Appearance Of Slow Waves Research Articles

Response from Sean M. Ward and Kenton M. Sanders

Response from Sean M. Ward and Kenton M. Sanders

Changes in cortical slow wave activity in healthy aging

A number of studies have demonstrated enhanced slow wave activity associated with pathological brain function e.g. in stroke patients, schizophrenia, depression, Morbus Alzheimer, and post-traumatic stress disorder. However, the association between slow wave activity and healthy aging has remained largely unexplored. This study examined whether the frequency at which focal generators of delta waves appear in the healthy cerebral cortex changes with age and whether this measure relates to cognitive performance. We investigated 53 healthy individuals aged 18 to 89years and assessed MEG during a resting condition. Generators of focal magnetic slow waves were localized. Results showed a significant influence of age: dipole density decreases with increasing age. The relationship between cognitive performance and delta dipole density was not significant. The results suggest that in healthy aging slow waves decrease with aging and emphasize the importance of age-matched control groups for further studies. Increased appearance of slow waves as a marker for pathological stages can only be detected in relation to a control group of the same age.

Percussion and electrical stunning of Atlantic salmon ( Salmo salar) after dewatering and subsequent effect on brain and heart activities

The overall objective of the study was to evaluate a percussive and an electrical stunning method under laboratory conditions in Atlantic salmon. Evidence of unconsciousness and insensibility of the salmon was provided on the electroencephalogram (EEG) by the appearance of slow waves and spikes, followed by a strong depression in electrical activity. This phenomenon was observed in 17 salmon after percussive stunning using an air pressure of 8.1 to 10 bars, whilst 8 fish were considered conscious at pressures below 8.1 bars although some were seemingly unconscious on behaviour. Consequences were a haemorrhage in the brain cavity in 15 out of 17 fish, broken upper or lower jaws in 9 fish and eye burst in 8 fish. A general epileptiform insult (unconscious and insensible) was obtained by delivering a voltage, consisting of a direct current (DC) coupled with 100 Hz alternating current (AC) with a peak value of ≈112 volt (V), head to body, for ≈ 0.5 s. The total duration of the insult was 62 ± 44 s (mean ± SD; n = 25) which was followed by minimal brain activity in 19 fish. The heart rate was 20 ± 7 beats/min prior to stunning. After stunning the electrocardiogram (ECG) revealed fibrillation for 22 ± 15 s and became irregular and showed extra systolae (ventrical contraction) afterwards. Exposing the salmon for 5 s with electricity followed by a gill cut resulted that 1 out of 3 fish recovered temporary after 3 min. Haemorrhages were not observed in the fillets. Average current for head to body electrical dry stunning was 668 milliampere (mA) root mean square (RMS) with an average stunning voltage of 107.9 V rms. Electrical head to body stunning can be recommended when using coupled AC and DC current of 668 mA rms and ≈ 107 V rms. The salmon can be stunned in ≈ 0.5 s. However, a correct bleeding procedure should be developed. For percussive stunning we conclude that if sufficient force is used the fish will be rendered unconscious insensible which result in damage of the carcass, whereas a combined AC and DC can be recommended source for dry electrical head to body stunning.

104 Dynamical features of event-related gamma-oscillations in the EEG of cat auditory cortex during acquisition of discriminant aversive conditioning

ÁNGYÁN, L. AND J. CZOPF. Exercise-induced slow waves in the EEG of cats. PHYSIOL. BEHAV 64(3) 267–272, 1998.—The aim of the present study was to investigate the early signs of fatigue. Cats were chronically implanted with electrodes in the frontal and occipital cortical areas, and a thermocouple was inserted into the nasal orifice to record respiratory rate. After a recovery of 10 days, the animals were trained for running on treadmill. On the day before recording, a catheter was tied into one of the common carotid arteries to record arterial blood pressure. The electroencephalogram (EEG), arterial blood pressure, and respiration were recorded continuously. At the time of deceleration of running high amplitude, slow waves appeared both in the sensorimotor and occipital cortical regions. The power spectra showed a significant increase in frequencies of 1–6 Hz in the sensorimotor cortex, and of 1–10 Hz in the occipital cortex, with a great increase in the total power. During rest the pre-running, brain activity reappeared gradually. The arterial blood pressure, the heart rate, and the respiratory rate were elevated during running, but no special changes occurred at the onset of the slow waves in the EEG. The blood glucose level was somewhat higher after the first 2-min running than the pre-running level. It is concluded that the appearance of slow waves in the EEG is an early manifestation of fatigue. The cardiorespiratory changes and the blood sugar concentrations play no role in the slowing of the electrocorticogram. The present results show the involvement of brain mechanisms in the onset of tiredness.

Exercise-induced slow waves in the EEG of cats

ÁNGYÁN, L. AND J. CZOPF. Exercise-induced slow waves in the EEG of cats. PHYSIOL. BEHAV 64(3) 267–272, 1998.—The aim of the present study was to investigate the early signs of fatigue. Cats were chronically implanted with electrodes in the frontal and occipital cortical areas, and a thermocouple was inserted into the nasal orifice to record respiratory rate. After a recovery of 10 days, the animals were trained for running on treadmill. On the day before recording, a catheter was tied into one of the common carotid arteries to record arterial blood pressure. The electroencephalogram (EEG), arterial blood pressure, and respiration were recorded continuously. At the time of deceleration of running high amplitude, slow waves appeared both in the sensorimotor and occipital cortical regions. The power spectra showed a significant increase in frequencies of 1–6 Hz in the sensorimotor cortex, and of 1–10 Hz in the occipital cortex, with a great increase in the total power. During rest the pre-running, brain activity reappeared gradually. The arterial blood pressure, the heart rate, and the respiratory rate were elevated during running, but no special changes occurred at the onset of the slow waves in the EEG. The blood glucose level was somewhat higher after the first 2-min running than the pre-running level. It is concluded that the appearance of slow waves in the EEG is an early manifestation of fatigue. The cardiorespiratory changes and the blood sugar concentrations play no role in the slowing of the electrocorticogram. The present results show the involvement of brain mechanisms in the onset of tiredness.

Veränderungen des EEG-Grundrhythmus und des Hyperventilations-Effektes in verschiedenen Stadien der HIV-Infektion

The visual evaluation of 370 clinical EEGs of 125 patients in different stages of the HIV-infection as well as 42 HIV-seronegative volunteers of the same high risk population (male homosexuals) proved the increasing appearance of CNS dysfunction with progression of the disease. An especially established hyperventilation-index for a semiquantitative evalution of hyperventilation response showed an increase of slow-wave activity in the course of the infection. The appearance of slow-waves as well as a significant slowing of background activity in advanced stages of the HIV-infection can be regarded as unspecific signs of a beginning diffuse functional CNS disorder caused by a direct affection of the CNS through the Human Immunodeficiency Virus (HIV). The EEG changes in early stages are not specific as to their causative agent and do not allow the distinction between primary and secondary CNS involvement. The changes may preceed clinical-neurological alterations.

INFLUENCE OF HIGH ALTITUDE ENVIRONMENT ON BRAIN FUNCTION

Acute and subacute altitude exposure tests were performed on 38 members of Himaraya expeditions in a laboratory with low atmospheric pressure, and EEG changes and reactions of physiological acute adaptation were examined in order to obtain informations that will prove of help in preventing hypobaropathy and in health management in high mountain climbing.Meanwhile, EEG during climbing Mt. Everest were recorded and analyzed using power spectrum to compare with the results of above-mentioned tests. An inquiry was also made into the effct of a long-term sojourn at altitudes on brain function which has remained almost unclarified so far.1. Acute exposure to the altitude up to 4, 000m was attended with little change in EEG pattern, while at the altitude around 6, 000m slow waves were observed on EEG in all subjects, suggesting marked depression of brain function.2. EEG changes caused by long-term exposure to altitudes (Mt. Everest climbing) were marked primarily by slowing of alpha waves with a subsequent appearance of slow waves. However, these changes varied grossly in severity with different indivisuals, depending upon the physiological compensatory function of the whole boby.3. A follow-up EEG study demonstrated that a conspicuous delta-bursts occurred on activated hyperventilation following a long stay in altitudes, suggesting that the effects of long-term exposure to high altitude on brain function may persist for a certain period of time.4. Hypoxic symptoms observed in high altitude environment were attributable to the disruption of various physiological compensatory functions and EEG could serve as an index for the evaluation of impairment of brain function.5. It may be concluded that it is difficult to evaluate an aptitude for climbing high mountains only from these results.

Dissociations between the effects of hallucinogenic drugs on behavior and raphe unit activity in freely moving cats

The hypothesis that the action of hallucinogenic drugs is mediated by a depression of the activity of brain serotonergic (raphe) neurons was testedby examining the behavioral effects of several hallucinogenic drugs while concurrently monitoring the activity of raphe neurons in freely moving cats. LSD produced a dose-dependent decrease in raphe unit activity and a dose-dependent increase in certain behaviors (e.g. limb flick and abortive groom), and the peak of the behavioral and unit changes were temporally correlated. However, there were three important dissociations between the behavioral and electrophysiological effects of LSD. Firstly, low doses of LSD produced only small decreases in raphe unit activity but significant behavioral changes. Secondly, the duration of LSD-induced behavioral changes significantly outlasted the depression of raphe unit activity. And thirdly, raphe neurons were at least as responsive to LSD during tolerance as they were in the nontolerant condition. Psilocin produced a dose-dependent decrease in raphe unit activity, while the behavioral changes were not dose-related. However, the peak behavioral changes corresponded to the maximal depression of raphe unit activity. The phenylethylamine hallucinogens. DOM and mescaline, both produced large behavioral changes but no overall effect on raphe neurons. Following administration of DOM or mescaline, some raphe units showed a significant increase, while some showed a significant decrease, othrs showed a significant increase, while some phenylethylamine hallucinogens may exert a depressant effect upon a subset of serotonin-containing neurons, and an amphetamine-like excitatory effect upon an other subset of these neurons. Consistent with previous studies, all hallucinogens produced a high concentration of slow waves in the cortical EEG. Following administration of LSD or psilocin, the appearance of slow waves in the EEG was often associated with a transitory decrease in unit activity, while this was not observed for the phenylethylamine hallucinogens. The present data, in conjunction with recent data from other laboratories, suggest that the serotonin hypothesis of hallucinogenic drug action should be re-evaluated.

Electrically and chemically induced spindling and slow waves in the encéphale isolé rat: A possible role for dopamine in the regulation of electrocortical activity

The effects of electrical and chemical stimulation of brain areas known to contain dopaminergic cell bodies or terminals on electrocortical activity have been studied in the encéphale isolé rat. Electrical stimulation of medial basal midbrain areas with single stimuli resulted in a single evoked spindle but stimulation of more lateral areas resulted in the appearance of slow waves and spindling. These effects were blocked or reduced by prior treatment with 6-hydroxydopamine. Electrical stimulation of the caudate nucleus also produced a single evoked spindle. Local injection of dopamine into the caudate nucleus induced spindling, with higher doses also resulting in slow waves. Electrical stimulation of the basal forebrain brought about slow waves, an effect which was also seen following injection of dopamine into this area. It appears that electrical stimulation of certain brain areas produces similar effects to those produced by the injection of dopamine. This suggests the involvement of dopaminergic pathways in the production of cortical spindling and slow waves and also the involvement of neurones of both limbic and striatal systems.

Effects of Various Lighting Regimes on Diurnal Rhythms of EEG Components in the Chicken

Effects of different photoperiods on the appearance of EEG slow waves were examined in freely-moving chickens by a radio telemetry system. The experiments were performed under 14L10D, 18L6D, 21L3D and 24L. It was clear that the EEG components were strictly synchronized to light-dark cycles. Continuous illumination exerted a dampening effect on the appearance of the slow wave diurnal rhythms. Chickens exposed to light-dark cycles of 14L10D and 18L6D maintained a constant daily level of slow wave activity. These levels are regarded as a normal amount of slow wave activity in male chickens. The daily amount of slow wave activity under 21L3D and 24L is probably regulated in a way different from that under 14L10D and 18L6D. The illumination seems to exert a strong effect on the mechanism controlling the appearance of the EEG in chickens when compared to mammals.

数種の工業中毒物質の中枢神経系におよぼす影響 : 動物における脳波の変化

Effects of methanol, ethanol, n-propanol, carbon disulfide and o-phthalodinitrile on the electrical activities of the central nervous system of cats and rabbits were studied. Also, from the results of the present investigation and of the pervious one dealing with the effect of nitroglycol, the use of the electroencephalographic technique to the study of industrial toxicology was discussed. 1. Methanol, ethanol and n-propanol: Oral administration of 1-3ml-kg of n-propanol to curarized rabbits induced slow waves with high amplitude in EEG of the neo-cortex. In the hippocampal lead, there were two types of changes, one with persisting appearance of regular slow waves and the other with appearance of irregular slow waves. In the latter cases, the waves were accompanied with synchronization in the cortical lead. Change of EEG was similar in the case of noncurarized, unanesthetized rabbits. The above-mentioned effects were quite similar to those observed after the administration of methanol or ethanol. 2. Carbon disulfide: The intravenous injection of 0.1-0.2ml/kg of carbon disulfide to curarized cats revealed an appearance of slow waves and a decrease of amplitude in the cortical tracing. According to the changes of frequency and voltage of the electrical activity and of time from the administration to the beginning of flattening, the EEG patterns after administration were classified into four types; (I) rapid decrease of amplitude of the electrical activity in the neo-cortex followed by flattening in each lead without delay, (II) some delay in the appearance of flattening, after the decrease of amplitude in the neo-cortex, (III) a transitory arousal pattern in the neo-cortex, the amygdaloid nucleus and the hippocampus just after the injection, then appearance of slow waves in the neo-cortex about five minutes after the injection, and finally flattening of EEG, and (IV) no particular change. These types were dependent on whether the intravenous injection had been performed quickly or slowly. Type I or II was seen in cases when animals were injected quickly. Type III or IV was seen in cases when injections were performed slowly. In curarized rabbits, injected intravenously with doses at 0.1-0.3ml/kg, the resulst were similar. In the case of intraperioneal injection, type III or IV was observed. 3. O-Phthalodinitrile: Oral administration of doses ranging from 50 to 300mg/kg revealed the appearance of the slow wave burst or the spike and wave complex in the electrical activity of the neo-cortex in both curarized and non-curarized rabbits. When slow wave burst or spike and wave complex was found in EEG, none of excitatory symptoms was observed in the behaviour of non-curarized, unanesthetized rabbits. Seizure discharge in EEG was observed in all the rabbits except a case which had been given a single dose at 50mg/kg. Seizure discharge in EEG of non-curarized animals was accompanied with motor seizures. It is thought to be possible to classify the action of chemicals on the electrical activities of the central nervous system according to the change of frequency, voltage and shape of waves. As far as the present investigation is concerned, changes of the electrical activities after the administration of chemicals were classified into three patterns, namely appearance of slow waves, flattening and appearance of spike waves. It appears that observation of changes of EEG after the administration of chemicals are useful for the classification of toxicity of chemicals and for the comparison of effective doses of them under a definite experimental condition as in the case of this study.

LOCALIZED SLOW WAVE ACTIVITY IN THE SOMATOSENSORY CORTEX OF THE CAT.

AbstractDepth recordings with microelectrodes have revealed that transection of the specific projection pathways in the spinal cord induces regular slow waves with a frequency of 8–12 waves per second in the parts of the somatosensory areas SI and SII corresponding to the projection from below the level of the lesion. Surface recordings showed an increased spindle activity in the same areas. The slow wave activity occurs at various depths of Nembutal anesthesia. There is evidence that the appearance of slow waves after interruption of the specific pathways is a general phenomenon in the specific projection cortical areas.

Correlations between the electroencephalogram and cortical histochemical changes in experimental brain lesions

The relationship of EEG findings, histochemical data on glycogen, and oxidative enzymes (DPN-diaphorase) were studied in experimental cortical lesions in the guinea pig. There was a correlation between more than 50 per cent decrease of oxidative enzyme reaction in cortical tissues, the deposition of glycogen in the tissue, and the appearance of slow-wave activity in the EEG. Slow-wave activity was related to the presence of tissue showing almost normal cell population but markedly decreased enzyme reaction; decrease of enzyme activity in necrotic cortical tissue was without significance for the appearance of slow waves. The significance of these data for the interpretation of a delta focus in the human EEG was discussed, based on histochemical and EEG data from forty-four neurosurgical human biopsies.

An electrophysiological investigation of the state of the central nervous system in experimental brucellosis

Experiments were performed on guinea pigs infected withBr. melitensis strains. Cerebral biocurrents and immunobiological reactivity were studied in dynamics. Already on the 3rd–5th day after the injection the presence of an electrophysiological reaction of the brain cortex was noted in the form of marked activation of the biopotentials; on the 10th–11th day it was replaced by depression of biocurrents. Later, in the majority of experiments there was a considerable increase of the biocurrent amplitude with the appearance of slow waves (2–5 per sec.). Such EEG shifts are the most marked at the chronic stage of the disease. Comparative investigation of the functional CNS state, immunobiological reactivity, infectious process bacteriology, and body temperature in brucellosis infected guinea pigs have demonstrated that the first response to invasion of brucella into the organism were changes in the central nervous system, followed by corresponding shifts in immunobiological reactivity and thermocontrol.

Clinical-electroencephalographic studies with "confusion"-inducing substances

Clinical experiences show that appearance of confusional-delirious episodes can have an influence on course and prognosis of endogenous psychoses. This has brought us about carrying out examinations with substances which produce confusional-delirious pictures of given in small doses. Our clinical EEG-examination have proven that the development of confusional-delirious pictures comes along with a special kind of dissolution of wakeness. Parallel to the development of these clinical pictures there is to be observed a desorganization of cortical activity in EEG. This desorganization is characterized by a dissolution of α-rhythm, decrease of voltage, and appearance of slow waves and fast activity at the same time. Our clinical EEG-examination have proven that drugs producing confusional-delirious pictures can clearly be differentiated from “hallucinogenic” drugs. Drugs mentioned in this paper (Ditran, Sernyl, Hexamid, WH 4849) show also in mode of action certain differences from ‘anticholinergic“ substances.

OBSERVATIONS ON THE CEREBRAL EFFECTS OF PASSIVE HYPERVENTILATION

BY 1952 there had developed a strong clinical impression that the use of controlled respiration for abdominal surgery carried out under thiopentone, relaxant, nitrous oxide anaesthesia, resulted in a reduction in the dosage of both relaxant and barbiturate. This led to the suggestion by Gray and Rees (1952) that controlled respiration, quite apart from its use to achieve adequate ventilation, supplemented in some way the anaesthetic and relaxant drugs being used. Dundee (1952) in controlled observations on patients undergoing upper abdominal operations of 2 hours duration confirmed that there was a reduction in dosage of thiopentone necessary but found less evidence of the need for a smaller dosage of relaxants. He associated these results with the lowered blood acidity which he found almost invariably accompanied controlled respiration. This work has been supported by Gray and Geddes (1959) who drew attention to the appearance of slow wave activity in the e.e.g. during nitrous oxide, oxygen relaxant, controlled respiration anaesthesia and produced some evidence that this was attributable to hyperventilation. They also pointed out that the work of Bonvallet and Dell (1956) suggested that the blood tension of carbon dioxide had an important influence on the activity of the reticular area of the mid-brain, and they suggested that depression of the reticular activating system under conditions of respiratory alkalosis might account both for the appearance of slow waves and for the increased potency of nitrous oxide which was clinically evident.

STUDIES UPON ELECTROENCEPHALOGRAM IN ESSENTIAL HYPERTENSION

E. E. G. in 101 cases suffering from essential hypertension were observed. The results can be classified into four groups according to the E. E. graphic patterns. Group A; Cases without any pathologic patterns in E. E. G.. Group B ; Cases with slight pathologic patterns in E. E. G.. Group C; Cases characterized with rapid waves; the mean period 84 msec. Group D; Cases with the appearance of slow waves. Following results are obtained, that is to say, group A is 36%, group B. 13%, group C. 36%, group D. 15% of all cases examined. 1) In essential hypertension there can not be observed any special E. E. graphic pattern. 2) There exists no clear correlation between E. E. graphic patterns and chief claims, renal function, Ecg., the classification according to K. W., findings of fuudus oculi, B. P. of central retinal artery, arterial B. P.. 3) Relationship between circulatory dynamics and E. E. G.; Group A are frequently found in W+E types and M types are often determined in group D. 4) In some cases, the E. E. graphic patterns show the changes of brain more clearly than the other clinical findings do. 5) The appearance of abnormal waves can be examined more closely by means of deep respiration and breathholding test than of merely deep respiration. 6) No special change of E. E. G. is observed in the breathholding test in health. 7) The breathholding test examined in essential hypertension reveals the occurrence of rapid waves “en salve” with large amplitude.8) In the breathholding, test observed in epilepsy, there occurs spike and wave during hyperpnea, while it disappears during apnea. 9) The breathholding test after medication of priscol. It is apt to turn the slow waves found in essential hypertension into normal pattern or into rapid waves, the same procedure performed in epilepsy shows no changes in E. E. G.. 10) Breathholding test after the use of Kallikrein facilitates the appearance of α waves and inhibits the rapid waves. 11) Low % and 100% of O2 were inhaled by the same individual; E. E. G. found in both examinations are similar patterns. Improvement or deterioration of E. E. graphic patterns can not pararell to those of clinical findings. This suggests that E. E. graphic changes must be not only understood medicaly, but also psychologically. 12) Apresoline turnes often the pathologic E. E. G. observed in es sential hypertension into normal pattern; one of important causes is thought to be the increase in the cerebral blood flow. Slow waves can be not frequently recognized immediately before the attack of hypertensive encephalopathy. 13) The degrees of lowering of blood pressure in the patients who are medicated with R. S. is remarkable roughly in proportion to the increase in mean period and in mean amplitude. In addition it may be pointed out that R. S. does not reveal sleep spindle. 14) R. S.-E. E. graphic pattern is quite similar to the pattern in the medication of Deserpidine.

Tonus sympathique et activité électrique corticale

Simultaneous recording of the electrical activity of the cortex and of the arterial blood pressure in animals (cats and dogs) under Flaxédil demonstrates the following: 1. 1. In an animal which has no external sensory stimulation, there is a spontaneous fluctuation in the electrical activity of the cortex and also in the level of sympathetic tone. These variations both in the electrical activity of the cortex and in sympathetic tone are always synchronous and parallel; activation of the cortex corresponding with an increase (even a small one) in the blood pressure. 2. 2. Nociceptive stimuli (e.g. electrical stimulation of the sciatic nerve) produce a marked cortical activation and an increase in sympathetic tone (vasomotor effects and adrenaline secretion, etc.). Analysis of the effects of such stimuli under different experimental conditions, shows that: 2.1. ( a) the duration of the cortical activation after the nociceptive stimulus is directly related to the intensity of the sympathetic response; 2.2. ( b) while pre-bulbar section completely eliminates the possibility of putting into action the reticular activating system of Moruzzi and Magoun by means of nociceptive stimulation, peripheral sympathetic discharge is still preserved. However, there is still an intense cortical activation corresponding with increase in sympathetic tone, but this activation appears later, i.e. during the ⪡adrenaline phase⪢ of the hypertension produced by sciatic stimulation; 2.3. ( c) stimulation of the peripheral end of the splanchnic nerve or injection of adrenaline, either in the normal animal or in the animal after pre-bulbar section, produces an intense activation of all cortical areas, an activation which develops in parallel with the increase in peripheral sympathetic tone; 2.4. ( d) intercollicular section of the brain stem, passing to the ventral surface just rostral to the pons (section A, fig. 18) completely suppresses the cortical activation in response to a peripheral sympathetic discharge. After a section slightly more caudal (section B, fig. 18) this cortical activation persists. Cortical activation corresponding with a peripheral sympathetic discharge is therefore not due to a direct action of adrenaline or to the increase of blood pressure (both of which factors are of course interrelated) on the cortex, but to an action on pontomesencephalic formations; 2.5. ( e) cortical activation in response to an nociceptive stimulus therefore occurs by means of two mechanisms which, in general, overlap each other: (i) an immediate nervous activation which operates by means of a mechanisms which is now well known, i.e., through the ascending reticular activating system, and, (ii) by means of a subsequent “humoral” activation which also works not directly on the cortex but through pontomesencephalic formations; 2.6. ( f) the “humoral” activation allows an adjustment of cortical activity to the peripheral sympathetic activity existing at the moment. The fact that the increase in sympathetic tone (adrenaline, slight hypertension) is able to produce an electrical picture of cortical activation which is indistinguishable from that produced by an exteroceptive stimulus, suggests that the level of peripheral sympathetic tone is just as important a factor in maintaining the waking state as the continuous inflow to the brain of proprioceptive and exteroceptive stimuli. 2.7. 3. All these effects on cortical activity of a peripheral sympathetic discharge are suppressed by very small doses of anaesthetics. 2.8. 4. Distention of the carotid sinus (within physiological limits) produces a progressive reduction in cortical activity and the appearance of slow waves. This effect is still seen after high spinal section combined with bilateral vagotomy, a procedure which suppresses the hypotensive response to carotid sinus distention, and which suppresses in the same time direct effects from the carotid sinus on the vasomotor control of the cerebral circulation. The reduction in cortical activity in response to carotid sinus distension is therefore independent of variations in the blood pressure and is mediated by purely nervous mechanisms. This appears to be the first example of an afferent inflow which “damps” rather than activates the cortex. 2.9. 5. The experimental facts described in this paper have been integrated in a provisional schema of the regulatory mechanisms responsible for the continuous adjustment and interrelations of cortical activity and peripheral sympathetic tone.

AN EXPERIMENTAL STUDY ON THE MODE OF ENERCY CONSUMPTION IN BRAIN

Summary and ConclusionThe EEG was recorded tipon 15 subjects in all, namely: 6 general paresis, 5 schizophrenia, 2 epilepsy, 1 hysteria and 1 hypomania. During rise in body temperature due to intravenous injection of typhoid‐paratyphoid vaccine, change of EEG in accordance with the temperature rise was studied from 2 or different points of view, especially from that of brain energy metabolism.First of all, judged from the obtained frequency, amplitude, wave pattern, continuity, and regularity of the brain wave, it was concluded that the brain wave change hereby follows a definitely systematic course. With the rise increase takes place first in regularity, then in amplitude, and then in spite of further increase in amplitude both regularity and continuity gradually get lost. At this stage, decrease of frequency, which begins with the appearance of slow waves at random, finally comes to be expressed through successive appearance of dysrhythmic high voltage slow waves corresponding to fever of above 40°C at the least. Thereby, a supposition is by no means unreasonable that the mode of such changes may also differ according to the different character of the diseases in question. For, in general paresis cases only slight rise of temperature as below 40°C can effect appearance of high voltage slow waves, and in epilepsy case with characterized pathologic brain wave figure the characteristicum gets further emphasis through the drastic temperature rise.The change of brain wave frequency in accordance with temperature change was obtained from the occipital region in 14 cases, where validity of straight line relation was proved between the log of frequency and inverse number of the absolute temperature, i. e., agreement of that relation with Arrhenius equation. Accordingly, it has been made evident that the standard value of temperature characteristics μ is to be classified in 3 orders, namely: 8000, 11009, and 16000 cal. Now, instead of being convinced of Hoagland's assertion that these values of μ are related with the degree of advancement in general paresis cases, we found in them characteristica pretty indicative of each disease. Thus it has been elucidated that the mode of brain energy metabolism at each stage of temperature rise varies in accordance to certain law, yet in case of extremely high fever there is left possibility of its transgression to other form of chemical reaction.Tracing of the status of electrical energy in the stage of temperature riee by means of Masuyama's energy distribution equation of brain wave reveals, as Kakegawa reported, its nonconformity with the exponential distribution quotient in most cases of normal temperature—contradicting to Motokawa's and his collaborators' assertion. However, the degree of conformity increases gradually with temperature rise. In other words, while the brain, as the ruling organ, possesses uniqueness to be able to maintain the maximum level of energy consumption almost permanently,—a characteristic never to be met with in other body organs—yet this maximum level, instead of being maintained constantly, is probably reached only when the substance metabolism is accelerated through intracerebral chemical reaction due to temperature rise. Thereby it seems pretty presumable that the reverse relation of conformity in epilepsy case will be attributed to certain reactive process of another quality, not to a continuous one of the same quality.

Effects of hemorrhagic shock upon the electroencephalogram.

Summary and ConclusionHemorrhagic shock in rabbits produces definite changes in the electroencephalogram. These are characterized basically by the appearance of slow waves of increased amplitude. In shock irreversible to transfusion there occurs a progressive decrease in cortical electrical activity which is shown on the electroencephalogram as a continued reduction in the frequency and voltage (amplitude) of the wave pattern. The effects on the electroencephalogram of blood transfusion in reversible and irreversible hemorrhagic shock are discussed. It is tentatively suggested that the electroencephalographic response to blood transfusions in shock may be used as a means of differentiating the reversible and irreversible forms.