Differences between descending and ascending slopes of the sleep cycle

S87

synaptic

level:

simultaneously

in real time.

A-5.07 THE DEGREE OF FUNCTIONAL COMPENSATION IN PARTIAL ROOT DAMAGE. R. Naumovski, N. NaumEevski, M. MirEev, I. Dz'onov and R. TrenEev (Skopje, Yugoslavia)

O-6.02 NON-SPECIFIC EVENT-RELATED REACTIONS TO SENSORY STIMULI IN SLOW WAVE SLEEP. P. Hala'sz, P. Rajna, I. Pal and G. Simon (Budapest, Hun-

The degree of functional compensation after collateral reinnervation was examined in m. exThe investigation was made in tensor brevis. 48 patients suffering from chronic SI lesions Another after orolaosed intervertebral disks. neurologist or neurosurgeon (19 of these 49 patients were operated) found symmetrical small muscles of the foot, estimated as normal. The following electrophysiological investigations were made in all patients and it was found: (a) domination of marked high voltage and long-lasting potentials in the damaged muscle by coaxial needle electrodes; (b) a number of motor units in the damaged muscle (mean 73) significantly decreased in relation to the healthy muscle; this decrease was 69% of the normal value; (c) amplitude of the M wave transmitted by skin electrodes reduced to 49.7% in relation to the healthy side, but of a smaller degree than the loss of motor units. The difference in these two findings denotes the degree of functional compensation in radicular damage which does not appear in the other symmetrical and distal polyneuropathies.

Numerous data refer to the important role of sensory input in the organization of slow wave sleep. This study was designed to investigate the elicitability and nature of non-specific evoked reactions durinq different staqes of slow Short auditory stimuli below the wave sleep. arousal threshold (clicks) were applied at a Different frequencies were used random rate. durinq different niqhts of the same sleeper. Eventlrelated reactions to stimuli were investigated by the use of an averaging technique. A well-defined event-related potential complex could be detected in all stages of slow wave The "nucleus" of this potential complex sleep. was identical with the K complex and earlier components seemed to be identical with "vertex spikes". The amplitude of components of the complex proved to be related to the functional state of the synchronization system (i.e., the sleep level). This non-specific event-related potential complex is considered as a "building stone' of the EEG morphology of slow wave sleep. We assume that even the spontaneous slow wave sleep EEG is built up from discrete rebound reactions of the synchronization (sleep) system to phasic environmental or inner sensory input, reaching the brain by non-specific routes.

C-4.07 A NEW METHOD OF EMG DATA DIGITAL PROCESSING BY VARIANCE RECURSIVE ESTIMATION. C. Doncarli, J. Calamel, C. niche1 and P.Guiheneuc (Nantes, France) The purpose of this method is to provide a catalogue of the various M.U.P. patterns from This record is composed of a an EMG record. noise assumed to be white (instrumentation and physiological noises), with unknown but constant variance and average. These statistical data are obtained with the muscle at rest. During contraction, every acquired point allows a tuning of the signal variance estimation which is compared to a threshold (a multiple of the noise variance). If the test is negative, no M.U.P. has appeared, and a new point is considered. If the test is positive, a significant signal is detected and recorded in a pattern catalogue. This step of detections-estimation is then applied both to the EMG signal and to the algebraic differences between every new selected pattern and the previously recorded ones. Possible superpositions of different M.U.Ps. with eventual phase shift are taken into account, so as not to record as a new M.U.P. a previously listed one. Moreover, the detection of a previouslv recorded M.U.P. leads to smoothinq of its reference pattern. This method, tested on EMG records, allows a catalogue of a number of patterns with all the morphological characters of each recognized M.U.P. to be obtained

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A-11.03 DIFFERENCES BETWEEN DESCENDING AND ASCENDING SLOPES OF THE SLEEP CYCLE. P. Hala/sz, I. Psi. P. Rajna and G. Simon (Budapest, Hungary) Taking into consideration the dynamic properties of sleep cycles the direction of the sleep process must be reflected in the inner structure of the cycles and sleep stages. The aim of this study was to explore the differences of sleep variables on the ascending (A) and descen ding (D)slopes of the sleep cycles. This presentation is based on 80 sleep records of 10 healthy subjects. In the hypnogram variables well-defined differences could be detected: the durations of the D slopes were significantly longer than of the A slopes, and A slopes contained larger numbers of "jumps" in the sequential order of sleep stages. Micro-arousals followed by stage shifts could always be found with a higher percentage on the A slope. The density and distribution of K complexes proved to be different in stages 2 of D and A slopes. The elicitability of K complexes was higher on the A slopes. The distribution of spontaneous EDG oscillations showed an increasina tendencv on the D slopes and a decreasing tendency on " the A slopes. The differences pointed out support the

view that the two slopes of sleep cycles represent different functional organization patterns. The role of sensory input is quite different: on the D slope it has a sleep promoting, while on the A slope an arousing, influence.

with an abnormal EEG who was treated at the onset showed normal EEG and CT. However, in cases where therapy was started at later stage, abnormal EEGs and CT scans would probably be unchanged.

D-13.03 EEG RECOVERY AFTER RESTORATION OF BLOOD FLOW TO ISCHEMIC BRAIN. A COMPUTER ANALYSIS OF EEG. U. Ito, H. Tomita, S. Tsuruoka, K. Hashimoto, Y. Inaba, Y. Ishima and M. Matsura (Tokyo, Japan)

C-2.01 ON THE USE OF MACRO-EMG IN DIFFERENT NERVE-MUSCLE DISORDERS. E. Stilberg. (Uppsala, Sweden)

We used Mongolian gerbils to study the recovery of brain function assessed bv EEG afterrestoration of the blood flow to the ischemic brain, and examined the relationship between recovery of brain function and duration of ischemia. The left common carotid artery of the ischemia-sensitive animal was clipped for 30 min, 1 or 3 h, and restoration of the blood flow was effected Awake animals were arby releasing the clip. tificially respirated. Monopolar EEGs were recorded by the data recorder, through epidurally placed electrodes in the bilateral parieto-occipital areas, just before and after restoration of blood flow, and 15, 30, 45 min, 1, 2, 3, 5, 8, 48 h thereafter. The number and mean amplitude of the EEG waves were analysed by an automatic EEG diagnostic system. After 30 min and 1 h of ischemia, the number of waves and the average amplitude in each frequency zone decreased markedly; they recovered rapidly during the first hour, then gradually until 8 h after restoration of the blood flow. However, they never reached the control value, and decreased again 48 h after restoration of the Following 3 h of ischemia, the EEG blood flow. recovered very slightly only in the higher frequency zone. A-15.05

CLINICAL

STUDY ON CEREBRAL

SCHISTOSOMIL.C. Tormis, J.S. Nosezas, B.L. Blas and M. Hayashi (Palo, Philippines and Kofu, Japan)

ASIS IN LEYTE ISLAND, PHILIPPINES.

Since 1975 we have studied the clinical symptoms and EEGs of cerebral schistosomiasis jaSome of these cases were treated with ponica. antischistosomal agents (AS) and anticonvul127 showed epileptic-like symptoms sants (AC). In 1980, a follow-up study of 73 of these paThe ratio of males to females tients was done. was 49 to 24. The ages ranged from 19 to 66 years with a mean of 39. Results: 1) clinical seizures completely disappeared in 48, diless than 50% in minished in frequency to 18, unchanged in 3 and aggravated in 4; 2) compared with the previous EEG result of 601, the rate of abnormal and borderline was remarkably improved at 41%; 3) as to the therapeutic results, the AS group showed the highest rate at 96%. As to the effects of therapy on improving EEG, both groups of AS + AC and AC showed almost the same rate at 39%; 4) the patient

A new electrophysiological method is presented. Recording of the muscle activity is made from the cannula of a modified SFEMG needle electrode. A remote electrode is used as reference. The SFEMG recording from one muscle fibre is used to trigger the oscilloscope and an averager to which the cannula signal is fed. After 128 or 256 discharges the contribution from one motor unit to the cannula signal can be extracIts amplitude and area are measured by ted. means of a microprocessor. These parameters reflect the size of the motor unit. The method is used to study the motor unit in different nerve-muscle disorders. The amplitude is typically decreased in myopathies and increased in neurogenic disorders but exceptions are seen. In some diseases the size is. principally unchanged but the organization of the muscle fibres within the motor unit has become abnormal. The combination of SFEMG, conventional needle EMG and macro EMG gives new insight into the normal and abnormal motor unit Examples of records from different diseases will be given. A-9.01 A SPECIAL MONTAGE CORDING OF SOMATO-SENSORY FROM DIFFERENT PERIPHERAL W.T. Liberson (Brooklyn,

FOR ONE-CHANNEL REEVOKED POTENTIALS AND BRAIN STRUCTURES. NY, USA)

In this montage, the F, electrode serves as reference and all the active electrodes (C3 or C4, cervical, Erb's point, etc.) are interconThe median nerve is stimulated at the nected. With this montage the Erb's point, root wrist. and brain-stem and cortical potentials are recorded in succession on the same channel withA reduced out any significant interference. montage using only C3 (or C4) and Erb's point electrodes may be almost as helpful as the full montage, the brain-stem potentials being reThis techique, juscorded as far field waves. tified by the appearance of any one somato-sensory potential only when the preceeding potential is present, permits one to calculate easily the local as well as interwave latencies, the whole graph being considered in the same way as the auditory brain-stem evoked potential recording. The same principle may be extended to the recording of median nerve potentials from the elbow, arm and axilla, followins stimulation at the wrist, thus permitting one to follow the conduction of evoked potentials from