Tasiz 10.—Results of the Paired t Tests for the Intensity Ratings Resulting From the Caloric Irrigations.

44°C to the left ear (Lw)

30°C to the right ear (Re)

Group Comparison Task Reverie Task Reverie
Control Pre vs. Post I 1.79 2.20 2.27% 3.968
Pre vs. Post II 2.78% 2.79% 6.308** 4.09%
Pre vs. Post I 23 114 3.89% 3.54%"
Moderate Aleohol Pre vs. Post II 3.06* 1.37 5.11 5.0388
+ Pre vs. Post I 63 1,42 3. 60** 1.27
High Alcohol Pre vs. Post II 3.11% 2.734 4, 21 3.29%
*p <.05
#4) <.01
ep <,001

Tasux 11.—Results of the Paired t Tests for the Durations
of the Subjects’ “Vertigo” Sensations Resulting From
the Caloric Irrigations Under the Task Condition.

44°C to the left ear 30°C to the right ear

(Lw) (Re)
Group Pre vs. Pre vs. Pre vs. Pre vs.
Post I Post IL Post I Post IT
Control 0.54 2.16 4,15** 4, A4ee
Moderate
Alcohol 2,04 3. 60** 0.02 2.61*
High
Alcohol 1.06 2..73* 3.24* 3.21*
*p <.05
ep <.01

Caloric Nystagmus in Darkness. Means and
standard deviations for the total number of de-
grees of slow phase eye displacement, frequency,
duration, and mean peak velocity of nystagmus
obtained during the caloric trials in darkness are
presented in Tables 2 to 5. Results of the analyses
of variance for these measures appear in Table
6; results of t tests are in Tables 12 to 14.

The Pre to Post I declines in control group
responses were much smaller than those noted for
either the moderate alcohol or high alcohol
groups; only the duration measures for the Lw
and Re irrigations under the Rev condition were
significantly below their Pre levels (Table 12).
Most of the scores for the Post ITI trials of the
control group were not significantly different
from Pre values.

18

With the exception of a 19% increase in peak
eye velocity for the Lw trial, all of the nystagmus
measures for the moderate alcohol group at the
Post I testing session were below their Pre levels.
All of the Post I reductions in nystagmus dura-
tion were statistically significant, and several
other measures also evidenced significant Pre to
Post I declines (Table 13), Although the ma-
jority of the Post II mean responses showed
recovery from their Post I levels, several re-
mained significantly below Pre values; the ma-
jority of the significant t tests occurred for the
duration measure.

Declines from the Pre to Post I trials were
much larger for the high alcohol group (16-46%).
According to t tests, all of the mean Post I
measures were significantly below their Pre
values (Table 14). At the Post II testing ses-
sion, all mean responses were above Post I levels,
and only (a) Post II durations for both Lw
trials, and (b) frequency for the Re Task trial
were still significantly below their initial levels.
In terms of per cent of change, the high alcohol
group evidenced greater response recovery on the
Post II trials than did the moderate alcohol
group.

These data indicate that aleohol had a depres-
sive effect on the nystagmic response to caloriza-
tions in darkness. The changes in the response
following alcohol ingestion are evident in the
slow phase and frequency response curves pre-
sented in Figures 3 to 10. A representative


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Froure 12. Response data for the average number of degrees of slow phase eye movement (upper half) and aver-
age number of nystagmic eye movements (lower half) resulting from the 15-second optokinetic trials. Pre re-
fers to the response obtained prior to the ingestion of alcohol, while Post I and Post IT refer, respectively, to
the data obtained 45 minutes and four hours after ingestion. “Lights on” indicates that the room lights re-
mained on both during and following the stimulus period. The values are plotted in 3-second intervals; each
point is a mean of 10 subjects.

22,


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Tanue 12.—Results of the Paired t Tests for the Pre vs. Post I and Pre vs. Post II Comparisons of the Nystagmic
Responses of the Control Group to the Caloric Irrigations.

44°C to the left ear (Lw) 30°C to the right ear (Re)

Measure Comparison Task Reverie Task Reverie
Displacement. Pre vs. Post 1 1,86 1.88 1.24 1.49
Pre vs. Post IT 1.49 2.63* 2.19 1,21
Frequency Pre vs. Post I 0.04 0.90 0.33 1.11
Pre vs. Post II 1.21 0.01 0.59 0.01

Duration Pre vs. Post I 0.72 2.84* 1,56 2,42*
Pre vs. Post IL 1,28 2.11 3. 724* 1.51

Velocity Pre vs. Post I 0.68 0.88 0.67 0.72
Pre vs. Post IT 0.96 1.58 1.66 0.10

*p<.05 p<. 01

Tape 13.—Results of the Paired t Tests for the Pre vs. Post I and Pre vs. Post II Comparisons of the Nystagmic
Responses of the Moderate Alcohol Group to the Caloric Irrigations.

44°C to the left ear (Lw) 30°C to the right ear (Re)
Measure Comparison Task Reverie Task Reverie
Displacement Pre vs. Post I 1.42 0.76 2.39% 7. 99%**
Pre vs. Post II 2.31" 0.89 2, 33* 1.91
Frequency Pre vs. Post I 2,97" 1.02 6, 13% 4,12
Pre vs. Post I 2,98" 0.98 1.89 2.84"
Duration Pre vs. Post I 3.04* 4.144% 4,61** 4,28%*
Pre vs. Post IT 1.85 3.21% 5. 60*#* 2,83*
Velocity Pre vs. Post I 0. 54 1.37 0.40 3.07*
Pre vs. Post II 1.61 0.59 0.13 0.71

*p<.05 **p<.01 tp <,001

Tapin 14,—Results of the Paired t Tests for the Pre vs. Post I and Pre vs. Post IT Comparisons of the Nystagmic
Responses of the High Alcohol Group to the Caloric Irrigations.

44°C to the left ear (Lw) 30°C to the right ear (Re)
Measure Comparison Task Reverie Task Reverie

Displacement Pre vs. Post I 3. 56** 1.99 4, 69% 3.93**
Pre vs. Post IL 1,04 0.51 0.08 0. 62

Frequency Pre vs. Post I 1.90 1.66 7. 16*** 4, 37%
Pre vs. Post II 1.69 0.72 2.29* 0.76

Duration Pre vs. Post I 4, 07** 5.77 4, 38** 6. 644#*

Pre vs. Post IT 3. 28%* 2.41* 1.59 2.14
Velocity Pre vs. Post I 2,38* 1,01 2.09 2.03
Pre vs. Post IL 0.18 0.09 0.78 0.35

*p< 05 p< 01 p< .0l

19



‘Tapue 17.—Results of the Analyses of Variance for the Number of Degrees of Slow Phase Nystagmus and Number of
Nystagmic Eye Movements Resulting from Optokinetic Stimulation. Stimuli Were of 15 or of 60 Seconds Duration.

Lights On Lights Off
Measure Group

15-see 60-sec 15-sec 60-sec

Slow Phase Displacement Control 0.38 0.05 0.03 0.36

Moderate Alcohol 0.88 3. 46* 0.84 3.57
High Alcohol 5. 45** 4,00* 5. 26* 4,12*

Frequency Control 0.17 0.12 0.12 0.30

Moderate Alcohol 0.95 1.02 0.44 1.17
High Alcohol 7. 29%* 8. 27** 8, 27%* 8. 46**

*p< 05
* p< 001

Tain 18.—Results of the Paired t Tests for the Pre vs. Post I and Pre vs. Post II Comparisons of Nystagmic Responses
to the Optokinetic Stimuli.

15 second stimulus

60 second stimulus

Measure Group Comparison
Lights On Lights Of Lights On Lights Of
Slow Phase Displacement Control —_Pre vs. Post I 0.97 0.50 0.05 0,02
Pre vs, Post II 1.22 0.08 0.31 1.99
Moderate Pre vs. Post I 2.23 1.72 4.32% 5. 80%"
Alcohol Pre vs. Post II 0.78 0.51 2, 52* 2.01
High Pre vs. Post I 3. 10* 3.67%* 3.14* 3.65%*
Alcohol Pre vs. Post IT 0,22 3..15* 0.88 1.58
Frequency Control Pre vs. Post I All 0.84 0.11 1.1L
Pre vs. Post II 0.09 0.18 0,80 1.78
Moderate Pre vs. Post I 2.18 1.68 2.17 2. 86*
Alcohol Pre vs. Post IT 1.31 1.99 1,02 1,22
High Pre vs. Post I 3.29% 3.674% 4,06** 3.60**
Alcohol Pre vs. Post IT 0.11 2.05 1.70 2.61*
*p <.05
**D <.01
ED <.001

25



tracing of a subject’s response before and after
the ingestion of alcohol is presented in Figure 2.
These findings support the report of Bochenek
and Ormerod‘ but are contrary to results pre-
sented by Manz", Schwab and EyTM*, and
Rauschke® who indicated that alcohol enhanced
caloric nystagmus. The data presented in the
following section offer a means of resolving these
differences.

Caloric Nystagmus in Room Iilumination.
These subjects were administered caloric irriga-
tions while attempting to fixate on a target.
Under the non-aleohol condition the subjects
were able, through visual fixation, to suppress
markedly the nystagmie response to the Le
caloric irrigations (see Figure 11). However,
following the ingestion of alcohol, a low-ampli-
tude, high-frequency nystagmus was obtained
(Figure 11) and the subjects reported difficulty
in maintaining fixation.

Alcohol, therefore, interfered with the ability
of the subjects to fixate. What earlier investi-
gators had described as an enhancing effect of
alcohol on vestibular responses, can now be more
accurately attributed to the depressive effect of
alcohol on the ability of the subject to maintain
visual fixation. Since the visual fixation mech-
anism was depressed, the nystagmic response to
vestibular stimulation was more evident. (Simi-
lar results were obtained when using rotatory
stimulation.) Jatho', by indicating that alcohol
ingestion interfered with the recovery movements
of the eyes following brisk head movements, pro-
vides additional support to this view of the action
of alcohol.

The interfering effect of alcohol on fixation is
similar to the effect noted by Rashbass and
Russell? for a barbiturate (sodium amytal).
Under dark conditions, the drug had little effect
on caloric nystagmus. In the light without the
drug, the subject was able to suppress the nys-
tagmic response through visual fixation. How-
ever, following drug administration, Rashbass
and Russell*® reported that the nystagmic re-
sponse was vigorous and nearly as strong as that
obtained under conditions of total darkness.
Thus, there is a strong similarity between the
actions of sodium amytal and alcohol on the
ability of the subject to fixate visually while
undergoing caloric vestibular stimulation.

21

Optokinetic Data. The results from the opto-
kinetic trials offer further evidence concerning
the depressive effect of alcohol on the oculo-
motor system. This depressive effect is evident
in the means (Tables 15 and 16) and mean re-
sponse curves (Figures 12-16) for the slow phase
displacement and frequency measures. The re-
sults of the analyses of variance and t tests are
presented in Tables 17 and 18. Throughout the
Post I and Post II testing sessions, the responses
of the control group remained very near their
Pre levels (Tables 15 and 16). In contrast, both
the moderate and high alcohol groups evidenced
considerable Pre to Post I declines in both fre-
quency and slow phase eye displacement; the
decline for the high alcohol group was much
larger (approximately 40% compared to approxi-
mately 15% for the moderate alcohol group).
The Pre to Post I declines in mean slow phase
and frequency scores for the 60-second trials,
with the exception of the frequency measure for
the 60-second (lights off) trial, were all signifi-
cant for the moderate alcohol group (Tables 17
and 18). All of the Post I mean values for the
high alcohol group were significantly below their
Pre levels (Tables 17 and 18). The response
evidenced considerable recovery during the Post
II testing session, where only three of the means
for both alcohol groups were still significantly
below their Pre levels (Tables 17 and 18). This
depressive effect. of alcohol on optokinetic nys-
tagmus supports previous studies® 1? 1° 27 2,

The suppression of optokinetic nystagmus by
alcohol may be due either to the action of the
latter on the eye muscles or its interference with
the ability of the subject to fixate. The latter is
a definite possibility since ter Braak®, Rademaker
and ter Braak*®, and Honrubia et al.* have all
shown that optokinetic nystagmus is dependent
upon how the subject views the stimulator. A
much stronger response is evident when the sub-
ject fixates on the surface of the drum rather
than fixating in front of or behind the stimulus.

Evidence from earlier studies by Bender and
O’Brien’ and Bergman, Nathanson, and Bender?
indicate that sodium amytal also interferes with
optokinetic nystagmus. The similarity of action
of alcohol and this particular barbiturate on
optokinetic nystagmus and on the ability of the
subject to maintain visual fixation during ves-
tibular stimulation would seem to indicate that
they are affecting similar centers.



Tanuw 6.—Results of the Analyses of Variance for the Various Measures of the Nystagmic Responses Resulting from
the Caloric Irrigations.

F
Slow Phase Frequency Duration Peak Subjective
Displacement Velocity Intensity
Group (G) 0.41 2.49 3.43* 0.60 0.59
0.30 0.97 2.45 2.96 8..83**
0.10 0.32 0,32 0.02 1.05
41, 52** 6.98* 6,.23* 6.67* 0.05
4..19* 1.38 0.39 1.45 1.20
16, 334+* 17. 10*#* 30. 96% 4.02% 21, 674#*
2.25 4,32* 0.79 2.45 1.19
0.68 0.00 0.77 1.12 0.03
0.07 1.04 0.15 0,28 LAL
0.44 1.52 0.46 0.11 6.81**
0.56 0.37 0.60 0.74 0.81
0.08 1.99 2.84 0.24 0,82
0.87 0.95 0.96 0.55 0.90
2.82 0.86 0.26 0.63 2.69
Ix Trx Tex G 0.13 1.02 1.65 0.45 0.66
*p<.05
p<. 01
+p <.001

‘Tabu 7—Means and Standard Deviations for the Intensity Ratings of the Vertigo Resulting From the Caloric Irrigations.
Each Group Was Comprised of Ten Subjects.

44°C to the left ear (Lw) 30°C to the right ear (Re)
Group Condition
Pre Post I Post II Pre Post I Post II
Task M 73.8 55.0 40.5 68.5 38.5 32.5
sD 29.4 26.1 25.1 26.5 34.8 27.2
Control
Rev M 76.0 54.5 44.5 75.0 33.5 24,1
sD 33.7 26.6 27.6 26.2 20.2 22.0
Task M 85.5 79.5 35.5 66.7 32.0 16.0
sD 53.5 $2.8 36.5 33.0 17.2 171
Moderate
Alcohol
Rev M 73.8 106.3 46.5 71.5 33.8 20.0
sD 44.5 80.9 35.4 38.7 30.0 24.9
Task M 81.5 90.5 40.0 73.8 53.5 37.4
8D 35.0 54.1 29.5 32.0 31.4 27.0
High
Alcohol
Rev M 63.3 87.8 36.0 69.1 52.8 41.5
sD 36.3 58.0 35.0 31.2 45.0 34,2

16


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28


TasLe 2.—Means and Standard Deviations for the Slow Phase Nystagmus Displacement (in Degrees) Resulting from
the Caloric Irrigations. Each Group Was Comprised of Ten Subjects.

44°C to the left ear (Lw) 30°C to the right ear (Re)
Group Condition
Pre Post I Post II Pre Post I Post II
Task M 1338.1 1048.3 1087.0 1387.5 1180.7 1129.8
sp 581.2 368.9 577.4 602.6 409.4 497.1
Control
Rev M 1285.9 1018.4 909.2 1295.0 948.2 1023.5
sD 601.1 473.6 331.7 796.3 382.5 453.2
Task M 1419.4 1175.2 1136.6 1467.3 1157.9 1166.3
sD 623.5 710.2 596.1 668.1 416.0 624.3
Moderate
Alcohol
Rev M 1192.4 1071.8 1050.2 1319.3 828, 2 1078.2
sD 666.0 650.5 588.6. 415.8 360.6 650.5
Task M 1481.7 795.0 1852.0 1485.4 967.5 1496.8
sD 785.6 473.5 783.6 668.6 493.0 546.5
High
Aleohol .
Rev M 1041.8 650.8 976.8 1144.2 614.0 1039.2
sD 828.3 505.4 608.3 564.2 426.7 616.6

Tapur 3.—Mcans and Standard Deviations for the Number of Nystagmie Beats Resulting from the Calorie Irrigations.
Each Group Was Comprised of Ten Subjects.

44°C to the left ear (Lw) 30°C to the right ear (Re)
Group Condition
Pre Post I Post IL Pre Post I Post If
Task M 228.5 228.2 216.2 234.4 237.9 228.2
sD 55.2 70.4 37.2 38.0 41.3 37.7
Control
Rev M 223.4 212.6 223.5 241.0 224.9 241.1
sD 38.3 57.5 50.4 38.9 40.4 44.6
Task M 242.1 202.4 215.1 250.7 202.6 215.4
sD 102.9 77.6 98.1 80.1 60.2 87.4
Moderate
Alcohol
Rev M 220.9 193.5 196.1 255.2 170.9 201.3
sD 110.9 83.6 83.9 87.4 69.6 91.2
Task M 197.3 145.4 174.5 214.9 130.5 189.5
sD 86.4 111.0 70.0 63.8 60.5 52.0
High
Alcohol
Rev M 177.5 126.3 185.1 189.3 115.2 172.9
sD 87.6 107.4 96.5 50.1 77.0 83.4



a few seconds following stimulation. To prevent
fatigue, there was a two-minute rest period be-
tween trials. The order of presentation of the
various trials was counterbalanced.

Alcohol Ingestion and Blood Tests. Subjects
given alcohol drank a mixture of 100-proof
Smirnoff vodka and orange juice. The mixture
contained 2.5 cc of vodka per kilogram of body
weight for the high alcohol group, and 1.25 ce of
vodka per kilogram of body weight for the mod-
erate alcohol group. Subjects who were given
the calorizations in the light received a dosage
of 2 ce per kilogram. The control group drank
orange juice with a few drops of rum extract.
added to alter the taste somewhat (they were not
aware that they would not receive alcohol), All
subjects consumed their drinks in a 15-minute
period,

Venous blood samples of from three to five cc
were drawn a few minutes prior to drinking, then
one-half hour, one hour, and four hours after
ingestion of alcohol. The blood alcohol levels
were determined by means of gas chromatog-
raphy. Whereas all blood samples were analyzed
for the alcohol groups, only the first sample was
analyzed for the control group.

Scoring. The caloric nystagmus was scored
with respect to duration, frequency, slow phase
output (degrees of eye movement), and slow
phase velocity (degrees/sec) at peak slow phase
output. Only the slow phase output and fre-
quency measures were used in scoring the opto-
kinetic nystagmus. Duration refers to the time
interval between the start of the stimulus and
the last nystagmic beat. Frequency was obtained
by counting the number of nystagmic beats within
specified time intervals. Amount of slow phase
eye movement was determined by measuring (in
millimeters) the amplitude of each nystagmic
beat from slow-phase peak to baseline; these
values were summed for all beats in three-second
intervals (optokinetic trials) or five-second inter-
vals (caloric trials). These sums were converted
into degrees of slow phase eye movement by
means of calibration factors calculated from
measurements of recorded eye sweeps through
known distances demarcated on special panels;
these eye sweeps were obtained from each subject
prior to each trial. Using Bodin’s® formula, the
velocity of the eye movement was calculated from
the average angle of the slow phase of the nys-

tagmus during the five-second interval where the
slow phase output was maximum.

IV. Results and Discussion.

Blood Alcohol Levels (BAL). Means and
standard deviations for the blood alcohol levels
are presented in Table 1. The mean value for
the high alcohol group was more than double
(87 vs 38 mg.%) that of the moderate alcohol
group at the one-hour testing session, At the
Post II testing session four hours after drinking,
the mean BAL for the high alcohol group
(65 mg.%) was still above the maximum level
reached by the moderate alcohol group.

‘Tanie 1.—Means and Standard Deviations for the Blood
Alcohol Levels (in mg. per 100 ml.), Each Value is
Based on a Mean for 10 Subjects.

Time Since the Ingestion of Alcohol

Group
Thirty One Four

Minutes Hour Hours

Moderate M 41.6 38.4 8.7

Aleohol Sp) 16.7 11.2 5.0

High M 70.9 86.9 64.8

Alcohol sD 23.6 15.3 10.1

Alertness. Almost all of the mean nystagmus
scores for the Task trials were above the mean
values for the Rev trials (Tables 2 to 5). Al-
though these differences were less apparent in the
peak velocity and frequency measures, the “in-
struction” variable was significant, according to
the analyses of variance (Table 6), for all meas-
ures of the nystagmic response.

Differences in the response under the Task and
Rev conditions are evident in the nystagmic trac-
ings for one of the subjects in the high alcohol
group (Figure 2). The effects of alertness are
apparent throughout the slow phase displacement
and frequency response curves presented in Fig-
ures 3 to 10. These data support earlier work,’ § *°
in that alerting instructions produced a higher
amplitude, longer duration response. According
to the present data, instructions may also affect
the frequency and peak velocity of the slow
phase nystagmus; the latter measures were not
obtained in previous studies.

Subjective Responses. Means and standard
deviations for ratings of the intensity of “vertigo”
resulting from the caloric irrigations are pre-


Tanie 8.—Means and Standard Deviations for the Duration (in Seconds) of the Subject’s “Vertigo” Sensations Resulting
from the Caloric Irrigations under the Task Condition.

44°C to the left ear (Lw)

30°C to the right ear (Re)

Group
Pre Post I Post II Pre Post I Post II
Control M 74.0 70.1 55.2 84.7 66.1 49,4
sD 22.4 19.3 16.7 23.3 21.4 22.9
Moderate M 85.0 73.7 46.5 62.1 62.3 38.1
Alcohol sD 29.5 20.8 30.1 38.3 28.3 27.1
High M 76.4 67.8 53.1 84.7 58.7 55.3
Alcohol sD 31.2 20.1 24.8 35.8 29.6 26.2

sented in Table 7; the durations of those sensa-
tions are noted in Table 8. Results of the analyses
of variance for these two measures (Tables 6 and
9) indicate a significant effect for the “trial”
factor, i.e. for Pre to Post. I to Post IT changes
in the intensity and duration of the “vertigo”

Taniy 9.—Results of the Analysis of Variance for the
Durations of the Subjects’ “Vertigo” Sensations
Resulting from the Calorie Irrigations

Source df Mean F
Squares

Groups (G) 2 510.27 0.24
Sub/Group (S/G) 27 2,121.81
Temperature (Te) 1 900. 48 1.13
TexG 2 1,068.07 1.34
Tex S/G 27 800.00
Trial (Tr) 2 12, 069. 52 31.71%"
TrxG 4 371.74 0.98
TrxS/G 54 380. 64
Trx Te 2 178.38 0.64
Trx TexG 4 454, 89 1.64
Trx TexS/G 54 277.92
#4 <.001

sensations, The “temperature” and “temperature
by trial” factors were also significant for the
intensity ratings.

A comparison of the mean intensity ratings
for the Lw and the Re trials revealed a possible
differential effect of alcohol. The Pre to Post I
declines in the intensity of the Re calories ap-
peared to occur equally for all three groups
(alcohol apparently produced ‘ little change).
However, the Post I intensity ratings by both
alcohol groups for the Lw trials were nearly the
same as or above, their Pre levels. In contrast,
the control group evidenced a decline in intensity

17

ratings. These rating differences between the
two stimulus temperatures, produced the signifi-
cant “trials by temperature” interaction and also
contributed to the significant effect noted for
“temperature.”

With the exception of the Lw trials for the
moderate alcohol group, the Post IT mean in-
tensity ratings were all significantly below their
Pre levels (Table 10).

The durations of the “vertigo” sensations failed
to evidence any significant alcohol effect. For all
groups, the durations for the Post I trials were
somewhat lower than their Pre levels although
most of these declines were not significant accord-
ing to t tests. However, the Pre to Post IT
declines were significant for all trials, except the
Lw trial for the control group (Table 11).

There was little evidence of any suppressive
effect of alcohol on the “vertigo” sensations re-
sulting from the caloric irrigations. The differ-
ential effect of alcohol on the intensity ratings
depending upon stimulus temperature was not
evident in the “vertigo” duration data or in any
of the objective (nystagmic) measures of the
response. Further research is required to deter-
mine if the difference between Lw and Re in-
tensity ratings is artifactual or a result of the
ingestion of alcohol.

The most noticeable change in the subjective
measures was a steady decline from the Pre to
Post II trials. Since the nystagmic response was
always in the same direction, the decline would
appear to be due to repeated stimulation (i.e.,
habituation). These effects were more evident in
the “vertigo” responses than in any of the objec-
tive (nystagmic) measures.



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age number of nystagmic eye movements (lower half) resulting from the 15-second optokinetic trials. “Lights
off” indicates that the room lights were turned off immediately after the end of the stimulus.

TIME IN SECONDS

and markings are identical to those used in Figure 12.

23

Other symbols


TECHNICAL REPORT STANCARD TITLE PAGE

1. Report No. 2, Government Accession No. 3. Recipient's Catalog No.
FAA-AM=71-6

4. Title and Subtitle 5. Report Date

ALCOHOL AND DISORIENTATION-RELATED RESPONSES. I. February 1971
NYSTAGMUS AND "VERTIGO" DURING CALORIC AND OPTO- 3, Performing Organization Code
KINETIC STIMULATION

7. Authorle) B. Performing Organization Report No.

David J. Schroeder, Ph.D.

9. Performing Organization Name and Address 10. Work Unit No.
FAA Civil Aeromedical Institute
P. 0. Box 25082 Ti. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report ond Period Covered

T2. Sponsoring Agency Name and Address
Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, S.W.
Washington, D. C. 20590

OAM Report

14. Sponsoring Agency Code

15. Supplementary Notes
The study was conducted under Tasks AM-B-69-Psy-10, AM-A-70-PSY-10,
and AM-A-71-PSY~-27.

16, Abstract

Although the sensory systems (vestibular and visual) most involved in disorientation
and "pilot's vertigo" would appear to be affected by the ingestion of alcohol, the
locus and nature of the effect are not established. For example, there are
apparently conflicting data concerning the effects of alcohol on vestibular responses
to caloric irrigations. While some authors report that alcohol enhances vestibular
responses, others indicate response suppression,

This study was designed to investigate the effects of two levels of alcohol on the
“vertigo” and nystagmic responses resulting from caloric irrigations with visual
conditions and the alertness of the subjects carefully controlled, Additional infor-
mation concerning the effects of alcohol on optokinetic nystagmus was also obtained.

The data clearly indicate that alcohol suppresses the nystagmic response to caloriza-|
tions in total darkness. However, under conditions where visual fixation is permitte}
and where visual fixation would normally inhibit caloric vestibular responses, the
ingestion of alcohol results in a high-frequency, low-amplitude nystagmus. This
response, however, is not due to increased vestibular sensitivity, but rather to the
suppression, by alcohol (directly or indirectly), of the visual fixation system.
This visual inhibition was also evident in the suppression of the optokinetic
response by alcohol. "Vertigo" responses to caloric irrigations showed only slight
suppression or some enhancement in darkness following alcohol ingestion; however,
blurring of vision was prominent when visual fixation was permitted.

17. Key Words 18. Distribution Statement

Availability is unlimited. Document may
be released to the National Technical

Alcohol, Nystagmus, Vestibular, Visual

Fixation Information Service, Springfield, Virginia
22151, for sale to the public.
19. Security Classif. (of this report) 2. Security Classif. (of this page) 21. No. of Pages 22. Price
Unclassified Unclassified 29 $3.00

Form DOT F 1700.7 (e-69)



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REFERENCES

Bender, M. B. and F. H. O’Brien: The influence of
barbiturate on various forms of nystagmus. AMER-
ICAN JOURNAL OF OPHTHALMOLOGY, 29:1541—
1542, 1946.

. Bergman, P. S., M. Nathanson, and M. B. Bender:

Electrical recording of normal and abnormal eye
movements modified by drugs, ARCHIVES OF
NEUROLOGY AND PSYCHIATRY,  67:357-374,
1952.

. Blomberg, L. H. and A. Wassen: The effect of small

doses of alcohol on the “optokinetic fusion limit,”
ACTA PHYSIOLOGICA SCANDINAVIA, 54 :193-199,
1962.

Z. and F. ©. Ormerod: The inhibitory
action of certain substances on the response to ves-
tibular stimulation, JOURNAL OF LARYNGOLOGY
AND OTOLOGY, 76 :39-44, 1962.

. Bodin, M. A.; Some practical notes for the analysis

of post-rotational nystagmus by determination of
time constants of decays. Unpublished manuscript,
1966.

J. W. G.: Untersuchungen uber opto-
kinetischen Nystagmus, ARCHIVES NEERLAND-
AISES DE PHYSIOLOGIE DE L’'HOMME ET DES
ANIMAUX, 21 :309-876, 1936.

. Collins, W. E.: Effects of mental set upon vestibular

nystagmus, JOURNAL OF EXPERIMENTAL PSY-
CHOLOGY, 63 :191-197, 1962.

Collins, W. E.: Manipulation of arousal and its
effects upon human vestibular nystagmus induced by
caloric irrigation and angular accelerations, AERO-
SPACE MEDICINE, 34:124-129, 1963.

. Collins, W. E.: Subjective responses and nystagmus

following repeated unilateral caloric stimulation,
ANNALS OF OTOLOGY, RHINOLOGY, AND
LARYNGOLOGY, 74 :1034-1054, 1965.

Collins, W. E.: Task-control of arousal and the
effects of repeated unidirectional angular accelera-
tion on human vestibular responses, ACTA OTO-
LARYNGOLOGICA SUPPLEMENTUM, 190:1-34,
1964.

Collins, W. E., R. A. Mertens, and D, J. Schroeder:
Caloric and rotation-induced “vertigo” responses
following habituation to unidirectional caloric stimu-
lation in total darkness. Paper presented at the
Aerospace Medical Association meeting in San Fran-
cisco, May 1969.

Ey, W.: Stortungen des oculo-vestibularen Systems
bei alkoholisierten Personen, BERICHT: DEUTSCH

29

14,

15.

16.

17.

18,

19.

20.

22.

23.

24.

OPHTHALMOLOGISCHE GESSELSCHAFT, 65:

349-353, 1964.

. Honrubia, W., W. C. Downey, D. P. Mitchell, and

P. H. Ward: Experimental studies in optokinetic
nystagmus. If. Normal humans, ACTA OTO-
LARYNGOLOGICA, 65 :441-448, 1968.

Jatho, K.: Die Wirkung der Alkoholintoxication auf
den Vestibularapparat unter besonderer Berucksichti-
gung der Storungen der vestibular-okulomotorischen
Regelfunktion, II. Mitteilung Ergebnisse experi-
menteller Untersuchungen, ZEITSCHRIFT FUR
LARYNGOLOGIE, RHINOLOGIE, OTOLOGIE UND
IHRE GRENZGEBLETE, 44:105-108, 1965.
Krauland, W., R. Schuster, and R. Klein: Uber das
Verhalten des optokinetischen Nystagmus bei alko-
holisierten personen, DEUTSCHE ZEYTSCHRIFT
FUR DIE GESAMTE GERICHTLICHE MEDIZIN,
51 :429-440, 1961.

Manz, Rudolf. Der Einfluss geringer Alkoholgaben
auf Teilfunktionen von Auge and Ohr, DEUTSCHE
ZEITSCHRIFT FUR DIE GESAMTE GERICHT-
LICHE MEDIZIN, 32: 301-312, 1940.

Mizoi, Y., ‘f. Ishido, and N. Ohga: Studies on post-
rotatory nystagmus in alcohol intoxication, JAPA-
NESE JOURNAL OF LEGAL MEDICINE, 16:247-
260, 1962.

Rademaker, G. C. J., and J. W. G. ter Braak: On
the central mechanism of some optic reactions,
BRAIN, 71:48-76, 1948,

Rashbass, C. and G. F. M. Russell: Action of a
barbiturate drug (amylobarbitone sodium) on the
yestibulo-ocular reflex, BRAIN, 84:829-385, 1961.
Rausehke, J.: Alkohol-Nystagmus und Leistung-
schadigung, MEDIZINISCHE, 12 :460-465, 1958.

. Schroeder, D. J.: Alcohol and disorientation-related

responses. II. Nystagmus and “vertigo” during
angular acceleration. FAA OAM Report No. 71-16,
1971.

Schwab, W. and W. Ey: Experimentelle Unter-
suchungen an Hor-und Gleichgewichtsapparat unter
Alkohol, ARCHIV FUR OHREN-NASEN UND
KEHLKOPFHEILKUNDE, 164 :519-528, 1954.
Schwab, W. and W. Ey: Das Hor-und Gleichg-
weichtsorgan beim Menschen under akuter Alko-
holeinwirkung; klinisch experimentelle Ergebnisse
und Moglichkeiten der praktischen Auswertung,
MUNCHENER MEDIZINISCHE WOCHEN-
SCHRIFT, 97 :658-662, 1955.

Scofield, C. F.: The effects of mild doses of alcohol
and caffeine on optic nystagmus, PSYCHOLOGICAL
MONOGRAPHS, 47 :217-241, 1936,



Tasiy 4.—Means and Standard Deviations for the Peak Velocity (Deg/Sec) of the Slow Phase Nystagmus Resulting

From the Caloric Irrigations. Each Group Was Comprised of Ten Subjects.

44°C to the left ear (Lw)

30°C to the right ear (Re)

Group Condition
Pre Post I Post IT Pre Post I Post II
Task M 19.2 17.8 16.8 18.3 16.9 15.8
sD 7.8 5.6 6.1 6.5 5.5 6.7
Control
Rev M 20.1 18.4 17.3 16.6 14.8 16.3
sD 8.5 6.9 6.5 8.4 5.9 5.1
Task M 23.4 22.1 20.5 21.7 20.4 21.2
SD 13.3 12.6 10.0 10.6 9.0 14.7
Moderate
Alcohol
Rev M 19.6 23.2 21.8 20.4 17.2 19.0
SD 13.4 14.3 9.6 8.2 6.8 9.5
Task M 24.8 1.4 24.4 20.6 17.2 22.1
sD 9.5 8.5 10,2 6.8 Tl 8.5
High
Alcohol
Rev M 1.8 16.5 21.4 19.2 15.4 18.4
sD 19.5 8.3 10.0 7.0 7 10.0

Tapiz 5.—Means and Standard Deviations for the Duration (in Seconds) of the Nystagmus Resulting From the Caloric
Irrigations. Each Group Was Comprised of Ten Subjects.

44°C to the left ear (Lw)

30°C to the right ear (Re)

Group _ Condition —
Pre Post I Post II Pre Post I Post I
Task M 163.3 187.2 150.8 182.3 166.8 161.4
sD 36.0 20.9 25.9 48.3 23.5 38.4
Control
Rev M 153.4 181.8 138.0 169.8 148.4 157.2
sD 29.9 21.3 19.2 30.9 24,2 27.0
Task M 187.1 149.5 161.2 185.3 156.4 166.4
sD 54.1 29.1 38.6 29.2 12.1 24,1
Moderate
Alcohol
Rev M 185.8 137.4 145.6 186.8 130.6 156.1
I) 52.0 41.4 44.6 35.4 35.6 30.5
Task M 162.5 108.1 135.6 171,0 128.7 149, 2
sD 25.6 48.4 21.7 Si. 30.6 34.4
High
Aleohol
Rev M 145.0 100.5 127.1 161.0 116.6 118.6
sD 25.9 38.3 17.3 30.0 38.7 50.9



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Optokinetic Drum. Horizontal optokinetic
nystagmus was elicited by rotation of a drum
positioned upright and painted alternately with
black (2-inch) and white (214-inch) stripes
along the longitudinal axis. The drum, 20 inches
in diameter and 16 inches high, was located three
feet in front of the subject. The drum speed
was set at eight rpm.

Recording. Silver disc electrodes were taped
by the outer canthi of the eyes to record hori-
zontal components of eye movements. An elec-
trode on the forehead served as a ground. The
electrodes picked up the changes in corneoretinal
potential that were relayed through a terminal
board to Offner recorders. These signals were
then amplified and recorded using a three-second
time constant.

Ill. Procedure.

Calorizations in Darkness. The caloric irri-
gations were administered while the subject re-
clined in a supine position on an examining table
in total darkness (see Figure 1). The subject’s
head was anteverted 30° by means of a head
rest which also served as a water receptacle.?

There were four caloric trials consisting of
two irrigations of the right ear with water at
30° C. (Re) and two irrigations of the left ear
with water at 44° C. (Lw). Both stimuli drive
nystagmus in the same direction, with the fast
phases of the eye movement to the left.

Prior to each trial, the subject was given in-
structions designed either to enhance or reduce
alertness. Under the Alert condition, the subject
was instructed to signal, by depression of a
microswitch, the start, peak, and end of his
“vertigo” sensation; he was also instructed to
pay careful attention to his sensation so that he
could describe it and rate its intensity at the
end of the trial. A few seconds after signaling
the end of his sensation, the subject was given
a reaction-time task, ie., he was told to react as
quickly as possible, by depression of the micro-
switch, to a series of 500 eps tones, each 1/10 of
a second in duration. The reaction time task was
used purely as an alerting technique.**° For the
Reduced Alertness Condition (Reverie), the sub-
ject was instructed to relax, ignore the environ-
ment, and daydream. Each subject received one
Re and Lw trial in the Alert condition and one
Re and Lw trial in the Reverie condition. The

order in which the subjects received these tasks
was counterbalanced. Trials were separated by
15-minute periods to insure a return to normal
of the temperature within the ear.

At the end of the second calorization, the sub-
ject was asked to rate the two trials in terms of
the intensity of the sensations. The trial with
the stronger sensation was rated as 100% and all
others were rated in reference to it. The subject
was instructed to remember the 100% trial be-
cause his ratings during subsequent testing would
be made in reference to that rating. This tech-
nique has been: used successfully in previous
studies.° +

The foregoing procedure for Pre-ingestion
testing was repeated the following day after
drinking. Post-ingestion sessions, I and ITI re-
spectively, started 45 minutes and four hours
after drinking.

Calorization in Room Illumination. Six addi-
tional subjects were administered Le caloric irri-
gations with the room lights on. Under this
condition, the subject was instructed to fixate on
a black dot located on the ceiling directly above
him. These Le irrigations were administered
one hour before and 45 minutes after the inges-
tion of alcohol.

Optokinetic Stimulation. Immediately follow-
ing each caloric testing session, the subject was
taken to an adjoining room and seated in front
of the optokinetic drum. He was told to fixate
on the surface of the drum during its rotation
and to maintain fixation after the rotation had
ended until he was told that the test was over.
While watching the drum, the subject was in-
structed not to track the stripes actively, but to
let his eyes follow naturally.

A 10-second practice trial was conducted to
insure that the subject was watching correctly
and to check the nystagmus recording. The test-
ing session comprised four trials; two involved
60 seconds and two involved 15 seconds of opto-
kinetic stimulation. For one 15-second and one
60-second trial, the light was turned off at the
end of the stimulus period. The subject’s eye
movements were recorded throughout the stimulus
period and for a subsequent period of 30 seconds
in darkness. On the other 15- and 60-second
trials the drum was stopped at the end of the
stimulus period and the lights remained on. The
subject’s response was recorded during and for


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ALCOHOL AND DISORIENTATION-RELATED RESPONSES.
I. NYSTAGMUS AND “VERTIGO” DURING CALORIC AND
OPTOKINETIC STIMULATION

I. Introduction.

Although the sensory systems (vestibular and
visual) most involved in disorientation and
“pilot’s vertigo” would appear to be affected by
the ingestion of alcohol, the locus and nature of
the effect are not established. For example, there
are apparently conflicting data concerning the
effects of alcohol on vestibular responses to
caloric irrigations. Manz‘? found that the dura-
tion of caloric nystagmus (a patterned eye-
movement response) frequently was prolonged
under alcohol; in one case, it increased as much
as 59 seconds. Schwab and Ey”** reported
variability (shortening in most cases) in the
duration of the nystagmic responses to caloriza-
tions following alcohol ingestion; however, they
also noted a reduction in the latency of the first
nystagmic beat. The latter finding was supported
by the work of Rauschke® who indicated an
earlier onset of caloric nystagmus following
alcohol consumption.

Data from a study by Bochenek and Ormerod*
contradicted the conclusions reached in earlier
studies; the response following alcohol ingestion
was reported to be clearly suppressed although
the authors failed to present any quantitative
data concerning the extent of the suppression.
The difference in results between early studies
and those of Bochenek and Ormerod‘ may be
due to the fact that visual fixation was allowed

Data presented here were submitted to the Psychology
Department, University of Oklahoma, in partial fulfill-
ment of the requirements for the degree of Doctor of
Philosophy under the guidance of Dr. William E, Collins.
The assistance of Gail Kranz, Ruth Ann Mertens,
Cynthia Cochran, Carlyn Manley, and Nancy Rice in the
conduct of this study, of Dr. Earl Folk and Mrs. Rosalie
Melton for some of the statistical analyses, and of
Dr. Delbert Lacefield and Mrs. Pat Roberts in the col-
lection and analysis of the blood samples, is gratefully
acknowledged.

in the earlier studies whereas Bochenek and
Ormerod! recorded the response under conditions
of total darkness.

An additional factor which was not controlled
in previous alcohol studies concerns the effect of
variations in alertness on the response to caloric
irrigations. Collins? *?° has shown that instruc-
tions designed to maintain alertness result in a
nystagmus of higher amplitude and longer dura-
tion than that obtained when the subject is in-
structed to relax and daydream. Control over
alertness would seem to be especially important
in studies involving pre and post testing, or in
studies where depressants are used.

This study was designed to investigate the
effects of two levels of alcohol on the nystagmic
response to calorization with visual stimulation
and alertness of the subjects systematically varied.
Additional information was obtained concerning
the effects of alcohol on optokinetic nystagmus.

II. Method.

Subjects. Subjects were 30 male college stu-
dents with no previous laboratory experience in-
volving vestibular stimulation. They ranged
from 21 to 30 years of age and were randomly
placed in three groups of 10 each. One group
was designated as “high alcohol,” one as “mod-
erate alcohol,” and the other served as a control
group without alcohol.

Caloric Apparatus. Two water baths equipped
with Bronwill constant temperature circulators
maintained water temperature at 380° C. and
44° C. Rubber tubing from the base of the water
baths passed through solenoids and ended in
plastic nozzles through which the caloric stimuli
were administered. The solenoids were opened.
and closed by a foot switch, through a Hunter
electric timer, to provide a 30-second period of
irrigation; the rate of water flow was 15 cc per
second.



‘Tanim 15.—Means and Standard Deviations for the Slow Phase Nystagmus Displacement (in Degrees) Resulting From
the Optokinetic Stimuli. Each Group Was Comprised of Ten Subjects.

15 see 60 sec
Group Condition
Pre Post I Post IT Pre Post I Post II
Lights M 165.1 155.8 158.0 616.7 618.0 604.4
On 8D 25.4 29.5 32.4 126.0 78.3 105.5
Control
Lights M 160.9 163.4 161.3 641.4 641.8 610.4
Off SD 15.9 27.1 23.9 79.1 103.6 99.0
Lights M 157.3 138.9 150.3 637.1 518.4 551.4
On SD 15.7 36.6 36.4 75.5 114.4 117.2
Moderate
Alcohol
Lights M 151.8 136.2 148.5 620.6 483.0 553.2
Off SD 21.0 34.4 28.4 88.3 119.8 132.9
Lights M 141.5 94.6 138.8 540.7 344.6 505.6
On sD 26.9 43.5 34.7 82.8 226.9 154.0
High
Alcohol
Lights M 154.6 92.1 129.7 580.6 343.2 511.4
of sD 23.3 58.5 28.4 145.5 260.0 140.7

Tasie 16.—Means and Standard Deviations for the Number of Nystagmic Beats Resulting From the Optokinetic
Stimuli. Each Group Was Comprised of Ten Subjects.

15 see 60 sec
Group Condition
Pre Post I Post If Pre Post I Post II
Lights M 39.4 41.0 39.6 148.0 147.4 151.9
On SD 5.6 6.2 7.8 26.9 18.4 20.5
Control
Lights M 42.1 41,1 42.2 154,2 158.4 159.9
Of SD 4.9 5.9 5.7 14.5 16.4 16.8
Lights M 38.2 33.1 33.7 144.4 124.1 135.1
On SD 7.6 9.3 10.0 34.5 27.2 33.4
Moderate
Alcohol
Lights M 36.4 33.0 34.0 136.2 115.3 126.5
Off sD 8.1 8.7 8.1 311 26.0 30.8
Lights M 35.6 24,7 35.8 141.4 81.7 130.5
On sD 8.0 6.5 6.1 31.3 46.7 22.6
High Aleohol
Lights M 37.9 23.6 34.8 140,2 73.5 124.3
Off SD 5.4 11,0 74 20.7 55.9 27.3





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