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The seizures of a mentally defective photosensitive epileptic child are described. They were complex and included repetitive hand movements. Cinefilm and EEG recordings of them are presented. Analysis of these suggests that the hand movements, in this particular patient, were part of the seizure pattern.

Clinical EEGs from six patients are studied to show the usefulness of computer calculated ratios in lateralizing focal abnormalities. Ratios related to electrode recording position were calculated, using all channels of the normal clinical EEG recording. This study of six patients was part of a larger study of which these six were the only ones to show focal lesions. The results suggest that these objective measures from the EEG should be useful to cliniciana as an aid in the diagnosis of focal lesions.

An all-electronic method is described whereby minute electrical responses in brain recordings can be measured reliably even in the presence of large noise-to-signal ratios. The signal in this instance is a discrete response to a controlled stimulus. The ``noise'' is not white noise in this case, but the normal rhythmic activity of the electroencephalogram (EEG) which is randomly related to the signal. The responses are usually invisible in the EEG recording but they can be detected by means of averaging and storing techniques. The system makes use of gated integrators and floating-grid vacuum-tube voltmeters.

In order to record directly the period (viz. frequency) of alpha-rhythm of human EEGs, the authors have designed an apparatus consisting of electrotachometric units, which were inserted into the circuit of a routine EEG recording machine. By this means, it is easily possible to measure the frequency of alpharhythm quantitatively and qualitatively in absolute values. Preliminarily technical notes on this apparatus and several findings obtained from normal subjects by practical application were reported in this paper.

An experiment was designed to test hypothesis that suppression of amplitude of alpha rhythm provides a reliable objective index of visual imagery under two conditions of problem solution, namely, solving a ‘verbal’ problem and solving a ‘visual’ problem. Sixty-nine subjects were examined in following way: first, preliminary ‘runs’ were made with each subject for EEG recording under conditions (a) eyes-shut, relaxed and (b) eyes-open, relaxed, yielding base lines for comparison; secondly, EEG recordings were made under conditions (a) concurrently with solution of ‘verbal-reasoning’ problem and (b) concurrently with solution of ‘visual-reasoning’ problem. It was found that, although visual content of awareness during two problem-solution periods as reported by subjects differed markedly, suppression of alpha rhythms occurred under both conditions, amplitudes in both cases falling about half-way between two values recorded in preliminary ‘runs’. There was, however, a greater suppression effect in case of the’ visual’ problem. results, as a whole, therefore, suggest that hypothesis is not tenable, since ‘imagery’ appears to be only one of many factors that may produce suppression effects. This conclusion is supported by a breakdown of subject sample, according to reports of imagery on verbal problem, which showed that there was no difference in basic patterns as between those who visualized verbal problem and those who did not. Repeated solution in a check period, immediately following solution period, made no significant difference to suppression of alpha in verbal problem, but did so in visual problem. suggested interpretation follows Fisher (1916) in regarding this as a possible decrease in image content.

Seizures induced electrically in the inferotemporal cortex, as monitored by EEG recording, produced retrograde amnestic effects upon the development of conditioned suppression of lever-pressing to a visual CS paired with shock US but not to a similarly paired auditory CS. The afterdischarges, which propagated to the amygdala among other structures, appeared to interfere with the association of the visual CS with the noxious US without blocking retention of information about the noxious US itself. By contrast, seizures induced in the amygdala, which showed a more variable pattern of propagation to inferotemporal cortex, produced no apparent retrograde amnestic effects.

Blinks and vertical eye movements were studied as artifacts of EEG recording. The electro-oculogram (EOG) and vertex vs joined mastoids EEG were recorded in 13 college-aged subjects. Subjects were asked to blink “normally, without excessive effort,” and move their eyes through vertical visual arcs of 5°, 10°, 20°, 30°, and 60°. The ratio EEG/EOG, the fraction of the EOG potential transmitting to the scalp EEG electrode as artifact, was calculated for potentials generated during both blinks and eye movement. Vertical eye movement scalp EEG artifact was a constant percentage of the vertical eye movement EOG across visual arcs of 10° to 60°. Mean percentage eye blink EEG artifact (9.3%) was significantly (p < .001) less than the mean percentage vertical eye movement artifact (13.9%). Thus, blink and vertical eye movement artifact fields are quantitatively different in terms of their transmission to the scalp (Cz) EEG electrode. Subtraction of a single subject specific percentage of the EOG from the EEG would correct for either artifact source, but different subtraction percentages must be used for each.

The method of intraventricular EEG recording as developed by the author is presented: suboccipital puncture is made with a special needle which consists of two barrels, one inside the other, each of which has a longitudinal slit on opposite sides. After the bundle of electrodes, which is composed of 2–8 insulated silver wires (diameter of each wire 0.065–0.12 mm) is inserted, it glides forward along the dorsal plane of the medulla and, by its medial position, reaches the ventricular system through the foramen of Magendi. Out of a total of 22 punctures the ratio of successful to unsuccessful attainment of the ventricular system was 1:3. The same insertion of the electrodes was performed on four dogs. Histopathological examinations showed neither damage nor later reactions of the brain tissue. A case of Jacksonian epilepsy is presented in which, during an attack, theta activity could be recorded in the brain-stem area. The hope is expressed that the method here presented will permit new insight into the electrical activity of the brain-stem area.

Afterdischarges induced bilaterally in inferotemporal (IT) cortex, as monitored by EEG recording, impaired subsequent performance on perceptually difficult visual discriminations of dimensionalized stimuli during the period of abnormal IT EEG activity. The defect seemed to relate to control levels of performance and varied somewhat in persistence. Such seizures also markedly impaired reversals of a visual pattern discrimination. Based upon information about propagation patterns of the afterdischarges, it was suggested that afterdischarges induced in IT cortex produce some form of visual perceptual or attentional disorder and an associative disorder in the encoding of visual stimuli with respect to reward contingencies.

Summary. An optical method for frequency analysis, suitable for EEG recordings is described. The analysis is continuous both with regard to frequency and time coordinates. Since photographic procedures form part of the method, simultaneous EEG recording and analysis are not possible. A large number of simultaneous records can be analysed. Phase relations between different leads are calculable. A “repeating of pattern”-analysis may be obtained.

One-hundred seventy-eight cases, presenting wave and spike activity in standard EEG recording, were reviewed with respect to type or types of seizures. The wave and spike activity was descriptively subclassified on the basis of frequency per sec. of the paroxysmal discharge. It was found that: 1. 1. (a) Only 16 per cent had seizures classified as the petit mal triad, without seizures of other types. This is in close agreement with the 1941 report of Jasper and Kershman; (b) twenty-two and a half per cent had seizures classified as grand mal (only); (c) seventy per cent of the total group had seizures of the petit mal triad, plus other seizures types (and, conversely, 30 per cent had no seizures classified as the petit mal triad). This is in closer agreement with the findings of Gibbs et al. than with those of Jasper and Kershman. 2. 2. Considering “variants” of the wave and spike as being slower or faster than the “classical” three per sec. paroxysmal pattern, or admixed with it, such variants were more evident in the clinical grand mal than the clinical petit mal triad group. Particularly, most cases exhibiting the fast 4 per sec. variant had grand mal epilepsy. Rarely did these cases exhibit petit mal symptomatology. 3. 3. Presumed organic etiology of seizures was found infrequently in those cases showing the classical 3 per sec. pattern. However, when slow variants are considered, the incidence of idiopathic and presumed organic etiology was equal; these data do not indicate that organic etiology can be accurately predicted from the fact that a slow wave and spike appears in the EEG. Idiopathic epilepsy does seem to be related to the 3 per sec. paroxysmal wave and spike.

1. 1. An analysis of variance of certain EEG indices was performed on 27 healthy subjects. 2. 2. Simple visual procedures were performed by each subject in order to maintain a constant level of attention. It was found that no particular procedure or alteration of the order of presentation had a greater stabilizing effect. 3. 3. Differences of age and sex had no effect on the variances of the EEG indices studied, nor did it seem necessary to allow for the effects of menstruation on the EEG. 4. 4. Marked fluctuation during the course of a single EEG recording usually foretold marked fluctuation from one day to the next. 5. 5. As the data did not conform to a normal distribution it was difficult to express EEG index variability in an orthodox manner. An ad hoc technique is described for this problem.

Prevalence of the cephalic skin potential (CSP) artifact was studied in 21 Ss during EEG recording of the Contingent Negative Variation (CNV), averaged evoked response (AER), and verbal free association test. Skin potential response and electro-oculogram (EOG) were also recorded. Subdermal pin electrodes and local anesthesia infusion were employed to eliminate the CSP artifact in the EEG. Results indicated that EEG recorded from subdermal pin electrodes or from locally anesthetized scalp was free of CSP artifact. The EEG recorded from subdermal pin electrodes demonstrated spontaneous potential shifts but appeared adequate for EEG recording of the CNV or the AER. Significant CSP artifact was demonstrated in the EEG of 10 of 21 Ss, both evoked by stimuli (10 Ss) and spontaneous (3 Ss). CSP artifact significantly increased CNV amplitude. CSP artifact significantly increased the AER late positive wave (P3) to infrequent tones. Studies of CNV and AER can be confounded by CSP artifact. Above techniques appear promising for recording EEG free of CSP artifact.

A simple eye movement monitoring system for use in clinical EEG is described, which does not involve recording of the corneo-retinal potential difference. The system, based upon the mechanical detection of movement by use of a pressure transducer, is shown to be sensitive to the smallest movements of the eye or lid, which cause artefact in EEG recording. The simplicity of both the system and its application makes it a reliable one for use by EEG technicians in clinical EEG.

In the previous papers, this author has briefly reported on a correlation between behavioral states and the EEG in the enucleated young chick (Ookawa, 1969, 1970). It would be of interest to know whether the blind bird will grow up or not, so that one of the blinded birds was brought up until about 7 months of age and comparing with an intact control. This paper will describe the relation between the EEG and behavior in a blind cockerel. Furthermore, the state of the comb and testes of this bird was noted. In this case, both eyes of a male White Leghorn chick were removed on 14th to 15th day after hatching. The second eye was removed 1 day after the first. Records were taken both on 49th day and on 182nd day after the enucleation. The EEG recording techniques have been described fully in the earlier papers (Ookawa and…

It seems to us that there has not been a paper about Average Reference Electrode Method since the publication by Goldman' and Offner2 in 1950. From the results mentioned above, comparing with MP, characteristics of Ave. R. are:(1) In many cases, localized EEG abnormality was more clearly represented.(2) As to non-focal EEG abnormality, records which are very useful to diagnosis can be obtained, except a extremely low amplitude brain potential.(3) Since Ave. R. did not use ear lobe as reference, the electrical activity in temporal region was easily observed, and artifact by abnormal electrical activity did not take place.(4) Physiological artifact was difficult to mix. On the other hand, alternative current artifact tended to slightly mix on some occasions. Since amplitude was represented lowerly than the case in which ear lobe was used as reference electrode, it is not suitable to record low amplitude.From those results, it can be emphasized that Ave. R. is much more helpful for localizing space taking lesion of the brain than MP. And we convince that accuracy of EEG diagnosis can be increased by using Ave. R.

When an EEG recording is to be taken in a conventional manner, the choice of method depends to a large extent on the nature of the electroencephalographic problem and on the personal preference of the investigator. However, when EEG data are to be stored in an electrical form for subsequent analysis, the bipolar method of derivation would appear to have some practical advantages over both the unipolar and average reference methods. For a given array of n electrodes and (n−1) channels of amplification, the same basic information can be obtained by the use of any of the methods discussed.

A method is described for minimizing cardiac potential by balancing the voltage between two points on opposite sides of the heart. Advantage can be taken of the cancellation thus obtained to utilize the base of the neck as a common reference for EEG recording. In the interpretation of electroencephalograms made with a common reference electrode (“monopolar” recording) account must be taken of the fact that activity at the reference electrode produces “universal” patterns, and that only differences are ascribable to the exploring electrodes. A relatively quiet reference facilitates interpretation, and the balanced reference electrode recommended here is relatively quiet even when focal abnormality occurs in the inferior portions of the brain. Petit mal discharges and true temporal spikes usually spread only slightly to the ears. In contrast, the anterior temporal spike discharge is commonly picked up with high voltage from the ear on the affected side and a temporal slow-wave focus also usually spreads to the ipsilateral ear.

Summary A series of experiments has been done to assess the effects of low-level, low-frequency electric fields on the behavior and EEG of monkeys. Three monkeys were implanted with subcortical and cortical EEG electrodes and trained to press a panel on a fixed interval-limited hold schedule. The monkeys were rewarded for pressing the panel once every 5 sec within a 2.5 sec enable period. After the animals were performing well, they were tested under low-level electric fields (2.8 V p-p); the voltage was applied to 2 large metal plates 40 cm apart so that the monkey's head was completely within the field. Fields frequency was set at 7 or 10 c/sec within the range of typical EEG recording (0-33 c/sec). Four hour daily tests of fields-on were randomly interspersed with 4 h runs with field-off. Under the 7 c/sec fields, the monkeys showed a significantly faster interresponse time in 5 of 6 experiments. Mean differences between fields-on and fields-off were 0.4 sec or greater. The 10 c/sec fields did not produce a reliable effect on behavior. Analysis of the EEG data showed a relative peak in power at the frequency of the fields (10 c/sec and 7 c/sec) for the hippocampus in all 3 monkeys. Similar peaks were seen less consistently in the amygdala and the centre median.

The more frequent use of standardized multiple contact depth probes has increased the sites for EEG recording.

Dural, orbital, and depth electrodes were chronically implanted in five monkeys, and 473 brain stem stimulations were given during 80 hr of EEG recording on 14 nights of sleep. Although occasional rapid eye movement sleep periods occurred soon after stimulations, no parameters or loci of stimulation consistently provoked REMPs, occurred. Statistical analyses did not demonstrate any precipitation of REMPs, and it is probable that only spontaneous REMPs occurred. When compared with previous reports, these findings emphasize the importance of statistical controls in neurophysiological studies of REMP origin.

There are many studies on the action of drugs on the central nervous system by means of EEG recording. But little has been made using EEG of an embryo. If drugs are applied to an embryo in which the nerve cells are still in process of maturation in the central nervous system, the changes caused in EEG may provide useful clues for elucidating the mode of action of the drugs. The present study was conducted following this idea. The development of the spontaneous electrical activity in the brain of chick embryos were studied in detail, and then the effects of several drugs were examined.

A 15-year-old girl with temporal lobe epilepsy was tested daily on a continuous choice response task, with simultaneous EEG recording, in order to examine the effects of two types of bioelectric activity: generalised spike-wave (SW) and theta-alpha background (B). The child was required to press keys corresponding with random digits presented serially upon a screen. The digits were selected from ensemble sizes of 2, 4 or 8 and could be presented either at a rate determined by the experimenter (the paced condition) or at a rate determined by the child's own speed of response (the unpaced condition). Performance was measured under three conditions of pacing (1 digit per sec, 1 per 2 sec and 1 per 4 sec) and compared with the unpaced condition in relation to S-W and B activity. The child's unpaced rate of work was found to approximate to the intermediate paced condition, viz. 1 digit per 2 sec. Reaction times were significantly increased during S-W activity under both paced and unpaced conditions. Under paced conditions, significantly more errors were made during S-W than during B activity, but under unpaced conditions, comparatively few errors were made during S-W. The following interpretation of the data was adduced. On a paced task, reaction times which approach the inter-stimulus interval necessitate the subject storing information about one stimulus whilst a response is made to another. Where several successive reaction times are of increased duration, the load upon immediate memory plus the processing load will eventually exceed the subject's information-handling capacity and errors will be made. Any source of interference whose effect is to increase reaction time, will cause an increase in errors by increasing the probability that stimuli and responses overlap. It was thus hypothesised that the relationship between probability of error ( P E ) and reaction time ( RT ) would be essentially similar for the two types of EEG activity: S-W would merely propagate a shift in the RT distribution. An analysis of P E in relation to RT was carried out for all stimulus-response pairs (from the 12 paced data), and for responses to "next-but-one" and "next-but-two" stimuli. The curves for S-W and B did not differ significantly from each other. This suggests that the causes of errors made on a paced task during S-W may not be qualitatively different from the causes of errors made during B activity. The child's poor performance on the paced task is a logical and necessary consequence of her slowness during SW activity. Clearly, unpaced performance is less vulnerable to the effects of paroxysmal disturbance than performance which is paced at an equivalent rate.

One of the penalties of high rejection ratio push-pull amplifiers of the type used in EEG work is that under certain situations the recording will occur in one channel with only one electrode in place. This recording may resemble the ordinary EEG record to such an extent that the operator is unaware of the break in continuity of the electrode in question. In usual situations where there is moderate amount of ambient 60 cycle airbone interference, such as a break in electrode continuity shows this promptly by the artifact of 60 cycle wave superimposed on the tracing. There are times of the day in the average laboratory when 60 cycle interference is at a minimum and in these laboratories with excellent shielding it might be at a minimum. In such situations one never knows when the electrode continuity have been defective, and errors in location and interpretation may become critical. Efforts at Relationship of the height of pen deflection with the circuit in place to resistance between the two electrodes being studied.

SUMMARY Our study was designed to test the hypothesis that the epileptiform activity of chronically isolated cortex is due to supersensitivity to endogenous acetylcholine. Eserine and atropine were administered systemically to cats with chronically isolated occipital cortex and implanted EEG recording electrodes. Eserine usually diminished the amplitude and increased the duration of the epileptiform EEG discharges in the isolated area. These changes were antagonized by a subsequent administration of atropine. Atropine, without a preceding application of eserine, did not abolish the paroxysmal discharges but tended to obscure them by inducing slow waves in the island. In contrast, diazepam was very effective in abolishing the paroxysmal discharges. The effects of both eserine and atropine on the paroxysmal activity of the island occurred only at those dosage levels that produced changes in the EEG from other areas of the brain. These results do not support the hypothesis investigated.

SUMMARY 1 Thirty-five epileptic patients with co-existent focal and bilaterally synchronous, diffuse paroxysmal electrographic discharges are evaluated and their electrographic features are correlated with clinico-pathological data. The findings are compared with information derived from a control group of 67 patients with clearly defined and uncomplicated focal epileptiform discharges. 2 Statistically significant differences were found between the control and study groups in regard to the following variables. (i). The mean age of onset of seizures and age at the time of EEG recording of the study group was lower and the mean interval of time between the two events was shorter. The age distributions within the two groups were different in a similar manner. (ii). A greater number of patients with frontal foci and fewer with temporal foci were found in the study group. (iii). Excessively slow background rhythms occurred more frequently in the study group. (iv). Partial, complex seizures with or without secondary generalization were more common in the control group. (v). Focal or lateralizing neurologic signs were more common in the study group. (vi). Non-electrographic evidence of cerebral abnormality extending beyond the temporal lobe in patients with temporal foci was more common in the study group. 3 When the effect of age was minimized by age matching the differences of the variables outlined above remained significant. 4 Patients with electrographic foci consistent with the clinical seizure pattern, abnormal findings on neurological examination and contrast radiography had electro-graphic evidence suggesting a lesion in areas other than the frontal region. 5 The localizing value of foci in the frontal regions, when associated with bilaterally synchronous discharges, would appear to be questionable: such foci were generally not supported and, in some cases, were actually contradicted by the various clinical data. RESUME 1 Trente-cinq malades epileptiques qui presentent des paroxysmes EEGraphiques focalises aussi bien que generalises (bilateraux synchrones et diffuses) sont etudies, les donnees de l'EEG etant correlees avec le tableau clinico-pathologique. Les resultats sont compares avec ceux obtenus dans un groupe (controle) de soixante-sept epileptiques dont l'EEG presente seulement des decharges epileptiformes focales. 2 Des differences statistiquement significatives entre les deux groupes ont ete trouvees pour les facteurs suivants. (i). L'âge moyen du debut des crises et l'âge moyen au moment du premier enregistrement EEG sont plus bas et l'intervalle de temps moyen entre ces deux evenements est plus court dans le groupe etudie que dans le groupe controle. Les distributions d'âge dans les deux groupes montrent une difference semblable. (ii). Dans le groupe etudie on trouve un plus grand nombre de malades avec un foyer frontal et moins de cas avec un foyer temporal. (iii). Les rythmes de base anormalement lents sont observes plus frequemment dans le groupe etudie. (iv). Les crises partielles a semeiologie elaboree sont plus communes dans le groupe de controle. (v). Les signes neurologiques focaux ou lateralises sont plus communs dans le groupe etudie. (vi). Une evidence non-electroencephalographique d'atteinte cerebrale extra-temporale chez des malades avec un foyer EEG temporal est plus commune dans le groupe etudie. 3 La signification statistique de ces differences persiste meme apres que le role du facteur âge ait ete minimise par une methode d'egalisation des divers sous-groupes par rapport a l'âge. 4 Chez les malades qui presentent un foyer EEG compatible avec leur type de crise clinique, leur semeiologie neurologique et les donnees de leur examen radiologique de contraste, les constatations EEG suggerent la presence d'une lesion en dehors de la region frontale. 5 La valeur localisatrice des foyers EEG dans les regions frontales, quand ils sont associes a des decharges bilaterales et synchrones, parait douteuse: ces foyers sont rarement confirmes par les differentes donnees cliniques et, parfois, sont actuellement en conflit avec ces donnees.

the proper stereotaxic instrument for thespecies, (2) some degree of surgical sophistication,(3) sterile surgical conditions, (4) an accurate atlas of thespecies' brain and cranial bones, and (5) an anestheticduring the recording session. One of the standardtechniques used to circumvent some of these problems isto use stainless steel screw electrodes that are screwedinto the skull and held by dental acrylic. However, theparakeet skull is extremely thin and fragile-asis the casewith most small birds. This precluded the use of screwelectrodes and prompted the development of alternativeand somewhat simpler methods for attaching electrodesto the parakeet. These procedures may be ofparticularvalue in view of the recent interest in avian sleepprocesses and sensory processes (Van Twyver & Allison,1972; Dooling & Saunders. 1974).The skin covering the underside of the lower beak inthe parakeet is thin. This enables one to insert a 30-ga,Kynar-coated solid wire through the underside of themandible into the oral cavity and wrap it tightly aroundthe lateral portion of the lower beak. (See lower half ofFigure 1.) The length of wire wrapped around the beakis stripped to permit good electrical contact. Thisprocedure is applied to both sides of the parakeet'sbeakto provide both a ground and a reference electrode. Theinsulated portions of these beak electrode wires are ledto the back of the bird'shead, pulled taut, and threadedthrough the side holes ofa standard three-poletransistorplug as indicated in the upper half ofFigure I.A number of types of skull electrodes have been usedin combination with these beak electrodes. Theseinclude a 2 mm in diam coil of silver wire or a disk ofsilver foil, dental screws, and inverted wire nails.Regardless of the electrode type, it is attached to theskull using the following general procedures.The bird's head is cleaned with alcohol, and anincision is made along the medial axis of the scalpextending from the cere about 2 ern posteriorly. Theskin is pulled back, the skull surface wiped clean with acotton swab, and the electrode cemented to the skullwith conventional dental acrylic. The electrode lead isthen led to the third pole of the transistor plug. The

This investigation of the relationship between occipital EEG and type of imagery differed from most previous studies in that objective performance and rating measures were used to assess individual differences in visual imagery ability independently of performance on tasks during EEG recording, and in its use of a double-blind procedure. Significant results were obtained which appear contrary to those reported in previous EEG-imagery investigations. The conflicting reports may reflect the influence of methodological variables.

Across a 24-h period in a confined EEG recording setting, the length of successive sleep and waking episodes in the rat show no direct relationship. These data imply a limitation to a hypothesis of sleep as a simple energy restoration or storage period.

The unilateral appearance of low voltage fast waves contralateral to the open or attentive eye has been reported in the chicken (Peters, et al., 1965; Ookawa, 1967; Ookawa and Takagi, 1968) and in the Japanese quail (Ookawa and Kadono, 1968). This means that the optic nerve of the bird undergoes complete crossing (Kappers et al., 1960; Cowan et al., 1961). The purpose of the present paper is to explore the effect of the unilateral optic enucleation on the electroencephalogram (EEG) in chicks. Eight male White Leghorn chicks, aged between 13 and 55 days, weighing from 85 to 560 grams were used. The EEG recording techniques have been described fully in an earlier paper (Ookawa and Takagi, 1968). All birds tested were recorded by the electroretinogram (ERG) before the enucleation, and they showed normal form (Ookawa et al., unpublished data). In most birds, the unilateral optic enucleation (left eyeball) was performed…

A battery-powered pulse generator of uncomplicated circuit arrangement has the advantage of being easily constructed and, also, can be positioned in a confined testing area in order to simulate the low-amplitude signals of a S. It may be especially useful for EEG recording systems for small animals. In this way, the complete recording system, including connecting cables, can be calibrated, and its performance readily assessed with respect to frequency response and to susceptibility to noise pickup.

The development of a stable hypodermic cathode follower has been accomplished for drug administration and concurrent EEG recording. The cathode follower is characterized by grid currents well below 10-11 and an input impedance of approximately 100 meg. ohms. The hypodermic cathode follower is designed to be used in conjunction with a stereotaxic apparatus, thus making it possible to apply drugs to highly localized areas in the vertebrate brain. Simultaneous drug administration and EEG recording are the main features of the instrument and as such offer wide application for neuropharmacology investigations.

A simply constructed and arranged apparatus and technique are described for the measurement of the finger-withdrawal response which have certain advantages over those previously reported. A pointer attached to the finger interrupts a beam of light as it rises and falls without impeding the finger's movement. Pulses from photoelectric cells and the CS and UCS are simultaneously fed into the multi-channels of an electroencephalograph, producing a record of the amplitude of the response and the various time relations.

Monkeys were trained on a behavioral task and instrumented with chronic EEG recording electrodes and systemic arterial catheters for blood pressure measurement. They were then exposed to a 2500-rad pulse of mixed gamma-neutron radiation. Spectral analysis of the cortical electroencephalogram revealed changes in both frequency content and amplitude of the EEG related to periods of behavioral incapacitation. Simultaneous measurements of systemic blood pressure did not show any close relationships with EEG or behavioral changes.

A list of ten one-syllable nouns was repeated as many times as possible to nine Ss during an eight-hour sleep period. A continuous EEG recording during the presentation of the training material was used to determine the sleep level at that time. The stimulus material was turned off as soon as cyclical activity within the alpha range was observed. The experimental Ss did not do significantly better than the control group in selecting the words on the training list of 50 words. Nor did they choose the training words any more frequently than they chose an equivalent list of untrained words. There was some indication that words presented during a period of deep drowsiness can be retained, but this was significant only when the S was also able to give an immediate response to the material being presented. The effects of sleep level and the importance of continuous EEG monitoring while presenting the training material are discussed in their relation to recall. It is concluded that material presented a number of times during sleep (using an EEG criterion) cannot be subsequently recalled. (Author)