High-amplitude Slow Waves Research Articles

The problem of animal models for psychiatric conditions, as illustrated by the immobilization reaction (catalepsy) in the rat (author's transl)

According to Venables the span of psychotic processes extends from a low level of arousal with an increased reactivity toward sensory stimuli to a high level of arousal with a reduced reactivity toward sensory stimuli. The level of arousal and the degree of reactivity, or breadth of attention, are apparently controlled by a regulatory mechanism which increases the threshold for sensory input in threatening situations. Any factor producing an electroencephalographic arousal reaction leads to a narrowing of attention. Underestimation of the size of a given object is an expression of such a reduction in the span of attention. Various authors have found a reduction in size-constancy in schizophrenics, in particular in patients exhibiting a merkedly reduced contact with their environment. A model is described in which a strong sensory stimulus induces a state of immobilization in rats treated with a low dose of morphine. Electroencephalographic recordings show that the initial state of arousal induced by peripheral stimulation is replaced by high-amplitude slow-waves and spindles as the state of immobilization develops. The current results suggest that the sensory stimulation leads to excitation of the ascending reticular formation and via the Centrum medianum and the Nucleus centralis, to activation of the striatal system, resulting in catalepsy. It would thus appear that the reticular formation and the striatum alternate in excercising a control function over the state of arousal. This would be a logical way of limiting over-reaction, which can be demonstrated most simply on the motoric response. It seems justified, therefore, to assume a relationship between catatonic stupor and the immobilization induced by stimulation. This concept is supported by the observation that of all the compounds investigated only clozapine is capable of inhibiting the immobilization in the rat model. Clozapine is a powerful antipsychotic agent with a pronounced inhibitory effect both on the reticular arousal reaction and on the schizophrenic catatonia.

Genotype-dependent electroencephalographic, behavioral and analgesic correlates of morphine: An analysis in normal mice and in mice with septal lesions

Electroencephalographic, locomotor, and analgesic responses were studied in two strains of inbred mice (C57BL/6J and DBA/2J) implanted with epidural cortical electrodes. For the C57 strain the injection of morphine produced a sharp increase of locomotor activity and the EEG showed high amplitude slow waves similar to sleep, while the same strain was less sensitive to the analgesic effects of the opiate. For the DBA strain the locomotor activity was not enhanced following morphine and there was no alteration of the EEG pattern, while a pronounced analgesic response was evident in this strain. Septal lesions antagonized morphine analgesia in both strains while locomotor and electroencephalographic responses were unaffected in C57 mice. The findings suggest the following. o (1) The electroencephalographic responses to morphine are genetically determined. (2) The septal area is implicated in morphine-induced analgesia but not in the locomotor responses or in the brain electrical responses to the opiate. (3) The electroencephalographic alterations induced by morphine do not seem to be directly connected with the analgesic properties of the drug.

Effect of hypoglycemia induced by insulin on the depth EEG in the chicken

Changes in the depth EEG activity resulting from hypoglycemia were demonstrated in hypnotized chickens. Hypoglycemia was induced by insulin injection. In waking birds, no distinguishable changes were clicited by hypoglycemia in the EEG activity of areas such as the surface, nucleus rotundus, anterior hypothalamus, and ektostriatum (EKT). However, in the EKT, the characteristic high-amplitude, lowfrequency EEG waves of the hypnotized chicken were replaced by low amplitude fast waves when the birds were hypoglycemic, and these low amplitude fast waves were replaced by high amplitude slow waves in hypnotized birds when plasma glucose levels were raised to the normal levels by glucose injection. The EEG of other areas studied was not affected by hypoglycemia even in the hypnotic state. These results indicate that the EKT is associated with plasma glucose changes in chickens.

Epileptiform seizures in domestic fowl. II. Intermittent light stimulation and the electroencephalogram.

The effects of intermittent light stimulation on chickens genetically predisposed to generalized convulsions are described. Epileptic chickens (homozygous recessive) convulse when exposed to intermittent light stimulation at 10–25 flashes per second, whereas normal (homozygous dominant) and carrier (heterozygous) hatch mates are not affected. The resting electroencephalogram (EEG) of epileptic chickens is markedly different from that of their nonconvulsive hatch mates, being characterized by high-amplitude slow waves with periodic spikes and spike–wave complexes. Prior to the onset of light-induced seizures, high-voltage spikes, at the same frequency as the stimulus, appear in all leads of the epileptic EEG. For a short time after a convulsion the EEG of epileptic chickens remains flattened, suggesting decreased electrical activity similar to the postictal depression seen in the EEG of human epileptics.

Immediate effects of total visual deafferentation on single unit activity in the visual cortex of freely behaving cats. I. Tonic excitability changes.

Effects of total visual deafferentation (eye enucleation) on maintained and evoked single unit activity in the cat visual cortex (VC) were studied. Three recording states were distinguished: resting arousal (RA), light sleep (LS) and deep sleep (DS). Two characteristic discharge patterns were noted in deafferented units. One was characterized by rhythmic synchronous firing of several units which was accompanied by high-amplitude slow wave bursts in the EEG (6–8/sec) during RA. Another was the abrupt occurrence of long-lasting spike trains which appeared unpredictively irrespective of vigilance levels. The overall discharge rate tended to decrease after deafferentation in both RA and DS while in LS tended to increase slightly. Three types of VC units were distinguished, as in intact ones, on the basis of the correlation function between the mean discharge rate in RA and its changes in LS. The relative incidence for the three types were different in the deafferented VC. The largest group (47.2%) had a sequence of mean discharge rate DS<RA<LS, while in intact animals the largest group (44.3%) had a sequence LS<RA<DS. For deafferented VC units the gradation of unit responsiveness to geniculate stimulation in the three states also paralleled that of the maintained discharge rate as in controls. A significant correlation between the mean discharge rate and the response latency to geniculate stimulation was not apparent following deafferentation due to loss of units with short latency responses and at the same time moderate discharge rates.

Immediate effects of total visual deafferentation on single unit activity in the visual cortex of freely behaving cats. II. Rhythmic EEG bursts and PGO waves.

Temporal correlations between single unit activity and phasic EEG waves in wakefulness and deep (REM) sleep were studied in the visual cortex (VC) of totally visually deafferented cats. In wakefulness single unit activity was either enhanced (41 units, 42.3%), suppressed (10 units, 10.3%) or unchanged (46 units, 47.4%) during high-amplitude slow wave bursts (6–8/sec) in the background EEG. The nature of “rhythmic” firing was common for both types of units which either increased or decreased discharge rates during this slow wave bursts. This rhythmic short-lasting synchronization in wakefulness was interpreted as an evidence of enhanced, synchronization in deafferented VC neurons. In deep sleep various relationships were observed between single unit activity and ponto-geniculo-occipital (PGO) waves following deafferentation including both excitatory (25 units, 29.7%) and, in contrast to intact animals, inhibitory (17 units, 20.2%) correlations. The remaining half (42 of 84 units) showed no obvious correlation with PGO waves. Six of 25 units which were activated by PGO waves started to fire immediately after the onset of PGO waves. Eleven of 17 suppressed units stopped to fire immediately after the onset of PGO waves. These units with close excitatory or inhibitory phase relation to PGO waves had extremely high discharge rates. The contrasting relationship of striate and nonstriate units to PGO waves seen in the intact VC waned after total visual deafferentation. Possible mechanisms for inhibitory influences of PGO waves on deafferented VC units were discussed.

Single cell activity in the ventral lateral thalamus of the unanesthetized monkey

Spontaneous single cell activity was studied in the ventrolateral region of the thalamus in the unanesthetized monkey. The method used allowed recording in stereotaxic conditions as well as behavioral observations. Recorded cells were localized on histological sections. Patterns of discharge were analyzed and their relationship to the state of vigilance, posture, and movements were examined. Phasic changes in neuron firing patterns were shown to have a clear-cut behavioral counterpart. During alertness, with or without movements, the thalamic cells displayed a sustained but irregular firing associated with a desynchronized EEG. During states of relaxation and immobility, the cells tended to fire in high frequency bursts associated with high amplitude slow waves on the EEG. This burst activity was present only in the absence of movement. In the ventral part of the ventrolateral nucleus most of the cells could be activated by various natural stimuli, particularly those which provoked a quick muscle stretch. In general, the firing frequency of the cells was much greater if the animal made a spontaneous movement than if the same movement was made passively. On the basis of the reported findings it is suggested that ventrolateral neurons play an important role in the general adjustment of posture preliminary to voluntary movement.

Development of the Sleep EEG in Normal Infants During the First Year of Life

SummaryIn order to aquire a comprehensive knowledge of the normal development of infant EEG, in particular its intra‐ and interindividual variations, a selected material of 29 full term healthy infants was studied longitudinally from birth to 1 year of age with EEG, neuropediatrie examinations and developmental tests. The program contained 2 examinations during the first 7 days, one at three weeks, and from 2 months an examination every second month. At follow‐up examinations at the age of 31/2–6 years all children were normally developed and without signs of neurological disease. The waking EEG:s have been described earlier. The present report gives an account of the neonatal records and the sleep records from the first year.The essential features of the “typical” or “ideal” neonatal EEG are known from a rich literature. In the present paper special interest has been paid to EEG‐components which have been designated in earlier works as “deviations” or “variations” of uncertain significance, from the “ideal” EEG.Paroxysmal activity was very frequent in the neonatal period. It appeared as typical, usually multifocal, sharp waves, but also in an atypical, rather blunt “sharp” wave form (the latter type of activity was designated as “questionably paroxysmal”). Bilaterally synchronous paroxysmal activity of diffuse distribution was infrequent. Paroxysmal activity was seen more often during sleep than in the waking state and more frequently in regular than in irregular sleep. The incidence of clearly paroxysmal activity amounted in the age group 4—7 days to 57.7%; if “questionably paroxysmal” records were included, the incidence rose to 69.2%. Only 4 of the 29 infants were consistently free from paroxysmal activity during their first 3 weeks of life. It is concluded, that paroxysmal activity of those types described in detail in the paper, must be regarded as a normal element in the neonatal EEG.Considerable asymmetries of slow activity were seen in the episodes of “tracé alternant”, usually, however, with shifting side predominance from one episode to the other.During the next few months the incidence of paroxysmal activity decreased rapidly and for the future such activity was present only occasionally. Towards the end of the first year, however, paroxysmal activity of an essentially new type appeared in a few records. In these cases diffuse and bilaterally synchronous bursts of high amplitude slow waves with spike components occurred.Asymmetries of low frequency activity, usually in fronto‐temporal leads, were rather common. Only in two records was the asymmetry persistent throughout the sleep record. In 13 other records the side difference was transitory.Sleep spindles displayed a considerable variability between individuals in respect to abundance, distribution over the cortex and synchrony between hemispheres.The results obtained from this group of strictly normal infants, all of whom were re‐examined and found normal after several years, will facilitate a more reliable evaluation of EEG:s from infants suspect for cerebral abnormalities. Ultimately it will also be possible to evaluate the EEG of neonates and small infants as an instrument for diagnosis and prognosis of cerebral dysfunction.

Subacute sclerosing panencephalitis.

records takenearly intheillness maynotshowperiodic complexes butthese typically occur later. Theinterval between thebilateral highamplitude slowwave complexes diminishes asthedisease progresses. Therecord maybemoreabnormal ononeside than theotherwithsomeclinical andradiological features suggesting aspace-occupying lesion. Finally theclinical diagnosis maybeconfirmed bytaking a brain biopsy during life. Theaetiology ofSSPEhasremained obscure until recently andaconference washeld in1967toreview theevidence foraviral aetiology ofthedisease (Sever & Zeman, 1968). Wemaynowconsider the contributions oflight andelectron microscopy, virology andimmunology towards theelucidation of oftheaetiology ofthis disease. Microscopy Theviral aetiology ofSSPEwassuggested bythe finding ofCowdry type Anuclear inclusions inbrain cells (Dawson, 1933). Manyearly investigators assumed that theCowdry type Ainclusions indicated infection withherpes simplex virus butitisnow knownthatthemeasles-distemper-rinderpest

Electroencephalogram in ruminants. 3. Effect of experimental hyperammonemia on the REG in goats

Electroencephalograms (EEGs) were recorded bipolarly from the frontal andparietal cortical regions in 7 female goats. Silver balls (1 mm in diameter) were usedas electrodes and implanted chronically on the cerebral dura mater through a small holeof the skull. Experiments were carried out to clarify the effect of experimental hyper-ammonemia on the EEG in goats.l. When ammonium chloride (aqueous solution) was injected in an amount of0.5 milli-molecules (ml) per kg of body weight into the anterior vena cava through apolyethylene cannula, the blood ammonia concentration increased rapidly. On theEEG there appeared high-amplitude slow waves (2O0s4O0pV, 4x5 c/s) at a durationof 2 to 3 seconds and an interval of 10 to 20 seconds. This pattern was induced when theblood ammonia concentration exceeded 500pg per TOO ml of blood. There was anincrease in duration and frequerncy of appearance of this pattern with an increase indose of ammonia.2.. When ammonium chloride was infused into the anterior vena cava at a rateof 0.033 mlVI per minute per kg of body weight for 60 minutes, the blood ammoniaconcentration increased gradually, and high-amplitude slow waves tended to appear.When it was infused at a rate of 0.05 ml per minute per kg of body weight, there wasa rapid increase in this concentration and induced pattern appeared. When the bloodammonia concentration was high and the respiratory movement was in a critical state, however, low-amplitude fast waves were observed on the pattern.3. When urea was injected in a dose of 3 to 12 mM per kg of body weight intothe anterior vena cava, no induced pattern appeared at all.4. When urea was infused in a dose of 4 ml per kg of body weight irtto therumen through a permanent fistula, the induced pattern appeared.5. When crystalline urea was mixed with powdered food and fed at a rate of6 ml per kg of body weight, it was a little slower in sltowing an effect than when itsaqueous solution was infused into the rumen, there was an increase in blood ammoniaconcentration and tlae induced pat

Subacute sclerosing panencephalitis

records takenearly intheillness maynotshowperiodic complexes butthese typically occur later. Theinterval between thebilateral highamplitude slowwave complexes diminishes asthedisease progresses. Therecord maybemoreabnormal ononeside than theotherwithsomeclinical andradiological features suggesting aspace-occupying lesion. Finally theclinical diagnosis maybeconfirmed bytaking a brain biopsy during life. Theaetiology ofSSPEhasremained obscure until recently andaconference washeld in1967toreview theevidence foraviral aetiology ofthedisease (Sever & Zeman, 1968). Wemaynowconsider the contributions oflight andelectron microscopy, virology andimmunology towards theelucidation of oftheaetiology ofthis disease. Microscopy Theviral aetiology ofSSPEwassuggested bythe finding ofCowdry type Anuclear inclusions inbrain cells (Dawson, 1933). Manyearly investigators assumed that theCowdry type Ainclusions indicated infection withherpes simplex virus butitisnow knownthatthemeasles-distemper-rinderpest

EEG of rhesus monkeys following prolonged low-level feeding of pesticides

Rhesus monkeys have been dosed for 18 mo with low levels of 4 pesticides (DDT, dieldrin, parathion, and carbaryl) and have been periodically evaluated by means of anesthetic-induced sleep electroencephalograms. Several characteristics of the EEG patterns have been visually quantitated. No specific alteration has been found to be characteristic of any one pesticide. DDT- and parathion-treated animals have shown a statistically significant reduction in the abundance of high amplitude slow waves; a reduction in the amount of low amplitude fast waves was seen in all groups. Bilateral synchrony between right and left hemispheres was increased in all the treatment groups. The significance of these findings remains to be determined.

Electroencephalogram in ruminants. 2. Effect of experimental hyperketonemia on the electroencephalogram in goats

Electroencephalograms (EEGs) were recorded bipolarly from the frontal andparietal cortical regions in 7 female goats. Silver balls (1 mm in diameter) were usedas electrodes and implanted chronically on the cerebral dura mater through a small holeof the skull. Experiments were carried out to clarify the effect of experimental hyper-ammonemia on the EEG in goats.l. When ammonium chloride (aqueous solution) was injected in an amount of0.5 milli-molecules (ml) per kg of body weight into the anterior vena cava through apolyethylene cannula, the blood ammonia concentration increased rapidly. On theEEG there appeared high-amplitude slow waves (2O0s4O0pV, 4x5 c/s) at a durationof 2 to 3 seconds and an interval of 10 to 20 seconds. This pattern was induced when theblood ammonia concentration exceeded 500pg per TOO ml of blood. There was anincrease in duration and frequerncy of appearance of this pattern with an increase indose of ammonia.2.. When ammonium chloride was infused into the anterior vena cava at a rateof 0.033 mlVI per minute per kg of body weight for 60 minutes, the blood ammoniaconcentration increased gradually, and high-amplitude slow waves tended to appear.When it was infused at a rate of 0.05 ml per minute per kg of body weight, there wasa rapid increase in this concentration and induced pattern appeared. When the bloodammonia concentration was high and the respiratory movement was in a critical state, however, low-amplitude fast waves were observed on the pattern.3. When urea was injected in a dose of 3 to 12 mM per kg of body weight intothe anterior vena cava, no induced pattern appeared at all.4. When urea was infused in a dose of 4 ml per kg of body weight irtto therumen through a permanent fistula, the induced pattern appeared.5. When crystalline urea was mixed with powdered food and fed at a rate of6 ml per kg of body weight, it was a little slower in sltowing an effect than when itsaqueous solution was infused into the rumen, there was an increase in blood ammoniaconcentration and tlae induced pat

Effects of alpha-methyl-meta-tyrosine on operant behavior, auditory evoked potentials and postreinforcement electrocortical synchronization in the cat☆

Abstract Cats injected with α-methyl-meta-tyrosine (50 mg/kg i.p.) exhibited a severe and prolonged (48 hr) inhibition of bar pressing for milk rewards which was concomitant with an increase in auditory evoked potentials recorded from both specific and nonspecific cortical projections as well as an increase in high amplitude slow wave activity in the general ECoG background. Subjects also displayed a marked but transitory increase (10 min–1 hr) in post-reinforcement electrocortical synchronization amplitude. Observation revealed no changes in home-cage eating behavior. Since the drug is known to reduce norepinephrine (NE) levels in the brain for at least 48 hr without markedly affecting dopamine or serotonin levels, it was hypothesized that NE is critical to the operation of nonspecific motivation and/or reinforcement in an appetitive instrumental conditioning situation.

The organization of motivation at the thalamic level of the cat

Abstract Three different behavioral tests in combination with recording of the electrical activities of different parts of the brain have been used to study the motivational effects elicited from different parts of the nonspecific thalamic system by electrical stimulation. Stimulation of the anterior region (anterior and dorsomedial group of nuclei) produced different forms of arrest reactions sometimes mixed with phasic movements and exerted a suppressing effect on conditional reflexes. In the case of low frequency stimulation a strict correlation was found between the suppressing effect and a late surface negative wave in the neocortical leads. In the case of high frequency stimulation a correlation between the hemispherical localization of high amplitude slow wave spindles and the direction of movements was obtained. In striking contrast to the anterior thalamus stimulation of the posterior thalamic (including the pretectal) region produced marked activating effects in a conditional environment. Self-stimulation could only be obtained from the anterior region. The effects are interpreted as the result of interactions of an internal negative feed-back and reciprocal inhibitory mechanisms showing increasing complexities as one ascends in a caudo-anterior direction through the thalamic nonspecific system.

Onset of cerebral electrical activity associated with behavioral sleep and attention in the developing chick.

AbstractBipolar electrical recordings from the cerebral lobes of chick embryos and of freely moving chicks after hatching indicate that spontaneous electrical activity begins about the eleventh to thirteenth day of incubation, but electroencephalographic patterns characteristic of behavioral sleep or attention appear within six hours after hatching. High amplitude, slow waves, are characteristic of behavioral sleep; low amplitude, fast waves are characteristic of behavioral attention. During sleeping postures the electroencephalographic record shows brief cyclic episodes of lower voltage fast waves (paradoxical sleep) and these cycles appear more definitely as the chick grows older. When the act of waking from sleep is associated with the opening of only one eye, the lower voltage, fast waves may appear only in the contralateral lobe, while the ipsilateral lobe shows the high amplitude slow waves. In the less mature chicks, the electrical waves are slower, less regular, and of smaller amplitude, especially during sleep, furthermore the cyclic episodes of activated sleep are less distinct and the span of attention is more brief. Although chick embryos may move following tactile stimulation, the response is probably due to reflex arcs involving lower nervous centers since the cerebral lobes do not show the transition to lower voltage faster waves characteristic of attention. After hatching electroencephalographic patterns associated with sleeping postures show more conspicuous developmental changes than those associated with attention.

Electroencephalographic and behavioural correlates of an instrumental reward conditioned response in rabbits a physiological and pharmacological study

In rabbits an instrumental reward conditioned response (ICR) was established. The animals were trained to pull a ring with the mouth when a buzzer sounded in order to obtain a piece of food (cabbage). The electrical activity of the cerebral cortex, the hippocampus and the thalamus was recorded by means of chronically implanted electrodes. The EEG tracing of the rabbit, when it was first put into the cage, was activated and consisted of low voltage 25–30 c/sec waves in the cortex and 4–6 c/sec synchronous waves in the hippocampal leads. In the anterior cortex high voltage 60 c/sec waves sometimes appeared. When the conditioned stimulus was presented, the most striking changes were seen in the hippocampal lead, in which the synchronous waves increased in amplitude and frequency (up to 9 c/sec). In the period of satiation high amplitude slow waves at 2–3 c/sec, intermingled with spindles in the anterior cortex, appeared. The tracing was not further influenced by the CS. During the eating period “masticatiry” waves appeared, particularly in the anterior cortex. The tracing was less activated, and sometimes synchronized. The ICR was found to be very sensitive to cholinergic drugs. Small doses of scopolamine (0.1 mg/kg) abolished it, but they did not interfere with the food intake. This action was accompanied by synchronization of the tracing. Eserine restored the performance of the test as well as the EEG activation patterns. Chlorpromazine and imipramine exrted a blocking effect only in doses which produced motor disturbances. Particularly with chlorpromazine, the unconditioned food intake was not disturbed. Amphetamine had two effects. In lower doses it facilitated the ICR. With higher doses the pulling of the ring occured, but was not folowed by taking the food from the feeding cup. Lysergic acid diethylamide (LSD) had an effect similar to that of amphetamine in prolonging the performance of the ICR. The appearance of “masticatory” waves was inhibited by scopolamine, chlorpromazine and imipramine, i.e., by “synchronizing” drug, as well as by LSD. Amphetamine, on the other hand facilitated these waves. The present work demonstrates that the simultaneous study of conditioned behaviour and the EEG may be useful to explain some finer details of the central action of drugs.

The effect of diencephalic and mesencephalic damage on cortical electrical activity in pigeons

Chronic experiments were performed on pigeons. Damage to the diencephalon and midbrain induced distinct changes of the electrical activity of the cerebral hemispheres. There was a definite relationship between the nature of the EEG changes and the site of the injury; when chiefly the diencephalon and especially the hypothalamus were affected, both the slow and rapid waves in the cerebral hemispheres were depressed; when the damage affected principally the midbrain, and particularly its dorsal portion, high amplitude slow waves appeared in the EEG, and the rapid waves were depressed. Compensation of the EEG changes due to diencephalic damage was slowet than it was for changes induced by midbrain injuries.

Management of Convulsive Seizures

We analyzed the electroclinical features, etiology, treatment, and outcome of 12 patients with West syndrome (WS) associated with focal hypsarrhythmia (FH).Between February 2005 and July 2013, 12 patients met the electroclinical diagnostic criteria of WS associated with FH. Hypsarrhythmia was considered to be focal when two or three brain lobes were involved. Patients with hemihypsarrhythmia were excluded.All patients had epileptic spasms (ES) in clusters of a structural etiology. Four had a porencephalic cyst, two had focal cortical dysplasia, two had open-lip schizencephaly, and one each had unilateral polymicrogyria, shunted hydrocephalus, glioma, and cerebral hemiatrophy. Age at ES onset was between 2 and 8 months, with a mean age of 5 and a median age of 6 months. Seven patients had asymmetric ES, three had symmetric ES, and two patients had unilateral ES. FH was seen over the posterior regions in nine and over the anterior regions in three. Ictal EEG recordings showed diffuse high-amplitude slow waves in six patients, diffuse slow waves followed by voltage attenuation in three, and diffuse fast rhythms in three others. In three patients the ictal paroxysms were unilateral. Six patients responded well to surgery.ES associated with FH are secondary to structural lesions. Surgery should be considered earlier in the management of this group of patients.

Central nervous activity in guinea pig anaphylaxis

1. 1. The changes in central nervous activity observed in the guinea pig during anaphylaxis, histamine injection, and asphyxia were characterized by high amplitude spike activity, flattening of background activity, desynchronization, and high amplitude slow waves. 2. 2. Pronounced disturbances in electrical activity are recorded in the cerebral cortex, dorsal hippocampus, preoptic area, and hypothalamus. These occur to a markedly lesser extent in the midbrain reticulum. 3. 3. These disturbances in electrical activity indicate that irritative mechanisms exist in the central nervous system during anaphylaxis. 4. 4. The data suggest that these irritative mechanisms are not confined to specific regions in the central nervous system and may be the result of generalized phenomena.