Hungarian society of electroencephalography, 24th Congress

Electroencephalography and Clinical Neurophysiology, 1982, 53: 5P--18P Elsevier/North-HoUand Scientific Publishers, Ltd.

5P

Society proceedings HUNGARIAN SOCIETY OF ELECTROENCEPHALOGRAPHY, 24th CONGRESS Debrecen, November 4--6, 1980

Secretary: I. TOMKA National Institute o f Neurosurgery , 1124, A merikai-ut, 50 Budapest (Hungary) (Accepted for publication: August 31, 1981)

1. The importance of the EEG in the diagnosis of cerebrovascular diseases. - - J. Grubits and F. K~kesi (Sopron) This study was designed to analyse EEG findings of 970 patients with various cerebrovascular diseases. TIAs in the territory of the internal carotid arteries of 193 cases showed normal EEGs in 34%, ipsilateral abnormalities in 30% and bilateral changes with a remarkable unilateral accentuation in 33%. Vertebro-basilar TIAs of 108 patients had normal EEGs in 45%, generalized disturbances in only 10%, bilateral diffuse abnormalities in 22%. A hemispheric unifocal (white) infarct of 339 patients was associated with a normal EEG in 14%, with ipsilateral abnormalities in 36% and with bilateral changes predominating ipsilaterally in 30%. 104 cases of multiple infarct showed bilateral EEG disturbances in 80%. A hemispheric (haemorrhagic) infarct in 112 cases presented a normal EEG in 10%, ipsilateral abnormalities in 29% and unilaterally accentuated bilateral EEG manifestations in 40%. The rest of the patients with other forms of cerebrovascular disease failed to g i v e conclusive results because o f the relatively small number of cases. A normal EEG in the early stages predicted a better prognosis for the clinical outcome, even though the clinical improvement came only later. The severity of the clinical state is correlated with the distribution and complexity of EEG abnormalities.

2. C o m p a r i s o n o f EEG and CT data in organic cerebral diseases. -- Zs. Frey, A. Farg6, M. Sikl6di, L. Bartha and S. Csob~ly (Budapest)

Correlation of EEG and CT data in certain cases of organic cerebral disease led to the following conclusions: according to the literature, the localizing value o f focal EEG signs can be corroborated by CT investigation without the risk of invasive techniques.

A more precies distinction can be established between the so~alled primary and secondary bilateral E E G anomalies on the basis of CT. Furthermore, it is suggested that electrographically silent or less active foci can be detected or identified with CT, especially the minor softenings and atrophies of the sylvian region in the dominant hemisphere, of vascular origin.

3. Comparative investigation o f rheo-, E E G and sonography in patients w i t h cerebrovascular d i s e a s e s . - A.G. Fej~r, P. Tariska and M. K~rp~thy (Budapest)

Angiography is generally used for localizing cerebrovascular lesions. However, this method is not without danger, the whole cerebrovaseular system can rarely be visualized and the possibility of repeated examination is limited. In those institutes where there is no possibility of applying Xenon clearance and computer tomography the employment of other, noninvasive methods seems to be useful. The authors applied EEG, rheoencephalography (REG) and carotid sonography (based on the Doppler principle) together; these methods often supplemented each other and their employment together gave more information. If the REG and sonography are done with compression of external and c o m m o n carotid arteries sometimes the correct diagnosis can be suggested in these cases also, where the EEG gave no relevant information. But the reverse is also true: in cases of stenosis or occlusion of the middle cerebral artery the results of sonography and REG correlated poorly with the lesion but EEG revealed the functional disturbance o f the corresponding cerebral region. In more complicated cases the understanding and the follow-up of the pathological process can be obtained better by using these methods than I ~ angiography. They can also usefully help in determining the site for further angiographic examination.

0013-4649/82/0000--0000/$02.75 © 1982 Elsevier/North-Holland Scientific Publishers, Ltd.

6P 4. Role of the EEG in the diagnostics o f cerebrovascular delirium. -- P. Tariska, l~. Siska and G. Ger~by (Budapest) The results of clinical, EEG and neuropathological examinations are presented (40 patients treated in a psychiatric department for men, age average 72.8 yr). 34 of them had a neurological deficit. All of them had pathological EEGs: slowing of the background activity occurred most frequently (in 38 cases). Mesodiencephalic functional disturbance and focal slowing were observed in 18 cases. The importance of the EEG is as follows. (1) In delirious states the neurological deficits are not so explicit; only the EEG can differentiate whether a diffuse or a focal disturbance of cerebral function is more prominent and so it can contribute to the differential diagnosis. (2) Clinically 'silent' brain infarcts, proved only by autopsy, are not infrequent - - t h e EEG can make the diagnosis more accurate; if the clinical examination suggests multifocal lesions the EEG can help in estimating that which contributes most to the functional cerebral disturbance. (3) Serial EEG examinations can explore certain electrical features which reflect different kinds and degrees of functional disorders and which cannot be detected by other methods (e.g., suppression-burst activity).

5. Basal forebrain and sleep regulation. -- F. Ob~l, Jr., G. Benedek and F. Ob~l (Szeged) In the past few years several data suggesting an EEG synchronizing/hypnogenic effect of the basal forebrain, primarily the olfactory tubercle (TbOf), were reported from our laboratory (Benedek et al., Acta physiol. Acad. Sci. hung., 1976, 1980; Arch. ital. Biol., 1979; Waking Sleeping, 1979; Behav. Brain Res., 1981; Ob~l et al., Acta physiol. Acad. Sci. hung., 1979; Exp. Neurol., 1980; Szikszay et al., Acta physiol. Acad. Sci. hung., 1981. To sum up: (1) local warming and low frequency stimulation in the basal forebrain resulted in cortical synchronization; (2) high frequency stimulation in the TbOf of acutely immobilized cats elicited cortical synchronization; (3) short latency evoked potentials were obtained over both the frontal and parietal cortical areas; (4) the synchronizing effect survived high mesencephalic transections; moreover, facilitation was observed which was parallel to the drop in NA level of the isolated forebrain; (5) in chronic preparations, high frequency stimulation increased the time spent in sleep, primarily in slow wave sleep, and significantly promoted falling asleep and inhibited awakening; (6) lesions in the TbOf resulted in severe

SOCIETY PROCEEDINGS insomnia. Our results suggest that the TbOf plays an important role in the sleep-inducing effect of the basal forebrain.

6. The activation of EEG changes by sleep deprivation. -- B. Roth, N. Rothov~i and S. Nevsimalov~i (Prague, Czechoslovakia) Graded, age adapted, sleep deprivation was used for EEG activation in 204 children and adolescents, mostly with suspected epilepsy, where the resting record was either negative or non~haracteristic. Activation was also used in other different paroxysmal affections with a view to ruling out epilepsy. In clinically certain cases of epilepsy, the proportion of positive epileptic findings rose after sleep deprivation from the original 10% to 52%, in patients with suspected epilepsy from 6% to 41%. This activation method also facilitated the differentiation of other paroxysmal affections from epilepsy. Epileptic EEG manifestations after sleep deprivation can often be observed during wakefulness, and even more so in superficial sleep stages. The authors warn of the need for a careful distinction between sleep and epileptic grapho-elements, and also of changes in sleep patterns activated by sleep deprivation. These are, in addition to some lengthening and deepening of stages 3 and 4 of NREM sleep, a frequent incidence of increased numbers of vertex sharp waves and K complexes coming in virtual volleys. In the authors' view, these EEG changes were manifestations of increased NREM sleep intensity, particularly NREM sleep phasic manifestations, following sleep deprivation.

7. Cluster analysis of broad-band EEG spectra i n identical sleep stages. -- J. Bak, I. Pill, P. Hal~sz, P. Rajna and O. Kundra (Budapest) Clusters in identical sleep stages were examined to clarify the fluctuations within the stages. Broad-band power spectra were derived by analogue method from a vertex-occipital derivation during night sleep in 20 sec time intervals in 1--3, 4--7, 8--13, 14-20, 21--30 c/sec frequency bands. First the cluster analysis was carried out on the whole set of data, then the clusters were compared to the Rechtschaffen-Kales sleep stages. The clusters were characterized by the relative power of the frequency bands. The 3 clusters corresponding to the stages 3 and 4 slow wave sleep were close to each other, as well as the 3 clusters corresponding to stage 2. The clusters corresponding to stage 1, REM and awake were often closer to clusters of other stages than to clusters of their own stage. The power of frequency bands of sleep spindles

H U N G A R I A N EEG SOCIETY differed very much even among the clusters of slow wave sleep. This observation may explain the insufficiency of the algorithms based on linear estimation of sleep stages from power spectra.

8. Relationship b e t w e e n spontaneous and evoked K c o m p l e x e s . -- P. H a l ~ z , I. P~il and P. Rajna (Budapest) The frequency and distribution of spontaneous and evoked K complexes (K) were studied in stage 2 of undisturbed sleep and with random click stimulation in one healthy young adult subject. Under the influence of auditory stimulation the frequency of Ks increased. The frequency of K in the ascending stages 2 remained higher than in the descending ones even during stimulation, and increased more than in the descending stages 2. Increasing the frequency of stimulation the K/min values decreased below the spontaneous values. The participation of the spontaneous Ks in the K/min values could be suppressed by optimal stimulation but this value could be limited only to 10%. In parallel with the suppression of K formation the distribution of the power density spectrum changed: the participation of the theta-delta band increased in all slow wave sleep stages. Data were discussed seeking a correlation between the slow wave synchronization of sleep and the environmental sensory inflow.

9. Long-term studies of sleep disorder in a case with brain stem turnout. -- P. Ki~ves, P. Hal6sz and J. Nikod~musz (Budapest) This is a report of a polysomnographic study of a patient with a slowly progressing basal t u m o u r followed through several years. According to anglographic, pneumographic and computer tomographic investigations the tumour originated from the left ponto-cerebellar angle, elevated the brain stem, spread through the tentorial cleft into the middle fossa, reached into the third ventricle and expanded toward the temporo-basal region. Bilateral n. VIII lesions, mild cranial nerve symptoms and pyramidal signs and a partial amnestic syndrome were associated since 10 years with a constant, severe insomnia. Several 24 h polygraphic registrations were done and a considerable curtailment of the REM and slow sleep stages were observed; the sleep cycles were completely disorganized and a large number of dissociated sleep phenomena also appeared. Biochemical studies were performed in parallel. The findings were discussed from the point of view of the correlation between the localization of the turnout and insomnia.

7P 10. Atropine sensitivity o f basal forebrain h y p n o genie mechanisms. -- G. Benedek, F. Obal, Jr., K. J6zsa and F. Ob~l (Szeged) The present experiments were carried out in order to obtain electrophysiological and behavioural data on the effect of a cholinergic antagonist, atropine, on the sleep-inducing mechanisms of the basal forebrain. In the first part of the study, 20 unanaesthetized, immobilized cats were treated with 1--5 mg/kg atropine. The administration of atropine failed to antagonize the synchronization elicited by high-frequency stimulation of the olfactory tubercle; instead a pronounced facilitation was found. A similar facilitation could be brought about by atropine treatment in experiments made on c e r v e a u isold cats. Chronic experiments were carried out on 5 unrestrained cats. Atropine elicited typical behavioural effects, restlessness and small twitch-like movements, while the EEG was characterized by highly synchronized slow waves. High frequency olfactory tubercle stimulation was still able to increase cortical synchronization; however, the behavioural inhibition and sleep posture, which characterize the sleepinducing properties of the basal forebrain, were totally absent. The results suggest a cholinergic mediation of the descending, behavioural effects of the basal forebrain hypnogenic area. However, the ascending projections bringing about the EEG synchronizing effects of the stimuli are assumed to be non-cholinergie or at least non-muscarinie type.

11. The effect of puncture of the preoptic thermodetector area on sleep-waking activity. -- P. Alf~ldi, F. Ob~il, Jr,, G. Benedek and F. Ob~il (Szeged) In unanaesthetized, freely moving rats, the anterior hypothalamic/preoptic thermodetector zone was damaged unilaterally by an acute mechanical puncture. As was reported by Rudy et al. (1977), the lesion resulted in hyperthermia, wich might be due to prostaglandins released from the injured tissue. The hyperthermia persisted 4--12 h. In response to the lesions, weakfulness increased while slow wave sleep decreased in the first hours. Apart from an initial vehement grooming activity the animals lay quietly in an extended posture. Paradoxical sleep was diminished for 5 h. By the second day, the amount of paradoxical sleep had returned to normal; however, slow wave sleep was less than in the control records. The different time courses of the effects on the two sleep stages suggest that the mechanisms by which they were affected differed from each other.

8P 12. The effect of chemical stimulation o f the central and peripheral thermosensors on sleep-waking activity, -- E. Hugyecz, Z. Lelkes, F. Ob~l, Jr. and F. Ohal (Szeged)

SOCIETY PROCEEDINGS

Rats were treated with capsaicin preoptically or subcutaneously and their sleep-waking activity was studied. Since capsaicin stimulates the warm-sensors t h e r m o l y t i c mechanisms are activated: a drop in the b o d y t e m p e r a t u r e was observed. A dose-dependent decrease in slow wave sleep and paradoxical sleep was also found. A f t e r a period of active e x p l o r a t o r y and grooming activity the animals lay d o w n in an e x t e n d e d posture. Their eyes were open. These data do not support the assumption that stimulation of warm-sensors i n the forebrain results in sleep.

The EEG activity was processed by Fast Fourier Transformation. The pimozide (Chinoin) was administered intravenously in doses o f 1, 2 and 3 mg/kg. We observed a transient, slight depression of electrocortical activity after administration o f pimozide which was followed by cortical synchronization exceeding the control value. Similar facilitation was observed in the s y n c h r o n i z a t i o n elicited by i 0 0 Hz stimulation o f the o l f a c t o r y tubercle. The amplitudes of potentials evoked by 10 Hz stimulation increased considerably after a small decrease. It is suggested that the initial diminishing o f spontaneous and evoked cortical synchronization was caused by an inhibition o f synchronizing mechanisms in the basal forebrains while the subsequent facilitation was elicited by an inhibition o f the ascending reticular activating system.

13. Studies on the cycles of sleep-waking rhythms. -F. Bari, G: Rubicsek, G. Benedek and F. Obfil (Szeged)

15. Fourier and Walsh spectra in the quantitati~:e analysis o f cortical electrical activity. -- R. TSrSk, Gy. Dib6 and I. GySri (Szeged)

Our e x p e r i m e n t s aimed at determining the specific parameters of rat's sleep-waking activity. The E E G and l o c o m o t i o n of rats were c o n t i n u o u s l y recorded during 120 h. The rats spent 38--45% in wakefulness, 45--50% in slow wave sleep and 8--12% in paradoxical sleep during t h e 12 h light periods; these values were 70--75%, 25--35% and 2--10% during the 12 h dark periods. The individual standard errors of the mean were in a narrow range while considerable differences were found a m o n g the rats. The records were scored every 1 rain. To characterize the sleep-waking activity, various algorithms were tested: direct Walsh transformations o f the h y p n o g r a m s were performed, binary autocorrelations and transition probability functions of the data were calculated and their Fourier transforms were obtained. These m e t h o d s showed the stationary parameters of the sleep-waking activity. T o study the t e m p o r a l organization of the sleep-waking activity, the m e t h o d described by Gaillard (1979) (calculation o f the c u m u l a t e d occurrences of sleep stages) was used.

Our study was devoted to c o m p a r e the Fourier and Walsh spectra o f EEG records o b t a i n e d in immobilized, unanaesthetized cats. 20 sec EEG records were recorded before, during and after basal forebrain stimulation. The effects o f stimulation were also studied under the effect of the dopaminergic blocker pimozide. The spectra o b t a i n e d by t h e t w o m e t h o d s were compared statistically (Fisher test for calculating the significantly d o m i n a n t frequencies, comparison of the original curve with that e s t i m a t e d on t h e basis of the d o m i n a n t frequencies obtained, d e t e r m i n a t i o n of the significant differences b e t w e e n stimulation and non-stimulation epochs, estimation of confidence intervals). It is suggested that Walsh spectra, which can be calculated in a simple way, are suitable to detect the changes in the electrical activity of the brain.

14. Effect o f a dopaminergic b l o c k e r on cortical synchronization. -- G. Dib6, G, Benedek, G. Rubicsek and F. Ob~il (Szeged)

In the EMG one can find the f o r m o f individual m o t o r unit activities and the form o f the resultant interfering activity derived f r o m superimposed m o t o r unit activities. In t h e n e i g h b o u r h o o d o f the recording electrode, the working m o t o r unit n u m b e r depends on the actual c o n t r a c t i o n and on t h e m o d e o f unit mobilization. T h e r e f o r e the resultant electrical activity will d e p e n d also o n the level o f contraction. A c c o r d i n g to these the electrical activity (EMG) has a static unit, unit structure and a d y n a m i c time-related structure depending on the contraction.

The effect of the d o p a m i n e r e c e p t o r blocking agent, pimozide, has been studied o n cortical sync h r o n i z a t i o n elicited by electrical stimulation of the o l f a c t o r y tubercle in 20 unanesthetized, immobilized cats. Stimulating parameters were 10 and 100 Hz, 0.5 msec duration, 250---400 pA. The EEG and the potentials evoked by 10 Hz stimulation were recorded.

16. C o m p u t e r analysis o f EMG. - - Sz. T 6 t h and T. Nagyp~l (Budapest)

HUNGARIAN

EEG SOCIETY

Quantitative analytic methods have to correspond with both activity structures: (1) histogram of parameters from m o t o r unit measurements, (2) analysis of interfering activity patterns representing different contraction levels. In the analysis of interfering activity patterns over longer time intervals (0.5--2 sec) by present methods (frequency, amplitude, interval-histograms, power density spectra) the electrical activity will lose its time relations and the original curve will be transformed into a set of parameters. The authors review the current methods of analysis and compared them with a new method taking into consideration the original time relations (i.e., the individual features) as well. There are different kinds of linear and non-linear mathematical models for the approximation of EMG activities; the simplest model is as follows: Xk(n+ 2) = 0/kX k (n+ 1 ) + flkXk(n) where: n = 1 . . . . , N (series of samples) The initial conditions: Xk(0 ) = Ck; Xk(1) = d k The optimized solution of the above gives timedependent parameters for the optimal approximation of the time function. The authors also used another model, based on coupled pairs of autoregressive models. This model gives an optimal approximation of spike-like time functions, such as the EMG.

17. The clinical and electrophysiological importance of the accessory deep peroneal nerve. -- J. K6mdr and M. Szegv6xi (Budapest) Under normal circumstances m. extensor digitorum brevis is innervated by the deep branch of the n. peroneus communis. As an anatomical variation, however, the so-called accessory deep peroneal nerve may also play a role in the innervation of this muscle. This latter nerve is a branch of the superficial peroneal nerve. However, this particular nerve rarely innervates this muscle alone. Studies were carried out using electrodes and stimulation methods. Altogether 194 persons (97 women and 97 men), all voluntary, were examined. In 33 of the cases (17%) abnormal innervation was found. In 11 of the cases (5.7%) the abnormality affected both legs, in 15 of the cases (7.7%) the right leg and in 7 eases (3.6%) the left leg. In two cases (1%) the muscle was innervated by only the accessory deep peroneal nerve. It's frequent occurrence should serve to direct attention to the importance of this nerve for the following reasons.

9P (1) M. extensor digitorum brevis is the muscle of reference for the deep peroneal nerve. Without knowledge of the possible existence of this accessory nerve the physician m a y easily overlook a complete failure of the deep peroneal nerve if action potentials can otherwise be demonstrated in the muscle. (2) If this nerve is not examined prior to operating, discovery of postoperative action potentials in the muscle m a y be incorrectly interpreted as a positive result. In fact the accessory nerve m a y have provided action potentials before the operation as well. (3) During suml nerve biopsies, the accessory deep peroneal m a y be mistaken for the sural nerve, resulting in a paresis of m. extensor digitorum brevis.

18. Experiences of measuring the segmental conduction velocity in diseases of the peripheral nervous system. -- T. J~d~nh~zy and D. Motika (Szeged) It is often necessary to localize the site of lesions along damaged nerves in neurological practice. It is very important in cases of the so-called 'tunnel syndrome', frequently studied by neurologists in recent years. The thoracic outlet syndrome was chosen from the sorts of 'tunnel syndrome' because of its relatively c o m m o n occurrence. The main results were as follows: (1)slowing of the conduction velocity was not always found in patients, where compression of a subclavia was indicated by Doppler sonography; (2) since the in and out gates of this tunnel are near to each other, it is very difficult to make precise measurements, and the differences of conduction velocity when measuring it between E r b - axilla and E r b elbow points are too small; (3) it is very useful to apply the p h e n o m e n o n of slowing of conduction velocity from proximal towards distal for localizing the site of compression, and its absence or reversal m a y indicate the lesion.

19. Electrophysiological studies in myotonic distrophy. -- l~. Csenk~r, I. Fekete, P. Di6szeghy and F. Mechler (Debrecen) The neuromuscular transmission and functional state of the muscle fibre membrane were studied by repetitive stimulation of m o t o r nerve fibres of the ulnar nerve with different impulse frequencies; the distal latency and m o t o r conduction velocity in ulnar, median and peroneal nerves were determined and the EMG was performed in various muscles of 4 patients with myotonic dystrophy. The EMG investigations confirmed the simultaneous existence of dystrophy and myotonia. Electroneurography showed prolonged distal latency, particularly in the

10P median nerve; the m o t o r c o n d u c t i o n velocity was slightly reduced in m e d i a n and peroneal nerves. Repetitive nerve stimulation d e t e c t e d abnormalities variable in nature and degree in different patients. These abnormalities varied from typical m y a s t h e n i c responses to the occurrence of facilitation and r e d u c t i o n o f amplitudes, d e p e n d e n t on impulse frequencies.

20. Changes in function of catecholamine receptors in vascular smooth muscle in myotonic dystrophy. -- F. Mechler (Debrecen)

The f u n c t i o n o f vascular adrenergic receptors was studied by measuring muscle b l o o d flow using the t33Xe clearance m e t h o d in the tibialis anterior muscle. Blood flow responses to intravenously administered adrenaline before and after p h e n t o l a m i n e and propranolol were recorded in 8 normal subjects and 11 patients with m y o t o n i c dystrophy. In cases with advanced involvement of the muscle the reduced resting muscle b l o o d flow was n o t altered by adrenaline before and after r e c e p t o r blockades. In cases with muscle showing considerable m y o t o n i a w i t h o u t a t r o p h y , a paradoxical r e d u c t i o n in the adrenalineinduced increase in blood flow was f o u n d after alpha b l o c k a d e and t h e adrenaline-induced b l o o d flow increase was n o t c o m p l e t e l y blocked by beta blockers as in the normal subjects. This finding points to a functional alteration in the properties of vascular adrenergic receptors in muscle in m y o t o n i c dystrophy.

21. Facial nerve stimulation and blink reflex in myasthenia gravis. -- I. F e k e t e and Gy. Cs~:~csey (Budapest) M o t o r responses evoked f r o m orbicularis oculi muscles (M) by stimulation of the facial nerve as well as early ( R t ) a n d late (R2) reflex responses to stimulation o f t h e supraorbital nerve were studied in patients with myasthenia gravis. The latency o f the M response was prolonged while that of R l and R2 responses was practically normal. The longest prolongation in latency o f M responses was found in bulbar and generalized forms o f myasthenia. The duration of responses showed no change but the decrease of amplitude in all o f the responses was conspicuous using a slow stimulation f r e q u e n c y of 1 Hz. The decrease was greatest i n t h e bulbar and generalized forms. Our findings suggest t h a t neuromuscular transmission and terminal c o n d u c t i o n are affected while t h e reflex pathways are intact in m y a s t h e n i a gravis.

SOCIETY PROCEEDINGS 22. Clinical and electrophysiological analysis in myasthenia gravis. - - E. Papp and J. C z o p f (P@cs) Clinical and electrophysiological data of 15 myasthenic patients (14 w o m e n and ] m a n ) h a v e been evaluated. M e a n age: 25.7 years. The clinicalform in 9 cases was of the generalized type, in 6 cases of the bulbar type. T h y m u s a n d muscle antibody, antinuclear factor, CPK, G O T , GPT, L D H , A L P enzymes, thyroid function, X ray (including mediastinal tomography) gave positive results exceptionally. In 8 of 11 cases investigated the H L A B8 antigen was found. The electrophysiological findings: (1)the rnyogram of 8 patients showed a reduced interference or mixed pattern at maximal effort; (2) in 6 cases a prolonged distal m o t o r latency could be measured on the n e u r o n o g r a m ; (3! 3 Hz repetitive stimulation showed pathological amplitude reduction o n l y in 9 patients (those with generalized clinical signs). T h y m e c t o m y was performed in 10 o f the 15 cases. The histological results showed t h y m u s hyperplasia in 9 cases, normal findings in one. Three patients improved postoperatively ( w i t h o u t need o f any therapy), 4 patients improved (with therapy tess than preoperatively); in 3 cases no change could be observed. In 4 o f the 5 postoperative electrophysiological controls the effect of repetitive stimulation r e m a i n e d pathological.

23. The evoked potential m e t h o d in diagnosing focal neurological diseases. -- Z. T 6 t h and Gy. Koll~r (Budapest) Evoked potential studies were p e r f o r m e d in cases in which, at the t i m e o f t h e first neurological examination, severe neurological deficits were recorded which later partly or c o m p l e t e l y disappeared. C o n s e q u e n t l y most of our studied patients were T I A cases. Carotid angiography, C T and repeated E E G s were performed in most of the cases. The bilateral somatosensory, auditory and visual evoked responses were compared. Bipolar needle electrodes, an ST-21 Medicor stimulator, an E M G photophonostimulator, an M G - 4 2 Medicor 4-channel amplifier and an ICA-70 K F K I multichannel analyser with a 4 K m e m o r y were used. Changes in somatosensory evoked responses were evident, according with the severe neurological deficit evaluated during the first neurological examination. A possible temporal lobe deficiency was reflected in the auditory evoked response while occipital lobe deficiencies, not detectable by routine ophthalmologlcal methods, were clearly s h o w n in the visual evoked responses. The disease process was not only reflected in amplitude changes but the structure of the evoked response was also altered. Lasting changes could be

HUNGARIAN EEG SOCIETY detected in the evoked responses long after the neurological symptoms had ceased to exist.

24. Paroxysmal activity in EEG and psychopathology. - - M. Koukkou (Zurich, Switzerland) The correlation between frequency and localization of paroxyr;mal EEG discharges and the degree and type of psychopathology was investigated in two longitudinal studies: (a) during psychotic episodes of 4 epileptic patients with bitemporal sharp waves with changing hemispheric dominance, and (b) an acute schizophrenic episode in 20 patients treated with clozapin in doses adjusted to the patients' needs (patients treated with clozapin develop paroxysmal EEG discharges without clinical seizures). EEG and psychopathology ratings (AMP scales) were collected on the same day at standard intervals. EEGs were evaluated by 'blind' reviewers. Correlation coefficients were computed between the values of the 9 psychopathological scales and the frequency of epileptic discharges in 3 brain areas of both hemispheres. The epileptic patients showed significant (P = 0.05 and less) negative correlations between the frequency of occurrence of temporal sharp waves and the values of the paranoid-hallucinatory scale on the one hand and the depressive scale on the other. The correlations were higher for the right hemisphere data. Clozapin patients with paroxysmal EEG patterns showed a negative correlation ( P ~ 0.02) between frequency of EEG paroxysms and intensity of the depressive syndrome and a positive correlation ( P ~ 0 . 0 1 ) between frequency of EEG paroxysms and reduction of the depressive syndrome with time. These results demonstrate a quantitative and graded relation between frequency of spontaneous (epileptic) and drug-induced paroxysmal discharges and the degree of improvement of some psychopathological syndromes in both populations, suggesting the hypothesis of a common neurophysiological mechanism.

25. Multichannel mapping of scalp potential fields. -D. Lehmann (Zurich, Switzerland) The topography of the spatial distribution of spontaneous and evoked EEG fields on the human scalp is not influenced by the choice of the reference point: at a given m o m e n t in time, potential differences between two points might be measured against an arbitrarily chosen third point. Simple, straightforward reference-free measurements are the location of the maximal (highest, peak) and minimal (lowest, trough) potential value within the recorded

llP field, and the potential difference between them. The highest potential difference between any two recording electrodes after a stimulus is one reference-free definition of the occurrence time of the major 'comp o n e n t ' of the evoked potential; locations of field peaks and troughs at this time indicate the location of this neural generator. Non-identical locations of field peaks and troughs in two stimulus conditions are to be interpreted as manifestations of different generators. These reference-free strategies might be used with as few as 3 electrodes. In multichannel (48 channel) records which result in series of isopotential contour line plots of the scalp fields, they are used for the required unbiased data reduction and assessment. Using such strategies, we could show, e.g., that upper hemiretinal stimuli result in earlier and more anteriorly located responses than lower hemiretinal stimuli, that ' o n ' responses of the upper hemiretina are more anteriorly located than 'off' responses (vice versa for lower hemiretinal stimuli!), and that words of n o u n meaning evoke positivities more anteriorly on the scalp than identically sounding (homophone) words of verb meaning.

26. Visual evoked potentials in children suffering from non-hemiplegic cerebral palsy. -- P. Laget and N. Gagnard (Paris, France) The authors compare visual evoked potentials (VEPs) produced by flashes or diffuse or patterned light stimulation in 50 normal children aged 3--15 years with VEPs recorded in 60 children in the same age range, suffering from non-hemiplegic cerebral palsy (spastic diplegia, choreo-athetosis and so on). In an important proportion of these patients (32%), VEPs produced by blank or patterned stimuli significantly differed with those recorded in normal subjects. Statistically significant correlations were encountered between these results and some clinical data, especially in term of birth and mental development.

27. Visual and somaesthetic evoked potentials (VEPs and SEPs) in neurolipidoses. - - P. Laget and A.M. d'Allest (Paris, France) The authors describe alterations of VEPs, SEPs and ERGs recorded in 24 children suffering from various forms of neurolipidosis. The physiopathological significances of these findings are discussed. Interpretations are attempted relating to neurohistological alterations observed in experimental neurolipidosis in animals.

12P 28. Fourier analysis o f evoked potentials to verbal stimuli in healthy subjects and in neurological patients. -- J. Szirtes (Budapest) and V. Dickmann, A. Rothenberger and R. Jiirgens (Ulm, G.F.R.) Evoked potentials (EPs) were recorded f r o m hom o l o g o u s scalp sites in healthy, left (aphasic) and right hemisphere damaged subjects. Stimuli were oneand two-syllable words and 4 stimulus c o n d i t i o n s were used: monaural left and right, diotic and dichotic. T w o main differences were observed b e t w e e n averaged EPs of healthy and aphasic subjects: (1) the N l l 0 c o m p o n e n t was markedly reduced in aphasic in contrast to healthy subjects and the P200 comp o n e n t was greater in patients; (2) the whole wave f o r m was shifted into negativity in healthy subjects and this displacement was reduced or absent in aphasics. 1 sec long pre- and post (EP)-stimulus averaged EEG e p o c h s were t h e n subjected to Fourier analysis and p o w e r density and phase spectra were determined. The greatest power appeared generally in the DC c o m p o n e n t or in the f u n d a m e n t a l sinusoid (1 Hz), and healthy subjects showed significantly greater power in the 0--3 Hz range than aphasics. In the phase spectra b o t h groups showed a clustering, a ' s y n c h r o n i z a t i o n ' o f phase values in the 1--5 Hz range. The major difference b e t w e e n healthy and aphasic subjects appeared at 6--9 Hz where aphasics showed no clustering o f phase values. No significant differences were observed between phase spectra f r o m t h e t w o hemispheres.

29. F u r t h e r experiences with brain stem auditory evoked potentials in neurological diagnosis. - - L. Cig~nek, A. Smieskov~ and P, Mtadonicky (Bratislava, Czechoslovakia) Brain stem a u d i t o r y evoked potentials need exact m e a s u r e m e n t ; this was realized by means o f a PDP1 1 / 4 0 c o m p u t e r in P D P - F O R T R A N IV language. The p r o b l e m in clinical diagnosis is to decide whether an individual response is still a normal one or just b e y o n d the normal group limits. We used the factor analysis r e c o m m e n d e d by Bennett and constructed for each potential c o m p o n e n t ( f r o m 50 normal subjects) in the time-amplitude field an ellipse delimiting normal values. These ellipses superimposed on the averaged potential o f the e x a m i n e d patient made it possible to evaluate t h e n o r m a l i t y or pathology o f the separate waves. This m e t h o d given no satisfactory possibility of evaluating the interpeak t i m e intervals, i m p o r t a n t for diagnosis. Therefore a m e t h o d for a u t o m a t i c identification as well as latency-amplitude m e a s u r e m e n t for each potential peak was developed.

SOCIETY PROCEEDINGS These values, including the interpeak time intervals, were then a u t o m a t i c a l l y c o m p a r e d with normative data. This m e t h o d was impossible w h e n the general shape of the response was altered. All described results were drawn by means of an X-Y plotter or printed out in an a u t o m a t i c way. Different ages in children must be taken into consideration, which complicates the situation

30. The different types o f oscillation o f the energy level in sleep-wakefulness. -- A. S61yom, J. T 6 t h , I. Tomka, O. Hoffmann and R. K~lm~nchey (Budapest) One of the characteristics o f cerebral electrical activity is the appearance o f periodic oscillating potentials, which are c o n n e c t e d to definite functional states o f the brain. The typical e x a m p l e of such activity is the regular alpha activity. The periodical energy level changes within the oscillating potential are called by us primary oscillation of energy level. If we arrange in chronological order the values of p o w e r density spectra of the single frequencies of 1 sec epochs forming the c o n t i n u o u s spectral picture, continual changes can be well noticed. These energy level changes are called secondary oscillations of energy level, where the period of oscillation is measured from peak to peak and that value m considered as a peak which has at least 25% higher value t h a n those of its neighbours. These distributions of oscillation-time are d e m o n s t r a t e d in sleep-wakefulness stages in healthy subjects and petit real epileptics. Examining the sequences of secondary oscillation o f energy level in the realm o f any frequency, one may notice c o n t i n u o u s l y increasing, then diminishing epochs, which p h e n o m e n o n indicates a still slower sinuous character of oscillation. This p h e n o m e n o n is called by us tertiary oscillation of energy level. The above 3 t y p e s of oscillation of the energy level are characteristics of the cerebral electrical activity, which can be f o u n d in all the EEG frequencies.

31. The relationship b e t w e e n p o w e r density spectra and sleep stages. -- I. Tomka, J. T6th and M. Bod6 (Budapest) The cerebral electrical activity o f y o u n g healthy subjects was analysed in sleep-wakefulness by polygraphic recording in all-night s t u d i e s In this paper the characteristic changes o f p o w e r density spectra are d e m o n s t r a t e d , which play a definite role in the electrophysiological c o n c o m i t a n c e of the states o f sleepwakefulness.

HUNGARIAN EEG SOCIETY The EEG activity was stored on a tape-recorder and digitalized at 500 samples/sec. Fast-Fourier proceasing was carried o u t by a PDP c o m p a t i b l e computer. The f r e q u e n c y s p e c t r u m of the chosen EEG epochs was processed directly f r o m the EEG activity f r o m DC to 31 c/sec with 1 c/sec resolution and a width o f 1 c/sec. The 60 sec epochs were resolved to 1 sec parts and the o b t a i n e d spectra were further analysed.

32. Power density spectral changes o f cortical and deep structures in petit mal p a r o x y s m s on the borderline o f sleep-wakefulness. - - O. H o f f m a n n , I. T o m k a and J. T 6 t h (Budapest) The characteristics of the total energy level and several frequency bands of 4 simultaneous derivations from scalp and deep structures before, during and after paroxysms in petit real epileptics were analysed. O n the basis of analysis of the electrical paroxysms in the 'hypersynchronous alpha state' the following principal characteristics can be emphasized: during paroxysms the increase of the total energy level reaches or surpasses one order of magnitude; after paroxysms the value of the total energy level shows a lower value than before the paroxysms. During a period of 8--10 sec before the electrical paroxysm a well discernible induction p h e n o m e n o n can be noticed, while the total energy content through an oscillation with successively increasing amplitudes reaches the energy level of the paroxysm. During paroxysms the 3 c/sec delta activity represents a prominently high value;however, here appears a widespread high level of the energy content in the whole E E G spectrum, in comparison to the resting value. A f t e r a p a r o x y s m t h e f r e q u e n c y s p e c t r u m narrows and its energy level decreases in c o m p a r i s o n to that o f the epochs before the p a r o x y s m . In the petit real electrical p a r o x y s m the relations o f the energy level and f r e q u e n c y s p e c t r u m of deep structures are similar to those o f cortical areas, o n l y their energy level represents a higher value.

33. The analysis o f f r e q u e n c y o f m a x i m a l energy c o n t e n t in sleep-wakefulness. - - J. T S t h and I. T o m k a (Budapest) The cerebral electrical activity of sleep-wakefulness o f y o u n g healthy subjects and o f epileptic patients with scalp and d e p t h electrodes was recorded. B e y o n d analysis o f t h e p o w e r density s p e c t r u m we e x a m i n e d in detail h o w the frequencies o f m a x i m a l energy c o n t e n t are distributed in a 1 sec epoch. 1--3 rain epochs o f the cerebral electrical activity

13P o f sleep stages and wakefulness were digitalized at 500 samples/sec, with 8 bits of resolution. Every program system was written in Fortran. Fast Fourier t r a n s f o r m a t i o n of the chosen epochs of the cerebral electrical activity was carried o u t from DC to 31 c/sec with 1 c/sec of resolution and a width o f 1 c/sec. The epochs were resolved to 1 sec parts and the spectral pictures stored on tape for further analysis, were carried o u t o f f line. T o summarize our results we m a y say that, with the help o f d e m o n s t r a t i o n of the frequencies o f m a x i m a l energy c o n t e n t in the spectral picture o f the cerebral electrical activity, we can present a new c o m puter evaluation, which exhibits definite precise changes and characteristics o f the cerebral electrical activity. These could n o t be d e m o n s t r a t e d o n l y by t h e percentage distribution of energy level of the p o w e r density spectrum.

34. E E G and clinical e x a m i n a t i o n of post-traumatic epilepsy. - - Gy. Ostorharics-HorvEith, M. Bencze and S. Liss~ik (Gy6r) The authors have studied 35 post-traumatic epileptic o u t p a t i e n t s a m o n g 596 epileptic patients under care: 32 were male and 3 female. T h e y were b e t w e e n the ages 8 and 70 years. Skull fracture in 11, contusion in 3 and c o m m o t i o n in 21 cases could be confirmed. The first epileptic seizure appeared s o m e days after the injury in 2 cases, after s o m e weeks in 3 cases, within one year in 13 patients, and in 18 cases b e t w e e n 1 and 30 years. The types o f seizure were grand real in 26 patients and partial seizures in 8. Neurologically 29 patients were normal, 3 had organic brain damage and 2 had local signs. A m o n g 11 epileptic patients p n e u m o e n c e p h a l o g raphy showed mild cerebral a t r o p h y in 5 cases. The authors observed a normal m e n t a l state in 5 cases, 12 patients had a different scale of c h a r a c t e r o p a t h y , 2 had s o m e psychopathological s y m p t o m s with alcoholsm, 8 reactive neuroses, 1 had dementia, and 1 had organic brain damage. A f t e r the different types o f cranial fracture in 11 patients 3 had a normal EEG and the others had a local or diffuse slowing of background activity. A f t e r antiepileptic m e d i c a t i o n in 9 cases slowing o f the background activity could be seen, and 4 had epileptic discharges. A f t e r c o m m o t i o n 15 patients had a normal EEG and 9 cases showed non-specific slight dysfunction. A f t e r m e d i c a t i o n 14 had normal EEGs, 3 had focal slow wave activity, 1 a focal spike activity, and 6 had slight diffuse slowing. The i m p o r t a n c e o f parallel E E G and clinical follow-up studies is stressed during the course of treatm e n t of post-traumatic epilepsy.

14P 35. T h e diagnostic value o f the EEG at the t i m e o f the first spell raising the suspicion o f epilepsy (analysis o f 2 2 5 cases). - - P. Rajna ( B u d a p e s t ) T h e diagnostic value o f t h e E E G in 2 2 5 a d u l t p a t i e n t s a f t e r t h e i r first spell raising t h e suspicion o f epilepsy was a n a l y s e d in a r e t r o s p e c t i v e s t u d y . Acc o r d i n g t h e t h e first E E G r e c o r d diagnostically valuable signs were n o t f o u n d m o r e f r e q u e n t l y in t h e epileptic g r o u p t h a n in t h e o t h e r diagnostic g r o u p , b u t using a c t i v a t i o n m e t h o d s t h e E E G signs o f diagnostic value increased t o 83% in t h e epileptic group. In a n i m p o r t a n t part o f o u r p a t i e n t s t h e E E G a b n o r m a l i t i e s were e r r o n e o u s l y j u d g e d t o be epileptic in o u t p a t i e n t practice. T h e s e a b n o r m a l i t i e s originated partly from synchronization after hyperv e n t i l a t i o n in y o u n g subjects, a n d p a r t l y f r o m abn o r m a l i t i e s caused b y vascular disorders in t h e aged g r o u p o f patients. T h e a u t h o r stresses t h e i m p o r t a n c e o f t h e clinical p o i n t o f view in t h e diagnostic j u d g e m e n t at t h e t i m e o f t h e first u n d e t e r m i n e d spell, while t h e E E G seems t o b e o n l y a useful a d d i t i v e tool:

36. P h o t o s e n s i t i v e e p i l e p s y and responses. - - K. Hegediis a n d L. Csiba ( D e b r e c e n ) I n t e r m i t t e n t p h o t i c s t i m u l a t i o n has b e e n used as a routine provocative procedure during EEG examinat i o n of 1 3 , 1 0 0 p a t i e n t s in t h e last 5.5 years. Abn o r m a l r e s p o n s e s were i n d u c e d in 33 p a t i e n t s . Parox y s m a l a b n o r m a l i t i e s were f o u n d in t h e f o r m o f bilaterally s y n c h r o n o u s irregular polyspike-wave discharges in 26 p a t i e n t s . Severe d y s r h y t h m i a , consisting o f irregular slow waves b u t n o epileptic paroxysms, was p r o d u c e d in 4 o f t h e p a t i e n t s . B o t h a b n o r m a l responses, d e p e n d i n g o n t h e f r e q u e n c y of s t i m u l a t i o n , o c c u r r e d in 3 p a t i e n t s . T h e p a t i e n t s are s u b d i v i d e d i n t o 3 clinical groups. ( 1 ) P h o t o s e n s i t i v e p a t i e n t s : t h i s g r o u p consists o f 5 w o m e n ranging in age f r o m 20 t o 26 years. T h e i r resting E E G s were n o r m a l ; t h e polyspike-wave activity appeared only during photic stimulation. The a b n o r m a l r e s p o n s e c o u l d b e e v o k e d for a long t i m e ( 1 - - 4 years), despite t r e a t m e n t w i t h a n t i c o n v u l s a n t drugs. (2) T h e epileptic discharges a c t i v a t e d b y p h o t i c s t i m u l a t i o n o c c u r r e d o n l y t e m p o r a r i l y in t h e EEGs o f 10 p a t i e n t s s u f f e r i n g from epilepsy: T h e y c o u l d b e seen o n l y w h e n t h e n u m b e r o f seizures increased. (3) T h e o t h e r p a t i e n t s h a d b e e n t r e a t e d b e c a u s e o f drug i n t o x i c a t i o n , e e r e b r o v a s c u l a r disorder, b r a i n tumour, a l c o h o l i s m or t r a u m a . T h e a b n o r m a l r e s p o n s e s to p h o t i c s t i m u l a t i o n d i s a p p e a r e d always parallel w i t h r e c o v e r y f r o m t h e p r i m a r y disease, w i t h o u t a d m i n i s t r a t i o n o f a n t i c o n v u l s a n t drugs. 11

SOCIETY PROCEEDINGS o f t h e m had no h i s t o r y o f e p i l e p t i c fits. During c o n t i n u o u s p h o t i c s t i m u l a t i o n o p e n i n g o f t h e eyes i m m e d i a t e l y s t o p p e d t h e seizure p a t t e r n , b u t it r e a p p e a r e d p r o m p t l y a f t e r closing t h e eyes. T h e i r a p p e a r a n c e c o u l d be p r e v e n t e d b y vestibular a n d painful s t i m u l a t i o n . These effects c a n b e r e f e r r e d t o t h e i n h i b i t i n g f u n c t i o n o f t h e non-specific p a t h ways.

37. T h e role o f light s t i m u l a t i o n in t h e j u d g e m e n t o f d i s p o s i t i o n t o c o n v u l s i o n in alcoholics. - - I. Hoffm a n n and L. Gy6ri (P6cs) Photic s t i m u l a t i o n as a regular s u p p l e m e n t a r y part o f clinical E E G e x a m i n a t i o n has c o m e i n t o the limelight of t h e clinical a n d e x p e r i m e n t a l l i t e r a t u r e again: in clinical p r a c t i c e to d e t e r m i n e t h e t y p e of d i s p o s i t i o n t o c o n v u l s i o n s o f alcoholic addicts, m o s t l y d u r i n g a b s t i n e n t periods. R e s p o n s e s to i n t e r m i t t e n t p h o t i c s t i m u l a t i o n of d i f f e r e n t frequencies, d u r a t i o n a n d i n t e n s i t y , ranging f r o m occipital spikes t o p h o t i c c o n v u l s i o n s r e c o r d e d in c h r o n i c alcoholic p a t i e n t s , are a n a l y s e d in this paper. A c o m p a r i s o n was m a d e b e t w e e n the freq u e n c y of t h e seizures o c c u r r i n g s p o n t a n e o u s l y a n d t h e r e s p o n s e s t o light s t i m u l a t i o n .

38. Averaged l a m b d a p o t e n t i a l s in m a n a n d m o n k e y . -- M. M a r t o n , J. Szirtes, N. D o n a u e r a n d F. Defik (Budapest) T h e p r e s e n t s t u d y deals with t h e c o m p a r a t i v e investigation of averaged l a m b d a p o t e n t i a l s ( l a m b d a c o m p l e x ) associated w i t h saccadic eye m o v e m e n t s in m a n a n d m o n k e y . R e c o r d s were m a d e f r o m midline o c c i p i t a l a n d parietal scalp p o i n t s in 11 h u m a n s a n d f r o m w i t h i n t h e occipital a n d parietal cortices in 3 rhesus m o n k e y s . B o t h in h u m a n s a n d m o n k e y s saccades were p e r f o r m e d (1) across gratings w i t h diff e r e n t l u m i n a n c e values; (2) across discreet or disc o n t i n u o u s p a t t e r n s a n d (3) in t o t a l darkness. In a f u r t h e r e x p e r i m e n t in h u m a n s visual s t i m u l a t i o n received at (4) saccade o n s e t a n d (5) offset was e x p e r i m e n t a l l y increased t o s t u d y its effects o n early, 'saccadic' a n d later, ' f i x a t i o n a l ' c o m p o n e n t s of t h e lambda complex (Kurtzberg and Vaughan 1977 Yagi 1 9 7 9 ) . It was s h o w n t h a t t h e decrease in l u m i n a n c e led t o a d i m i n u t i o n in the a m p l i t u d e o f t h e first large negative c o m p o n e n t (N1 at 5 0 - - 6 0 msec f r o m saccade o n s e t ) o f t h e cortical l a m b d a c o m p l e x ; f u r t h e r m o r e , t o a n increase in t h e l a t e n c y o f cortical and scalp P 3 c o m p o n e n t ( a p p e a r i n g at 130 msec in m o n keys a n d at 170 msee in h u m a n s ) . A larger N2 comp o n e n t was o b s e r v e d over t h e parietal region and

H U N G A R I A N EEG SOCIETY when saccades were performed across discreet/discontinuous patterns, and in darkness. Saccades in total darkness were accompanied by a negative shift of the lambda complex with discernible N1 and N2 peaks. At the offset of eye movement the extra stimulation led to an increase both in the amplitude and latency of the P4 peak. These results are interpreted in the light of the recent single unit data on visuomotor mechanisms and with reference to the phenomenon of space constancy.

39. Serial EEG investigations in prolonged comatose states. -- L. GySri (Budapest) The most c o m m o n alteration of cerebral activity in comatose states is the organized or disorganized theta-delta activity, the parameters of which have been correlated with the seriousness of unconsciousness in the literature. Important exception is the alpha~coma pattern. Many writers emphasized that numerous, differently organized, activities can also be found in comatose states, such as the alternation of the waking-sleeping cycle, paroxysmal activity, etc. In diabetic ketoacidosis, uraemia, hypoglycaemia, cardiac arrest and cerebral turnout the cerebral electric activity of unconscious patients had been monitored continuously. Summarizing, our observations, in prolonged coma periodic or pseudoperiodic complexes (suppression-burst, periodic paroxysmal events, frontal intermittent delta activity) frequently occur and the importance of these patterns is discussed.

40. Computerized EMG examinations in clinical pharmacological examination. -- Z. Sz~plaki, G. T6th, M. A n t o n y and I. B~n (Budapest) The authors deal with experiments with computerized EMG for objective evaluation of drug effects. They examine standard EMG records before and after drug effects. A computerized EMG analysis was carried o u t in parallel with the visual analysis of records with the help of a mathematical model based on the changes of parameters of the EMG. The results were in close correlation with the results of visual analysis. Minor changes can be evaluated by the method, therefore it is recommended to be useful first of all in clinico-pharmacological studies. The authors discuss the problems of computerized analysis, centred on the limits of the method.

15P 41. Study of evoked field potentials in the depths of the auditory cortex of freely moving cats. -- Gy. Karmos, M. Molndr and V. Cs~pa (Budapest) In spite of numerous electrophysiological studies our knowledge about the origin of the sensory evoked potentials recorded on the surface of the cortex is still scanty. This is especially true for the late components because most of the classical neurophysiology was carried out on immobilized and anaesthetized animals in which late components could not be studied. A new type of multielectrode was constructed which allowed the simultaneous recording of evoked field potentials (EFPs) from the surface and 5 or 6 different depths of the cortex. The multielectrodes were chronically implanted in the auditory areas of cats. The click elicited EFPs were recorded in freely moving animals in different behavioural situations and under the effects of various types of anaesthetics. Considerable latency differences were found between the early surface positive and deep negative components, indicating that the surface potential is not a volume conducted mirror equivalent of the components generated in the depth of the cortex. During the development of anaesthesia the late components of the surface and deep EFPs displayed dynamic changes relatively independent of each other.

42. Changes of click-evoked intracortical field potentials during the wakefulness-sleep cycle in cat. M. Moln~r, Gy. Karmos and V. Cs~pa (Budapest) Auditory cortical evoked potentials were studied in the wakefulness-sleep cycle in cats. A chronically implanted multielectrode served for the recording of the surface and intracortical field potentials. Only minor amplitude changes were observed in the early components while the late waves displayed complex configurational changes in the different stages of sleep. Phase reversal in the depth of the cortex appeared only in the case of the early surface positive component. However, latency differences between the early surface and deep components indicated that this phase reversal cannot be explained by the classical dipole theory. In most cases late components occurred with the same polarity in the whole depth of the cortex. In slow wave sleep a homogeneous late positive-negative oscillation developed in the A1 area, the amplitude and duration of which was proportional to the depth of sleep. The conclusion was drawn that the study of intracortical field potentials in behavioural experiments may shed more light on the sensory cortical mechanisms.

16P 43. M o d e r n e l e c t r o p h y s i o l o g i c a l s y s t e m for clinical use. -- L. Kell~nyi, J. Czopf and Gy. Kell~nyi (P~cs) In t h e clinical e l e c t r o p h y s i o l o g i c a l l a b o r a t o r i e s o f o u r c o u n t r y t h e a n a l o g u e signal registering apparatuses are to b e supplied with t h e digital t e c h n i q u e . T h e PBS a n a l y s e r ( P r o g r a m m e d Biological Signal A n a l y s e r ) h a s b e e n developed for this p u r p o s e . T h e c o n s t r u c t i o n is similar t o c o m p u t e r s m a d e in H u n g a r y earlier (e.g. K E K I N T A 5 1 2 ) b u t its price is a b o u t 1 / 1 0 t h o f t h a t . Wired p r o g r a m , t i m e interval ( T I H ) , p o s t s t i m u l u s (PSH) l a t e n c y h i s t o g r a m , multiscaler f u n c t i o n (MSC) a n d averaging are possible. T h e m e m o r y c o n t e n t is: 5 1 2 × 16 bits in 7 groups. By m e a n s o f t h e digital delay circuit o f t h e s y s t e m prea n d p o s t s t i m u l u s averaging w i t h a n a l o g u e s a n d discrete signals a n d on-line analysis c a n be p e r f o r m e d . T h e results can b e p r e s e n t e d o n a n X-Y p l o t t e r a n d s t o r e d o n a casette tape r e c o r d e r in t h e f o r m : 512 x 16 bits. T h e c o n t e n t c a n be c o n n e c t e d b y a h i g h s p e e d o u t p u t to every digital c o m p u t e r used in o u r c o u n t r y .

44. P a t t e r n p r e s e n t a t i o n and pattern reversal evoked p o t e n t i a l s in h e a l t h y s u b j e c t s a n d in MS patients. -- J. Czopf, L. Kell~nyi a n d J. C z o p f (P~cs) A comparison of the pattern presentation, pattern reversal a n d flash evoked p o t e n t i a l s o f 1 0 h e a l t h y subjects a n d 20 p a t i e n t s (18 w i t h m u l t i p l e sclerosis) has b e e n p e r f o r m e d b y t h e a u t h o r s . T h e p a t t e r n pres e n t a t i o n a n d flash stimuli were p r o d u c e d b y m e a n s o f a r o u t i n e x e n o n t u b e s t i m u l a t o r , t h e p a t t e r n reversal w i t h t h e aid of LEDs a n d a T V g e n e r a t o r p r o d u c e d c h e c k e r b o a r d . T h e p a t t e r n reversal stimuli resulted in p a t h o l o g i c a l e v o k e d p o t e n t i a l in m u c h higher ratio c o m p a r e d w i t h t h e flash a n d p a t t e r n p r e s e n t a t i o n . T h e p a t t e r n reversal e v o k e d p o t e n t i a l elicited w i t h t h e LED a n d T V m e t h o d s were highly similar in amp l i t u d e , wave form a n d l a t e n c y o f t h e c o m p o n e n t s . T h e t w o m e t h o d s ( p a t t e r n p r e s e n t a t i o n a n d reversal) given c o m p l e m e n t a r y i n f o r m a t i o n as t o t h e lesion of t he visual system.

45. Short latency auditory brain stem evoked potentials (BAEPs) in clinical practice. -- L. KellSnyi, J. Czopf and M. Bauer (Budapest) T h e e l e c t r o p h y s i o l o g i c a l analysis of t h e f u n c t i o n o f t h e a u d i t o r y a n d o t h e r b r a i n s t r e m s t r u c t u r e s is possible with t h e aid o f b r a i n s t e m a u d i t o r y e v o k e d p o t e n t i a l s (BAEPs). T h e i r clinical use is in t h e early diagnosis o f acoustic n e u r i n o m a , t u m o u r a l a n d d e m y e l i n a t i n g processes o f t h e brain s t e m , a n d in t h e c o n t r o l o f b r a i n s t e m f u n c t i o n in t h e cases o f b r a i n death. T h e a m p l i t u d e a n d l a t e n c y changes o f c o m p o -

SOCIETY PROCEEDINGS n e n t s in t h e early 10 msec range of t h e p o t e n t i a l indicate a d e f i n i t e l o c a l i z a t i o n level o f t h e lesion w i t h clinical signs. In o u r I n s t i t u t e a n e w a n a l y s e r has b e e n d e v e l o p e d f o r clinical practice, w i t h t h e possibility o f digitalized m a g n e t i c tape storage o f t h e signals for later off-line signal analysis.

46. Spinal e v o k e d p o t e n t i a l s in m u l t i p l e sclerosis. - J. C z o p f a n d L. Kell~nyi (P~cs) T h e spinal e v o k e d p o t e n t i a l gives a new possibility to the electrophysiologicat control of the somatosensory system. T h e spinal p o t e n t i a l s at t h e l u m b a r a n d cervical spinal levels to s t i m u l a t i o n o f t h e p e r o n e a l a n d m e d i a n nerves were registered in 14 m u l t i p l e sclerotic p a t i e n t s and 5 c o n t r o l s . B e t w e e n 15 a n d 20 msec a negative c o m p o n e n t o f large a m p l i t u d e c o u l d b e registered, d e p e n d i n g o n muscle t e n s i o n . In 9 o f t h e 14 p a t i e n t s a n d 3 of t h e c o n t r o l s i d e n t i f i a b l e c o m p o n e n t s were o b s e r v e d giving t h e possibility o f spinal c o n d u c t i o n velocity m e a s u r e m e n t . O n l y in 4 o f t h e 9 p a t i e n t s was a r e d u c t i o n o f t h e c o n d u c t i o n velocity o b s e r v e d ( b e t w e e n 30 m / s e c a n d 50 m/sec).

47. T h e effects o f i n t r a - m o d a l selective a t t e n t i o n o n pattern-specific visual evoked p o t e n t i a l s . -- I. Czigler and M. TSlgyesi (Budapest) In a c o m p l e x c h o i c e r e a c t i o n t i m e e x p e r i m e n t p a t t e r n e d stimuli w i t h o u t l u m i n a n c e c h a n g e were p r e s e n t e d a n d p a t t e r n - s p e c i f i c visual evoked p o t e n tials to l o w e r half-field s t i m u l a t i o n were r e c o r d e d . T w o e x p e r i m e n t a l c o n d i t i o n s were used. (1) B e t w e e n field selection, w h e r e square p a t t e r n s were p r e s e n t e d to e i t h e r t h e l o w e r or t h e u p p e r half o f t h e visual field. In a given s t i m u l u s r u n o n e o f t h e half-fields was task-relevant a n d t h e subjects task was to press a m i c r o s w i t c h at t h e o n s e t of stimuli of higher spatial c o n t r a s t (GO stimuli), while t h e y h a d t o ignore t h e stimuli o f l o w e r spatial c o n t r a s t (NO-GO stimuli). T h e y h a d to ignore t h e stimuli a p p e a r i n g in t h e irrelevant half-field ( I R R stimuli} as well. In o r d e r to e n s u r e p r o p e r f i x a t i o n , t h e s u b j e c t s had to press a n o t h e r m i c r o s w i t c h at t h e o n s e t o f a dim light at the f i x a t i o n p o i n t ( C R T stimuli}. (2} Within-field selection, w h e r e t h e GO, NO-GO, a n d I R R stimuli a p p e a r e d in t h e l o w e r half o f t h e visual field. G O a n d NO-GO stimuli were square p a t t e r n s while I R R stimuli were c o n s t r u c t e d o f circles, o r vice versa. ( T h e C R T stimuli were t h e s a m e as in t h e p r e v i o u s condition.} T h r e e p a t t e r n - s p e c i f i c visual e v o k e d p o t e n t i a l c o m p o n e n t s were identified, i.e. CI (70 msec l a t e n c y ) , CII ( 1 0 0 msec l a t e n c y ) , a n d CIII ( 1 7 0 msec latency). T h e r e were m a r k e d selective a t t e n t i o n effects o n b o t h

H U N G A R I A N EEG SOCIETY the CI-CII and CII-CIII peak-to-peak amplitudes. In both experimental conditions responses with the largest amplitude were evoked by the GO stimuli, while I R R stimuli evoked the smallest responses. According to these results, attention effects on the pattern-specific visual evoked potentials in the first 200 msec cannot be attributed to a simple stimulus set type of selection.

48. Manic-depressive disorder and EEG abnormalities. - - Z. R i h m e r , P. Tariska and N. Csisz~r (Budapest) Three previous reports (Dal~n 1966; Hays 1976; Kadrmas and Winokur 1979) presented a relationship between a negative family history for affective disorder and EEG abnormalities in manic-depressive patients. The authors analysed the conventional EEG data, family history and other clinical variables of 44 female patients with manic-depressive illness. The family history was positive in 17 cases and abnormal EEGs were recorded in 13 patients. Out of these 13 patients 11 had a negative family history for affective illness. The presence of EEG abnormalities was unrelated to age, diagnostic subgroups, i.e., bipolar I/bipolar II, or past or present drug treatment. Only the association of negative family history and positive EEG was significant (P ~ 0.05). The findings confirm the earlier results and are indicative that manic-depressive illness may not be a homogeneous entity.

49. Episodic schizophreniform psychosis following complex partial status epflepticus. -- B. Clemens and K. Bacskal (Debrecen) A detailed clinical and EEG study of a previously healthy, 60-year-old woman with a long-lasting twilight state of epileptic nature (complex partial status epilepticus or psychomotor status) is presented. Administration of diazepam (i.v.) abolished both abnormal behaviour and paroxysmal EEG activity. Next day a typical schizophreniform epileptic psychosis developed with productive symptomatology and without any alteration of vigilance. Psychotic symptoms disappeared completely after 3 weeks. The case seems to be interesting because: (1) complex partial status epilepticus is a rare condition especially when documented by EEG; (2) the generally accepted circumstances which favour the evolution of schizophreniform psychotic episodes in epilepsy are psychosis developed without long history of epilepsy; difficulties in controlling the seizures; high dose anti-epileptic treatment, sometimes with toxic side effects.

17P The authors concluded that relatively short but intensive bilateral epileptic dysfunction of some temporal structures may alter the patterns of temporal lobe function and in this way may lead to psychosis.

50. EEG abnormalities in Sydenham's chorea. -- S. Dobi and K. Cs~mi (Gyula)

In recent years several papers are found in Western and Soviet literature about the clinical symptoms and pathogenesis of Sydenham's chorea. These observations emphasize that abnormal EEG activities, occasionally even clinical epileptic attacks, may be present in the acute period of Sydenham's chorea. The authors have observed several patients suffering from Sydenham's chorea and followed them clinically and electroencephalographically during a year. In some of their cases not the dyskinetic movements but epileptic fits have called the attention to the disturbance of the CNS. EEG abnormalities were observed at the time when the patients were admitted to hospital and later during the treatment and also at the time of control investigations. The authors think anticonvulsive treatment to be necessary and useful in such cases. 51. EEG examinations in experimental WernickeKorsakow encephalopathy (preliminary study). -- A. Auguszt, M. T~rczy, M. Papp and A. Takers (Budapest) The Wernicke-Korsakow encephalophathy is a consequence of B1 avitaminosis (lack of thiamine). This condition can also be provoked by giving a diet with thiaminase content. The experiments were carried out in 5 cats. Epidural electrodes were implanted and the EEG was r e c o r d e d before and during the diet of food containing thiaminase, and after giving B 1 vitamin. The first alterations could be observed after the onset of the clinical signs. The earlier beta-rich EEG altered to show polymorphy with the continuous appearance of theta waves. Later generalized electrical convulsions with sharp and spike waves appeared with clinically observable convulsions. After intraperitoneal administration of 15 mg/kg BI vitamin the EEG showed reorganization, and records taken 24 h after the B1 vitamin administration were similar to the controls. The authors suppose that the EEG findings can be explained by the typical biochemical alterations of the disease rather than by the well-known histological alterations.

18P

52. Comparative study on EEG and REG. -- M. Bod5, A. P~sztor, E. P~ztor, L. lilts (Budapest) and Yu. Moskalenko (Leningrad, U,S.S.R.) T h e m i n u t e c h a n g e s in a u t o r e g u l a t i o n o f cerebral b l o o d flow c a n n o t b e e x a m i n e d well b y t h e c u r r e n t m e t h o d s b e c a u s e o f t h e i r invasion o r c o m p l e x i t y a n d also b e c a u s e o f t h e i r expense, R h e o e n c e p h a l o g r a p h y ( R E G ) seems to be s u i t a b l e for this p u r p o s e f r o m t h e suggestion o f M o s k a l e n k o ; R E G reflects t h e r e a c t i v i t y o f c e r e b r a l b l o o d vessels t o f u n c t i o n a l loads. In t h e first step of t h e m o d e l e x p e r i m e n t - - b a s e d on the hypothesis mentioned above -- the functional load was t h e d i r e c t a n d i n d i r e c t increase o f t h e ICP

SOCIETY PROCEEDINGS of a n a e s t h e t i z e d dogs in a c u t e e x p e r i m e n t s , Polygraphic r e c o r d i n g a n d data processing were carried o u t . All t h e d a t a were related t o t h e l o n g i t u d i n a l l y c o n s t r u c t e d d a t a o f t h e EEG p o w e r d e n s i t y spectrum. In spite o f t h e p r e l i m i n a r y n a t u r e of o u r results it m a y b e c o n c l u d e d t h a t t h e R E G is a m o r e sensitive t e c h n i q u e for following ICP c h a n g e s t h a n EEG. We s u p p o s e t h a t this is in c o n n e c t i o n w i t h t h e d i f f e r e n t speeds o f t h e h a e m o d y n a m i c a n d m e t a b o l i c syst e m s . O u r results m a y be h e l p f u l in early recovery a n d in t h e t h e r a p y o f c e r e h r o v a s c u l a r spasms, w h i c h seems to be o n e of t h e u n s o l v e d p r o b l e m s of n e u r o surgery.