Società Italiana di elettroencefalografia e neurofisiologia

Società Italiana di elettroencefalografia e neurofisiologia

82 Electroencephalography and Clinical Neurophysiology Elsevier Publishing Company, Amsterdam - Printed in The Netherlands SOCIETY PROCEEDINGS SOC...

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Electroencephalography and Clinical Neurophysiology Elsevier Publishing Company, Amsterdam - Printed in The Netherlands

SOCIETY

PROCEEDINGS

SOCIETA ITALIANA DI ELETTROENCEFALOGRAFIA E NEUROFISIOLOGIA Parma, March 11-12, 1967

Secretary: DR. E. LUGARESI Clinica Neurologica dell'Universit/t di Bologna (Italy) 1. EMG ~

ia ~ k l e m ~ of ~

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and s i t w a sll~'t com,se o f m o ~ c ~ e d , m s ~ A C T H . ~

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In severe cases of myastbenia gravis administration of 500-1000 U o f A C T H over a period of 5 days may induce a significant and often fairly complete remission some weeks later. However, a rapid and serious deterioration with accentuation of the myasthenic symptoms accompanies the treatment. I have confirnlcd this effect (noticed already by Torda and Wolff, Freydberg, yon Reis et al.) in a moderate case of myasthenia gravis treated with the same doses of ACTH. My new experience concerns the treatment of moderately ill eases of myasthenia gravis with smaller doses of A C T H in order to obtain the late improvement without the dramatic early deterioration. This was shown in a myasthenic patient who was treated with 25 U of A C T H intramuscularly every 2 days for 8 doses, and intravenously for a further 2 doses. I n new cases a n additional 25 U of A C T H was given every 6 h on the 1st day, making a total of 350 U of ACTH for the whole course. No s'~gnificam deterioration was observed; a transient partial blocking ( - - 2 5 % ) of the response to single supramaximal stimuli at rest and a reversible deterioration of the late post-tetanic inhibition at low rates of stimulation were the only impairments revealed by E M G investigations, which were carried out daily during the ACTH administration and also in the week following the treatment. A significant clinical improvement took place a month after the last injection of ACTH. At that time the E M G recordings showed: (1) a stable amplitude increase ( + 40 %) of the response to single supramaximal stimuli; (2) an enhanced facilitation ( + 6 0 % ) during tetanic stimulation; (3) an increase of more than 100~o in the half-time before exhaustion of the responses at 25-50 stimuli/see. A less marked improvement in the late post-tetanic inhibition was observed. A further course of ACTH after some months induced further remission. 2.

Symlflomatic noctm'nal myodonie jerks. - C. ~ a i d E. ~ i (Bolol~).

Four cases in which restless legs (Ekbom) and nocturnal myoclonus (Symonds) arose in the course of polyneuropathies of the lower limbs and of myelopathies of

the dorso-lumbar tract are reported. Nocturnal polygraphic recordings were carried out in all the cases and the findings may be summarized as follows: (1) restless legs and nocturnal myoclonus arising in the course of neuropathies and myelopathies showed clinical and polygraphic appearances which were identical to those seen in the "essential" forms. In one ease the symptomatology was somewhat atypical, with intermediate features. (2) Our observations strengthen the hypothesis that restless legs and nocturnal myoelonus should be included in the same ~ picture as suggested by Behrman. (3) The fact that both restless legs and nocturnal myoclonus may originate from spinal disease suggests that the basic trouble is also situated at this level in the "essential" forms. We put forward the hypothesis that the frequently periodic character of the myoclonic jerks has a humoral origin. It is pointed out that in one case the myoclonic jerks present in the paradoxical stage of sleep were inhibited during the bursts of rapid eye movements.

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The following results have been obtained with high frequency thaiamic stimulation during avoidance conditioning in cats: (a) When the C R is established, stimulation during avoidance impairs the performance. (b) In experiments with a paired CS technique, when the C R is established with avoidance occurring at the 2nd signal only, stimulation preceding the 2nd CS causes avoidance at the 1st signal. This is a regression to a behaviour that in control experiments occurs only in the early conditioning stages. (c) Under the same conditions as in (b), stimulation given in all trials from the beginning of training does not facilitate the course of the learning process. A critical discussion of the so-called attentional and motivational significance of high frequency thalamic stimulation is based on these data. 4. An d ~J-,:--,.-: qin~ae i m i s o ~ .

_ _-:: investigation in acute - - A. Coedfl and G. Invemtgzi

(M~). EEG studies have been done on 11 patients who were

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ITALIAN SOCIETY

83

suffering from acute quinine poisoning. The poisonous action of quinine is mainly due to spasm of the small arteries, the symptomatology of which in mild cases is limited to tinnitus and some loss of hearing. With higher doses the patient may be in a confused state, torpid, giddy and having disturbances of vision. The patients in this study had a series of EEGs taken from the time of hospital admission until the complete disappearance of the clinical symptoms. In the initial stage the E E G tracings tended to be fiat and to show a poor alpha rhythm and theta elements at irregular intervals. These findings would support the thesis of functional danmge to the cerebral tissue caused by the quinine, which could be reversed, depending on the speed and efficacy of the adopted therapy. The vasodilator drugs causing the clinical improvement determine the improvement of the electrical cerebral activity and the reappearance of a normal alpha activity.

in a cage similar to its usual shelf. A periscope allowed observation of the animal's behaviour so that any social intercourse was prevented. I n addition, identical records were carried out on 4 control cats. The conclusions from this study axe as follows: (a) waking, light sleep and deep sleep occur in the E E G of cats with chronic damage to the thalamus or with retrograde degeneration of the non-specific nuclei; (b) the percentage time of waking and the 2 stages of sleep show individual variations within the group of cats with thalamic damage, similar to those observed in the control animals under the same experimental conditions; (c) both the animals of the control g r o u p a n d those with thalamic lesions sleep for a longer time than they are awake, light sleep representing the greater amount of total sleep; (d) EEG changes occur in the records of eats with thalamic damage but such changes do not prevent the recognition of the waking and sleeping patterns.

5. Partial and generalized seizures induced by cobalt powder in the ventral amygdala of the eat. - - R. Mmani (Turin).

7. Megi'mlde aad intraearotid Amytal in egdlelJe subjects and the compm-ison of the convulsive tin'eslmld of the two cerebral hemispheres. - - G. B. Rieei and P. Silipo

The introduction of cobalt powder into the cat's ventral amygdala was able to produce a very active epileptogenic focus. The epileptic activity lasted about a month. Two days after cobalt introduction local electro-clinical phenomena with focal E E G activity and psychomotor seizures were observed. A week later, E E G abnormalities spreading from a contralateral rhinencephalic secondary focus appeared. Electrical and electro-clinleal generalized seizures of myoclonlc type were also observed, mixed with partial phenomena. The difference between the effects produced by epileptogenlc substances commonly used to obtain a chronic experimental amygdaloid epilepsy and those produced by cobalt are emphasized; with cobalt there is: (1) the very early beginning of focal ipsilateral as well as secondary contralateral seizures; (2) the appearance of generalized "centrencephalic" seizures. These differences are related to the particular action of cobalt, which is supposed to interfere chemically with neuronal metabolism and to give rise to cerebral hyperexcitability and a n increase in "central t o n u s ' . This particular reactivity could provide the background which is needed for the appearance, following the primary focal firing, of secondary "centrencephalic" and contralateral seizures and could also explain the very early onset of the latter. 6. A statistical study of waking-sleeping and sleep stages in cats with chronic lesions of the flml~nms. - - F. Angeleri, G. F. Marchesi and A. Quattrini (Perugia). A qualitative and quantitative study of waking and sleep patterns has been carried out with prolonged (average of 9 h for each cat) EEG, E M G and ocular records from 27 cats with direct lesions or retrograde degeneration of aspeeific and specific thalamic nuclei. Retrograde degeneration was achieved by electrolytic lesions of the head of the n. caudatus. Records were carried out 20-90 days after the surgical intervention and prolonged samples of tracings were taken over 24-72 h while the cat remained

(Rome). Ten patients with focal and multifocal epilepsy have been subjected to this test. The patient is fasting and has been given no anti-epileptic therapy for at least 48 h prior to the test, which takes place in 2 successive stages. First, intracarotid Amytal is given (Rovit et aL 1961) and 20-30 rain later 0.25 % Megimide is given via the carotid in doses of I ml every 2-3 sec until the first symptoms of the seizure appear. A t this point 100 mg of Amytal are injected in the same way in order to prevent spread of the seizure. The intracarotid Amytal test has been of supplementary value, the results having confirmed previous findings in 5 cases and clarified a further 2. In 2 o t h e r cases the Megimide test also made it possible to establish that the epileptic activity was predominant over one hemisphere, there having been no evidence of asymmetry in the various E E G examinations previously. In one case the test gave no further information. The findings are only of value if they are considered together with other clinical data and the EEG. Generally the induced seizures and the paroxysmal E E G features are without specificity; probably only marked differences in the convulsive threshold of the two hemispheres can, by themselves, be of value. 8. Intraearotid Megi'mide in the study of the hemis]01~ml convulsive threshold in man. - - F. Corletto, G. Rosadini and G. F. Rossi (Genoa). Ten epileptic patients were examined, with the following findings: (1) the fractionated intracarotid injection of 0.1 ~ Megimide always induced a generalized convulsion, with focal onset in 75% of the cases; (2) there was generally a difference in the convulsive thresholds of the two hemispheres of the same subject, the average amount of Megimide required being 0.64 mg for the lower threshold hemisphere and 1.78 mg for the other; (3) Electroenceph. clin. Neurophysiol., 1968, 2 5 : 8 2 - 8 7

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the convulsive threshold was lower when the drug was injected into the carotid artery than with intravenous injection; the difference was even greater for the lower threshold hemisphere; (4) the hemisphere showing a lower convulsive threshold was the one in which a dominance for epilepsy was also shown by all the other tests (clinical, radiological and EEG, obtained both under resting conditions and during activation procedures). 9. Preliminary observations on the power spectrum of the huw-~q EEG. - - G. Romdilfl, F. M. Puca and C. R. Rtvano (Genoa). In 10 healthy adult subjects a spectral analysis el the EEG was performed, using a Fourier integral transform of the autocorrelogram. This research, restricted to the spectrum between 6.25 and 100 c/see, was carried out with the subject under the following different conditions: (a) relaxed with eyes dosed; (b) relaxed with eyes closed while listening to reading; (c) relaxed with eyes closed while speaking; (d) relaxed with eyes open; (e) relaxed with eyes open while reading. The results obtained were as follows: (I) each subject when relaxed with eyes closed showed a fundamental frequency as indicated by a narrow Gaussian curve with the apex between 8 and 12.5 c/see. In addition, a secondary frequency with a lower power could be observed at about 20 c/see; (2) all the spectral modifications occurring under the other conditions studied were related only to height or width variations of the " m a i n " peak, no new frequencies ever being observed. 10. Conduction velocity in the sciatic nerve of man. - F. lkignolio and L. Fra (Turin). A study of motor and afferent conduction in the sciatic nerve was carried out on 15 normal subjects. In order to determine the sensory conduction velocity, the sensory fibres were stimulated at the second and third toe by ring electrodes. The motor conduction velocity (motor action potential of the abductor haUucis, recorded from a concentric needle electrode) and the afferent nerve conduction velocity were determined by stimulation of the nerve trunk at various levels (ankle, popliteal fossa and upper thigh), using needle electrodes inserted in pairs. The same needle electrodes were used for recording the sensory and mixed nerve action potentials. In all subjects the conduction velocity of the fastest sensory fibres was only determined in the more distal segment of the nerve. The sensory action potential was recorded at the popliteal fossa only in 6 cases and never at the upper thigh. In all subjects it was possible to record the nerve action potentials evoked by stimulation of the mixed nerve at various levels. The values of the afferent and motor conduction velocities are compared with those obtained by other authors. 1 I. Modifications of nerve action potentials in relation to different parameters of stimulation, m D. ~ i n i , E. Sala and G. Valli (Milan). Nerve action potential (NAP) changes in relation to varying parameters of stimulation were studied in 4

healthy subjects. Single square wave pulses (0.01-500 msec in duration) were delivered through a twin-ncedle electrode to the ulnar o r median nerve at the wrist; NAP recording was performed by an electrode of the same type at the elbow and the compound muscle action potential (MAP) was led off from the hand muscles by means of an Adrian-Bronk needle. At threshold level, strengthduration curves were plotted with values of chronaxie ranging from 0.03 to 0.09 msec. NAP activation appeared earlier than the MAP, using short stimuli at threshold voltage; the N A P / M A P activation ratio was reversed for long lasting stimuli. The slope of increasing amplitude for NAP at supraliminal voltage was smoother in comparison with the slope for MAP. V/V0 ratio at the maximum level was significantly higher (t = 3.97) for NAP than for MAP. Shortening of NAP latency ( - - 4 to 8%) occurred at maximal and supramaximal levels. Multiple responses were elicited by supraliminal stimuli of long duration, their discharge rate being within the range of 330 to 480 puises/sec. 12. The problem of epileptic p s y ~ : presmtation of three cases. - - G. B k ~ c o , S. ]Dram, M. T. De Giorgia and R. B. Valeate (TWin). After briefly reviewing the literature, the authors presented 3 epileptic patients who were affectedby psychotic disorders of variable duration. The following parameters and their mutual relationships are emphasized: mental confusion, E E G findings and psychotic behaviour. The authors believe that there is no reason why any one particular form of epilepsy should give rise more frequently than others to psychotic disorders. The acute psychosis in epileptic patients usually follows an increase in the frequency of attacks and this is in relation to the increase in focal abnormalities and deterioration of the basic E E G activity. This deterioration is directly related to a psychotic state of confusion. These cases, which are by far the most frequent, correspond to the Landolt psycho-organic complex. In other less frequent types of case, the authors consider that the cerebral epileptogenic damage is the basis for alterations in vigilance during which the mass recruitment of neurones ns inhibited or interfered with, resulting in a psychosis with dysphoria and rich but poorly constructed delusions. 13. Papez circuit and re~plation of the h i ~ theta rhythm in the cat. - - A. At~m'ont.and P. L. P a t t e l t n i (Bologna). The appearance of hippocampal theta rhythm on sciatic stimulation depends primarily upon an afferent system running from the midbrain to the septum through the hypothalamus medialis (cf., Heir. physiol, pharmaco/. Acta, 1963, 21: C 10). The regulation of this rhythm may be explained on the basis of either feedback circuits existing within the afferent system itself or other more complex loops such as the Papez circuit. (1) Bilateral coaguhttions o f the anterior thalamic nuclei or the gyrus cinguli (between F4 and FI 1) depress both frequency and duration of the theta rhythms following sciatic stimulation. Such an effect does not depend

Electroenceph. clin. Neurophysiol., 1968, 25:82-87

ITALIAN SOCIETY on non-specific depressive influences of the coagulation procedure. (2) Theta-like rhythms are eiicited predominantly in the ipsilateral hippocampus by short repetitive trains (4/see, 0.1 sec) of stimuli (100-200/see, 0.5-1.0 msec, 2-6 V) delivered to either anterior thalamic nuclei or the gyrus cinguli (F7 or F11). On the contrary, continuous low (4/see) or high frequency (100/see) stimulation (0.5-1.0 msec, 2-6 V) of the same structures is ineffective. Theta-like rhythms elicited by train stimulation of the anterior thalamic nuclei or the gyrus cinguli (FII) are not affected by coagulation of the septum and the fornix but are strongly depressed by ipsilateral coagulation of the gyrus cinguli (F7). The evidence collected supports the hypothesis that the Papez circuit acts as a feedback loop sustaining the hippocampal them. rhythm. 14. Micro-eleetrode recordings from the human thalamus. Some observations on the functional characteristics of somato-sensory neurones. - - M. Carreras, D. Mancia and C. A. Pagni (Parma and Milan). During the last few years we have made use of a microelectrode technique which allows us to record the electric.al activity of individual units in the human thalamus during stereotactic surgery. This technique makes it possible to obtain satisfactory extracellular recordings of spontaneous firing, during responses to various types of natural stimulation and during voluntary movements in unanaesthetized patients. TaMirach's stereotactic apparatus has been used in this study. Impulse discharges of single cells and fibres in subcortical structures are recorded through fine tungsten micro-electrodes (2-4 p tip, prepared according to Hubel's technique slightly modified) protruded from the tip of a needle probe by means of a micro-drive attached to the upper end of the probe. The probe is lowered into the brain through a perforated screw guide driven into the skull. The micro-drive allows a total vertical movement of the electrode of 18 ram, at a rate of 250/~ per turn. The data presented in this report are taken from observations made in patients affected by Parkinson's disease or other forms of dyskinaesia. We are chiefly concerned with the functional properties of neurones isolated in the thalamic region which can be activated by physiological stimulation of cutaneous receptors over the body surface. We have also considered some electrophysiological data pertaining to units responding to movements of joints, which were encountered in the thalamus just rostral to the ta~ile region. 15. Neurophysiological and clhfical observations in a case of epilepsia partinlis continmms. - - B. Bergamasco, F. lkignolio, G. Broggi, T. Dori~guzzi, R. Mutani and A. Rlccio (Turin). The results of the neurophysiological study of a case of epilepsia partialis continuans are reported. The interest of the observations is essentially based on the fact that the EEG constantly failed to show any epileptogenic abnormalities whereas corticography showed bioelectrical abnormalities which were considered to be steady

85

potential (SP) shifts. The possibility that such SP shifts are related to a subcortical cerebral involvement which may be responsible for the myoclonic syndrome is discussed. 16. The recovery cycle of the visual evoked potentials in normal subjects and in patients with endogeaous depression. - - V. Floris, G. Anml-41e, G. llernardi, C. Morocutti, P. A. Rizzo and C. Vasconctto (Sien). Following some research work on the recovery cycle of the visual evoked potential (VEP) in psychiatric patients, the findings in patients with endogenous depression arc now considered. The recovery cycle for the latency of the peak of the first wave of the VEP showed some variability in individual depressed patients, but on average the course of recovery of the iateucies was constant and uniform for all waves and it was identical to the behaviour of the latencies in normal subjects. The recovery of voltage for Cig~nek's wave III, which was systematically analysed by measuring the amplitude of the peaks II-III/III-IV, showed some difference in the depressed patients compared with normal subjects. Such differences concerned the time interval between 100 and 200 msec. In fact the graph referring to the average ratio of I I - I found in this interval, even if slightly greater than one in psychopathic patients, reached lower levels than those found in normal subjects. The statistical elaboration of the voltage recovery of normal and depressed subjects shows clearly the importance of the differences between the mean values, with a probability greater than 0.95. The different reactivity of the brain to afferent stimuli in depressed patients is discussed from the physiopathological point of view. 17. A statistical study of the m o u n t of diffuse synchronous spike and wave activity during nocturnal polygraphic recording in epileptics. - - F. Angderi, P. Bergonzi and A. Ferroni (Perugia). Separate computations of: (a) epileptic diffuse synchronous 3 c/sec spike and wave activity; (b) diffuse synchronous poly-spike and wave activity; and (c) diffuse synchronous activity of other types, has been carried out in 16 cases of epilepsy with 29 polygraphic nocturnal records. The types of seizure that occurred were 5 cases of petit real with typical absences, 6 cases of petit mal and grand real seizures (in some cases akinetic seizures) and 5 cases of only grand real seizures with prevalent poly-spike and wave activity in the EEG record. The study of the averages of the recurring epileptic activity in various stages of sleep showed that: (1) the epileptic activity of nocturnal records shows almost constant numbers of spike and wave complexes in the various stages of sleep, both in a number of subjects and in the same subject with many recordings before and after therapeutic treatment; (2) this quantitative evaluation of the spike and wave complexes is valid for subjects who only have absences as well as for those with absences and grand mal seizures; (3) in the records showing prevalently spike and wave activity, the diffuse synchronous activity is poorly formed and behaves almost like spike and wave

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complexes; (4) the poly-spike and wave activity in the records of those subjects with grand real seizures shows a different behaviour, especially when the diffuse synchronous activity appears prevalent. A statistical evaluation of the behaviour of the ictal and interietal activity has still to be done and this study is in progress. 18. C U n i c o - ~ p l f i c com/tkgations on "slow sleep" idiopatl~ nte~ole~y. - - G. Berti Ceroni (Bologna). Three cases of narcolepsy are reported, In all the cases 24 h polygraphic recordings have been carried out. In 2 cases diurnal sleep episodes constantly began with slow sleep; the structure of night sleep was substantially normal. In the 3rd case failing into the paradoxical phase o/ sleep alternated with attacks beginning with slow sleep; awakening in the course of the night occurred several times and was protracted in every instance. Our observations demonstrate that, as well as the cases of narcolepsy with rapid eye movement sleep onset, the existence of other cases in which falling asleep takes place into slow sleep should be recognized. Slow sleep onset cases are distinguishable from the others because of the absence of auxiliary symptoms (such as cataplexy, sleep paralysis, hypnagogic hallucinnsis) as well as the presence of a normal structure of night sleep. 19. Motor conduction velocity in alcoholic patients. - C. C. Perfetti, F. Ferro Milone and A. Pucchinni (Pisa). Many clinical and E M G studies have been performed in alcoholic patients (Co6rs, Mawdsley, Bexgamini, Cosi, RameUi). The latency of the motor and sensory nerve action potentials could remain unchanged or, when there were signs of peripheral neuropathy, could be increased. But the conduction velocity was not always in relation to the clinical manifestations and never exceeded the level of 40 m/see and, in exceptional cases, could be 22 m]sec (Mawdsley). The dispersion of the different fibre velocities was not dealt with. After studying the different conduction velocities of the ulnar nerve in 20 chronic alcoholic patients, we compared the results with those obtained from 20 patients of the same age without any alcoholic history and who were unaffected by any neuromuscular disease. Hopf's technique was used. The values of the maximum velocity obtained by the classical technique (Pinelli 1953) differed from those obtained by Hopf's technique. This was due to an error in latency in Hopf's technique because of the absolute and refractory periods (0.75-2 msec) of the nerve. The similarity between the observed values in normal and alcoholic subjects was verified. The maximum velocity was also maintained (average 47 m]sec, as in the control group) in patients with clinical symptoms and signs of peripheral neuropathy. On the other hand, the dispersion of the lower fibre velocity spectra in the motor nerve was increased very noticeably in alcoholics (P < 0.001 ; average : 15.69 m/see; ~ : 16.52 in alcoholics. Average = 8.67 m/see; g 2 ~ 5.05 in normal subjects). These results are related to an early metabolic alteration in the small alpha motor neurones, secondarily

involving all the fibres. As the maximum velocity was maintained, we deduced that the large alpha motor neurones were not relatively affected. The alteration implies a progressive change in the nmtabolism (nutrition deficiencies, particularly thiamine lack) of the nerve cell and secondary segmental demyelination of the fibre along its entire length. 20. Autonomic attacks and ptlroxy~m.ql EEG features during develolmmat. - - E. M ~ q s t t l m d M. G ~ r m m ~

(Modem). A study has been carried out on 15 children aged between 6 and 14 years suffering periodically from fits of an epileptic nature without motor components and with only vegetative symptoms (cardio-vaseular, vasomotor, sweating and digestive disturbances, such as vomiting and gastric or abdominal pain). Only one of the patients had shown other epileptic symptoms some years previously. Except for 2 cases in which the pattern appeared normal, the EEGs showed paroxysmal changes between attacks: in 6 cases the abnormalities appeared to be generalized; in 4 cases, although generalized changes were present, the abnormality was mainly over one hemisphere (3 cases on the left and 1 case on the right). One subject showed a right temporal epileptogenie focus (the boy who had previously suffered from epileptic seizures) and 2 subjects showed a left temporal epileptogenic focus. No EEO pattern characteristic of this type of clinical picture was found; in particular, no 14 and 6 c/see positive spikes were seen during the waking hours. Our experience from a large study of case histories shows that there is a certain frequency with which E E G abnormalities of paroxysmal type are found in patients with attacks of visceral disturbance, supporting the epileptic nature of these syndromes. In addition the good response to anti-epileptic treatment that has been found in all our patients helps to confirm this hypothesis. 21. Subeortical linkages between thainmic trigeminal relay nuclei, m A. Bava and T. M ~ o n i (Catlulin). The experiments were carried out on 18 curarized D artificially ventilated cats (ether during surgery; local anaesthesia); the animals underwent complete section of the corpus callosum or large removal of the rostral regions of cerebral cortex, including sensori-motor and suprasylvian associative areas. During micro-electrode explorations (tungsten micro-electrodes) of nucleus ventralis postero-mediatis of the thalamus (VPM; stereotaxic method; histological control), 77 neurones were identified and tested for their reactivity: (a) to stimulation (electrical and physiological) of peripheral fields located within the terminal distribution area of the Vth cranial nerve and (b) to electrical stimulation (concentrie electrodes) of the contralateral homonymous nucleus. Only excitatory responses were taken into consideration. All neurones identified, of course, reacted to the ascending impulses elicited by stimulation of cutaneous or intra-oral trigeminal territories. Twenty-one units out of the 77 were also found to be reactive to "transverse" impulses brought about by contralateral VPM stimulation. Fourteen such units were diseharg©d by single

Electroenceph. clin. Neurophysiol., 1968, 25:82-87

ITALIAN SOCIETY shocks to contralateral VPM (threshold intensity: 0.1 msec, 2 V) whereas the remaining ones (7 units) could only be caused to fire if short repetitive trains (10-50/sec) were delivered. Four units reactive to single shocks exhibited only one spike in their responses, after short and constant latencies (0.7-1.2 msec). They were seen to follow stimulus frequencies up to 400/sec and were therefore regarded as antidromically activated. The latencies of the trans-synaptic responses (brief bursts of 1-7 spikes) ranged between 3 and 10 msec; these units failed to follow stimulus frequencies higher than 50-100/ sec. The "transverse" activation was also observed after hemisection of the mesencephalon, performed ipsilaterally to the stimulated nucleus. 22. Sleep EEG patterns during the apallie syndrome. - G. Rosadini and A. Gentilomo (Genoa).

Three patients, each in a prolonged coma due to a severe cerebral lesion, were studied with longitudinal EEG analysis both during the coma and the apallic syndrome. The results were as follows: (1) spontaneous modifications of the EEG frequently occurred during coma, even though the clinical condition remained unchanged; (2) while passing from coma to the apallic state the records became stabilized towards normal and the EEG sleep phases characterized by "spindles" and slow waves appeared; (3) when the apaltic syndrome was completely evident, the sleep phase characterized by rapid eye movements reappeared. The functional meaning of this progressive recovery and its prognostic interest are discussed. 23. The sleep eyrie in coma: prognostic value. - - B. Bergamas~, L. Bergamini, T. Duriguzzi and I. Saeerdote (Turin). Polygraphic recordings (EEG, EMG, EKG, EOG) have been performed during the night on patients in posttraumatic coma. The patients were divided into two groups according to the severity of coma. In the first group (coma III, according to Fischgold and Mathis) nocturnal recordings showed, in 3 subjects out of 4, slow sleep and fast sleep with rapid eye movements. In the 4th subject of this group, however, there was sleep activity similar to normal. In the patients of the second group (coma II, according

~7

to Fisehgold and Mathis) nocturnal recordings showed an organized sleep with rather normal activity. In those patients showing ~near-normal nocturnal bioelectrical activity the clinical evolution of the pathological condition has been satisfactory; but in the other cases the outcome was poor. Thus from these results it seems that the study of sleep in coma may help with regard to the prognosis. 24. Intrneellainr study of synalaie activities in neurones of nucleus leaticolaris. - - A. blAIllani and D. P. Purpura (New York, U.S.A.). Neurones located in various subdivisions of the lenticular nucleus (putarnen, giobus pallidus, n. entopeduncularis) exhibit three general patterns of post-synaptic potentials (PSPs) in response to repetitive stimulation of the caudate or thalamus of enc~phale, isoid cats. (1) The most consistent synaptic event observed ,ha ventral putamenpallido-entopeduncular regions=is an 8-20 msec latency inhibitory post-synaptic potential (IPSP) of 50-80 msec duration, elicited by candate stimulation. T h e ~ IPSPs are occasionally preceded by a short latency evoked post-synaptic potential (EPSP). IPSPs in this ..'location are of constant latency in any one cell a n d summate smoothly during high frequency caudate stimulation. Convergence of caudato-lenticular and thalamo-lenticular effects on the same elements is prominent. However, thalamic evoked IPSPs are of much longer latency than those elicited by caudate stimulation. (2) Both types of stimulation elicit shorter latency EPSPs with variable discharges, in some superficial location of the putamen. (3) Complex EPSP-IPSP sequences during caudate stimulation are frequently observed in regions corresponding to n. entopeduncularis. IPSPs are also observed in elements in intermediate sublenticular regions bordering on and involving the amygdaloid nucleus. PSPs evoked in lenticular neurones by caudate stimulation are not related to involvement of internal capsule by stimulating currents, as shown by the longer latency of IPSPs produced by direct stimulation of the capsule. The data obtained indicate the operation of powerful intrastriatal inhibitory pathways which appear to regulate the excitability of pallidofugal projections.

Electroenceph. clin. Neurophysiol., 1968, 25:82-87