Japan society of electroencephalography and electromyography, 13th annual meeting

Electroencephalography and clinical Neurophysiology, 1985, 60:1 P - 12P

1P

Elsevier Scientific Publishers Ireland, Ltd.

Society proceedings JAPAN ANNUAL

SOCIETY

OF ELECTROENCEPHALOGRAPHY

AND

ELECTROMYOGRAPHY,

13th

MEETING

Nara, December 1-3, 1983

Meeting Secretary: Dr. S H O Z A B R O U T S U M I Hongo Sky Building 703, 3- 38-11 Hongo, Bunkyo -ku, Tokyo (Japan) (Received for publication: June 7, 1984)

1. Attention-related brain potential. - - S. Niwa (Tokyo)

ERP correlates of selective attention were studied in an experiment employing syllable discrimination tasks similar to those employed by Hink et al. (1978). N100 and P200 components of ERPs derived from the Cz region were examined in particular. Normal subjects demonstrated an enhancement of N100 amplitudes, as well as a reduction of P200 amplitudes, to all stimuli in the attended channel (ear) in comparison to those of the non-attended channel. Endogenous negative shifts, Nd as reported by Hillyard et al. (1980), were speculated to be responsible for these attention-related effects on N100 and P200 components. In the present study, measurement of these effects was applied to the research of schizophrenic attentional deficits. Although judged as rather motivated in performing tasks, nonmedicated schizophrenics failed to display these effects for either the N100 or P200 component. While medicated schizophrenics, with less symptoms as compared to non-medicated patients, showed the effect for P200 components, but not for N100 components. Psychotropic drug treatment was thought to be effective in improving attentional disturbances of schizophrenics. Based on the above results, measurements of attention-related brain potentials were concluded to be useful in clinical psychiatric fields. 2. A computer system to measure ERP (P300) for clinical examination. - - Y. Nageishi, T. Shimura and S. Shimokochi (Osaka)

In order to examine the event-related potential (ERP), one must average each brain potential under the same conditions in a large number of trials for a given psychological task. However, this procedure is quite difficult to do during clinical examinations. Therefore, it may be convenient to have a simple computer system which will be able to control the psychological tasks and obtain the wave shape of the ERP at the same time. Since the ERP usually involves several components, it is also desirable for the system to be able to identify these

components and measure their properties. To meet these requirements, we devised a personal computer as indicated below. It controlled an oddball paradigm, in which two different stimuli were presented in a random order with probabilities of 0.2 and 0.8. It also illustrated the averaged wave shapes of the brain potentials induced by both the rare and frequent stimuli presentation, and printed out the values of the amplitudes and latencies of the major ERP components such as N100, N200, P300 and slow waves. 3. Negative slow potentials in non-stimulus and non-response situations. - M. Nakamura, N. lshida, H. lida, Y. Sato, T. Matsuoka and S. Takahashi (Shiga)

The CNV is a complex wave. We investigated the CNV components in the presence or absence of stimulus a n d / o r response. EEGs were recorded at Fz, Cz, Pz and Oz of 7 healthy males. Fifty millisecond light stimulus (LS) and its missing stimulus (MS) constituted both trials A (LS-LS-MS-MS-LS-LS) and B (LS-LS-MS-MS-MS-LS-LS) with interstimulus interval of 1 sec. Both trials were presented in a random sequence and the subject was instructed to discriminate between trials A and B at consecutive 1 sec intervals and to press a button immediately after the last stimulus (LS) of only trial A. Artifact-free trial As were averaged and treated by an inverted Fourier analysis. Negative slow potentials emerged in 5 consecutive intervals of trial A including the 3rd interval without either stimulus or response. The early C N V component occurred only with existence of the actual stimulus (LS) as a signal at the beginning of the interval. The late CNV component appeared with expectancy at the end of the interval and was enhanced by equivocal occurrence of the 2nd stimulus or by the motor response. 4. Localization of generator sites for the contingent negative variation. - - T. Tsubokawa and Y. Katayama (Tokyo)

The electrical slow shifts in brain potential (contingent negative variation: CNV) obtained during a warned reaction

0013-4649/85/$03.30 © 1985 Elsevier Scientific Publishers Ireland, Ltd.

2P time task with a foreperiod of 1 sec were recorded in 145 cases who had a localized lesion in various parts of the brain caused by tumors, cerebrovascular disease and head injuries. A slow shift like a C N V was also recorded in some parts of the deep brain structure during stereotaxical surgery by using S 1 (flash stimulation) - - S2 (electrical medium nerve stimulation) - - R (push button) paradigm. In order to know the localization of C N V generating sites in the brain, the relationship between alteration of CNV amplitude and location of the brain lesion and also distribution of the area recording slow shifts like a CNV in the deep brain structure during stereotaxical surgery were studied on 145 cases. In this study, the normal mean amplitudes were 13.6 + 2.4 /~V (Fz) and 14.2__+2.8/~V (Cz) and the low amplitude was less than the mean value - - 2 S.D. According to analyses of these results, decrease of the amplitude of CNV was observed to be cases where the lesion was in the mediobasal frontal lobe, subcallosal area, internal capsula and medial thalamus. It might be suggested that these structures have a relation with the mediothalamic frontocortical system (Skinner), pallidothalamic system (Hassler) or cholinergic basal forebrain cortical system (Price). 5. Morphological characteristics of input-output relationship in the motor cortex. - - Y. Shinoda (Tokyo)

Thalamocortical projection neurons in the ventrolateral nucleus of the thalamus of the cat were intracellularly stained with H R P and branching patterns in the motor cortex were reconstructed, using serial sections. All neurons stained had a b u n d a n t dendrites radiating in all directions. The dendritic spread was about 300-500 /~m. None of them had axon collaterals in VL-VA complex in the thalamus but some collaterals were observed in n. reticularis thalami. Axon branches in the motor cortex spread very widely. Just below the cortical grey matter, stem axons started branching, successively bifurcated and spread in a delta-like fashion. Terminal boutons were distributed mainly in layer III and the upper part of layer V and some were found in layers II and VI. In most cases, two or more axonal bushes, each of them having a dimension of 4 0 0 × 5 0 0 - 2 0 0 0 × 3 0 0 0 p.m, were identified for each neuron. This very wide and multiple distribution of a single thalamocortical neuron suggests that a single thalamic neuron could innervate multiple ' m o t o r efferent columns' defined by intracortical microstimulation. 6. Nuclear magnetic resonance imaging; a new approach to brain function. - - T. Araki (Yamanashi)

Nuclear magnetic resonance ( N M R ) has been used for h u m a n imaging. We began the clinical trial of this new diagnostic modality, N M R - c o m p u t e d tomography (CT), for the first time in Japan in 1982. As far as the brain is concerned, 1H_NMR_CT provides a better contrast resolution than X-ray CT, in addition to giving out valuable information such as 1H density, T 1 and T 2 relaxation times and blood flow. However, a

SOCIETY P R O C E E D I N G S much stronger magnetic field is needed for the imaging of chemical shift which has been most widely used for chemical analysis. Chemical shift imaging of other nuclei such as 31p and 13C is expected for the evaluation of brain function. 7. Xenon CT CBF study. - - J. Karasawa, K. Kuriyama and H. Kikuchi (Osaka)

This report describes an on-line method of measuring the local cerebral blood flow (I-CBF) using the G E C T / T 8000 apparatus during stable xenon (50-70%) inhalation. As to the data acquisition method, scannings are performed on the cervix and the brain alternately by use of table incrementation. We call this the 'shuttle' method. The shuttle method has the following characteristics: (1) Using a table cradle, the method makes possible the in vivo measurement of the arterial blood xenon concentration as well as that of brain tissues. (2) An exponential-curve fitting is made for the calculation of 1-CBF, the partition coefficient (~,), and the build-up rate (K). (3) This method includes ROI analysis, mapping the images of 1-CBF, X, and K. The time required to process the data of I-CBF and ~. is only 5 min. A variety of mapped images of these cerebral circulation parameters are displayed, such as a normal case, a case with stenosis of the internal carotid artery, a case with moyamoya disease, a case with a frontal arteriovenous malformation and a case with focal epilepsy. 8. Positron CT in neuropsychiatry - - present data and new vista. - - I. Namura (National Institute of Mental Health, Tokyo)

The principal findings revealed by our [18F]fluoro-2-deoxyglucose (18-FDG) and [1SO]oxygen study were reviewed in the former part of this lecture. (1) The effect of surgical severing of fiber connections on the terminal gray matter was clearly demonstrated in the following examples. A patient with the injured left optic radiation showed a markedly decreased F D G uptake in the ipsilateral primary visual cortex. The extent of the decrease was larger in the secondary visual cortex ( - 6 0 % ) . The patient with bilateral frontal leukotomy (lobotomy) showed about 30% decrease of oxygen accumulation not only in the frontal cortex but in the anterior half of the temporal cortex. (2) The effect of electrical stimulation of the left median nerve can be detected as an increased 18-FDG accumulation in the corresponding sensory and motor areas in the right preand postcentral cortices. The slight to moderate increase in the right central region would be related to the muscle movement caused by the stimulation. (3) The neuro-degenerative disorders such as Huntington's chorea and parkinsonism could be diagnosed by demonstrating the decrease of 18-FDG in the degenerating focus or the increase in the secondarily affected area. An example was provided by a case of Huntington's chorea patient who showed a markedly decreased 18-FDG uptake in the striatal region in spite that 13N-ammonea visualized this area.

J A P A N EEG A N D E M G SOCIETY, 13th A N N U A L M E E T I N G (4) Dementia gives another field where the 18-FDG and 15-O 2 studies are demonstrated to be quite useful. (5) The 18-FDG studies on the intrinsic psychosis are also reviewed. But consistent results seemed to be very difficult in this area by using labeled sugars and oxygens which are nonspecific gray matter imagers. Therefore, new tracers and new techniques in positron emission tomography are briefly described in the latter part of this lecture. 9. Positron CT study on epilepsy. - B. lshijima, H. Shimizu and H. Takahashi (Tokyo) Positron C T (PCT) studies were performed on 32 epileptics, 13 temporal lobe epilepsies, 10 primary general seizures and 9 elementary partial seizures. [llC]Glucose (oral intake) and [llC]CO2 (inhalation) was used. All the studies were done in the interictal stage. In all cases of focal epilepsy, the focus was depicted as a hypometabolic and hypocirculatory area on the PCT film. X-Ray CT (XCT) of 6 cases of elementary partial seizure had some findings, from slight cortical atrophy to subcortical hematoma, in the area corresponding to the hypometabolic region of PCT, but the remaining 3 cases had nothing in particular on the XCT films. The hypometabolic areas were, in general, wider than those expected from the EEG findings. The dynamic topography of the single spikes was made in some cases, which clearly showed the initial starting point of the spikes in the focus. Temporal lobe epilepsy was categorized into 3 groups according to the locus of the hypometabolic area in the medial, lateral and in both structures. These categorization roughly corresponded to their seizure types. No definite abnormality was demonstrated on X C T films of temporal lobe epileptics, except for one case of A V M in the amygdala. The generalized seizure group had no special findings in PCT, as well as in X C T images, except that some showed diffuse hypometabolism in one or both hemispheres. 10. Frontal midline theta rhythm (Fro0). - - Y. Yamaguehi, T. Ishihara and Y. Mizuki (Osaka) The theta rhythm, usually at 6 - 7 c/sec, in the frontal midline area during performance of mental tasks has been called Fm0. F m 0 appears widely in the normal subjects and in about 40% of normal young adults (18-28 years old) during performance. It may appear also during sleep. F m 0 is apt to appear more in those who are less neurotic and less anxious. The kind and difficulty of mental tasks adopted influences m u c h the appearance of Fm0. According to introspective observations F m 0 is concerned with certain concentration of attention to the tasks. After F m 0 feedback trainings, the subjects are able to guess correctly the appearance of Fm0 in their EEGs. The above data led us to consider F m 0 as an EEG entity and the definition of F m 0 is proposed as follows. Fm0: theta rhythm, usually at 6 - 7 c/sec, being most prominent in the frontal midline area, present most markedly during performance of mental tasks. It may also appear during sleep.

3P 11. Theta or delta burst in vertigo eases. - - T. Morimoto, K. Takemura, T. Sakaki, Y. Hori, K. Kyoi and S. Utsumi (Nara) EEG was performed in 78 severe vertigo cases and paroxysmal abnormality such as theta or delta burst was found in 5 cases. There are characteristic clinical pictures and outstanding EEG findings in these 5 cases. The first characteristic picture of vertigo in these 5 cases is that the vertigo is always transient and ceases completely in several seconds or in several minutes. The second characteristic picture is that the associated symptom responsible for the unbalance of autonomic nervous system such as nausea, vomiting or sweating is infrequent during vertigo attack. The third characteristic picture is that these vertigo cases are best improved by the regimen of antiepileptic drugs. The outstanding findings on EEG include the following: (1) the most outstanding paroxysmal abnormality is theta or delta burst, (2) a small spike or small sharp wave is sometimes visible, (3) high frequency of the provocation of irritable beta or spike by hyperventilation, (4) remarkable shortening of alpha reappearance time (3-14 sec). The mechanism of these vertigo cases is still obscure, but epileptic mechanism might be responsible for their development because of their high curability by antiepileptic drugs. 12. Prolonged spindle in small thalamie hemorrhage. - - M. Honda, S. Utsumi, K. Kyoi, S. Miyamoto, K. Kamada and H. lwanaga (Kashihara) We selected 20 patients with small thalamic hemorrhages which had been certified by CT, and analyzed the sleep spindles both in 7 cases with caudate lesions (group A) and in 13 cases without any caudate lesion (group B). In group A, production of sleep spindles was inhibited in the bleeding side and the mean duration of sleep spindles was significantly prolonged in the contralateral side as compared wiht group B. The producing mechanism of sleep spindles was assumed to happen as follows. Sleep spindles are produced in the generators of the thalamus and projected on cerebral cortex. Both the generators are regulated by mechanism of maintaining symmetry and inhibited by the nucleus caudatus. When the generator or projection system is disturbed by thalamic hemorrhage, a lazy pattern of sleep spindles is recorded in the bleeding side. But in caudate extension, if the functions of the generators are somewhat intact, the overactivity of a generator produced by hypofunction of the inhibiting force of the nucleus caudatus is transmitted to the contralateral generator via the mechanism of maintaining symmetry, and prolonged spindles are projected onto the contralateral cerebral cortex. 13. A study on the development of EEG during infancy and childhood by EEG topographic mapping. - - H. Yoshida, S. Miyake, K. lyoda and S. Ohtahara (Okayama) EEG development was investigated on 202 normal subjects aged from 27 days to 27 years, using the EEG topography system.

4P (1) The central-parietal dominant pattern of the alpha 1 band (8-9.5 c/sec) was the main feature of 1 - 3 years of age, while the occipital dominant pattern increased rapidly from age 3 reaching up to 100% at 6 years of age, then decreased again after 15 years of age. The occipital dominant pattern in the alpha 2 band (10-12.5 c / s e c ) became apparent after 3 years and was consistently noted in almost all the cases after 6 years of age. (2) Equivalent potentials of the alpha band at the occipital area increased markedly at 3 years of age with a peak at 6 - 9 years of age in the alpha 1 band, and a peak at 9-12 years of age in the alpha 2 band. (3) In the alpha band, equivalent potentials showed rightsided predominance at the occipital area especially at 6 - 1 2 years of age. EEG topography could objectively display the developmental aspect of the brain function in infancy and childhood. 14. Topography of alpha blocking - - J. Tatsuno (Tokorozawa) Time course of alpha envelope (connecting peaks of alpha waves) during alpha blocking fits satisfactorily to Gompertz curve which has two parameters: alpha=l/(1-x(O)/N), g a m m a = R(0)/(ln N - I n x(0)), where N denotes the total n u m b e r of the neuron colonies, x(0) is the number of the desynchronized neuron colonies at time t = 0, and R(0) is initial growth rate. Topographies of g a m m a and initial desynchronization ratio IR ( = X ( 0 ) / N = 1 - 1 / a l p h a ) , instead of alpha, were investigated in this study. EEGs from 12 locations of 10 healthy students were recorded, applying flashes which elicited alpha blocking. IR m a p and g a m m a map revealed characteristic patterns. M a x i m u m of IR was found in the fronto-central area around midline approximately corresponding to location of agranular type cortex which has a poor IVth layer. The poverty of the recurrent circuits to be rich in the IVth layer might have relation to large IR. M a x i m u m and m i n i m u m areas of g a m m a were found in the posterotemporal and anterotemporal regions of both hemispheres respectively. Both areas were included in the location of parietal type cortex, but the former seemed to correspond to Brodmann 39, while the latter to Brodmann 46. The former has thicker Vth and Vlth layers, from which m a n y neurons send intercortical fibers. That might explain the rapidity difference of gamma. 15. Topographic analysis of EEG associated with hypnotically induced visual hallucination. - - S. Torii, H. Fukuda, T. Miyauchi, Y. Kato, R. Tanaka and T. Kamishita (Tokyo) E E G data were recorded in hypnotically resting and in hypnotically induced visual hallucination conditions in 5 healthy female subjects aged 19-22 years. EEG spectral energy was computed using ATAC-450 (Nihon Koden) and numerical matrices representing the topographic distribution of spectral energy in a specific band were constructed and displayed as color images. Significance probability mapping was employed to identify the region of cortex presumably activated by visual hallucina-

SOCIETY P R O C E E D I N G S tion; it was found that increased fast beta activity (18-25 Hz) in the right temporal area was associated with hypnotically induced visual hallucination. 16. Multi-channel EEG segmentation based on the spatial distribution on the scalp. - - H. Ozaki, D. Lehmann and I. Pal (Mito) EEG is not homogenous over time and space. Our segmentation into spatially homogenous epoch was performed based on the potential field on the scalp where 16 electrodes were arranged equidistantly in space. After digital filtering of the alpha band, reference free computation of global field power over time was performed. At the moment of each maximal field power, the locations of the most positive and most negative potentials were identified as the positions where the most powerful activities were generated. As long as these extreme positions remained at constant locations, the field was classified into the same segment. The length of each segment varied for 50 msec up to 2500 msec in the resting state. Spectral power vs. average reference for the segment showed similar spatial distribution of the field extrema. It was suggested that these different segments might be correlated to some extent to the different functional states of the brain. 17. A study on the laterality of sleep EEG by using a high-speed automatic sleep analyzer. - - H. Matsuoka, H. Kondo, H. Saito, T. Tomiyama, T. Ueno, H. Hiraga, S. lchijo, K. Toyomura and T. Okuma (Sendai) Hemispheric differences of elementary parameters of polysomnogram such as percent time delta, integrated value of delta, integrated value of fast activity, number and density of spindles were investigated on 16 normal male volunteers (8 right-handers and 8 left-handers) on baseline nights and hypnotic drug nights with a new benzodiazepine derivative 450191-S. Elementary parameters of polysomnograms were analyzed by using a high-speed automatic sleep analyzer and the ratio of their values on the left and right central EEGs were calculated. Some significant correlations were found between percent time delta activity in baseline nights and handedness, and also between number and density of spindles in hypnotic drug nights and handedness. These parameters were found to be lateralized to the hemisphere contralateral to the handedness of the subjects. Other hemispheric differences observed in some parameters had no consistent relation to the handedness or to the laterality of occipital alpha rhythm. 18. The neuroendocrinological study on the sleep-wakefulness of 24 h in senile dementia. - - H. Satowa and T. Sasamura (Tokyo) Four dementia subjects, 3 men and 1 woman, aged 70-81 years and 1 normal subject aged 21 years were studied with sleep-wakefulness pattern and with plasma levels of pituitary hormones (GH, PRL, CS), dopamine, c A M P and c G M P during 24 h.

JAPAN EEG A N D E M G SOCIETY, 13th A N N U A L M E E T I N G

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All of the dementia subjects showed lack of stage 3 and 4 sleep and reduced a m o u n t of REM sleep, accompanied by increase of wakefulness at night. A significant reduction of peak elevation of plasma G H and PRL were observed in these demented subjects across the night, but plasma CS levels remained in normal secretory pattern. As to plasma DA, c A M P and c G M P levels, normal subjects showed higher mean levels during the daytime which became lower at night, but in demented subjects impaired plasma levels were found in both periods. These results suggest that impaired sleep pattern would influence the secretion pattern of hormones and neurotransmission.

min after its medication only when F (1 or 2 mg) had been premedicated before bedtime. (3). This arousal effect of Ro is time-dependent as well as dose-dependent. Ro (10 mg) caused 1 - 3 h of complete arousal when given at 4 : 0 0 a.m. to the subjects premedicated with F 2 mg. However, Ro (10 or 20 mg) caused no arousal when given at 12:00 p.m. or 1:00 p.m. to the same subjects. Incomplete or short arousal was observed when Ro (10 mg) was given at 2:00 a.m. or 6 : 0 0 a.m. Therefore the antagonizing effect of Ro against the induced sleep process was at its m a x i m u m at 6 h after the premedication. (4) R E M sleep was often observed shortly after the Ro medication. This was thought to be caused by the shift of arousal level as a consequence of interaction between Ro and F.

19. Pre- and postoperative studies of sleep levels in patients with normal pressure hydrocephalus. - - H. Kuchiwaki, N. Hirai, S. Takada, N. Misu, A. lkeda, H. lshiguri, N. Kageyama and M. Terashima (Nagoya)

21. Effects of tricyclic and tetracyclic antidepressants on the sleep-wakefulness cycle. - - N. Yamaguchi, T. lto, Y. Kiyota, M. Kubota, S. Sawada, H. Yoshimoto and K. Nakamura (Kanazawa)

Normal pressure hydrocephalus (NPH) was evaluated by the correlations between the simultaneous appearance of the pressure waves and apneas in pre- and postoperative patients using polygraphic analysis. Thirteen of 17 patients were treated with ventriculoperitoneal shunts. A B type pressure wave appeared frequently for hours accompanied by an apnea at a resting state (so-called sleep) for the operated patients: an arousal response in EEG was observed in the rising period of the pressure wave. At the peak respiration was resumed with transient activities in E M G and continued until the disapperance of the pressure wave. The level of their sleep was frequently interrupted by the appearance of the pressure wave and apnea (sleep apnea syndrome) and altered frequently between an awake stage and stage 1. After the operations apneas were extraordinarily rare during sleep. Then the sleep stage became stable and showed a long period of stage 2, including an increase of R E M sleep. These findings correlated with postoperative improvements in the neurological states of the patients. In conclusion, the abnormal sleep levels seem to be important for the diagnosis and the understanding of the progression of NPH.

For a neurophysiological interpretation of the clinical effects of antidepressants, the influence of tricyclic and tetracyclic antidepressants on the sleep-wakefulness cycle was studied by using cats with chronically implanted electrodes in the brain. Continuous polygraphic recordings were carried out during the period 2 h before and 4 or 6 h after the intravenous injection of various antidepressants (1 m g / k g , respectively). The sleep-wakefulness cycle was divided into 4 stages of wakefulness, drowsiness, slow-wave sleep and paradoxical sleep (REM sleep). The percentage and the latency of the appearance of each stage were examined statistically before and after the administration of drugs. Administration of imipramine, amitriptyline and clomipramine increased the percentage of slow-wave sleep and inhibited the appearance of the paradoxical sleep stage. Administration of maprotiline produced no statistically significant changes of sleep-wakefulness cycle and the transition of each stage of sleep-wakefulness was frequent. It is presumed that the stronger the REMS-suppressing effect of tricyclic antidepressants, the better the clinical antidepressive effect. However, tetracyclic antidepressant, maprotiline did not show obvious REMS-suppressing effect, so it seems that another neurophysiological explanation for the antidepressing effect of maprotiline is necessary.

20. A study of the mechanism of induced-slecp process using benzodiazepine and its antagonist Ro15-1788. - - !. Namura, Y. Sakurai, Y. Takahashi, K. Yamazaki and Y. Saito (National Institute of Mental Health, Tokyo) The nature of nocturnal sleep under the influence of benzodiazepine hypnotics was studied by the competition between flunitrazepam and Ro15-1788. All-night polysomnographies were performed on normal male volunteers (n = 10, age 20-25 years) from 11:00 p.m. to 7 : 0 0 a.m. with oral medications of flunitrazepam (F) a n d / o r Ro15-1788 (Ro). Results revealed the following findings. (1) A single dose of Ro had the least effect on the sleep structures whether it was given at 10:00 p.m. or 4 : 0 0 a.m. (2) Ro (5 or 10 mg) caused a definite arousal 20-50

22. A longitudinal electroencephalographic study on the earlyinfantile epileptic encephalopathy with suppression burst. - Y. Ohtsuka, Y. Yamatogi, T. Terasaki, H. Yoshida, M. Matsuda, E. Oka and S. Ohtahara (Okayama) A longitudinal electroencephalographic study was carried out on 10 cases of the early-infantile epileptic encephalopathy with suppression burst (Ohtahara, EIEE), the earliest type of the age-dependent epileptic encephalopathy. All cases showed suppression bursts in their EEG during the period of EIEE. In most cases suppression bursts became indistinct at around 3 months of age and gradually disap-

6P peared. Suppression bursts changed to hypsarrhythmia between 2 and 6 months of age in 6 of 10 cases. A m o n g these 6 cases, further development of hypsarrhythmia to diffuse slow spikeand-waves on EEG was observed in 2 cases at the ages of 1 year 1 m o n t h and 3 years 1 month, respectively. A close correlation and sequential transition a m o n g these 3 types of EEG were clarified. Evolutional change in their EEGs probably occurred at the critical periods of age, namely, at the specific developmental stages of brain maturation. It is noteworthy that focal cortical spikes were seen in 4 cases after disappearance of suppression bursts or hypsarrhythmia. This fact probably suggests important roles of cortical as well as subcortical abnormalities in the pathophysiology of EIEE. 23. Three cases with non-convulsive status epilepticus and continuous run of temporal spikes in interictal EEG. - - T. Fujiwara, K. Yagi and M. Seino (Shizuoka)

Seven episodes of non-convulsive status epilepticus were observed by simultaneous recording on 3 patients whose interictal paroxysms were characterized by runs of continuous temporal spikes. The ictal EEG expressions of each case were: irregular high-voltage slow waves intermingled with spiking (female at age 13 years), anterior dominant high-voltage slow waves with spikes in the left temporal area (male, 25 years), and diffuse high-voltage slow waves often coupled with spikes (male, 27 years). These more or less generalized discharges were coincident with clouding of consciousness and lasted without interruption for 19-36 rain. The c o m m o n interictal EEG features during waking were rhythmic and continuous spikes or sharp waves localized in the left anterior temporal leads which lasted for 13-77 rain and were apt to generalize. When asleep, the continuous focal discharges were replaced by solitary temporal spikes. The non-convulsive status epilepticus is conventionally classified into absence status and complex partial status epilepticus. Of the 3 cases, the seizure manifestation was reminiscent of the former while the inter-seizure EEGs of the latter. The rarity and taxonomic issues of the non-convulsive status shown by the 3 case were emphasized. 24. Usefulness of rectal diazepam in childhood epilepsy - - a clinical and electroencephalographic study. - - E. Takaesu, K. Watanabe, N. Yamamoto, K. Aso, K. lnokuma, A. Matsumoto and T. Negoro (Nagoya)

The anticonvulsant effect of rectal diazepam was investigated in 24 epileptic children aged 4 m o n t h s - 1 3 years. 0.3-0.5 m g / k g of diazepam solution was administered rectally during seizures in 7 patients with infantile spasms, 6 with atypical absence, 3 with complex partial seizure, 2 with myoclonic seizure, 2 with tonic seizure, and 4 with generalized tonic clonic seizure. The EEGs were monitored in 17 patients before and after diazepam administration. Seizures were controlled in 13 patients, but not in 6 patients. In another 5, a diminution of seizures was noted. The EEG showed good suppression of

SOCIETY P R O C E E D I N G S epileptiform discharges in 10 out of 17 patients, but in 7, only poor suppression. The present study has shown that rectal administration of diazepam has a rapid clinical and EEG effect without serious side effects. 25. Two cases of induced microseizures. - - M. Ogihara, T. Miyagima, A. Hoshika, T. Mathuno and T. Honda (Tokyo)

We experienced 2 cases of secondary generalized epilepsy in which peculiar minor seizure appeared when the dosage of benzodiazepine was increased. The symptoms were a slow opening and closing of the eyes and increased respiratory rate, occasionally followed by myoclonia of lips and arms. The ictal EEG was diffuse hypersynchronous 10 14 c / s e c rapid wave bursts in amplitude up to 300-400/~V, lasting 1-5 sec. Because of these findings, the seizures are thought to be induced microseizures (IMS) proposed by Ohtahara et al. Case 1: 3-year-old female, Lennox syndrome which developed from West syndrome. She was suffering from tonic spasm and myoclonic absence. She had been treated with some anticonvulsants (PB, PTH, VPA, ACZ, CZP), but her seizures had resisted such therapy. After an increase of nitrazepam (NZP) from 2 mg to 8 m g / d a y , IMS appeared 81 times/night. %REM reduced to 19.8%. Next, N Z P was decreased to 4 m g / d a y , reducing the IMS to 15 times/night. %REM increased to 30.6%. Case 2: 4-year-old female, corticoreticular epilepsy which developed from West syndrome. In spite of multi-anticonvulsant therapy, frequent tonic spasms occurred. Under the usage of diazepam (DZP) of 8 mg, we observed IMS 38 times/night. %REM was 6.6%. By discontinuation of DZP, 1MS decreased 6 times a night. % REM increased to 25.0%. When CZP was increased from 0.7 mg to 0.9 mg, IMS appeared 24 t i m e s / n i g h t and %REM reduced to 11.5%. Recently, it was found that a decrease of R E M sleep may result in mental retardation, Also, from this point of view IMS shows new aspects, and gives us new way in the treatment of intractable epilepsy. 26. Epilepsy and central cholinergic systems: an interaction between electrical and carbachol kindling in cats. - - K. Morimoto, T. Moriwake, K. Morita, T. Ogawa, T. Nakatsu and M. Sato (Okayama)

An interaction between electrical and carbachol kindling was examined to study a possible role of central cholinergic systems in epilepsy, using 27 adult cats. First, effects of the amygdaloid or hippocampal kindling on the subsequent intra-amygdaloid carbachol kindling were studied. Minimal carbachol dose required to produce epileptic discharges of the kindled cats did not differ from that of control. Although the minimal test dose produced a partial seizure with a brief epileptic discharge in control, it evoked generalized convulsive seizures or epileptic status in 7 of 8 kindled cats. These findings indicate a widespread sensitization to carbachol after electrical kindling. Secondly, effects of the amygdaloid carbachol kindling on

J A P A N EEG A N D E M G SOCIETY, 13th A N N U A L M E E T I N G the amygdaloid electrical kindling were examined. The results were: (1) carbachol kindling was possible in cats, in which seizure development was less stable than that of electrical kindling, (2) the subsequent electrical kindling was facilitated significantly, and (3) the facilitation of electrical kindling after carbachol kindling was due to loss of seizure stages which appear in the early stage of electrical kindling. it is concluded that a biological change resulting from carbachol kindling is not essential for electrical kindling, and that electrical kindling can result in a lasting cholinergic hyperreactivity. 27. Neuropharmacological and histopathological changes induced by intra-amygdaloid injection of excitatory amino acids in rats. - - H. Nakai, T. Tanaka, H. Fukuda, A. Hashizume and Y. Yonemasu (Asahikawa) The neuropharmacological and histopathological changes after intra-amygdaloid injection of excitatory amino acids were examined in rats. The epileptogenicity on EEG was defined in the following order: kainic acid > domoic acid >> quisqualic acid > a-allo-kainic acid >> D-glutamic acid. D-Glutamic acid caused only a transient paroxysmal discharge on EEG. Intraamygdaloid injection of m i n i m u m epileptogenic dose of these amino acids resulted in marked but different severity of degeneration and depletion of pyramidal cells in the ipsilateral hippocampus, which was defined in the following order: domoic acid >= kainic acid > D-glutamic acid > a-allo-kainic acid > quisqualic acid. The result demonstrated a poor correlation between epileptogenicity and histopathological changes in the ipsilateral hippocampus by these amino acids. Therefore histopathological changes induced in the ipsilateral hippocampus are considered to be not only due to epileptic excitation of the hippocampus but also related to some neuropharmacological effects of excitatory amino acids. 28. Anticonvulsive effects of liposome-entrapped GABA against kindling-induced seizures in rats. - - T. Sato, N. Mori, K. Terayama and H. Kumashiro (Fukushima) G A B A (y-aminobutyric acid) is regarded as a major inhibitory transmitter against epileptiform activity, though G A B A itself, administered peripherally, does not cross the blood-brain barrier (BBB) well. Liposomes acting as carriers for drugs appear to be taken up into a variety of tissues including the brain when injected peripherally. The present study was performed to elucidate anticonvulsive properties of peripherally injected liposome-entrapped G A B A (LEG) against kindling-induced siezures in rats because GABAergic actions in the brain are postulated to have important roles in this model of epilepsy. Kindling stimulations were delivered to the left amygdala until a full convulsive seizure was achieved. After the threshold triggering a generalized seizure was determined, convulsion tests were performed. G A B A (4.0 g/kg), liposomes, or LEG (4.0 g / k g of G A B A entrapped within liposomes) were injected intraperitoneally 1 h before the convulsion tests.

7P Results showed G A B A alone and liposomes alone did not suppress the seizures, but LEG showed a claer reduction of seizures. These observations suggest that LEG may cross the BBB, subsequently releasing G A B A from the liposomes to attenuate the kindling-induced seizure. 29. Errors and clinical significance of the sensory nerve conduction velocity calculated from S E P latencies. - - H. Sugioka, N. Tsuyama, T. Hara and A. Nagano (Tokyo) Somatosensory evoked potentials (SEPs) of 109 patients suffering from traumatic lesions of the peripheral nerve - carpal tunnel syndrome (42), cubital tunnel syndrome (39) and neurorrhaphy/nerve graft (28) - - and 16 normal subjects were obtained to calculate the conduction velocity (CV) and compared with the m a x i m u m sensory CV calculated from the onset latency of the sensory nerve action potentials (SNAPs). SEPs of a diseased nerve were classified into type Ia (N 1/P1 peak obtained), Ib (disappearance or multiplication of N 1 peak) and iI (late components only), and CV was calculated by measuring the first peak latencies of SEPs. Sensory CV of a diseased nerve calculated from SEP latencies was always - - up to 84% - - below the value calculated from SNAPs, whereas in a normal nerve it was within 10 m / s e e range of CV calculated from SNAPs. We also noted that strong stimuli decreased the latency of SEPs in diseased nerves to a degree much greater than was encountered in normal nerves. Strong stimuli contaminated SEPs by mediation via other intact nerves which by-passed the damaged nerve and entered into the spinal cord unless stimuli were applied to the area propria. 30. Spinal and scalp-recorded short latency somatosensory evoked potentials following posterior tibial nerve stimulation. - - H. Tomoda, S. Tobimatsu, R. Fukui, M. Kato and Y. Kuroiwa (Fukuoka) Short latency SEPs following posterior tibial nerve stimulation at the ankle were recorded in 12 normal subjects. Recording electrodes were placed on the spinous processes (L4, Th12, Th6 and C7) and the scalp (foot sensory area and the other areas), and referred to the knee (unstimulated side). Fz also served as reference for the scalp SEPs. The bandpass of the amplifiers was 80-1200 Hz (knee reference) and 8-1200 Hz (Fz reference). For each run, 1024 or 2048 responses were averaged. In the spinal SEPs, a triphasic wave with a prominent negativity was recorded at L4 (N17), which was progressively increased in latency rostrally. Also recorded was a non-propagating negative potential, which was identical in latency to NI7 throughout the spinal and scalp area. This was not recorded in the bipolar derivation, indicating that the spinal and scalp-recorded N17 reflect far-field potentials (FFPs) from the caudal spinal cord. In the scalp SEPs with the knee reference, P24, P28, P35 and N42 were identified. Only P35 and N42 were recorded by the bipolar derivation, indicating P24 and P28 to be FFPs. P35 and N42 were more prominent over the scalp ipsilateral to the stimulation. This was considered to be paradoxical lateralization due to the dipole orientation.

8P 31. Evaluation of brain-stem damage in severe head injury with multimodality brain-stem evoked potentials. - - Z. Suzuki, T. Tsubokawa, S. Maejima, T. Hirayama, T. Yamamoto and H. Nishimoto (Tokyo) In order to evaluate the prognosis of severe head injury, both auditory brain-stem evoked potentials (BSRs) and short latency brain-stem evoked potentials (short-SEPs) were examined in severe head injury, and compared with the results of intracranial hypertension by means of balloon inflation at the supratentorial and infratentorial cavities. Results were as follows. (A) Experimental results show that (1) in supratentorial balloon inflation, although the Vth wave of BSR disappeared at pressures of 40-60 m m Hg and all components of BSR disappeared at pressures over 100 m m Hg, short-SEP only showed the prolongation of P3 wave at pressures over 100 m m Hg. (2) In the infratentorial balloon inflation group, all components of BSR and P3 wave disappeared at the pressure of 50 m m Hg. (B) In severe head injury cases, BSR recording was more sensitive and adequate than the results of short-SEP recording as in our experimental results; but if the P3 wave of short-SEP disappeared, the head injury was total. Based on these results, it was concluded that multimodality brain-stem evoked potentials are useful indicators concerning brain-stem function and prognosis. 32. Experimental study on trigeminal evoked potentials - - their origins and application to the evaluation of trigeminal function. - - T. Konishi, H. Handa, K. Moritake, H. Suwa and Y. Takebe (Kyoto) Three positive peaks and one negative peak, P1, P2, P3 and N1, were recorded in the bregma of cat as far-field potentials following electrical stimulation of the infraorbital nerve. The average peak latency of each potential and its standard deviation from 19 cats were as follows: P~, 0.71+0.06 msec; N 1, 0.95+0.09 msec; P2, 1.48+0.14 msec; P3, 2.18+0.14 msec. The specific generators of these early components were identified: P1, infraorbital nerve; N1, Gasserian ganglion; P2, principal trigeminal nucleus; P3, spinal trigeminal nucleus. Following the thermocoagulation below 65°C of the Gasserian ganglion, the P3 and A8 action potentials decreased in amplitude. On the other hand, thermocoagulation over 75°C decreased the amplitude and prolonged the latency of the P2 and AJ3 action potentials. After injection of glycerol into the trigeminal cistern, P3 gradually decreased in amplitude. These experimental results suggest that sequential TEP recording is useful for objective assessment of trigeminal nerve function, especially in order to evaluate the efficacy of newly developed therapeutic procedures, including cisternal glycerol injection. 33. The effect of manipulation of visual field on pattern reversal visual evoked potential in healthy subjects. - - R. Fukui, M. Kato and Y. Kuroiwa (Fukuoka) Effects of experimentally induced central scotoma and visual field constriction on pattern reversal visual evoked potentials

SOCIETY P R O C E E D I N G S (VEPs) were studied in 21 healthy subjects. The pattern reversal stimulation was introduced by projecting a checkerboard via a rotating mirror on a screen, which subtended 16 ° in radius. Experimental scotoma and visual field constriction were produced by masking either the central or peripheral part of the screen. The sizes of central scotoma were 2 °, 4 °, 6 °, 8 ° and 10 ° in radius, and those of visual field constriction were 4 ° and 10 ° in radius. The P100 latency and the P100-N130 amplitude were measured, and compared with those obtained by full-field stimulation. With central scotoma of 2 °, no significant alteration was noted in both latency and amplitude. Central scotoma of 4 ° or larger radius, however, induced significant reduction of the amplitude and prolongation of the latency. These alterations were more pronounced as the central scotoma became larger. With visual field constriction of 10 °, there was no significant change in both latency and amplitude. With constriction of 4 °. the amplitude was reduced significantly while the latency remained unchanged. These results indicate an important role of the afferent impulses arising from the foveal 4 ° in producing the 'normal' latency and amplitude of VEP. 34. Clinical study of somatosensory evoked potentials in 100 cases with unilateral supratentorial infarction. - - Y. Hasegawa, T. Yamaguehi, R. Waki, T. Tanaka and T. Mori (Osaka) Somatosensory evoked potentials (SEPs) were recorded in 100 cases with unilateral supratentorial infarction in the chronic stage. Abnormalities of wave form were more frequently observed in cases with CT lesions involving the primary sensorimotor area, the thalamus or the internal capsule, than those without such lesions (Chi square test, P < 0.01). Cases with major cerebral artery occlusion, however, occasionally showed wave form abnormalities, even when the lesions detected by CT spared the above-mentioned regions. In cases with deep-seated lesion in which the thalamus and the internal capsule were not included, N17-P21 peak to peak amplitudes were higher than those of normal controls (non-parametric statistics, P < 0.01). When those cases were divided into two categories by angiographic findings, i.e., cases with major cerebral artery occlusion and those without occlusion, the abnormal enhancement of the amplitude was seen only in the latter. From these results, it is suggested that SEPs may be helpful for detecting the presence or absence of major artery occlusion in small infarction. 35. Changes of somatosensory evoked potential accompanying ischemia and hypoxia in cats. - - K. lwayama, K. Mori, K. Yamashiro and S. Sakai (Nagasaki) Changes of evoked potential accompanying hermorrhagic hypotension and hypoxia were investigated in cats to determine the usefulness of SEP as a monitor in ICU. Though evoked potentials of various wave forms were recorded widely over the scalp by radial nerve stimulation, the negative component with

J A P A N EEG A N D E M G SOCIETY, 13th A N N U A L M E E T I N G the latency of approximately 18 msec was most prominent. This negative potential showed the largest amplitude on the scalp over the somatosensory cortex, and was thought to correspond to N20 (N1) of h u m a n SEP. In the initial stage of hemorrhagic hypotension, both positive and negative components of SEP usually increased in amplitude. By profound hypotension in which CBF fell to less than the critical level of 30 m l / 1 0 0 g / m i n , the latency was retarded and the amplitude was decreased. At CBF less than 10 m l / 1 0 0 g / m i n , SEP disappeared. Within the range of CBF between 10 and 30 m l / 1 0 0 g / m i n , a close correlation was noted between CBF and SEP amplitude. Transient increase of amplitude was also observed during hypoxia induced by inhalation of nitrogen gas. Because of the initial impairment of the inhibitory interneurons by ischemia and hypoxia, the amplitude of SEP might increase transiently. In conclusion, the authors thought that SEP might be less useful than EEG in ICU, because of its insensible change to hypoxia or ischemia. 36. Comparative study of spinal cord evoked potential elicited by spinal cord stimulation with that elicited by peripheral nerve stimulation. - - H. Takano, T. Noguchi and T. Tamaki (Toyama) Giving a gradually increasing compression to the spinal cord, we studied the change of wave patterns in spinal cord evoked potential elicited by spinal cord stimulation or by peripheral nerve stimulation (spinal SEP) in cats. Spinal SEPs were recorded in the epidural space at the high thoracic level and the sciatic nerve was exposed to deliver stimulation. Spinal cord stimulation was performed at the same level of spinal SEP recording, the evoked potentials were picked up at the level of conus medullaris. Comparing the decreasing rate of both potentials, the potential elicited by spinal cord stimulation changed more dominantly in amplitude than spinal SEP. When the amplitude of the potential elicited by spinal cord stimulation decreased to 50% of control level, which is regarded to be a critical level, spinal SEP remained at 65% (_+ 21.6%) of control level. The conclusion is that the potential elicited by spinal cord stimulation is more sensitive than spinal SEP to spinal cord compression. 37. Changes in ERPs in relation to the order of presentation of event related stimuli. - - T. Ohtsuki, Y. Nageishi and M. Shimokohchi (Nara) ERPs were recorded from Fz, Cz, C;, C~ in S1-$2 response C N V paradigm. Three key-pressing tasks were employed as the response tasks, i.e., key pressing with right hand, left hand and both hands, one of which was designated visually by S1 (LED) given 2 sec preceding auditory $2 (1 kHz, 250 msec). Nine normal healthy right-handed adult females served as subjects. Two conditions of the order of S1 presentation, i.e., condition ' F ' in which the order of S1 was fixed and condition ' R ' in

9P which it was randomized, were prepared. Principal component analysis of averaged EEG wave forms after SI revealed that P300 and late CNV in S1-$2 interval and PMP(?) after $2 were greater in amplitude in condition ' R ' than in ' F ' (e.g., P300: R, 12/~V; F, 9 /tV; CNV: R, - 15 /~V; F, - 13/~V at Cz). These differences would suggest that in condition 'R,' 'recognition' of the kind of S1, 'selection of response' following it, and 'inhibition of contralateral motor area' during response are performed only after S1, while in ' F ' these processes ar executed even before S1. 38. Asymmetry of event-related potentials induced by the visual stimulation of two syllable nouns. - - tt. Ninomiya and T. lkeda (Miyazaki) Functional asymmetry of each hemisphere in language processing was investigated using an event-related potential (ERP) as an index. Six right-handed subjects participated in the experiment. Meaningful words condition (MWC) and nonsense symbols condition (NSC), each consisting of a classifying session and a reaction time session, were conducted. EEGs were recorded from F3, F4 and P3, P4 (2 sec in time constant). Results were as follows: (1) Examined by a wave form similarity curve analysis, wave forms of left and right ERPs in M W C were significantly more dissimilar than those in NSC at around the latencies of 100 and 240 msec in the frontal region, and at around 230 and 440 msec in the parietal region. (2) When we compared the subtracted ( l e f t - r i g h t ) amplitudes of M W C with those of NSC, in the frontal region the former was significantly more negative than the latter from the trigger point to the meah reaction time, and in the parietal region the former was significantly more negative than the latter at around the latencies where significant differences were found in the wave form similarity curve analysis. It is suggested that in specified hemispheres, specified latencies exist where the processing of two syllable nouns is mainly done. 39. Event-related potentials and selective attentional functioning in siblings of schizophrenic probands. - - O. Saitoh, S. Niwa, K. Hiramatsu, T. Kameyama and K. Itoh (Tokyo) Event-related potentials (ERPs) were recorded at the Cz region during syllable discrimination tasks in 20 siblings of schizophrenic probands, 12 medicated schizophrenics, 10 unmedicated schizophrenics, and 20 normal control subjects. All schizophrenics met the diagnostic criteria of DSM-1II for schizophrenic disorders. ERPs in these siblings were compared to those of normal controls and schizophrenics. Siblings, similar to normal controis, displayed both an increase in N100 amplitudes and a decrease in P200 amplitudes according to allocation of their attention between two different channels (ears). However, siblings, different from normal controls, failed to demonstrate an augmentation of late positive components (P300) upon detection of target stimuli in the attended channel. Mean amplitudes of late positive components elicited by target stimuli in the

10P attended channel for siblings were nearly equal to those of unmedicated schizophrenics, with these values in siblings being significantly smaller compared to those of normal controls. Based on these results, it was concluded that abnormalities of late positive components in siblings m a y reflect a genetic predisposition to schizophrenia. 40. Relative advance of eye movement to the target in the rightward tracking in schizophrenics. - - Y. Matsue and T. Okuma (Sendai)

Time relationship between the horizontal smooth pursuit eye movement (SPEM) and tracking target in the leftward or rightward tracking was investigated in 21 normal and 32 schizophrenic subjects. Normal subjects were more liable to show a relative advance of SPEM in relation to the target in the leftward pursuit than in the rightward pursuit. These findings suggest that the spatial task such as SPEM depends more on the right hemispheric function in normal subjects. On the other hand, m a n y schizophrenic subjects showed a relative advance of SPEM to the target in the rightward pursuit. These findings suggest the dominance of the left hemispheric function in eye tracking tasks in schizophrenic subjects. The finding in the present study would support the hypothesis of the left hemispheric overactivation in schizophrenic patients. 41. Effect of facilitating position on EEG arousal with reference to cerebellar lesions. - - K. Kosaka and R. Nakamura (Tohoku)

Reaction times (RTs) depend upon the posture (Nakamura and Viel 1974). Vocal RTs became fast at facilitating positions (FPs) which are utilized in physiotherapy, compared to neutral position (N) ( N a k a m u r a 1983). The dependence of RTs on the posture could not be found in some patients with cerebellar lesions (Nakamura 1976/77). In this study the relationship between the postural change and EEG activation was analyzed using 10 normal subjects and 6 patients with SCD. EEGs were recorded under N and FP. EEG spectral energy analysis was performed for 60 sec, using data processing system. The topographic distribution of EEG spectral energy from all regions was simultaneously displayed on a color CRT. Compared to N, FP induced the bilateral enhancement of alpha and beta bands and also the extension of alpha distribution in the normal subjects. Such shift of EEG parameters caused by the postural change was not observed in the patients. It is assumed that the cerebellum is functioning to moderate the cortical activities, transmitting the proprioceptive input. 42. The effect of electrical stimulation to the soles on the postural stability of ataxic patients. - - Y. Mano, T. Sakakibara, S. Morimoto and T. Takayanagi (Nara)

By application of electrical stimulation with high frequency (100 Hz) to soles of ataxic patients (16 cases) and normal controls (5 cases), postural stabilities were measured by recording the sway of the center of gravity, in order to investigate the central regulating system.

SOCIETY P R O C E E D I N G S In both groups by strong electrical stimulation to the anterior or posterior part of the soles, the center of gravity was moved to the reverse part with stimulation. By mild electrical stimulation to the anterior or posterior part of the soles, the center of gravity was moved to the same part with stimulation. By application of mild electrical stimulation to both anterior and posterior parts of the soles of patients with ataxia, the sways of the center of gravity were decreased in groups with decreased muscle stretch reflex of lower limbs, and they were increased in groups with increased muscle stretch reflex of lower limbs. By this study it might be said that mild electrical stimulation to the soles could induce the positive supporting response of lower limbs, and that strong electrical stimulation to the soles could induce the withdrawal response of lower limbs. 43. Glabella tap sign. Eyelid movement and orbieularis oculi reflex. - - N. Sunohara, H. Tomi, K. Ando, E. Satoyoshi and S. Tachibana (Tokyo)

In 30 patients with Parkinson's disease, 55 patients with other neurological disorders and 25 normal subjects, eyelid movement and orbicularis oculi reflex on the repetitive glabella taps were simultaneously recorded. The eyelid movement was measured using a phenomenon that the change of length of a fine wire in the water alters the electrical resistance between the wire and the water-filled cylinder. The blink reflex showed 4 patterns: (1) positive glabella tap sign with R2 habituation, (2) positive glabella tap sign without R2 habituation, (3) negative glabella tap sign with R2 habituation, and (4) negative glabella tap sign without R2 habituation. The eyelid began to close from the R1 component. Even if each R1 component represented the similar amplitude and duration to those to the first few taps which elicited eyeblinks, the following taps did not provoke eyeblinks in m a n y subjects without a glabella tap sign. From these results, the occurrence of the glabella tap sign was considered to be due to the persistence of the reciprocal inhibition of the levator palpebrae superior muscle in addition to the increased excitability of the R1 reflex arc, but not the result from the absence of the R2 habituation. 44. Frequency response analysis of oculomotor function - comparative study with spinocerebellar degeneration and normal subjects. - - F. Hayashi, Y. Koike, R. Hibino, 1. Sobue and N. Ishii (Nagoya)

Pathological horizontal eye movements were studied from biocybernetic points of view emphasizing functional relationships. The silver chloride electrode was used to detect the DC voltage changes generated by eye movements. The target was moved through a 20 ° visual angle. Saccadic and pursuit testing were performed as the patient moved his eyes left and right, looking at the target spots. Subjects of the present study were 15 healthy and cerebellar patients 21 and 78 years old. (1) Records of horizontal eye movements during tracking square wave targets. In normal subjects, the eye movement often preceded the change of target position. At very low repetition rates, prediction is minimal but reaction times be-

JAPAN EEG A N D E M G SOCIETY, 13th A N N U A L M E E T I N G came shorter with increasing frequency. The histogram of time delays at a moderate repetition rate (0.8-1.0 Hz) demonstrated the high frequency of prediction when the eye follows a regular pattern. Such a predictive behavior was not observed in the patients with cerebellar deficit. (2) Records of horizontal eye movements during tracking sinusoidal wave targets. The decrease of gain in the cerebellar group was greater than that in the healthy group. In addition, the phase lag in the cerebellar group was more prominent as compared with the healthy group. Therefore, oculomotor disfunction with cerebellar disease is caused by disturbance of predictive control for timing and velocity changes. 45. Quantitative analysis of electromyography. - - Y. Nakamura, H. lmaoka, M. Takahashi and S. Tarui (Osaka) In order to make a more detailed study of the diagnostic quantitative electromyographical method, interference patterns at different degrees of voluntary effort were analysed, depending basically on Willison's method. The electrical activity was led off from the branchial biceps muscle, and recognized as significant when more than 50 btV. In healthy volunteers (N = 10), the mean amplitude had a linear relationship with the force of effort, but the n u m b e r of spikes ( t u r n s / 2 ) increased with the force up to 50% maximum, then reached a plateau. Six patients with myopathy including 5 with polymyositis and 6 patients with neuropathy including 3 GBS were examined. The mean amplitude of myopathic patients was lower than that of neuropathic patients. The number of spikes of 50-100/xV of myopathic patients was more frequent than that of neuropathic patients. It was concluded that the spike change over 50/~V should be recognized as significant rather than that over 100 ~V, and that m a x i m u m force was more diagnostic than 30% force in the myopathic patients. 46. Staircase phenomenon and spasticity. - - H. Tomi, N. Sunohara, E. Satoyoshi, K. Shibasaki and S. Tachibana (Tokyo) In 6 patients showing involvement of pyramidal tracts with marked spasticity (A), 7 showing involvement of pyramidal tracts with slight spasticity (B), 7 showing damage of peripheral motor neuron with slight muscular atrophy (C) and 2 with disused atrophy (D), twitch tensions evoked by electrical repetitive stimuli on the right ulnar nerve were examined. In group A, there was no staircase phenomenon. In groups B and C positive staircase phenomenon was observed, which showed a gradual increase of twitch tensions on repetitive stimuli. In group D, positive staircase phenomenon was not seen. It is well known that the patients of groups A and D have type 2 atrophy on histochemical study of the muscle. These results suggest that the absence of staircase p h e n o m e n o n was due to the spasticity itself a n d / o r type 2 atrophy of the muscle.

I1P 47. Motor unit activity during voluntary non-isometric muscle contraction in man. - - S. Murakami, K. Yasuda and M. Kato (Hokkaido) The discharge frequency of motor units during voluntary muscle contraction was studied in the tibialis anterior muscle of h u m a n subjects trained to shorten the muscle linearly from the natural position to 50% of m a x i m u m dorsi-flexion of the ankle joint at 1, 2, 3 and 5 sec. In each examination, the load was given with 0, 5 and 10% of the m a x i m u m contracting tension. Motor units were recorded in such a condition as the change of contraction speed and load with intramuscular wire electrodes. The discharge frequency was almost constant even though the muscle was shortening in those conditions, and most motor units showed discharge frequency of about 10 Hz. Integrated surface EMG, however, increased as the muscle was shortened. The faster the contraction speed and the heavier the load, the increase of integrated surface E M G was steeper. These results suggest that the change of muscle length in non-isometric contraction is controlled by new recruitment of motor units, but not by the discharge frequency. 48. Free functional museulocutaneous transfer: electrophysiological studies. - - Y. Ugawa, M. Sakuta, I. Okutsu, N. Kuroshima and S. Ninomiya (Tokyo) The paper describes two reconstruction cases of forearm crush injuries. Microneurovascular anastomoses were performed in transplanting the patients' own medial gastrocnemius into their forearms. Transplanted muscles were electrophysiologically examined regularly over the period of time. At 1 month postoperatively, E M G showed fibrillation potentials only. Low amplitude and short duration neuromuscular units ( N M U ) appeared 3 months after transplantation. High amplitude, long duration and polyphasic N M U s were observed 6 - 7 months later with the gradual increase of the number of N M U . Nerve conduction showed the gradual shortening of distal latency which eventually reached the normal level by the end of the first year. S F E M G examination indicated the gradual decrease of the mean consecutive difference, but it returned to the normal range 6 months after the distal latency achieved a steady state. These electrophysiological findings suggest that the muscles continue to regenerate long after the regeneration of the neuromuscular junction which is completed about 6 months after the nerve regeneration. Muscle biopsy performed 6 months after transplantation confirmed the many features of both degeneration and regeneration of the electrophysiological findings. 49. Dynamic behavior of stretch reflex loop in the acute decerebrate, standing cat. - - Y. Atsuta, T. Sakamoto and S. Mori (Asahikawa) Discharge properties of neuronal elements constituting stretch reflex loop were studied in relation to the levels of hind

12P limb extensor muscle tone in acute decerebrate, reflex standing cat. Alpha motoneurons, Renshaw cells, group Ia and Ib muscle afferents innervating soleus muscle were identified from their characteristic responses to intramuscular stimulation. A series of stimuli delivered to the dorsal area of mid-pontine tegmentum decreased hind limb force from 0.5 to 0.1 kg in a staircase manner. Most alpha motoneurons discharged tonically (5-15 spikes/sec) and each one of them terminated its firing with a

SOCIETY PROCEEDINGS decrease in the force. Critical force levels for discharge termination differed depending on alpha motoneurons. In contrast, Renshaw cells decreased their firing rates at a maximum of 70 to a minimum of 12 spikes/sec with the force decrease. Group Ia and Ib afferents decreased their firing rates from 40 to 2 and 50 to 2 spikes/sec, respectively. This study demonstrated that the smaller the level of extensor muscle tone, the lower the firing rate of each neuronal element constituting the stretch reflex loop.