols
are
presented. in Appendix D.
Results with Protocol II
These were the first
the Z-X,
experiments performed which included tests in
longitudinal supine orientation.
again obtained of horizontal nystagmus
While clear evidence was
(figure
8)
in the upright orien-
tation, none of these subjects exhibited significant compensatory vertical eye movements in the supine position.
This protocol was designed to include the conditions to be used for
similar
experiments
using
the European
32
Space Agency Flight
Sled to be
I
30
20
10
0
10
30
15
0
I
30
20
10
0
-10
-20
5
20
X 12105
0.9g
40
30
YZ
0.4Hz
t tmeCsec)
Fig. 8
Horizontal eye position (in degrees) during linear motion..
Cart
velocity is presented arbitrarily scaled to indicate phase.
33
on
flown
the
Mission
D-1
profiles
acceleration
For
in 1985.
were included in
the
protocol.
From
confirmed.
was
required
these results,
low
However,
the
acceleration
from the previous experiments that sufficient
finding
several
reason
this
a
it appears
is
minimum
amplitude of 0.2g is required to obtain compensatory eye movements.
Results with Protocol III (Spacelab Crew Testing)
The
eye movements recorded with this
movements - were obtained in all subjects for at
amplitudes (0.6g and 0.9g)
acceleration
tion.
the
of
protocol
evidence of nystagmus (figure 9) although distinct
little
eye
majority
However,
compensatory
the
least
in the lateral upright orientain
Vertical compensatory eye movements were observed
(figure
in only two subjects during several runs in the Z-X orientation
A
higher
two subjects did show signs of nystagmic response
Y-Z orientation.
10).
show
more typical vertical eye movement recored
is shown in
Figure
11.
The
protocol
with
the
shroud.
only
major difference in experimental conditions between
were
III tests and the previous ones was that they
room
The
light leakage.
lights
on and the helmet surrounded
new shroud,
while an improvement,
by
a
the
performed
redesigned
still permitted
some
As a result, dim, diffuse light was observed inside the
helmet by the subjects.
Despite the absence of the characteristic fast phases of nystagmus,
the
distinct
analysis.
horizontal
compensatory eye movements were
amenable
to
Since protocol III includes four profiles at an amplitude of
34
30
20
10
0
-10
-20
-30
10
15
2 D
20
0
-10
- 20
-30
20
30
N2S 101
0.6g
0.28z
40
YZ
T (Ie
Csec)
Fig. 9
Horizontal eye position (in degrees)
during linear motion.
Cart
velocity is presented arbitrarily scaled to indicate phase.
35
30
20
-2
10
0
-10
-
-
-20
-30
0
5
10
20
25
20
20
20
10
0
10-
20
30
N1S
1 115
0 .
Fig.
Vertical
eye position (in
7
S-z
10
degrees)
during linear motion.
Cart
velocity is presented arbitrarily scaled to indicate phase.
36
30
20
10
0
-1
-10
-A
-20
- 30
20
10
0
30
20
1
10
0
1
-10
-
~
AN
-20
-~
I
20
20
30
N31
16
0.6g
0.8Hz
Fig.
Vertical
i r-e C secD
II
eye position (in degrees)
during linear motion.
Cart
velocity is presented arbitrarily scaled to indicate phase.
37
while the frequency varies from 0.28 Hz to 0.8 Hz,
0.6g
dependence of the response can be investigated.
three profiles
includes
Similarly, the protocol
at 0.4 Hz with acceleration
amplitudes of 0.2g,
From these, amplitude dependence and linearity can be
and 0.9g.
0.6g,
frequency
the
assessed.
If
gain
the
the response is expressed as the
over
m/s),
then
gain is
this
increasing frequency for a constant
observed
is
difficult
to
determine
to
the nature of
of
the
velocity
increase
acceleration of 0.6g.
increases over this same range (figure 12).
it
ratio
slow phase eye velocity to the amplitude of cart
amplitude of
(deg/sec
of
The phase
with
lag
Beyond these observations,
the
frequency
response
without experiments extending over a wider frequency range.
Relating
frequency
(fig
13).
the phase velocity (SPV)
to accelerations at
a
reveals that the SPV increases as the acceleration
Linear
regression
of this relation gives a slope
deg/sec/g.
38
constant
increases
of
9.8
BODE PLOT
3.0-
N5
N6
Ni
N2
N3
4 2.0
NI
N3
N2
1.0N6
N5
0.28
0.4
0.56
0.8
Log Frequency(Hz)
0.8
0.56
0.4
0.28
w
F'-
N3
Ni
-
90
N3
Ni
N5
N2
180
N5
Fig. 12
39
LINEARITY PLOT
Ni
12.0±
Slow Phase
Velocity
(deg.sec)
N2
6.0-N5
N3
3.1
N1
2 .0--
N5
N2
1.0
N3
0.6
0.2
0.9
Acceleration (g)
Constant Frequency 0.4Hz
Fig. 13
40
DISCUSSION
can be readily
Horizontal nystagmus and compensatory eye movements
given
elicited
an
adequate
the subjects
correspondence
is not much direct
Protocols
between
profiles)
I,
0.2Hz).
difference
(i.e.
several
and Protocol
II
III,
that there is a
examination of the time series plots clearly illustrates
remarkable
at
tested.
Although there
identical
0.2g
were not present in most of
on the other hand,
Vertical eye movements,
that
(greater
stimulus
in responses obtained under the two lighting
conditions. Tests conducted with all room lights off produced highly
compensatory eye movements (smooth
nystagmic responses while either
movements)
there was
or greatly reduced nystagmic responses are mainly seen when
of conducting the experiments
result underlines
This
diffuse light present.
in total
darkness.
the necessity
If this condition
cannot be attained using the helmet and shroud,then provisions should be
conduct these tests with room lights turned off.
made to
There is also
a noticable difference in the magnitude of the slow phase velocity under
the two different lighting conditions.
In general the magnitudes of the
slow phase velocity are higher for those tests
conducted in complete
darkness.
Subject responses obtained under conditions of diffuse lighting
exhibit,
subjects
few,
clear
among
themselves,
two distinct
consistantly exhibited
if any,
saccades.
nystagmus
responses.
Three
of
the
smooth compensatory *eye movements with
Two of the remaining three subjects exhibited a
but of
greatly reduced
41
slow
phase
velocity when
compared with the nystagmus observed under conditions of
complete dark-
ness.
Figure
profiles
14 displays
in Protocol I,
Gain is
the
the gain and phase relationship
Protocol III,
amplitude ratio
and the results
phase eye velocity is referenced
the origin.
of 0.4 Hz while
to cart velocity and is depicted as an
All data included
the acceleration
were obtained at a frequency
amplitude was 0.58g,
a nystagmic response (Niven et al.,
mic responses from Protocol III)
and -140
degrees.
In contrast,
the
0.6g,
or 0.9g.
that for
subjects
Protocol
phase
the Protocol
both 0.6g and 0.9g
who
and the nystagbetween -120
III subjects with smooth
-40
decidedly phase advanced of the nystagmic responses.
included
I,
angles are
compensatory responses have phase angles between
with Protocol III
to
The phase angle of slow
The most distinctive feature of this plot is
exhibit
of Niven et al.
of slow phase eye velocity (deg/sec
m/sec) and is represented as vector magnitude.
angle about
for comparable
and -50
degrees
-
Responses obtained
amplitudes
at 0.4Hz.
For
both the nystagmic and smooth responses the trends of higher gain and
increasing phase lag with higher amplitude of acceleration are apparent.
Overall,
the nystagmic responses
at this
frequency
show
good
aggreement with Niven et al. while the smooth compensatory responses are
significantly different.
responses observed
However,
where comparable,
in this study are only in partial
the frequency
agreement with
Niven et al.
Both studies indicate an increasing phase lag between
0.2 and 0.8Hz.
In the present study the gain was observed to increase
with frequency whereas Niven et al. found a constant gain over the same
42
POLAR PLOT
Niven et al.
Protocol I
0
A)
0.58g 0.4Hz
0.9c 0.4Hz
Protocol III (nystagmic)
Protocol III Csmooth)
0 degrees
-180 degrees
Cart velocit.y
0.6g 0.4Hz -
0.6g 0.4Hz
0.9g 0.4Hz
0.9g 0.4Hz
0.9g 0.4Hz
0.58g 0.4Hz
a
(Niven et al.
Fig. 14 Polar Plot
43
Reference)
frequency range.
In
comparing the results of Niven et al with those of the
there is an additional consideration of data analysis which
study,
to differences.
contribute
the
present
Niven et al.
found the peak SPV by measuring
cycle,
maximum slope of the eye movement recordings for each
taking
the
mean of these measurements.
The data analysis
and
techniques
used for this thesis took the nystagmic response and removed all of
saccades
using
may
a detection algorithm developed by
Massoumnia
the
(1983).
The cumulative eye position record that resulted was differentiated with
a 9
point digital filter to obtain the slow phase velocity (Massoumnia,
A sinusoidal fit for the amplitude and phase of the SPV was then
1983).
made
(Arrott,
reflects
the
1982).
slow
It
is
felt that this
method
more
phase velocity than the maximization
Niven et al.
44
accurately
procedure
of
SUMMARY
During
linear
can consistantly be obtained,
nystagmus
appears
can
evidence
nystagmic
0.2g.
In order to
a
be
light
compensatory
eye
Over the limited frequency range of testing possible on the
the repsonse dynamics are not clearly
clear
trend
discernable.
However,
of rising gain and increasing phase lag was observed
the range 0.2 - 0.8 Hz.
0.2g -
only
elicit
It would appear that even small amounts of diffuse
sled,
good
horizontal
response the amplitude of the stimulus should
transform a highly nystagmic response to smooth,
movements.
of
while vertical nystagmus
in a small fraction of the population.
horizontal
above
acceleration in the dark,
amplitude
a
over
Measurements at a frequency of 0.4 Hz indicated
linearity with respect
0.9g.
45
to acceleration over
the
range
SUGGESTIONS FOR FUTURE RESEARCH
In order to completely test
reflex,
more
the linearity
tests should be conducted.
of
the otolith-ocular
If possible
the frequency band
should be expanded in order to determine the specific behavior of the
otoliths.
The MIT Sled Facility
is
somewhat
because of track length and motor torque
nystagmus
is more easily elicited,
limiting
limitations.
more
studies
in this
respect
Since horizontal
should be done
to
completely understand the function of the system in the Y-Z orientation.
Once
this
examining
analysis
is
the affects
completed,
of
then
the other
more
energy
orientations.
could
be
spent
The Y-X acceleration
with the subject lying supine would be particularly interesting to
examine.
Theoretically one would expect to see horizontal nystagmus
since the visual field that the subject would be viewing is moving along
this
axis.
If this
Also
this result
is the case,
it
would
confirm
the findings of Niven et al.
would be interesting
to compare the responses of
the Y-X acceleration to the Y-Z acceleration to see if
the gain and
phase are similar.
For the 1NS102 ground based experiments,
only
the
nystagmus
Y-Z
lateral
is not
time is limited,
Finally,
effects
of
upright
consistantly
position
exhibited
the Z-X fore-aft
an independent
electrode/skin
be
it
is recommended
tested.
in all
Since
subjects,
that
vertical
and
testing
supine tests should be discontinued.
test
should
artifacts.
If
be
these
made
artifacts
change the nature of the eye recordings being made,
measurement technique may need to be employed.
46
to determine
the
significantly
then an alternate
Of particular
concern in
this
especially near
the
during large amplitude stimuli.
If
area is the possible movement of the skin,
horizontal recording electrodes,
present,
correlated,
this
type of movement could introduce
signals
that obscure
the eye movements
taking place.
47
spurious, albeit
which are
actually
BIBLIOGRAPHY
Arrott,
"'orsional Eye Movements
A.P.
tions",
Balliet R,
in Response
to
Linear Accelera-
Thesis, MIT,1982.
S.M.
Nakayama K.
Training of Voluntary Torsion.
Insvet Ophthalmol
Visual Sci 1978;17:303-14
Bles, W. and Kapteyn, T. S. (1973) Seperate Recording of the Movements
of the Human Eye During Parallel Swing Tests. Actaotolaryngol 75:6-
9.
Lichtenberg,
B.
tion, Sc.D.
K.,
"Ocular Counterrolling Induced by Linear Accelera-
Thesis,
MIT,
1979.
Human Ocular
Lichtenberg, B. K., Young, L. R., and Arrott, A. P. (1982)
Accelerations.
Linear
by
Varying
Induced
Couterrolling
Experimental Brain Res 48: 127-136.
Massoumnia,
"Detection of Fast Phase of Nystagmus Using Digital
M.,
Filtering", S.M. Thesis, MIT, 1983.
F.
McCabe, B.
Laryngscope
V.
(1964)
76.
Nystagmus
Response
of
the
Otolith
Organs.
of
Niven, J. I., Hixson, W. C., and Correia, M. J. (1966) Elicitation
Otolar.
Acta
Acceleration.
Linear
Periodic
by
Nystagmus
Horizontal
62:429-441.
Oman,
Charles M. (1982) "Space Motion Sickness and Vestibular Experiments in Spacelab", SAE Technical Paper 820833.
Tole,
Background and Procedures for Electro-oculography.
J.R.,
Harvard/MIT Biomedical Engineering Center. 1979.
Spacelab Mission I Experiment Descriptions, NASA, 1982.
Vidic, T.R., "Clinical Test for Abnormal Human Response
eration", S.B. Thesis, MIT, 1976.
Weiss,
J.A.,
"Motion Artifacts
in Surface
to Linear Accel-
Electrodes," S.B.
Thesis,
MIT,
1976.
Young, L.R., Effects of Linear Acceleration on Vetibular Nystagmus.
Progress Report, NASA Grant NGR 22-009-156.
"Cross-coupling Between Effects of Linear and
(1972)
L.R.,
Young,
Bibl. Ophthalm.
Angular Acceleration on Vestibular Nystagmus",
82:116-121.
48
L.R. Human Orientation in Space.
Young,
AIAA Dryden Lecture
in Research,
1982.
Young,
L.R.
and Meiry,
AMRL-TR-66-209;
J.L., (1969)
"A Revised Dynamic Otolith Model",
Aerospace Medicine 39:606-608.
49
Appendix A: Detailed Protocol
F07-SB Experiment
Crew Baseline Testing
MIT
April 19-21, 1983
Test Protocol
1.
Sled Preparation
2.
Helmet Preparation
3.
Subject Preparation
50
1.
Sled Preparation
1.1
SLED: Place chair in proper axis.
1.2
HELMET: Mate helmet and cables to chair.
1.3
HELMET: Attach EOG amplifier and leads.
1.4
SLED: Start sled and computer
1.5
SLED: Load Protocol file XICBT.PCL.
1.6
SLED: Set computer options.
1.7
SLED: Enable sequential data storage.
1.8
SLED: Perform stationary sled safety test.
1.9
SLED: Perform empty sled motion test.
2.
2.1
systems.
Helmet Preparation
Helmet: Check function of the following:
light array
fan
masking noise
communication system
2.2
HELMET: Check to see that everything on
the helmet is secure.
3. Subject Preparation
3.1
SUBJECT: Apply five electrodes to subject
3.2
SUBJECT: Check electrodes with impedance meter.
3.3
SUBJECT/HELMET: Place subject in chair
and adjust helmet height.
3.4
SUBJECT/SLED: Adjust
foot rests.
3.5
SUBJECT: Attach body restraint straps
and secure subject.
3.6
SUBJECT: Check level of masking noise
and communication system.
51
3.7
SUBJECT/HELMET:
Attach EOG leads to electrodes.
3.8
SUBJECT: Give subject panic button and demonstrate.
3.9
SUBJECT: Give subject instructions for the test.
3.10
HELMET: Lower helmet.
3.11
SLED: Zero offset and perform.
manual EOG calibration.
3.12
HELMET:
3.13
HELMET: Attach shroud.
3.14
SUBJECT: Obtain subject's comments on light leaks.
Turn on fan and masking noise.
52
F07-SB Timeline
TIME(min:sec)
ITEM TO BE COMPLETED
00:00
Begin Experiment F07-SB
05:00
Subject
07:00
Zero the offset
08:00
Do EOG calibration
09:00
Run Profile #1
09:30
Do EOG calibration
10:30
Run Profile #2
11:00
Do EOG calibration
12:00
Run Profile #3
12:30
Do EOG calibration
13:30
Run Profile #4
14:00
Do EOG calibration
15:00
Run Profile #5
15:30
Do EOG calibration
16:30
Run Profile #6
17:00
Do EOG calibration
18:00
Run Profile #7
18:30
Do EOG calibration
19:30
Run Profile #8
20:00
Do EOG calibration
26:00
Change orientation of the sled
29:00
Subject secured in chair
31:00
Zero Offset
Secured in Sled
53
32:00
Do EOG calibration
33:00
Run Profile #1
33:30
Do EOG calibration
34:30
Run Profile #2
35:00
Do EOG calibration
36:00
Run Profile #3
36:30
Do EOG calibration
37:30
Run Profile #4
38:00
Do EOG calibration
38:30
Run Profile #5
39:00
Do EOG calibration
40:00
Run Profile #6
40:30
Do EOG calibration
41:30
Run Profile #7
42:00
Do EOG calibration
43:00
Run Profile #8
43:30
Do EOG calibration
48:00
Subject out of sled
49:00
Secure sled
50:00
End of Experiment F07-SB
54
Appendix B: Electrode Study
In the
thesis,
first
process of conducting
the initial
several questions concerning
concern
experiments
the electrodes
was whether or not the offset
for this
were raised.
The
potential
between the
proper EOG amplifier
performance.
electrodes
was
The offset
potential is the difference between the potentials at the
skin-electrode
within
the range
interface
metal-electrode
and the
junction potentials
that exist
interface of the electrodes (Weiss 1981).
long should the electrodes be
state?
for
Thirdly,
how
allowed
important
is
to "settle"
the
use
at
the
Secondly,
how
or reach a steady
of
alcohol
as
a
skin
preparation?
Since the corneo-retinal potential is in the range of 0.2-1.0 my,
the offset pontential between any two electrodes
is very important.
The
EOG amplifier was designed for optimal performance for offset potentials
of
less
than 125 mv.
important,
to
stability of
the
electodes
especially when scheduling subjects
Therefore
constraints.
need
The
be
on
the
subject
Finally,
if the use of
then its
use
In this
it
is
also
very
within strict time
is useful to know how long the electrodes
before
alcohol
reliable
has no
recordings
bearing on electode
can be
made.
performance,
can be discontinued.
study,
Infant ECG Electrodes
(Hewlett-Packard
Trace Pellet Electrodes (MED1901
FB08042),
Electrodes
In order
(Part No.
Harco 157
three different electrodes were examined:
9430-300).
55
Part No.
14389(H157)),
Medi-
and Marquette Electronics ECG
to
study the offset
potentials
of
the electrodes,
7-9
were
electrodes
placed
on the
After 30 minutes were allowed for the electrodes
author's
down,
to settle
potentials between the various pairs of electrodes were made.
of the data gathered
Figure B1,
B2,
and B3.
All offset potentials
are
absolute
time of the electrodes,
offset potentials between two
A summary
electrodes
values.
recordings of
were made over a period of 15
(Figure B4.)
Offset potentials
the use
the
as well as histograms are shown in Table BI and
To determine the settling
minutes.
forehead.
of
alcohol
and settling times were measured with and without
to study its
effects.
(Figure B5)
Conclusions
The Harco and Meditrace Elecrodes have small offset potentials
ranging
up
Electrodes
to
are
only
offset
generally higher,
However all three electrodes
amplifier
The
40mv.
performance.
ten
to
fifteen
of
the
Marquette
with a maximum of approximately
65mv.
are within the desired range for proper EOG
The Harco
and Meditrace
down more quickly than the Marquette's.
after
potential
minutes
while
Electrodes
The Harco Electrodes
the Meditrace
ten minutes.
The Marqeutte Electrodes
settle down.
More importantly,
also
take at
are
least
settle
settle down
stabilized
after
twenty minutes
to
the difference in offset potentials from
the initial placement and twenty minutes later is more than 20mv for the
Marquette
time,
so
Electrodes.
Even if
the offset
you would like the changes
that
the
consistant.
Electrodes
recordings
While
were found
made
conducting
potentials
are
changing
with
to be small over short periods of time,
during
this
an
hour
study,
session
several
to have very high offset potentials
56
are
of
the
f- irly
H
5
(greater than
the
that
125mv that the EOG amplifier
they not be used for
can record).
these experiments.
the use of alcohol should be continued.
Therefore,
Finally,
suggested
appears
The offset potentials
when alcohol was not used are too high to be tolerated.
57
it
it
that
recorded
Table Bi
Type of Electrode
#samples
#electrodes
Mean(mv)
Harco 157(alcohol)
57
16
11.22
0.3-26.5
51
16
10.94
0.4-38.5
Marquette (alcohol)
42
14
20.19
0.5-64.4
Medi-Trace (no alcohol)**
60
18
19.66
0.2-76.4
Medi-Trace
(alcohol)*
*One electrode had offset potential greater than 125mv.
**Two electrodes had offset potentials greater than 125mv.
58
Range(my)
20
Harco Electrodes
# of samples: 57
Mean 11.2mv
15
# of
samples
10
5
10
15
20
25
Offset Potential
Fig. BI
59
30
(mV)
10
# of
9-
samples
Marquette El ectrodes
Total # of samples: 42
Mean: 20.2mv
7
6
543
215
0
15
20
45
50
Offset potential
(mV)
30
25
Fig.
.35
B2
60
40
55
U 03
# Of
samples
20
Medi-Trace Electrodes
Total # of samples: 51
Mean: 10.9mv
15
10
T
.1.
5
T
I5
10
15
20
30
2! i
35
Offset Potential (mv)
Fig.
B3
61
40
10.
Medi -Trace El ectrodes
of
(without alcohol)
Total # of samples: 60
Mean: 19.7mv
samples
7t
4-.
3.
21.
5 10
15 20 25 30 35 40 45 50 55 60-
Offset potential (mv)
Fig. B4
62
75 80
Settling Times
30-
A Harco Electrodes
C Marquette Electrodes
0 Medi-Trace Electrodes
20S
'U
0
0D
(D
'1
0
0
10-
(D
0
0
0
O 0((O
5-
A
2
4
6
8
10
12
14
Time(sec)
Fig. 35
63
16
18
20
Appendix C: Individual Test Results
The following pages
contain the eye position records from selected
tests as well as summaries of those tests.
64
Summary of Results
subject- XlC
protocol- I (XlSB4)
Orientation- YZ
Eyes - Horizontal
data code
stimulus
frequency
amplitude
[az)
[g]
res ponse
amplitude
phase
[deg/sec]
Edeg]
coherence
[%]
X2C101
XIC104
XlC107
0 06
0.06
0 06
0 1
0.1
0 1
0 90
0.94
0 24
-148
-41
-18
6
0.5
0 03
X1C102
X1C105
X1C108
0.2
0 2
0.2
0.2
0 2
0.2
2.54
3 09
1.48
-119
-104
-70
3
1 1
0.7
XIC103
XIC106
X1C109
0 9
0.9
0 9
0 4
0.4
0.4
39 45
30-95
26 26
-157
-134
-131
25
63
37
VAX/VMs *se PwLOT 1-MAY-13 03:01:27.28 gE2:(P3441.ARDTT.SPACELADIXICIO02A.PLT;2
AROTT wse
VAX/VMU
20
10
30
0
10
20
20
30
40
20
10
-10
-20
-
30
xIC102
0. 2g
0.2"z
YZ
Horizontal eye position (in degrees) during
t L --e C sec )
linear not ion.
Carr velocity
trace is presented arbitrarily scaled to indicate phase relationsnip.
f
vAX/yM
s
18-MAY-LOW
EN
03:02:28.59
XE2: [P3441.AAA.CTTSPACELAB1X1C103A.Pt.; I AARTT
se VAX/VM8
20
10
0
-10
-20
A
-30
2 0
10
0
--
1
Iv~
20
10
0
-10
-20
-
:30
40
30
20
X
1C 103
0.Gg
0.4-4z
Y7
Horizontal eye position (in degrees)
T
rIe Csec)
during linear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
VAX/V1
see
...
VPLOT 1-KAY-1983 03:03:29.20
1S2:(P3441.AAOTr.SPAC..ABJXICIO4A.?PLT;I AAAOTT *s
VAX/VWS
30
2010
0
-10
- 0
-
-30
0
5
10
15
20
25
30
35
40
302
20
-
10-
- 10
-2Z
- 30
20
X iC104
0.06g
0. 1?-z
YZ
Horizontal eye position (in degrees) during
T ime Csec
rinear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
se
VAX/VNM
PEOPLT Ia-MAY-
1983 03:04: 34. 61
R2:
(PS441.AAIOT
SPACELABX1C108A .PLT; 1 AAO1T
see VAX/VMB
I
10
0
-le
10
-30
10
0
20
30
20
~NJN~Ni~~
0
-20
-
I
20
I
-
- -
30
X LC
105
0.2g
0.2Hz
Horizontal eye position (rn degrees)
--
40
YZ
r ,me
during linear motion.
C sec D
Cart velocity
trace is presented arbitrarfily scaled to indicate phase relationship.
VAX/VH3
*00
PVanLOT 18-MAY-193 03:05:34.87
20
RWE2: CP3441.AART.SPACELAB)X1CIO8A.PLT;1 AAR=T eme VAX/VM3
41A
10
0
-10
-20
-53
10
0
15
20
30
20
10
/
0
I
-10
-
30
20
30
25
x
1C 106
0
.
9g
0 . 4HZ
Horizontal eye position (in degrees)
35
YZ
40
It rle C s ec
during linear motion.
Cart veracity
trace is presented arbitrarily scaled to indicate phase relationship.
VAX/V1M see PEMPLOT 16-fAY-1963 03:06:14.06
3132:[P5441.AUCTT. SPACE.ABX1C107A.PLT;I ABBOTT
se VAX/VMS
30
-5
10
-
0
-10
-20
-30
10
0
15
20
20
10
.0
-10
-20
20
30
x1107
0.08g
0.
I"=
4orrzontal eye position (in degrees)
40
t
rime C sec D
during linear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationsnip.
VAX/Vg ese
PZMKL=
19-MAY-1983 03:11:14.11
VE:2:(P3441.AA1TT.SPACELABIX1C1OA.PLT;I ARROT 006 VAX/VM
20
10
0
10
20
-30
0
152
0
05
I
1~
20
10
l
AV
~
~
vN\
0
-10
-20
-
30
40
30
20
x
C 108
0.2g
0.2H z
Yz
r
-ie
C sec )
Horizontal eye position (in degrees) during linear motiOn.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
VX/VM *w0
PDfPWT
18-MAY-Ig3
03:13:04.75
IU2:CP3441.A3OTT.SPACELABIX1C109A.PLT;1
AAROTT
s
VAX/VM
-vvvvVV"
30
10
0
-10
-20
30
-
0
10
15
20
20
10
0
-10
- 20
-
30
L
/
Vj
1~
4\fW
IF
20
40
x 1C 109
0 . 9G
0 .4H z
Horizontal eye posit ion (;n deg rees)
trace
Y Z
tr
m eCs ec
during linear mot ion.
Cart veloci ty
is presented arbitrarily scaled to indicate phase relationship.
VAX/VI
*..
3-
-
PPUT 16-IAY-1963 03:13:06.76
ES2:CP3441.AARTT.SPACELABIX1C109A.PLT;1
AARTT
VAX/VMS
20
10
0
-10
-20
-
30
0
510
20
25
15
20
35
40
30
20
-20
X1C109
0.9g
30
0.4Hz
Horizontal eye position (in degrees)
YZ
t
-ieCsec)
during linear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
Summary of Results
subject- Nl
protocol
III (XlCBT)
Orientation- YZ
Eyes- Horizontal
data code
stimulus.
frequency
amplitude
[HzJ
[g]
response
amplitude
phase
Cdeg/sec]
Cdeg]
coherence
C%]
N1B104
NL1Bl08
0 2
0-2
0 2
0.4
2 51
2-.66
-87
-95
0 8
0.6
N1B102
NlB105
N1B106
N1BI09
0 6
0.6
0 6
0.6
0 28
0-4
0-56
0-8
5 23
4.69
4 99
7.19
-28
-50
-67
-79
5
3
5
8
N1B103
0 9
0 4
1181
-52
19
VAX/VM
000 PEOPOT .17-MAY-O93 21:42:02.33
3fE2:
[P3441 .ARMTT.SPACE.AB N2B101A.PLT; I AlAOTT
s*
VAX/vMf
30
20
10
0
-10
/
L0
0
20
/
30
20
10
%
ttJ~J
0
10
-30
20
40
N2S 10 1
0 .g
0.2
8H z
YZ
- 'r-leC S ec
Horizontal eye position (in degrees) during linear motion.
trace
Cart veloci ty
is presented arbitrarily scaled to indicate phase relationshrip.
VAX/Mviu
PpWLfT
17-MAY-LMa3 21:27:07.39
3EU2:(P3441.AAR8TT.SPACE.ABIN1102A.PLT;1
AAROT
se VAX/VMS
20
-20
-30
20
0
20
r~~
\a/i~A4
10
- 10
-20
-
30
40
30
20
N le 102
0.t=g
0.28H
z
YZ
Horizontal eye position (in degrees)
t
- e C Sec
during linear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relaionsetip.
VAX/V@ see
PLOT
EN
17-MAY-193
21:31:00.81
ES2: CP3441.AA
TT.SPACELAO)N18103A..PLT;1
AATr *e
VAX/VMS
30
-V
"
,"
10
0
-10
30
0
20
VV
30
V
20
10
10
-
30
40
30
N
18 103
0.9g
0.4Hz
YZ
7
me
Cs
Horizontal eye pasrtran (in degrees) during linear motion.
eC)
Cart velocity
trace is presented arbitrarily scaled to indicate pnase relationship.
vAX/vm
se
PErPL.T
17-MAY-19
21:39:14.64
Z132: (P3441.AMOTT.SPACZLABJI
HS109A.PT.; 1 ARROTT
se
VAX/YM3
AAAAKAhA
20
10
0
10
20
0
10
20
'1
20
10
0
10
i
%>1
t
2Q
0
30
25
N
I 8 109
Horizontal
trace
o
. eg
0
.
8"Zz
eye position (in degrees)
40
3s
i -e C s c
during linear motion.
Cart
velocity
is presented arbitrarily scaled to indicate phase relationship.
VAX/VMS
so
PEPM.T 17-fAY-O93 21:32:43.57
RE2:[P3441.AAAOTT.SPACELA IN13104A.PLT;1 A*RUTT
***
VAX/V1U
20
-2
10
0
-10
-20
-30
5
10
.iS
D
20
aI
20
10
-
20
20
20
NIS104
Horizontal
trace
0.6g
0.4Hz
YZ
Tr-ie
eye position (in degrees) during linear motion.
Csec)
Cart velocity
is presented arbitrarily scaled to indicate phase relationship.
VAX/VMN
PDPLOT 17-MAY-1903 21:35:41.94
U.
IU2: P3441.AAMOTT.SPACELAIN1OIGA.PLT1
AATT se
VAX/VMS
30
20
10
0
-10
-20
-30
0
510
15
2530
3540
20
30
20
L
10
0
-10
-20
-30
20
N18106
0.eg
O.56HZ
Horizontal eye position (in
trace
degrees)
YZ
T
-meCsec)
during linear motion.
Cart velocity
is presented arbitrarily scaled to indicate phase relationship.
VAx/w
...
Pwniar 17-IAy-Is.
21:37:18. 11
RE2: (P3441.AIUTT.SPEACLA2IN1B1OSA.PL.T; 1 AA*OTT
***
VAX/VMS
20
10
0
10
-30
20
10
0
20
10
-10
K A
YYN
40
30
20
N
B 108
0
2G
0.4Hz
Horizontal eye position (in degrees)
YZ
T
(Ge
during linear motion.
C Sec )
Cart veloci ty
trace is presented arbitrarily scaled to indicate phase relationship.
Sunmary of Results
subject- N2
protocol- III (XlCBT)
Orientation- YZ
Eyes- Horizontal
data code
stimulus
amplitude frequency
EHz I
[g]
response
.
phase
amplitude
Cdeg/sec]
Cdeg]
coherence
C%]
N2BI03
N2B107
0 2
0.2
0 2
0.4
0.40
1.21
6
-188
0-.
1.2
N2B10 1
N2B104
N2B105
N2B108
0 6
0.6
0 6
0.6
0 28
0.4
0 56
0.8
3 74
4.66
4.30
6.00
-7
-45
-54
-91
8
10
7
12
N2B102
N2B106
0 9
0.9
0.4
0.8
9 80
13.75
-54
-93
27
45
VAX/Vi
so
PZ. M
17-Y-1963
21:44:29.84
=E2: (P3441. AAR0T=. SACELAB
28102A.P.T;
1 AAR*T
s-
VAX/VM1
30
20
10
0
-10
-20
-30
20
15
10
30
7vv\\-
20
VI~jI
0
-10
-20
-30
N2102
0.-Gg
0.;-iz
Horizontal eye position (in degrees)
40
'35
- 30
20
Z
I' [
t-e C Sec )
during linear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate pnase relationship.
VAX/M
PVWLDT
*we
17-MAY-1983 21:44:02.94
RE2: (P3441.AAROTT.SPACELABIN2BZO3A..PLT;
AARIOT
se VAX/VM
30
-
10
0
-10
-20
2 0
15
10
5
0
I
1~~
I
-
10
0
-10
-30
25
2(2
N29103
0.2g
3
0.2H"z
Horizontal eye position (in degrees)
YZ
T-e
during linear motion.
CS 9
C
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
VAX/VI
see PDL T 17-MIAY-ISU 21:47:47.33
Eu2:
(P3441.AARCTT.SPACELABN2314A.PLT;I
ARM=T 00
VAX/V1U
30
20
10
0
-10
-20
0
5
10
20
25
30
20
15
30
20
10
-10
-20
-:30
N23
10
4
o.6
Horizontal eye position (in
0
-
degrees)
YZ
t
durirrg linear motion.
meCsec)
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
vAMx I
*a
PlP.DLT
1Ja-MAY- 196 02:44:02.67 &02:(P3441
SPAC.AhJN21OSA.P.T; I AUOTT see VAX/VM
.AI=.
r
30
20
10
0
10
20
-j
-30
0
30
20
15
10
20
10
-]
z
- 10
-A
-20
30
20
N2I
10c5
0 .g
Z . 5-z
Horizontal eye position (in degrees)
YZ
T L Ie C s ec)
during linear mnotion.
Cart velocity
trace Is presented arbitrarily scaled to indicate phase relationship.
-ue PENPLOT 17-*AY-19M3
VAX/VMS
21:57:47.60
RME2:CP3441.AAROTT. SPACELABI
N2210A.PLT.
1 AAROTT see VAX/VMS
30
10
0
10
-30
I
30
20
10
0
I
I
20
10
- 10
-20
-
30
N28 108
0.eg
0.8Hz
Horizontal eye position (in degrees)
40
35
30
25
20
YZ
r
r-leCsec)
during linear motion.
Cart velocity
trace is presented arbitrarily scaled to indicate phase relationship.
VAX/VMS. a*
PENPLOT
17-MAY-L963
22:22:63.82
RES2: (P3441.ARROTT.SPACELABIN6BIO3A.PLT;
1
ARRMTT o*o VAX/VMS
-
30
-
20
10
0
10
20
0
10
I
/
-1
/
I
i
t
20
10
- 0
8 103
0 . s g
ol.
28
H Z
r
,
1- e C s e c )
VAX/VMS **a
PENPU.T
t8-MAY-1983
21:44:25.87
RES2:fP3441.AROTT .SPACEL.AB)NSB104A.PLT
1 ARROTT
s*.
VAX/VMS
30
20
0
-10
-20
15
10
0
20
20
-
10
-5(_7
40
320
20
N-I5s 104
0.9g
0.4-
z
7 t me C sec )
VAX/VMS
***
PDPLOT 18-MAY-1983
30
01:24:46.70
RE2:fP3441.ARROTT.SPACEl.AD]N68107A.PLT;1
ARROTT *..
VAX/VMS
--
-A
20
10
0
10
--
20
30
10
0
20
20
-
10
- 10
-1
-20
20
30
N58f
10 7
0 .eg
0 . 56HZ
35
i i m ee
Cs
ec 3
VAX/VMS oo* PENPLOT
~/
\\
18-MAY-1983
/
RES2: [P3441.ARROTT.SPACELAB)N6B109A.PLT;2
01:27:52.69
/1
ARROTT ***
VAX/VMS
\
-
/
>-I
/
30
20
10
...
-.....
10
-30
10
0
20
7\J
10
-0
-
30
20
30
N28
1 09
0N. 2g
0. 4-Hz
40
Y-Z
oe
-i
Cs
e c
VAX/VMS ***
PENPLOT iB-MAY-1983
01:30:25.14
RES2: LP3441,ARROTT.SPACELAB]N691 10A.PLT; 1 AAROTT ***
VAX/VMS
30
-2
10
0
-10
--
-20
-30
0
10
I!
30
20
10
I'
lj
V
L
~1
~~AI
NJNlAJJNJ\V
~-v~JN,
V
j
-10
7
1
-
30
N5B8 1 10
0 . =-g
40
30
25
20
0.
H-Z
Z
Ye
Y
1 ( -,- e
C s e c
VAX/VNS
u.PENPLOT
IS-KAY-1983 02:30:08.88
RS2:CP3441 AAAROTT.SPACELA8]X12106A.PLT~1
ARUTT seVAX/VMS
20
20
10
0I
-102
-201
-20
0
5
0
15
20
20&
201
10
0[
-20K
-20
2-0
25
x
20
1240
4
z
y Y7