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The diagnosis and management of seizure disorders is the area in which routine EEG has been of greatest clinical value. The episodic nature of epilepsy, however, renders routine EEGs inadequate to evaluate all seizure disorders because of sampling error. This problem has been partially solved by the development of EEG/video/polygraphic monitoring, which facilitates recording of ictal events. Intensive monitoring must be accurate and precise if it is to be cost effective. Good data are obtained by technologists who are present and in communication with comfortable patients who are on-camera throughout the recording.

The evaluation and outcome of 22 patients who had onset of complex partial seizures (CPS) of temporal lobe origin in childhood and subsequently underwent anterior temporal lobectomy are described. All patients showed improved seizure control; 81.8% had a reduction greater than or equal to 95% in seizure frequency. However, many patients had difficulty adjusting to a seizure-free life. Psychosocial, behavioral, and educational problems occurred more frequently in patients whose surgery was delayed until adult life. We conclude that attempts should be made early in the course of CPS of childhood to determine whether the seizures are truly intractable to medical management so that surgical intervention can be expedited.

Traditionally, human focal epilepsy has been thought to arise from an area of cortical damage, and the models of focal epilepsy used in research have been based on this concept. However, although the concept holds true for the adult brain, focal epilepsy is more common in children who have no evidence of such a lesion. This chapter gives a description and analysis of two types of focal epileptogenesis that are unique to the developing brain and for which there is no historical, clinical, or laboratory evidence of a structural brain lesion. In the first type, the focal epileptogenesis has its origin in a genetically determined cellular defect. In the second, the focal epileptic process is a result either of deprivation or chronic distortion of sensory input during a critical period of brain development.

The influence of ACTH on the prognosis of patients with infantile spasms remains controversial. We have examined retrospectively the long-term benefits of initially successful ACTH therapy in patients treated at this institution between 1961 and 1974. Individuals with equivocal or minimal improvement during ACTH therapy were excluded from this study. Eighteen affected infants showed a favorable early response consisting of cessation of seizures for at least 3 weeks during ACTH therapy and concurrent disappearance of the hypsarhythmic EEG pattern. Modal age at last follow-up was 5 years (range, 15 months to 16 years). Infantile spasms recurred in 7 patients (39%), and 8 patients subsequently had other seizure types. All epileptiform (spike) activity disappeared from the EEGs of 8 patients during ACTH therapy, but in 4 of these cases epileptiform activity was present in later tracings. In the remaining 10 patients the hypsarhythmic pattern disappeared in association with ACTH therapy, but the EEG remained epileptiform (often only in sleep). Later EEGs were free of epileptiform activity in 5 of the 10 patients whose tracings contained spike discharges in the early follow-up period. Four patients (22%) were seizure free and without intellectual impairment when last evaluated.

We report the long-term outcome of 64 infants with infantile spasms, followed prospectively, using controlled treatment schedules and objective techniques (24-hour EEG and video monitoring) to determine response. Average age at follow-up was 50 months. Of the 64 infants, three (5%) died; of the others, 41 (67%) had developmental retardation of 50% or more or an IQ of 50 or less. Eight patients (13%) composed our cryptogenic study group and were so classified on the basis of normal CT scan, normal development prior to onset of infantile spasms, and undetermined cause. These patients had the better outcome; 38% had normal development or were only mildly retarded. Both the responders and nonresponders in our symptomatic group had a poor outcome; only 5% had normal development or mild impairment. Outcome was not significantly influenced by short versus long treatment lag or by response to therapy. Other types of seizures occurred in 34 patients (53%). In summary, the overall prognosis for long-term outcome in these 64 patients with infantile spasms was poor.

Neocortical death is a form of the persistent vegetative state characterized by the maintenance of sleep/wakeful cycles and spontaneous respirations and the lack of cognitive function. It is difficult to diagnose in neonates and young infants because their cognitive skills are limited by inexperience and by immaturity of the central nervous system. Because neocortical death has not been described previously for this age group, we report the neurologic, behavioral, electroencephalographic, and computed tomographic characteristics of three infants who survived in the persistent vegetative state following severe brain injury. Each infant appeared to exhibit some complex behaviors, including interaction with the environment and the examiners, although the electroencephalograms documented no electrical activity of cerebral origin. Computed tomography revealed extensive destruction of the cerebral hemispheres. Infants and newborns with a history suggesting brain injury and with the neurologic and behavioral characteristics described here should be evaluated with serial electroencephalograms and computed tomography to diagnose the syndrome of neocortical death.

Twenty-four patients with infantile spasms were entered in a double-blind, placebo-controlled, crossover study to compare the therapeutic effectiveness of ACTH (20 to 30 units/day) with that of prednisone (2 mg/kg/day). Response to therapy was determined by utilizing a comprehensive monitoring system and was defined as a complete cessation of spasms and disappearance of the hypsarrhythmic EEG pattern. A major difference between the effectiveness of ACTH and that of prednisone in stopping the spasms and improving the EEG pattern was not demonstrated. Nine patients responded to ACTH (five initial drug, four crossover), and seven patients responded to prednisone (four initial drug, three crossover). Twelve responded within two weeks of initiation of therapy, and four within six weeks. Therapy was tapered and discontinued immediately after a response was obtained. Five patients had a relapse; four responded rapidly to a second course of therapy. Of the eight patients who failed to respond to hormonal therapy, seven were given clonazepam with no improvement.

Summary: A controlled study of 12 patients with infantile spasms was performed to determine the effectiveness of prednisone treatment. Patients were monitored serially, using a time-synchronized polygraphic and video system. Three patients (25%) showed prompt reduction in seizure frequency and normalization of the EEG after institution of treatment. The remaining patients showed no improvement in seizure frequency or significant change in the EEG. RESUME Une etude controlee a ete effectuee chez 12 sujets souffrant de spasmes infantiles pour apprecier Ľefficacite du traitement par la prednisone. Les patients etaient controles a Ľaide Ďun systeme de polygraphie et de video synchronises. Trois sujets (25%) ont eu une reduction rapide de la frequence des crises et une normalisation de ĽEEG apres Ľinstitution du traitement. Les autres sujets n'ont pas presente de diminution de la frequence des crises ni de modification notable de ĽEEG. RESUMEN Se ha realizado un estudio controlado de 12 enfer-mos con espasmos infantiles para determinar la efec-tividad de un tratamiento con prednisona. Los enfer-mos se monitorizaron seriadamente utilizando un sistema video poligrafico y sincronizado. Tres pacientes (25%) mostraron una rapida reduction en la frecuencia de los ataques y una normalization del EEG tras la instauracion del tratamiento. El resto de los enfermos no presento ninguna majoria en la frecuencia de los ataques ni cambios significativos en el EEG. ZUSAMMENFASSUNG Eine kontrollierte Untersuchung von 12 Patienten mit BNS-Krampfen wurde durchgefuhrt um die Wirksamkeit der Prednison-Therapie zu bestimmen. Die patienten wurden fortlaufend uberwacht mit einer zeitsynchronisierten Polygraphie- und Videoein-richtung. 3 Patienten (25%) zeigten eine prompte Reduktion der Anfallshaufigkeit und Normalisierung des EEG nach Beginn der Therapie. Die ubrigen Patienten zeigten keine Besserung der Anfallshaufigkeit oder eine signifikante EEG-Veranderung. RESUME Une etude controlee a ete effectuee chez 12 sujets souffrant de spasmes infantiles pour apprecier Ľefficacite du traitement par la prednisone. Les patients etaient controles a Ľaide Ďun systeme de polygraphie et de video synchronises. Trois sujets (25%) ont eu une reduction rapide de la frequence des crises et une normalisation de ĽEEG apres Ľinstitution du traitement. Les autres sujets n'ont pas presente de diminution de la frequence des crises ni de modification notable de ĽEEG. RESUMEN Se ha realizado un estudio controlado de 12 enfer-mos con espasmos infantiles para determinar la efec-tividad de un tratamiento con prednisona. Los enfer-mos se monitorizaron seriadamente utilizando un sistema video poligrafico y sincronizado. Tres pacientes (25%) mostraron una rapida reduction en la frecuencia de los ataques y una normalization del EEG tras la instauracion del tratamiento. El resto de los enfermos no presento ninguna majoria en la frecuencia de los ataques ni cambios significativos en el EEG. ZUSAMMENFASSUNG Eine kontrollierte Untersuchung von 12 Patienten mit BNS-Krampfen wurde durchgefuhrt um die Wirksamkeit der Prednison-Therapie zu bestimmen. Die patienten wurden fortlaufend uberwacht mit einer zeitsynchronisierten Polygraphie- und Videoein-richtung. 3 Patienten (25%) zeigten eine prompte Reduktion der Anfallshaufigkeit und Normalisierung des EEG nach Beginn der Therapie. Die ubrigen Patienten zeigten keine Besserung der Anfallshaufigkeit oder eine signifikante EEG-Veranderung. RESUME Une etude controlee a ete effectuee chez 12 sujets souffrant de spasmes infantiles pour apprecier Ľefficacite du traitement par la prednisone. Les patients etaient controles a Ľaide Ďun systeme de polygraphie et de video synchronises. Trois sujets (25%) ont eu une reduction rapide de la frequence des crises et une normalisation de ĽEEG apres Ľinstitution du traitement. Les autres sujets n'ont pas presente de diminution de la frequence des crises ni de modification notable de ĽEEG. RESUMEN Se ha realizado un estudio controlado de 12 enfer-mos con espasmos infantiles para determinar la efec-tividad de un tratamiento con prednisona. Los enfer-mos se monitorizaron seriadamente utilizando un sistema video poligrafico y sincronizado. Tres pacientes (25%) mostraron una rapida reduction en la frecuencia de los ataques y una normalization del EEG tras la instauracion del tratamiento. El resto de los enfermos no presento ninguna majoria en la frecuencia de los ataques ni cambios significativos en el EEG. ZUSAMMENFASSUNG Eine kontrollierte Untersuchung von 12 Patienten mit BNS-Krampfen wurde durchgefuhrt um die Wirksamkeit der Prednison-Therapie zu bestimmen. Die patienten wurden fortlaufend uberwacht mit einer zeitsynchronisierten Polygraphie- und Videoein-richtung. 3 Patienten (25%) zeigten eine prompte Reduktion der Anfallshaufigkeit und Normalisierung des EEG nach Beginn der Therapie. Die ubrigen Patienten zeigten keine Besserung der Anfallshaufigkeit oder eine signifikante EEG-Veranderung. RESUME Une etude controlee a ete effectuee chez 12 sujets souffrant de spasmes infantiles pour apprecier Ľefficacite du traitement par la prednisone. Les patients etaient controles a Ľaide Ďun systeme de polygraphie et de video synchronises. Trois sujets (25%) ont eu une reduction rapide de la frequence des crises et une normalisation de ĽEEG apres Ľinstitution du traitement. Les autres sujets n'ont pas presente de diminution de la frequence des crises ni de modification notable de ĽEEG. RESUMEN Se ha realizado un estudio controlado de 12 enfer-mos con espasmos infantiles para determinar la efec-tividad de un tratamiento con prednisona. Los enfer-mos se monitorizaron seriadamente utilizando un sistema video poligrafico y sincronizado. Tres pacientes (25%) mostraron una rapida reduction en la frecuencia de los ataques y una normalization del EEG tras la instauracion del tratamiento. El resto de los enfermos no presento ninguna majoria en la frecuencia de los ataques ni cambios significativos en el EEG. ZUSAMMENFASSUNG Eine kontrollierte Untersuchung von 12 Patienten mit BNS-Krampfen wurde durchgefuhrt um die Wirksamkeit der Prednison-Therapie zu bestimmen. Die patienten wurden fortlaufend uberwacht mit einer zeitsynchronisierten Polygraphie- und Videoein-richtung. 3 Patienten (25%) zeigten eine prompte Reduktion der Anfallshaufigkeit und Normalisierung des EEG nach Beginn der Therapie. Die ubrigen Patienten zeigten keine Besserung der Anfallshaufigkeit oder eine signifikante EEG-Veranderung.

This study provides preliminary evidence that computer-derived parameters of interictal spike waveforms can be used to assess seizure hazard in a quantitative manner. Thirteen children with spike foci and simple or complex partial seizures were studied before and during treatment with carbamazepine or phenobarbital; spike parameters were determined from 5- to 30-minute electroencephalographic samples obtained during non-rapid eye movement sleep. Measurements included spike amplitude, duration, and sharpness, and a mathematical combination of these three parameters (the composite spike parameter). Achievement of seizure control was associated with a decrease in spike amplitude, duration, and composite spike parameter, and an increase in normalized sharpness, compared to baseline values. These results suggest that this method may provide a prospective means for estimating drug efficacy that can be applied shortly after attainment of steady-state serum drug levels.

An examination was made of 967 initial and follow-up electroencephalograms of 371 children with clinically diagnosed cerebral concussion to determine whether the EEG could provide an objective measure of injury. For each patient, the degree and distribution of EEG abnormalities, as well as their rate of resolution, were correlated with the severity of clinically assessed injury. A close relationship was found between the severity of both initial and longitudinal EEG disturbances and the clinically suspected grade of concussion. Serial EEGs of individual patients showed a similar relationship between time elapsed since injury and degree of abnormality. The rate at which the sequence of EEG resolution took place varied in direct relation to the severity of concussion. It was concluded that the initial EEG and the rate and degree of resolution of EEG abnormalities, together with the time elapsed since injury, can provide objective and reliable information to the clinician for the establishment of the diagnosis and assessment of severity of cerebral concussion in children.

Evaluation of the changes in the waking EEGs of six healthy male subjects who received 30 mg daily oral doses of flurazepam hydrochloride for two weeks. A placebo was then substituted for flurazepam for another two weeks. An increase in beta activity with a maximum in fronto-central leads was observed during the test period. A small increase in the mean wavelength of the alpha and theta activities in the central-occipital derivations was also apparent in the subjects during the period.

Summary The recently reported observation that the sleep state activates the appearanceof epileptiform abnormalities in the electroencephalogram are confirmed and extended. Furthermore it is shown that the use of mildly sedative doses of Nembutal to promote sleep in children does not significantly reduce the activating properties of this state. The routine use of sedative-induced sleep is shown to be a valuable adjunctto routine clinical electroencephalography in children for the following reasons: 1. Latent epileptiform activity not present in a waking record and not activated by such measures as hyperventilation may nevertheless become manifest during sleep. 2. A primary convulsogenic focus may be revealed in sleep when the wakingrecord is of a type suggestive of a generalized convulsive state. 3. Sleep produced by mild sedation provides a means of obtaining diagnostictracings in children in whom, because of mental retardation, physical handicap, or behavioral difficulties, it would not otherwise be possible. The characteristics of the various clearly abnormal electrical dischargeswhich occur during sleep are described and discussed in relation to their clinical correlates.

The effect of hippocampal ablation on acquisition, retention, and learning-set formation in a simple auditory discrimination task was studied in rhesus monkeys. Hippocampal ablation was found to interfere with the retention of discriminations, those learned postsurgically being more affected than those learned presurgically. Successive postsurgical discrimination reversals resulted in the formation of discrimination reversal learning sets. It was concluded that while the hippocampus may subserve a facilitatory function in retention, its presence is not an essential condition for retention or for new learning.

The electrical response from the cochlea has been used by many investigators to study the psychophysiology of hearing, and most of the theories in vogue at the present time are based on the results of experiments in which this technic was used. For this reason the "cochlear response" has a special significance for the otologist, as his final evaluation of the various theories rests on his evaluation of the experimental technic employed. A developmental analysis of the phenomenon is herein presented. However, the conclusions arrived at are qualified by the reservation that while the ultimate psychologic discriminations must be imposed within certain limits by the events taking place in the middle ear, the cochlea and the auditory nerve, the presence of a particular discriminatory pattern at one level does not insure its presence at higher levels. HISTORICAL REVIEW In 1927 Forbes, Miller and O'Connor 1 reported an experiment in which they

Utilizing long time-constant EEG recording techniques, magnetic tape storage, and electronic averaging, the phenomenon designated the “contingent negative variation” or “expectancy wave” was studied in 3 Rhesus monkeys. Three basic conditioning paradigms were used: escape conditioning with a warning cue, discrimination task with aversive reinforcement following SD, and discrimination with appetitive reinforcement. Trials were presented in blocks of 12 and averaged on line with an Enhancetron electronic averager. In each case, during acquisition trials, a surface negative slow potential gradually developed only following the evoked response to SD and preceding the meaningful stimulus. No shift followed the unreinforced stimulus. During extinction trials, the shift gradually diminished. During discrimination reversal, a negative shift developed following the previously unreinforced stimulus, while the shift following what had been SD gradually diminished. Results demonstrate the appearance of the “contingent negative variation” in these monkeys and support the contention that this shift is a result of cerebral electrical activity during conation.

Because the cochlea is a minute and delicate organ embedded in thick bone it has been impossible to make direct observations of the events taking place in the inner ear in response to acoustic stimuli. For this reason the dynamic behavior of the ear has been considerably neglected in the formulation of theories of the analysis for pitch. However, a great deal of experimental evidence has come forward during the last ten years which clearly sets down certain fundamentals on which the final picture will be based. In this paper I have attempted to tie all this evidence together into a uniform pattern of thought, so as to present a broad functional analysis of the processes responsible for the subjective discrimination of sound. COCHLEAR MECHANICS Although little is known of the physical constants of the inner ear, reasonable assumptions can be made regarding the nature of such factors as the

SUMMARY A group of 459 children having episodic attacks of headache or abdominal pain, or both, associated with autonomic disturbances such as pallor, sweating, nausea, vomiting, anorexia, dizziness, light-headedness, lethargy and temperature alterations are reported. These symptoms are grouped together into a specific syndrome because of the consistent pattern of the symptoms and clinical findings and because of the consistent presence of particular electroencephalographic abnormality (the 14 and 6/sec positive spike pattern). The majority of these cases occur in children between the ages of 5 and 16 years, occasional cases being seen in younger or older children and adults. In most of the patients no etiology can be demonstrated, although a history of head injury or encephalitis is present in a significant number (37%). These symptoms respond to treatment with anticonvulsant medication, the drugs of choice being dilantin and diamox. RESUME Rapport sur l'examen d'un groupe de 459 enfants souffrant d'acces periodiques de maux de tete ou de douleur abdominale, ou des deux a la fois, associes a des troubles autonomes tels que pâleur, transpiration, nausees, vomissements, anorexie, vertiges, sensation de legerete dans la tete, lethargie et alterations de la temperature. Ces symptomes sont groupes en un syndrome specifique a cause du type constant des symptomes et des constatations cliniques, et aussi a cause de la presence constante d'une anomalie electroencephalographique particuliere (le type positif de pointes de 14 et 6/sec). La majorite de ces cas concerne des enfants âges de 5 a 16 ans; des cas fortuits se sont presentes chez des enfants plus jeunes ou plus âges et chez des adultes. L'etiologie n'a pu etre determinee chez la plupart des malades, bien qu'une lesion a la tete ou une encephalite soient mentionnees en un nombre assez important (37%). Ces symptomes reagissent au traitement par des anticonvulsivants; les medicaments a choisir sont le diphenylhydantoinate de soude et le diamox.

Summary A study of a series of 550 patients showing the electroencephalographic pattern known as 14 and 6 per second positive spikes has shown that this pattern is a particular correlate of convulsive equivalent disorders in children and provides objective laboratory evidence to support such a diagnosis. The high incidence of paroxysmal attacks of headache, abdominal pain, and behavioral and autonomic disturbances in patients with the 14 and 6 per second positive spike pattern may be considered the basis of definition for a specific electroclinical syndrome. This syndrome has its greatest incidence between the ages of 4 and 15 years but may occur at any time of life. The prognosis in children is favorable for spontaneous remission of symptoms with increasing age, and good therapeutic response to anticonvulsant drug therapy is usually the case.

Nineteen patients, aged 4 to 44 years, with generalized epilepsy and generalized 3 Hz spike-and-wave activity, were monitored for 24 or 36 hours on one to nine occasions to determine the time distribution of ictal and interictal electroencephalographic discharges and the consistency of the time patterns observed. Two patients with a low incidence of spike-and-wave activity had a random pattern of occurrence; the other 17 showed one of three types of time modulation. The latter can be explained by the interaction of two modulative processes, one with a period of about 100 minutes and the other of approximately 24 hours. The pattern observed depends on the phase angle of the two cyclic processes. Treatment with ethosuximide altered the pattern of time modulation, and eventually, when the spike-and-wave activity was reduced to a low level, the time distribution became random.

An effective, time-synchronized monitoring system for the study of patients with infantile spasms has been developed. This system utilizes concurrent graphically recorded data, including EEG, body movement via triaxial accelerometry, respiration, electrocardiogram, electromyogram, electro-oculogram, and galvanic skin response. These data, when evaluated in conjunction with a closed-circuit TV recording of the patient, greatly facilitate the differentiation of seizures from nonictal activity and permit the characterization and quantification of the behavioral, motor, and autonomic phenomena intrinsically associated with infantile spasms.

To characterize and classify neonatal seizures, we studied 349 neonates, using a portable, cribside EEG/polygraphic/video monitoring system. We recorded 415 clinical seizures in 71 infants; 11 other infants had electrical seizure activity without clinical accompaniments. Each seizure was analyzed in terms of its clinical character and its relationship to the presence of EEG seizure activity. Focal clonic seizures, some forms of myoclonic seizures, and focal tonic seizures were consistently associated with electrical seizure activity. Most "subtle" seizures, all generalized tonic seizures, and some forms of myoclonic seizures were either not associated with EEG seizure activity or had an inconsistent relationship with such activity. Seizures that were consistently and coherently related to focal EEG seizure activity had a high correlation with focal brain lesions and a favorable short-term outcome. Seizures with no relationship or an inconsistent relationship to EEG seizure activity were correlated with diffuse processes such as hypoxic-ischemic encephalopathy and a poor short-term outcome. The clinical and background EEG features of infants whose seizures were not accompanied by EEG seizure activity suggest that these seizures may not be epileptic in character.

Summary: Epileptic mechanisms in the brain are subject to long-duration, time-ordered neuromodulatory processes controlled by endogenous oscillators which are responsible for appropriately phased modulation of various normal physiological processes, including the 24-h sleep/wakefulness cycle and the ultradian 100-min cycle of rapid eye movement/non-rapid eye movement sleep. Both focal and generalized types of epileptiform activity in humans are subject to biorhythmic modulation, and the various modulation patterns observed are in accord with a model which explains these patterns as a consequence of the interaction of two endogenous modulatory processes: one with a period of about 24 h, the other with a period of about 100 min. Differences in the phase angle between the two cyclic processes, determined by time of sleep onset, explain the various modulatory patterns observed. The mechanisms involved in the genesis and elaboration of electrical epileptiform activity in animal models are examined in relation to known processes involved in the physiology of sleep, and compared with data derived from long-term studies of the time distribution of epileptic events in humans. In infantile spasms, clinical seizure activity and the ictal and interictal EEG patterns in relationship to the phases of the sleep cycle, the significant defects in the quality and quantity of sleep in this disorder, and the changes that take place in all of these when seizures are abolished by effective treatment, suggest that pontine mechanisms responsible for the sleep cycle may be involved in the elaboration of infantile spasms and hypsarrhythmia.

The effects of cerebellar stimulation were studied in monkeys with chronic alumina-cream epileptogenic foci in motor cortex. Low-frequency stimulation (5–15 c/sec) was ineffective in altering spontaneous cortical spiking. Clinical and electrographic seizures were elicited following high-frequency cerebellar stimulation (100 c/sec). This was a consistent finding following cerebellar stimulation, although no spontaneous seizures had been seen in these animals. These studies suggest the existence of facilitatory cerebellar mechanisms and indicate the need for further studies in chronic animal models.

The existence of critical periods in the ontogenesis of behavior, such as that associated with imprinting (Sluckin 1972), has been well-documented in recent years in morphologic, cytochemical, and electrophysiologic studies of the developing nervous system. Behavioral scientists have suggested that ontogenetic criticality can be understood if growth and behavioral differentiations are based on organizing processes and if organization can be modified only when active processes of organization are in progress (Scott 1962).

With the use of a time-synchronized video and polygraphic recording system, 5,042 infantile spasms were monitored and analyzed in 24 infants aged 1 to 43 months. Of these, 33.9% were flexor, 22.5% extensor, and 42.0% mixed flexor-extensor. Sometimes the spasms were followed by a period of akinesia and diminished responsiveness lasting up to 90 seconds, and rarely (1.0%) this "arrest" effect constituted the entire seizures. More than one type of seizure occurred in 21 of the 24 infants. In the same number, 78.3% of the seizures occurred in clusters, and the intensity and frequency of the spasms in each cluster often increased to a peak, then progressively decreased until they stopped. Predominantly, the clusters occurred soon after arousal from sleep. The number of seizures occurring at night (55.2%) was similar to the diurnal number (44.8%). The electroencephalographic seizure pattern was variable, but a marked generalized attenuation of electrical activity was a feature of 71.7% of the attacks. Attenuation episodes of similar degree and duration occurred with no evidence of a seizure.

A hierarchical approach to automation of EEG interpretation is described. The system utilizes an array of special-purpose processing units to accomplish parallel, real-time analysis of background activity in eight EEG channels. A PDP-11 40 computer is used to perform higher-order analytical functions and to generate both numerical and narrative reports. The system's design permits expansion of analysis capability by the incorporation of additional processing modules.

A surgical technique has been devised which permits complete neural isolation of the cortex of an entire cerebral hemisphere while preserving the blood supply and drainage. The status of the arterial circulation and venous drainage of the isolated hemisphere is evaluated at the termination of each experiment by comparison of the intact and isolated sides following aortic injection of a particulate dye. Such preparations show continuous or semicontinuous electrical activity consisting of high voltage aperiodic 0.5–4 cycle/sec oscillations and a superimposed lower voltage 25–70 cycle/sec rhythm. This activity may be interrupted by brief isoelectric episodes which may occur in all regions of the cortex simultaneously. The fast rhythm is essentially similar to that seen in the intact brain, and appears to constitute an autochthonic activity of the superficial neural feltwork of the cortex sustained in the absence of afferent neural influences. The high voltage aperiodic slow activity appears to be a consequence of the surgical procedure, but is probably related to neural isolation rather than to circulatory or mechanical insult. The isoelectric episodes are directly related to the physiological condition of the isolated hemisphere, and any factor which tends to compromise this state increases their incidence and duration. The isolated hemisphere is totally inactive only in the presence of significant hypoxia or ischemia. In contrast, the surgically isolated thalamus exhibits continuous rhythmic 6–9 cycle/sec activity of sinusoidal waveform. Thus, the aperiodic slow activity of isolated cortex is not a necessary consequence of deafferentation per se but reflects some characteristic peculiar to the cortex, perhaps a dependence of certain elements of its neural population upon subcortical influences for the development of an organized rhythmic behavior.

To the Editor:— The undersigned testified at the recent trial of Jack Ruby for and at the request of the state. We submit the following statements to the many physicians responsible for the health and peace of mind of nearly 1 million patients with various types of epileptic seizures: Neither the clinical history nor the electroencephalogram of Mr. Ruby indicated any definite evidence of epilepsy. Epileptic seizures are never associated with complicated and planned criminal acts or violence. Epileptics are as safe to be with as any group of people except in extremely rare and usually predictable situations.

A reduction in the number of spontaneously active units was found in the isolated cortex as compared to normal cortex under similar experimental conditions. Furthermore, any spontaneously active unit either ceased firing completely or markedly decreased in rate of firing during the silent periods which occasionally interrupted the spontaneous electrical activity (EEG) of the isolated hemicortex. While in all cases the EEG active periods and silent periods coincided with single unit active and silent periods, within the active periods the majority of cells had no particular recognizable relationship to the EEG phase or amplitude. A few units, however, increased their rate of firing during the positive phase of slow waves in the EEG, and, rarely, others appeared to decrease their discharge rate during EEG negative going slow waves. If the concept that EEG activity represents summated postsynaptic potentials is valid, one might expect to find a more highly synchronized (to EEG) unit population than was observed, since the only source of presynaptic drive in this preparation was the cortical neurons themselves. The results also suggest that silent periods were produced in both EEG and unitary activity by the influence of some third factor, possibly involving the cerebral circulation.