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EEG and the measurement of visual performance
FREE COMMUNICATIONS IN EEG placed on the necessity of understanding and knowing the reactions since widespread effects appear throughout the b o d y or else appear in areas very distal to the site of the lesion.
149. Paradoxical activating EEG responses to the intracarotid Amytal test in focal and multifocal bilateral epilepsies.-G. B. Rieci, P. Silipo and F. Gagliardi (Rome, Italy). The test was performed in a total of 64 patients. Of these, 26 had unilateral and 37 bilateral epileptogenic foci, in 18 the injection was followed by an increase in epileptiform EEG activity and in two also by seizures. Two principal types of responses were found: 1) a paradoxical response with injection on both sides-this occurred with 5 cases of unilateral and 5 cases of bilateral foci; 2) a response observed with injection on one side o n l y - t h i s occurred with 3 cases with injection on the opposite side, in 4 cases on the same side and in 1 case with bilateral independent loci. It is suggested that these phenomena depend on the abolition by the Amytal of defenses against epileptic activity that normally exist on the same and/or opposite side to the foci. This concept is supported by the clinical improvement that occurs in these cases with use of non-barbiturate therapy and also, in cases of independent bilateral foci, by the shifts that occur in relation to the drugs used. Further proof seems to lie in the results of surgery which aims to save the defense system particularly after exploration with the use of topical KC1 (25%) to produce spreading depression. Further recent work by the authors also stress this idea since it has been found that excellent postoperative results occur in patients showing paradoxical responses to contralateral Amytal injections. The experiments underline the fact that the epileptic disturbance should be considered as a dynamic process which such mechanisms as defense systems, although improperly understood, coming into effect. 150. The electroencephalogram in endemic juvenile goiter and in acute goiter.-L. Pacini, M.
Mortara and R. Alessandria, Italy).
Rubino
(Milan
and
EEG studies were carried out in 27 cases of endemic juvenile goiter and in 5 cases of acute goiter from endemic areas. In the patients with endemic goiter the EEG was abnormal in 26 cases (96.3%) and within normal limits in 1 case. The most common changes were in the appearance of theta rhythms at 4 to 5 c/see in 14 and at 5 to 7 c/see in another 9 cases. This activity was of regular form, sometimes paroxysmal and of
707
medium to high voltage. In 3 records the theta rhythms were associated with fairly frequent delta activity of moderate to distinctly high voltage and often rhythmic. In 24 cases, in addition to the above anomalies there were sharp, spike and spike slow wave complexes. The theta and delta rhythms were accentuated by hyperpnea although they were already fairly marked in the resting state. The e p i l e p t i f o r m patterns were present before hyperpnea in I l cases and appeared during overbreathing in 13 other cases. in the 5 patients with acute goiter the EEGs showed theta rhythms of 4 to 5 c/sec in 1 case, of 5 to 7 c/sec in 2 cases and intermixed theta and delta activity in the other 2 cases. The patterns and voltages were similar to those for the juvenile endemic goiter. Hyperpnea again made the changes more marked and in 4 of these 5 cases high voltage sharp waves appeared only during this test. These EEG findings are unlike those of other workers in so-called primary hyper and hypothyroidism but are like those reported in the secondary condition. The changes described above w o u l d suggest diencephalic-hypophyseal disturbance. 151. EEG and the measurement of visual per-
formance.-W. Clusin (Chicago, I!1., U.S.A.). Investigators concerned with the relationship between EEG and higher cortical organization have long suspected that features of the alpha rhythm might correlate with intelligence. Although measurements of the IQ and alpha amplitude have been unproductive, relating studies of alpha index have produced controversial results. The dubious reliability of such correlations is not surprising since the alpha rhythm is rather specifically associated with the neural activity of the visual system. Whereas most IQ tests take account of perceptual and occular-motor performance, there is little to suggest that intelligence is primarily a property of the visual apparatus. The present experiment was performed to determine whether alpha activity would be related to a subject's performance on a more specifically visual task. F o r this purpose, we employed the scaled score of Wechsler's Coding subtest, which measures the speed and accuracy of transcribing digits into corresponding abstract symbols. Digitized EEG signals were recorded on magnetic tape from 16 monopolar electrodes from a sample of 32, 11 to 13 year old right-handed males. The power-density of the activity in each of several frequency bands was calculated by a computer. The alpha score obtained for each electrode was a combined measurement of alpha amplitude and alpha index. We found that Spearman correlations be-
708
INTERNATIONAL FEDERATION - 7TH CONGRESS
tween alpha activity and Coding were positive at all electrode loci, and significant (p=0.005, onetailed) in 12 of the 16 areas. Our correlations were no less significant in anterior electrodes. The highest correlation, 0.70, reached a significance of p<0.00005. The hypothesis that these correlations reflect an association between alpha activity and visual performance is supported by the fact that the power density of activity outside the alpha range was not significantly correlated with Coding and that the alpha scores were not related to Full IQ, or other such non-visual measurements as Information, Comprehension, and Vocabulary.
152. Inertia of the nervous processes of the brain. -J. G. Kratin (Leningrad, U.S.S.R.). When positive and negative conditioned reflexes have been formed, the electrical reactions of the brain can be recorded as a switch from resting EEG activity to various activated rhythms. The duration and intensity of the EEG response depends on stimulus quality. A positive signal evokes a long lasting and prominent reaction. A fine negative differential stimulus also activates the EEG and the finer the differentiation the longer the EEG reaction. Only a gross differentiation induces little or no change. Repetitive presentation of gross differential stimuli restores the resting EEG pattern after cessation of the positive or fine negative stimuli. The length of time required for this restoration reflects the degree of inertia of the brain function. The inertia of inhibition, which is manifested as negative after-activity, is of special interest. This problem was explored in experiments on cats. Negative after-activity results from repetition of differential stimuli and consists of a blocking of the subsequent action of positive signals. F o r gross differentiation this effect appears after many negative stimuli and for fine differentiation after only several stimuli. In both cases effector blocking persists during desynchronization of the EEG, a change which reflects acceptance of the signal by the system and its excitation. These findings suggest a duality of CNS inhibition: while the analyser system is in a state of excitation the effector mechanism is blocked. A more intense state of after-inhibition develops with a diffuse inhibitory state and is reflected in the slow wave EEG patterns. It can be eliminated by gradual activation of the EEG from repetitive positive signals. It is suggested that EEG recordings of the inertia of processes of the brain show the same external manifestations as behavior (rest and inaction) and underlying these, there exist many interactions of different nervous processes.
153. The role of some subcortieal structures of the brain in the forming of internal conditioned inhibition.-N. F. Suvorov (Leningrad, U.S.S.R.). Studies of behavioral reactions suggest there are structures and inhibitory mechanisms in the CNS which modulate the parameters of the excitatory process or block output. Both innate and acquired forms of inhibition exist and can be investigated by the method of conditioned reflexes. The behavioral studies of inhibition are now complemented by neurophysiological techniques. In this paper the dynamics of bioelectrical activity (EEG, primary and evoked responses and neuronal activity) has been studied in different regions of the brain, (thalamus, basal ganglia, amygdala, hypothalamus and midbrain reticular formation) during acute interrupted extinction of the orientating reaction and during differential, extinctive and other forms internal conditioned inhibition. It has been shown that the inhibitory systems of the brain (head of caudate nucleus, n. basolateralis of amygdala, n. medialis of thalamus) partake in forming conditioned inhibition. Destruction of these structures causes delay in forming conditioned inhibition. Low frequency stimulation of some of these structures hastens formation of inhibition, but the genesis of formation of conditioned inhibition is not identical in all of them. Some structures take part in forming inhibitory responses directly (n. caudate and septum) others only are involved indirectly; that is, they do not belong functionally to systems involved in the formation of the act which is inhibited. It is suggested that the principle of vertical organization of nervous processes in the brain during formation of acquired forms of inhibition is important. 154. Microphysiology of cortical single neurons in Papio Papio.-F. MorreU, R. Naquet and C. Menini (Stanford, Calif., U.S.A. and Marseille, France). The baboon, Papio Papio, may display epileptic seizures when exposed to stroboscopic illumination; previous investigations have indicated that the seizures originate in the pre-frontal cortex of both hemispheres. In the present study, single unit analysis of area 6 and occipital neurons was carried out by means of extraceltular micro-electrodes. The sensitivity of these cells to various stimulus modalities was explored. (a) In area 6, striking correlations were observed between single unit activity and both surface and depth epileptiform or paroxysmal discharge as viewed with gross electrodes; (b) neither spontaneous or photically elicited unit abnormality was observed in occipital cortical units; (c) cellular discharge patterns in
149. Paradoxical activating EEG responses to the intracarotid Amytal test in focal and multifocal bilateral epilepsies.-G. B. Rieci, P. Silipo and F. Gagliardi (Rome, Italy). The test was performed in a total of 64 patients. Of these, 26 had unilateral and 37 bilateral epileptogenic foci, in 18 the injection was followed by an increase in epileptiform EEG activity and in two also by seizures. Two principal types of responses were found: 1) a paradoxical response with injection on both sides-this occurred with 5 cases of unilateral and 5 cases of bilateral foci; 2) a response observed with injection on one side o n l y - t h i s occurred with 3 cases with injection on the opposite side, in 4 cases on the same side and in 1 case with bilateral independent loci. It is suggested that these phenomena depend on the abolition by the Amytal of defenses against epileptic activity that normally exist on the same and/or opposite side to the foci. This concept is supported by the clinical improvement that occurs in these cases with use of non-barbiturate therapy and also, in cases of independent bilateral foci, by the shifts that occur in relation to the drugs used. Further proof seems to lie in the results of surgery which aims to save the defense system particularly after exploration with the use of topical KC1 (25%) to produce spreading depression. Further recent work by the authors also stress this idea since it has been found that excellent postoperative results occur in patients showing paradoxical responses to contralateral Amytal injections. The experiments underline the fact that the epileptic disturbance should be considered as a dynamic process which such mechanisms as defense systems, although improperly understood, coming into effect. 150. The electroencephalogram in endemic juvenile goiter and in acute goiter.-L. Pacini, M.
Mortara and R. Alessandria, Italy).
Rubino
(Milan
and
EEG studies were carried out in 27 cases of endemic juvenile goiter and in 5 cases of acute goiter from endemic areas. In the patients with endemic goiter the EEG was abnormal in 26 cases (96.3%) and within normal limits in 1 case. The most common changes were in the appearance of theta rhythms at 4 to 5 c/see in 14 and at 5 to 7 c/see in another 9 cases. This activity was of regular form, sometimes paroxysmal and of
707
medium to high voltage. In 3 records the theta rhythms were associated with fairly frequent delta activity of moderate to distinctly high voltage and often rhythmic. In 24 cases, in addition to the above anomalies there were sharp, spike and spike slow wave complexes. The theta and delta rhythms were accentuated by hyperpnea although they were already fairly marked in the resting state. The e p i l e p t i f o r m patterns were present before hyperpnea in I l cases and appeared during overbreathing in 13 other cases. in the 5 patients with acute goiter the EEGs showed theta rhythms of 4 to 5 c/sec in 1 case, of 5 to 7 c/sec in 2 cases and intermixed theta and delta activity in the other 2 cases. The patterns and voltages were similar to those for the juvenile endemic goiter. Hyperpnea again made the changes more marked and in 4 of these 5 cases high voltage sharp waves appeared only during this test. These EEG findings are unlike those of other workers in so-called primary hyper and hypothyroidism but are like those reported in the secondary condition. The changes described above w o u l d suggest diencephalic-hypophyseal disturbance. 151. EEG and the measurement of visual per-
formance.-W. Clusin (Chicago, I!1., U.S.A.). Investigators concerned with the relationship between EEG and higher cortical organization have long suspected that features of the alpha rhythm might correlate with intelligence. Although measurements of the IQ and alpha amplitude have been unproductive, relating studies of alpha index have produced controversial results. The dubious reliability of such correlations is not surprising since the alpha rhythm is rather specifically associated with the neural activity of the visual system. Whereas most IQ tests take account of perceptual and occular-motor performance, there is little to suggest that intelligence is primarily a property of the visual apparatus. The present experiment was performed to determine whether alpha activity would be related to a subject's performance on a more specifically visual task. F o r this purpose, we employed the scaled score of Wechsler's Coding subtest, which measures the speed and accuracy of transcribing digits into corresponding abstract symbols. Digitized EEG signals were recorded on magnetic tape from 16 monopolar electrodes from a sample of 32, 11 to 13 year old right-handed males. The power-density of the activity in each of several frequency bands was calculated by a computer. The alpha score obtained for each electrode was a combined measurement of alpha amplitude and alpha index. We found that Spearman correlations be-
708
INTERNATIONAL FEDERATION - 7TH CONGRESS
tween alpha activity and Coding were positive at all electrode loci, and significant (p=0.005, onetailed) in 12 of the 16 areas. Our correlations were no less significant in anterior electrodes. The highest correlation, 0.70, reached a significance of p<0.00005. The hypothesis that these correlations reflect an association between alpha activity and visual performance is supported by the fact that the power density of activity outside the alpha range was not significantly correlated with Coding and that the alpha scores were not related to Full IQ, or other such non-visual measurements as Information, Comprehension, and Vocabulary.
152. Inertia of the nervous processes of the brain. -J. G. Kratin (Leningrad, U.S.S.R.). When positive and negative conditioned reflexes have been formed, the electrical reactions of the brain can be recorded as a switch from resting EEG activity to various activated rhythms. The duration and intensity of the EEG response depends on stimulus quality. A positive signal evokes a long lasting and prominent reaction. A fine negative differential stimulus also activates the EEG and the finer the differentiation the longer the EEG reaction. Only a gross differentiation induces little or no change. Repetitive presentation of gross differential stimuli restores the resting EEG pattern after cessation of the positive or fine negative stimuli. The length of time required for this restoration reflects the degree of inertia of the brain function. The inertia of inhibition, which is manifested as negative after-activity, is of special interest. This problem was explored in experiments on cats. Negative after-activity results from repetition of differential stimuli and consists of a blocking of the subsequent action of positive signals. F o r gross differentiation this effect appears after many negative stimuli and for fine differentiation after only several stimuli. In both cases effector blocking persists during desynchronization of the EEG, a change which reflects acceptance of the signal by the system and its excitation. These findings suggest a duality of CNS inhibition: while the analyser system is in a state of excitation the effector mechanism is blocked. A more intense state of after-inhibition develops with a diffuse inhibitory state and is reflected in the slow wave EEG patterns. It can be eliminated by gradual activation of the EEG from repetitive positive signals. It is suggested that EEG recordings of the inertia of processes of the brain show the same external manifestations as behavior (rest and inaction) and underlying these, there exist many interactions of different nervous processes.
153. The role of some subcortieal structures of the brain in the forming of internal conditioned inhibition.-N. F. Suvorov (Leningrad, U.S.S.R.). Studies of behavioral reactions suggest there are structures and inhibitory mechanisms in the CNS which modulate the parameters of the excitatory process or block output. Both innate and acquired forms of inhibition exist and can be investigated by the method of conditioned reflexes. The behavioral studies of inhibition are now complemented by neurophysiological techniques. In this paper the dynamics of bioelectrical activity (EEG, primary and evoked responses and neuronal activity) has been studied in different regions of the brain, (thalamus, basal ganglia, amygdala, hypothalamus and midbrain reticular formation) during acute interrupted extinction of the orientating reaction and during differential, extinctive and other forms internal conditioned inhibition. It has been shown that the inhibitory systems of the brain (head of caudate nucleus, n. basolateralis of amygdala, n. medialis of thalamus) partake in forming conditioned inhibition. Destruction of these structures causes delay in forming conditioned inhibition. Low frequency stimulation of some of these structures hastens formation of inhibition, but the genesis of formation of conditioned inhibition is not identical in all of them. Some structures take part in forming inhibitory responses directly (n. caudate and septum) others only are involved indirectly; that is, they do not belong functionally to systems involved in the formation of the act which is inhibited. It is suggested that the principle of vertical organization of nervous processes in the brain during formation of acquired forms of inhibition is important. 154. Microphysiology of cortical single neurons in Papio Papio.-F. MorreU, R. Naquet and C. Menini (Stanford, Calif., U.S.A. and Marseille, France). The baboon, Papio Papio, may display epileptic seizures when exposed to stroboscopic illumination; previous investigations have indicated that the seizures originate in the pre-frontal cortex of both hemispheres. In the present study, single unit analysis of area 6 and occipital neurons was carried out by means of extraceltular micro-electrodes. The sensitivity of these cells to various stimulus modalities was explored. (a) In area 6, striking correlations were observed between single unit activity and both surface and depth epileptiform or paroxysmal discharge as viewed with gross electrodes; (b) neither spontaneous or photically elicited unit abnormality was observed in occipital cortical units; (c) cellular discharge patterns in