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The reactivity of alumina cream foci in rabbits
747
ELECTROENCEPHALOGRAPHY AND CLINICAL NEHROPHYSIOLOGY
CLINICAL
AND
LABORATORY
THE REACTIVITY OF ALUMINA IN RABBITS
NOTES CREAM FOCI
S. L. VISSER, M.D. Valeriuskliniek, Amsterdam (The Netherlands) (Received for publication: February 7, 1962) INTRODUCTION
METHOD
In 1942 Kopeloff et al. introduced the method of producing chronic epileptogenic foci experimentally in test animals with the aid of alumina cream. This method has since been used, in various modifications, in a variety of experiments. It has been pointed out by several investigators that the quantity and the intensity of the focal activity produced show relatively marked fluctuations from time to time. Chow and Obrist (1954) saw maximal focal activity during sleep. Schmalbach and Steinmann (1955) mentioned that pathological activity is sometimes almost continuous, whereas at another time, between the clinical seizures, the EEG is virtually free from pathological activity. Morrell (1959) also pointed out that this pathological activity sometimes shows considerable variability. He established an individual variability in focal activity from day to day (Morrell et al. 1959). In the course of our experiments, in which foci were produced with alumina cream in rabbits, a special study was made of fluctuation and variability in the amount of the pathological focal activity. It was found that extrinsic conditions exerted a striking influence on the pathological activity.
The alumina cream was prepared according to the original prescription of Kopeloff et al. (1942). Surgery on the rabbits was carried out under general (urethane) and local (procaine) anaesthesia. A quantity of 0.1 ml alumina cream was injected into, and immediately below, the parieto-occipital cortex. The injection was given at point D, c, - - 4 according to the coordinates indicated by Monnier and Gangloff (1961). The injection was made into the sensory cortex because, with a view to further investigations, no clinically manifest seizures were primarily required; the object was merely to study pathological focal activity in the EEG. Permanent electrodes were fixed in the skull for direct registration of the electrocorticogram. At first two electrodes were applied, parieto-occipital (coordinates D, c), one on the left and one on the right side. Subsequently four were used, namely, left and right on the premotor cortex (coordinates A, b) and left and right on the occipital cortex (coordinates E, c). The degree of pathological focal activily was expressed in per cent time, calculated, as a rule, over 10-minute periods. All delta, sharp wave and spike
TABLE I Per cent time focal activity (calculated from a 10-min record) Rabbit V 1st
2nd
9 5 5 3 13 9 7 3 9 4 M--6.7
11 5 6 7 14 6 10 10 15 10 M--9.4
Rabbit V1 1st 5 1 6 1 3 6 2 2 1 2 M~2.9
2rid 6 3 10 3 4 4 2 5 3 5 M--4.5
Rabbit VIII 1st 19 3 6 4 27 11 6 2 2 4 M=8.4
Rabbit 1X
2ha
1st
2ha
16 1 22 11 24 19 10 5 9 9 M -- 12.6
3 9 15 3 3 l 1 2 3 3
9 17 16 10 3 1 2 2 6 6 M--7.2
M
4.3
Rabbit XV 1st 21 6 10 4 10 5 8 12 11 10 M--9.7 M
2rid 16 17 11 8 4 2 9 20 15 7 -
10.9
Comparison of the amount of focal activity between a first and a second recording with a 30-minute interval. Observations in the course of 10 days. The Wilcoxon signed rank test proved that four (V, VI, VIII, IX) of the five rabbits showed a statistically significant increase (P <0.05) of focal activity.
Electroenceph. clin. Neurophysiol., 1962, 1 4 : 7 4 7 - 7 5 0
748
s.L.
VISSER t
!
AS LE -LPO
LPO-RPO
RPO-RE RABBIT AS LE - L P O
LPO-RPO
RPO-RE RABBIT !
!
AS LE -LPO
LPO-RPO
RPO-RE RABBIT ' ~ Fig. 1 Suppression of pathlogical focal activity by means of an auditory stimulus. L E - L P O : left e a r - l e f t parieto-occipital; L P O - R P O : left p a r i e t o - o c c i p i t a l - r i g h t parieto-oceipital; R P O - RE: right parieto-occipital- right ear; AS: auditory stimulus. Calibrations: 200 ,uV/cm and 1 sec/3 cm. activity was regarded as being pathological focal activity. Such bilateral changes as occurred were, if unilateral phase reversal was present and if the amplitude was larger on that side, also regarded as being pathological focal activity. RESHLTS
The following observations demonstrate the influence which may be exerted by extrinsic conditions on the fluctuation in the amount of pathological focal activity. It was repeatedly found possible to suppress pathological focal activity by means of an auditory
stimulus. The focal activity was abruptly arrested in response to the stimulus, while attenuation often occurred more or less unmistakably on the contralateral side. Fig. i illustrates this phenomenon, as it was seen in different test a n i m a l s When two animals, each with an alumina cream focus, were simultaneously submitted to E E G examination, the fluctuation in the amount of the pathological activity often showed a strikingly parallel course in the two animals. This was found by comparison of the data obtained at hourly intervals in the course of a day (Fig. 2A). It was also often shown by comparison of series of consecutive 20-second
Electroenceph. clin. NeurophysioL, 1962, 14:747-750
REACTIVITY OF ALLIMINA CREAM FOCI (A) 3O
~
20
o
10
--
rabbi%
IiA'
....
rabbit 3/2]I
,
"
,.'-. ",, '
,/ / ".
.
.
.
rvl
(B)
tI
t~ / ~
•
4
749
--rabbi+. .... rabbi+. ~23Z[
.53C
~2c
/
! I
~10
I I
i
1 2 1 3 14 15 Time (h)
16 17 18 19 2 0 21 22 23 24 (A) - - r a b b i t
2 3 4 5 Time (rain)
7
(B)
X
- - - rabbi% ~
30
1
I 8
--rabbi+.
....
~_>'30 >
r a b b i t ]E
.>
-~ 2o
o 2C "6 tJ
,2.o
10 .o
/.....-------_.~ 8
10 12 Time (h)
14
10
10
20
I
2
34 56 T i m e (rain)
7
•
9
10
Fig. 2 Fluctuation of the per cent time focal activity in the course of time simultaneously recorded with two rabbits. A: data of 10-minute periods at intervals in the course of one day; B: data of a series of consecutive 20-second periods in the course of a continuous registration.
periods in the course of a continuous registration (Fig. 2B). A striking feature of Fig. 2B (of the rabbits V and VIII) is that the first two peaks in these animals show a virtually parallel course, while the third peak, which is relatively low in rabbit VIII, no longer appears in rabbit V. As a rule, the pathological activity of the focus at the beginning of a period of observation was less than that seen at renewed registration some time later. Focal activity was suppressed, therefore, immediately after transfer of the animals from their cages to the examination room; after some time, the pathological activity showed, as a rule, increase. Up till now operations have been done on fifteen rabbits, eleven of which showed a focus 1-5 weeks after the operation. At a certain time five available rabbits with a focus were chosen to prove this observation. Details on these observations are presented in Table I, which also gives the statistical account.
observed suppression of the focal activity of the amygdaloid nucleus in the cat by sensory stimuli. The observations described above would seem to warrant the conclusion that extrinsic conditions exert an influence on pathological focal activity'. This influence is based, at least partly, on the suppression of focal activity by attention-alerting stimuli. On the other hand, pathological activity increases when concentration of attention on the environment diminishes. This agrees well with the observation of Chow and Obrist (1954), who saw maximal focal activity during sleep. It can therefore be assumed that a correlation exists between the activity of an alumina cream focus in the rabbit and the degree of alertness of the test animal. In order to obtain comparable results in pharmacological experiments, care should be taken to examine simultaneously the test animal and a control animal.
DI SCLIS SION
SUMMARY
The three observations described all indicate an extrinsic influence on pathological focal activity arising from alumina cream foci. For the first and the third observation, this influence can be described as an alerting effect. The same holds true for the second part of the second observation. On the basis of the curves in Fig. 2A, the possibility of diurnal fluctuations must be taken into consideration in addition to possible alerting effects. This suppression phenomenon has been investigated only on interictal paroxysms. Vigouroux (1959) also
An electroencephalographic study of loci produced in rabbits by the alumina cream method of Kopeloff et al. (1942) shows that there are extrinsic conditions which exert an influence on the amount of the pathological focal activity. This influence is revealed by the fact that alerting stimuli suppress focal activity, while pathological activity increases when the concentration of attention on the environment diminishes. It can be assumed that there is correlation between the amount of the pathological focal activity and the degree of alertness of the test animal.
Electroenceph. clin. NeurophysioL, 1962, 1 4 : 7 4 7 - 7 5 0
750
S . L . VISSER
I wish to express my thanks to R.P. van Hoeven (Laboratory for Chemical Physiology of the Free University, Amsterdam) for preparing the alumina cream. REFERENCES ChoW, K. L. and OBRIST, W. D. E E G changes on application of AI(OH):~ cream on the cortex. A. M. A. Arch. Neurol. Psychiat., 1954, 72: 80-87. KOPELOFF, L. M., BARRERA, S. E. and KOPELOFF, N. Convulsive seizures produced by immunologic and chemical means. Amer. J. Psychiat., 1942, 98: 881-902. MONNIER, M. and GANGLOFF, H. Atlas for stereotaxic
brain research on the conscious rabbit. Elsevier, Amsterdam, 1961, 76 p. MORRELL, F. Experimental focal epilepsy in animals. A. M. A. Arch. Neurol. Psychiat., 1959, 1: 141147. MORRELL, F., BRADLEY, W. and PTASHNE, M. Effect of drugs on chronic epileptogenic lesions. Neurology (Minneap.), 1959, 9: 492-498. SCHMALBACH, K. und STEINMANN, H. W. Bioelektrische Untersuchungen mit chronischen epileptogenen L~isionen. Dtsch. Z. ,Vervenh., 1955, 173: 377-384. VIGOUROUX, R. P. Physiologie dt,~ rhinenc~phale non olfactifi Thbse, Ed. Charbonnier, Marseille, 1959, 164 p.
Reference: VISSER, S. L. The reactivity of alumina cream foci in rabbits. Electroenceph, clin. Neurophysiol., 1962, 14: 747-750.
ELECTROENCEPHALOGRAPHY AND CLINICAL NEHROPHYSIOLOGY
CLINICAL
AND
LABORATORY
THE REACTIVITY OF ALUMINA IN RABBITS
NOTES CREAM FOCI
S. L. VISSER, M.D. Valeriuskliniek, Amsterdam (The Netherlands) (Received for publication: February 7, 1962) INTRODUCTION
METHOD
In 1942 Kopeloff et al. introduced the method of producing chronic epileptogenic foci experimentally in test animals with the aid of alumina cream. This method has since been used, in various modifications, in a variety of experiments. It has been pointed out by several investigators that the quantity and the intensity of the focal activity produced show relatively marked fluctuations from time to time. Chow and Obrist (1954) saw maximal focal activity during sleep. Schmalbach and Steinmann (1955) mentioned that pathological activity is sometimes almost continuous, whereas at another time, between the clinical seizures, the EEG is virtually free from pathological activity. Morrell (1959) also pointed out that this pathological activity sometimes shows considerable variability. He established an individual variability in focal activity from day to day (Morrell et al. 1959). In the course of our experiments, in which foci were produced with alumina cream in rabbits, a special study was made of fluctuation and variability in the amount of the pathological focal activity. It was found that extrinsic conditions exerted a striking influence on the pathological activity.
The alumina cream was prepared according to the original prescription of Kopeloff et al. (1942). Surgery on the rabbits was carried out under general (urethane) and local (procaine) anaesthesia. A quantity of 0.1 ml alumina cream was injected into, and immediately below, the parieto-occipital cortex. The injection was given at point D, c, - - 4 according to the coordinates indicated by Monnier and Gangloff (1961). The injection was made into the sensory cortex because, with a view to further investigations, no clinically manifest seizures were primarily required; the object was merely to study pathological focal activity in the EEG. Permanent electrodes were fixed in the skull for direct registration of the electrocorticogram. At first two electrodes were applied, parieto-occipital (coordinates D, c), one on the left and one on the right side. Subsequently four were used, namely, left and right on the premotor cortex (coordinates A, b) and left and right on the occipital cortex (coordinates E, c). The degree of pathological focal activily was expressed in per cent time, calculated, as a rule, over 10-minute periods. All delta, sharp wave and spike
TABLE I Per cent time focal activity (calculated from a 10-min record) Rabbit V 1st
2nd
9 5 5 3 13 9 7 3 9 4 M--6.7
11 5 6 7 14 6 10 10 15 10 M--9.4
Rabbit V1 1st 5 1 6 1 3 6 2 2 1 2 M~2.9
2rid 6 3 10 3 4 4 2 5 3 5 M--4.5
Rabbit VIII 1st 19 3 6 4 27 11 6 2 2 4 M=8.4
Rabbit 1X
2ha
1st
2ha
16 1 22 11 24 19 10 5 9 9 M -- 12.6
3 9 15 3 3 l 1 2 3 3
9 17 16 10 3 1 2 2 6 6 M--7.2
M
4.3
Rabbit XV 1st 21 6 10 4 10 5 8 12 11 10 M--9.7 M
2rid 16 17 11 8 4 2 9 20 15 7 -
10.9
Comparison of the amount of focal activity between a first and a second recording with a 30-minute interval. Observations in the course of 10 days. The Wilcoxon signed rank test proved that four (V, VI, VIII, IX) of the five rabbits showed a statistically significant increase (P <0.05) of focal activity.
Electroenceph. clin. Neurophysiol., 1962, 1 4 : 7 4 7 - 7 5 0
748
s.L.
VISSER t
!
AS LE -LPO
LPO-RPO
RPO-RE RABBIT AS LE - L P O
LPO-RPO
RPO-RE RABBIT !
!
AS LE -LPO
LPO-RPO
RPO-RE RABBIT ' ~ Fig. 1 Suppression of pathlogical focal activity by means of an auditory stimulus. L E - L P O : left e a r - l e f t parieto-occipital; L P O - R P O : left p a r i e t o - o c c i p i t a l - r i g h t parieto-oceipital; R P O - RE: right parieto-occipital- right ear; AS: auditory stimulus. Calibrations: 200 ,uV/cm and 1 sec/3 cm. activity was regarded as being pathological focal activity. Such bilateral changes as occurred were, if unilateral phase reversal was present and if the amplitude was larger on that side, also regarded as being pathological focal activity. RESHLTS
The following observations demonstrate the influence which may be exerted by extrinsic conditions on the fluctuation in the amount of pathological focal activity. It was repeatedly found possible to suppress pathological focal activity by means of an auditory
stimulus. The focal activity was abruptly arrested in response to the stimulus, while attenuation often occurred more or less unmistakably on the contralateral side. Fig. i illustrates this phenomenon, as it was seen in different test a n i m a l s When two animals, each with an alumina cream focus, were simultaneously submitted to E E G examination, the fluctuation in the amount of the pathological activity often showed a strikingly parallel course in the two animals. This was found by comparison of the data obtained at hourly intervals in the course of a day (Fig. 2A). It was also often shown by comparison of series of consecutive 20-second
Electroenceph. clin. NeurophysioL, 1962, 14:747-750
REACTIVITY OF ALLIMINA CREAM FOCI (A) 3O
~
20
o
10
--
rabbi%
IiA'
....
rabbit 3/2]I
,
"
,.'-. ",, '
,/ / ".
.
.
.
rvl
(B)
tI
t~ / ~
•
4
749
--rabbi+. .... rabbi+. ~23Z[
.53C
~2c
/
! I
~10
I I
i
1 2 1 3 14 15 Time (h)
16 17 18 19 2 0 21 22 23 24 (A) - - r a b b i t
2 3 4 5 Time (rain)
7
(B)
X
- - - rabbi% ~
30
1
I 8
--rabbi+.
....
~_>'30 >
r a b b i t ]E
.>
-~ 2o
o 2C "6 tJ
,2.o
10 .o
/.....-------_.~ 8
10 12 Time (h)
14
10
10
20
I
2
34 56 T i m e (rain)
7
•
9
10
Fig. 2 Fluctuation of the per cent time focal activity in the course of time simultaneously recorded with two rabbits. A: data of 10-minute periods at intervals in the course of one day; B: data of a series of consecutive 20-second periods in the course of a continuous registration.
periods in the course of a continuous registration (Fig. 2B). A striking feature of Fig. 2B (of the rabbits V and VIII) is that the first two peaks in these animals show a virtually parallel course, while the third peak, which is relatively low in rabbit VIII, no longer appears in rabbit V. As a rule, the pathological activity of the focus at the beginning of a period of observation was less than that seen at renewed registration some time later. Focal activity was suppressed, therefore, immediately after transfer of the animals from their cages to the examination room; after some time, the pathological activity showed, as a rule, increase. Up till now operations have been done on fifteen rabbits, eleven of which showed a focus 1-5 weeks after the operation. At a certain time five available rabbits with a focus were chosen to prove this observation. Details on these observations are presented in Table I, which also gives the statistical account.
observed suppression of the focal activity of the amygdaloid nucleus in the cat by sensory stimuli. The observations described above would seem to warrant the conclusion that extrinsic conditions exert an influence on pathological focal activity'. This influence is based, at least partly, on the suppression of focal activity by attention-alerting stimuli. On the other hand, pathological activity increases when concentration of attention on the environment diminishes. This agrees well with the observation of Chow and Obrist (1954), who saw maximal focal activity during sleep. It can therefore be assumed that a correlation exists between the activity of an alumina cream focus in the rabbit and the degree of alertness of the test animal. In order to obtain comparable results in pharmacological experiments, care should be taken to examine simultaneously the test animal and a control animal.
DI SCLIS SION
SUMMARY
The three observations described all indicate an extrinsic influence on pathological focal activity arising from alumina cream foci. For the first and the third observation, this influence can be described as an alerting effect. The same holds true for the second part of the second observation. On the basis of the curves in Fig. 2A, the possibility of diurnal fluctuations must be taken into consideration in addition to possible alerting effects. This suppression phenomenon has been investigated only on interictal paroxysms. Vigouroux (1959) also
An electroencephalographic study of loci produced in rabbits by the alumina cream method of Kopeloff et al. (1942) shows that there are extrinsic conditions which exert an influence on the amount of the pathological focal activity. This influence is revealed by the fact that alerting stimuli suppress focal activity, while pathological activity increases when the concentration of attention on the environment diminishes. It can be assumed that there is correlation between the amount of the pathological focal activity and the degree of alertness of the test animal.
Electroenceph. clin. NeurophysioL, 1962, 1 4 : 7 4 7 - 7 5 0
750
S . L . VISSER
I wish to express my thanks to R.P. van Hoeven (Laboratory for Chemical Physiology of the Free University, Amsterdam) for preparing the alumina cream. REFERENCES ChoW, K. L. and OBRIST, W. D. E E G changes on application of AI(OH):~ cream on the cortex. A. M. A. Arch. Neurol. Psychiat., 1954, 72: 80-87. KOPELOFF, L. M., BARRERA, S. E. and KOPELOFF, N. Convulsive seizures produced by immunologic and chemical means. Amer. J. Psychiat., 1942, 98: 881-902. MONNIER, M. and GANGLOFF, H. Atlas for stereotaxic
brain research on the conscious rabbit. Elsevier, Amsterdam, 1961, 76 p. MORRELL, F. Experimental focal epilepsy in animals. A. M. A. Arch. Neurol. Psychiat., 1959, 1: 141147. MORRELL, F., BRADLEY, W. and PTASHNE, M. Effect of drugs on chronic epileptogenic lesions. Neurology (Minneap.), 1959, 9: 492-498. SCHMALBACH, K. und STEINMANN, H. W. Bioelektrische Untersuchungen mit chronischen epileptogenen L~isionen. Dtsch. Z. ,Vervenh., 1955, 173: 377-384. VIGOUROUX, R. P. Physiologie dt,~ rhinenc~phale non olfactifi Thbse, Ed. Charbonnier, Marseille, 1959, 164 p.
Reference: VISSER, S. L. The reactivity of alumina cream foci in rabbits. Electroenceph, clin. Neurophysiol., 1962, 14: 747-750.