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PubMed1990

The effects of intravenous succinylcholine on cerebral function and muscle afferent activity following complete ischemia in halothane-anesthetized dogs.

The effects of iv succinylcholine (SCh) on cerebral blood flow (CBF), the electroencephalogram (EEG), muscle afferent activity (MAA), electromyographic activity (EMG), and PaCO2 were tested in six halothane-anesthetized dogs (1.0 MAC) more than 1 h after a 10-min period of complete cerebral ischemia. All dogs received treatments of both iv SCh (1.0 mg.kg-1) and saline placebo in a random sequence. Fasciculations and substantial increases in EMG activity were observed in all dogs following SCh administration. At the onset of fasciculations, there was an increase in MAA to a peak value of 353 +/- 74% of control (mean +/- SE; n = 5 for MAA; n = 6 for all other variables) at the 1-min measurement point. Thereafter, MAA gradually declined toward control values. There were delayed increases in PaCO2 throughout the 45-min study period, achieving values of 106 +/- 1% to 118 +/- 4% of control (an increase in PaCO2 of 2-7 mmHg). Despite the increases in MAA and PaCO2, there were no significant increases in CBF during the study. The control EEG 1-h after complete cerebral ischemia, but immediately before administering the drug treatments, consisted predominantly of a delta rhythm, denoting cerebral dysfunction. In one dog, SCh administration produced transient attenuation of the delta rhythm, a change consistent with cerebral stimulation. In the remaining five dogs, SCh had no effect on the EEG. Treatment with saline placebo did not affect any variable measured. The authors conclude that, in the electrically dysfunctioning brain (e.g., as occurs following resuscitation from complete cerebral ischemia), the cerebral (i.e., CBF and EEG) response to iv SCh is attenuated when compared to the previously reported response in normal brain.

Anesthesia, Inhalation↗
PubMedDate not supplied

The feedsideward of cephalo-adrenal immune interactions.

The feedsideward phenomenon is the interaction of three or more rhythmic physiological entities by a diversified spectrum of rhythms that constitute a rhythmic network. These rhythmic units are: a) the modulator, b) the actor, c) the reactor and d) the integrative unity. Rhythmic interactions are characterized by an alternating sequence of algorithmically predictable effects of attenuation, no effect, and stimulation occurring in different frequencies. The basis of this phenomenon was determined from experimental evidence derived from cephalo-adrenal ex vivo studies. Internal phase-shift studies allow the demonstration ex vivo of a collateral hierarchy of rhythmic neuro-endocrine interactions as alpha, beta, gamma and delta rhythms. Linear least squares analyses describe and quantify circadian (alpha, beta and gamma) and infradian (delta) rhythms in the original series and the differences in responses [beta-alpha] and [gamma-delta]. These spontaneous and response rhythms reveal a collateral neuro-endocrine hierarchy and validate a pineal feedsideward phenomenon. Circadian-infradian murine rhythmic intermodulations are demonstrated in the epithelial corneal mitosis; brain neurosteroids and pineal melatonin content. A circadian rhythm in pineal melatonin content in female B6D2F1 mice and the chronomodulating action of melatonin + ACTH upon adrenal corticosterone production are confirmed. A chronopilot ex vivo study "suggests" that melatonin chronomodulates mouse aldosterone production. In a second chronopilot study, HrIL-2 chronomodulates rat corticosterone production ex vivo. Feedsidewards in vivo were seen in the chronomodulation of tumor-host balance occurring after melatonin, IL-2, cefodizime, and cyclosporine treatments that enhanced or delayed tumor growth and survival time of tumor-bearing mice.

Adrenal Glands↗
PubMed1991

The effect of exposure to impulse X rays on normal and epileptic activity in rabbit brain.

Exposure to X rays (20 impulses of 4 Hz frequency, total dose 0.6-1.1 mGy) increased the epileptic activity of a focal area, which was produced in the visual cortex of rabbit brain by freezing with liquid nitrogen, and by stimulating with flashes of light at frequencies of 5-6 Hz. The number of seizure complexes during photostimulation for 5 s increased by 80% compared with the initial level, and this effect continued for 15 min. In control animals (with no epileptic foci), a decrease was observed in the main frequencies of the delta rhythm and the theta rhythm (by 90% and by 10%, respectively) over the cortex as a whole. In rabbits with experimental epilepsy, the delta rhythm decreased only in the frontal lobes and in the lateral geniculate body (by 30%), whereas the theta rhythm decreased only in the visual cortex (by 10%). Possible mechanisms for these effects are discussed.

Animals↗
PubMedDate not supplied

[Spatial organization of the electrical potentials of the brain in the rabbit during low-frequency electric stimulation of subcortical structures].

The influence of low-frequency (2-9 Hz) electric stimulation of some limbic system structures (mammillary bodies (MB), field CA1 of the dorsal hippocampus, subiculum), thalamus midline nuclei on spectral-correlative characteristics of potentials of the neocortex and some subcortical formations and elaboration of the defensive conditioned reflex (CR) was studied in 19 rabbits. Electric stimulation of all studied formations with the current of 0.1 mA and 2-4 Hz frequency contributed to the appearance of delta-rhythm in the neocortex, especially highly expressed when MB was stimulated at the beginning of CR elaboration. The appearance of delta-rhythm in the neocortex and other examined structures impeded CR elaboration; during MB stimulation with a frequency of 2-4 Hz, CR could not be elaborated. The most favourable conditions for maintaining the theta-rhythm and CR elaboration were established when each of the examined structures was stimulated with frequency of 7 Hz, but CR elaboration was not accelerated.

Animals↗
PubMed1995

Ultradian rhythm in the delta and theta frequency bands of the EEG in the posterior hypothalamus of the rat.

The EEG signal of the area hypothalami posterior (PH) was recorded in the urethane anaesthetized rat. The main characteristic of the EEG in this brain region was intermittent oscillations of high amplitude in the delta and theta frequency bands. Oscillations of the alpha and beta frequency bands showed comparatively lower variations. Time distribution analysis of the EEG spectral power revealed that the delta and theta rhythms appeared and disappeared according to an ultradian rhythm with a frequency of approximately 1 cycle per 100 min. No significant rhythm was found in the alpha and beta band. The rhythm frequency of neuronal activity in the PH is very similar to the ultradian frequency of pulsatile neurotransmitter release in the PH demonstrated previously.

Activity Cycles↗
PubMed1989

Temporal evolution of electroencephalographic abnormalities in Creutzfeldt-Jakob disease.

Frequent serial EEG investigations of three patients with neuropathologically confirmed Creutzfeldt-Jakob disease lasting 13, 24 and 68 weeks revealed typical periodic activity of short duration with stereotyped bilateral sharp waves at the 7th, 8th, and 12th week, respectively, after the onset of symptoms. During the later stages, there were several deviations from this typical pattern. However, periodic activity was preceded between the 3rd and 9th week by intermittent localized or lateralized delta rhythms, which gradually changed into periodic activity. This early temporal evolution of EEG abnormalities may be helpful in the early diagnosis of Creutzfeldt-Jakob disease when accompanied by other investigations to exclude other causes of intermittent delta rhythms.

Aged↗
PubMedDate not supplied

[Change in the human electroencephalogram during brief mental loads].

Frequency-amplitude characteristics of EEG beta-, alpha-, theta- and delta-rhythms were studied in 33 male subjects with different maximal velocity of effective processing of visual information. Dosed mental load enhanced the total activity of EEG frequency components of parieto-occipital parts of the brain. The most substantial changes were revealed in the delta-rhythm range. A statistically significant correlative connection was found between integrative amplitude values of EEG slow rhythms and success in performing mental tasks. The higher the maximal velocity of effective processing of visual information, the greater the magnitudes of theta- and beta-activity. No statistically significant connection has been revealed between the maximal velocity of effective processing of visual information and the frequency-amplitude EEG characteristics before and after mental loads.

Adult↗
PubMed1987

[Parasympathetic regulation of cardiac rhythm in delta sleep-inducing peptide deficiency].

The effect of delta-sleep peptide (DSP) deficiency on the parasympathetic regulation of the heart rate was studied on 35 rabbits. It was established that the injection of an-serum (titer-1:2000-1:3000) leads to the attenuation of parasympathetic influences: heart rate increase in freely behaving animals and a decrease in negative chronotropic effect with direct vagus irritation. Antiserum, like DSP, administration causes practically no damage of the myocardial ultrastructure.

Animals↗
PubMed1992

Delta frequency (1-4 Hz) oscillations of perigeniculate thalamic neurons and their modulation by light.

Neurons in the perigeniculate sector of the reticular thalamic nuclear complex were recorded extra- and intracellularly under deep urethane anesthesia. They were identified by burst responses to optic chiasm stimulation and depolarizing spindle oscillations in response to internal capsule stimulation. Perigeniculate neurons displayed oscillations within the frequency range of electroencephalogram delta waves (1-4 Hz). One-third of extracellularly recorded neurons discharged rhythmic (2.5-4 Hz), high-frequency (150-200 Hz) spike bursts. This was similar to an intrinsic oscillation that was recently observed in dorsal lateral geniculate cells studied in vitro and in vivo. Other oscillating neurons displayed trains of single spikes (20-50 Hz) crowning rhythmic (2.5-4 Hz) depolarizing envelopes that were best expressed at the "resting" membrane potential (-60 to -65 mV). It is suggested that this oscillation reflects synaptic drives from dorsal lateral geniculate neurons. Changes in ambient room luminosity disrupted both types of delta rhythms. These data demonstrate for the first time that delta oscillations are present in the visual sector of the reticular thalamic nucleus. The results suggest that the two types of delta rhythmicity result from intrinsic and network properties of visual thalamic neurons and that perigeniculate cells may synchronize, through backward connections, the activity of dorsal lateral geniculate cells during deep stages of resting sleep.

Animals↗
PubMed1999

Biological rhythm disturbance in depression: temporal coherence of ultradian sleep EEG rhythms.

BACKGROUND: Recent studies have suggested that major depressive disorders are associated with a breakdown in the organization of ultradian rhythm in sleep EEG. The present study used cross-spectral analysis of sleep EEG to confirm this finding, in a larger-scale study, evaluating the influence of gender and age on ultradian rhythms in depression. METHODS: Temporal coherence of ultradian (80-120 min) rhythms in beta, theta and delta, recorded from central and parietal sites, were compared in 120 symptomatic, unmedicated, depressed outpatients and 59 healthy normal controls. RESULTS: Few macro-architectural differences were noted between patients and controls. However, interhemispheric beta and theta coherence and intrahemispheric coherence between beta and delta rhythms were significantly lower in depressed patients. Coherence measures were lowest in women with depression and highest in men in the control group, but were not strongly influenced by age. Over 65% of depressed patients were > or = 2 standard deviations below normal on at least one coherence measure, in sharp contrast to less than 10% of patients on macro-architectural variables. CONCLUSIONS: It was concluded that dysregulation of ultradian rhythms characterizes the majority of depressed out-patients, primarily women, even when macro-architecture did not differentiate groups. The outcome of this study supports the view that the pathophysiology of depression is strongly influenced by gender. It was suggested that low temporal coherence in depression reflects a breakdown in the organization of sleep EEG rhythms within and between the two hemispheres.

Activity Cycles↗
PubMed2005

Quantitative EEG analysis in children with hemiparetic cerebral palsy.

Clinical assessment and imaging studies of twenty-six children with hemiparetic cerebral palsy (HCP) were conducted. For each child 20 artifact-free EEG epochs, each of 2 s duration were selected for spectral analysis to calculate spectral power and coherence functions. A fast Fourier transformation alogorithm of signal processing was used to obtain the power spectrum of each lead. The objective of this study was to estimate EEG spectral power as well as the interhemispheric (ICoh) and intrahemispheric (Hcoh) coherence in children with hemiparetic cerebral palsy (HCP) as compared with healthy children. Significant differences between the HCP and control children were noted in the distribution of the alpha, theta and delta rhythms over the left and right hemispheres. In this study we found significant differences between the HCP and control children in the distribution of alpha, theta, delta and beta rhythm over the left and right hemispheres. Significant differences between the HCP and control children were in the distribution of the theta rhythm over the right and left hemispheres. The lower ICoh at the temporal, parietal and occipital derivations in the alpha band implies hypoconnectivity between the right and left hemispheres. The HCoh asymmetry, which implies relative hypoconnectivity within the right and left hemispheres, suggests the functional hemispheric differentiation may be diminished in comparison with the controls.

Alpha Particles↗
PubMed1996

[The genetic aspects of the neuropsychology of verbal memory in schizophrenia].

Genetic study methods were used while examining the families with schizophrenic patients to study the relationships between computerized tomographic and resting ECG parameters with memory for information, which differed in degrees and ways of organization. In patients, memory performance was affected both by genotype-controlled high-frequency alpha-rhythm subranges and by integral delta-rhythm values determined by environmental factors. A significant role of the right hemisphere was found for all forms of remembering. In a group of relatives, predictors of different memory forms differed in frequency and topographic characteristics to a greater degree. These predictors mainly included neuromorphological parameters and power values of alpha-rhythm ranges. Most predictors were under considerable genetic determination.

Adolescent↗
PubMed2005

Cerebral correlates of delta waves during non-REM sleep revisited.

We aimed at characterizing the neural correlates of delta activity during Non Rapid Eye Movement (NREM) sleep in non-sleep-deprived normal young adults, based on the statistical analysis of a positron emission tomography (PET) sleep data set. One hundred fifteen PET scans were obtained using H(2)(15)O under continuous polygraphic monitoring during stages 2-4 of NREM sleep. Correlations between regional cerebral blood flow (rCBF) and delta power (1.5-4 Hz) spectral density were analyzed using statistical parametric mapping (SPM2). Delta power values obtained at central scalp locations negatively correlated during NREM sleep with rCBF in the ventromedial prefrontal cortex, the basal forebrain, the striatum, the anterior insula, and the precuneus. These regions embrace the set of brain areas in which rCBF decreases during slow wave sleep (SWS) as compared to Rapid Eye Movement (REM) sleep and wakefulness (Maquet, P., Degueldre, C., Delfiore, G., Aerts, J., Peters, J.M., Luxen, A., Franck, G., 1997. Functional neuroanatomy of human slow wave sleep. J. Neurosci. 17, 2807-S2812), supporting the notion that delta activity is a valuable prominent feature of NREM sleep. A strong association was observed between rCBF in the ventromedial prefrontal regions and delta power, in agreement with electrophysiological studies. In contrast to the results of a previous PET study investigating the brain correlates of delta activity (Hofle, N., Paus, T., Reutens, D., Fiset, P., Gotman, J., Evans, A.C., Jones, B.E., 1997. Regional cerebral blood flow changes as a function of delta and spindle activity during slow wave sleep in humans. J. Neurosci. 17, 4800-4808), in which waking scans were mixed with NREM sleep scans, no correlation was found with thalamus activity. This latter result stresses the importance of an extra-thalamic delta rhythm among the synchronous NREM sleep oscillations. Consequently, this rCBF distribution might preferentially reflect a particular modulation of the cellular processes involved in the generation of cortical delta waves during NREM sleep.

Adult↗
PubMedDate not supplied

Reciprocal relationship between the major EEG rhythms and latencies of evoked potential intermediate components. A tentative explanation.

We recently demonstrated that there is a reciprocal relationship between the known brain wave rhythms (delta, 3.3 c/sec, 5 c/sec, theta, alpha, spindle, and beta) on the one hand, and the averaged evoked potential mid component latencies, on the other. In other words, the latter are closely related to the periods of the known brain wave frequencies. In this paper we offer a hypothetical explanation of this puzzling relationship, by assuming the following: 1) Whenever the fastest component of a sensory signal reaches the cortex it depresses EEG except for those waves of different frequencies which at that very instant exhibit a high amplitude peak of a preferential polarity. One half period later, different in real time for each brain wave frequency, high amplitude peaks will emerge from the record with opposite polarity to that which was preferential at the time of the signals' arrival. These segmental peaks are the same as those that express evoked potential components of mid latencies. For the somatosensory evoked potentials the time of occurrence of these peaks are defined by the following expression: (Formula; see text) where N is equal to successive numbers between 1 and 12, as well as to the fractions of 1; 20 msec is the moment of arrival of the fastest signal to the cortex. Some of the latencies correspond to the arrival of the delayed components of the somatosensory signals. Some correspond to the time of arrival of the auditory and visual signals, in an apparent expectation of multi-sensory signals.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha Rhythm↗
PubMed1994

Sleep oscillations and their blockage by activating systems.

There are three major oscillations in thalamocortical systems during the state of sleep with synchronization of the electroencephalogram: 1. Spindles (7 Hz to 14 Hz) are generated in the thalamus at sleep onset and are blocked during arousal or rapid-eye-movement sleep by cholinergic systems that decouple the synchronizing network of the reticular thalamic nucleus. 2. Delta potentials (1 Hz to 4 Hz) appear during late stages of electroencephalogram-synchronized sleep. At the thalamic level they are produced by the interplay between two intrinsic currents of neurons with cortical projections. Delta rhythm is suppressed by cholinergic and noradrenergic systems. 3. A slow oscillation (< 1 Hz) is generated in the cerebral cortex and has a pivotal role in grouping the thalamic-generated sleep rhythms within wave-complexes recurring periodically, every two to five seconds. The slow rhythm is blocked by cholinergic and noradrenergic projections. Sleep rhythms consist of long-lasting inhibitory components that obliterate synaptic transmission and disconnect the brain from the outside world.

Cerebral Cortex↗
PubMed1999

Increased gamma- and decreased delta-oscillations in a mouse deficient for a potassium channel expressed in fast-spiking interneurons.

Kv3.1 is a voltage-gated, fast activating/deactivating potassium (K(+)) channel with a high-threshold of activation and a large unit conductance. Kv3.1 K(+) channels are expressed in fast-spiking, parvalbumin-containing interneurons in cortex, hippocampus, striatum, the thalamic reticular nucleus (TRN), and in several nuclei of the brain stem. A high density of Kv3.1 channels contributes to short-duration action potentials, fast afterhyperpolarizations, and brief refractory periods enhancing the capability in these neurons for high-frequency firing. Kv3.1 K(+) channel expression in the TRN and cortex also suggests a role in thalamocortical and cortical function. Here we show that fast gamma and slow delta oscillations recorded from the somatomotor cortex are altered in the freely behaving Kv3.1 mutant mouse. Electroencephalographic (EEG) recordings from homozygous Kv3.1(-/-) mice show a three- to fourfold increase in both absolute and relative spectral power in the gamma frequency range (20-60 Hz). In contrast, Kv3.1-deficient mice have a 20-50% reduction of power in the slow delta range (2-3 Hz). The increase in gamma power is most prominent during waking in the 40- to 55-Hz range, whereas the decrease in delta power occurs equally across all states of arousal. Our findings suggest that Kv3. 1-expressing neurons are involved in the generation and maintenance of cortical fast gamma and slow delta oscillations. Hence the Kv3. 1-mutant mouse could serve as a model to study the generation and maintenance of fast gamma and slow delta rhythms and their involvement in behavior and cognition.

Animals↗
PubMed2000

Effects of bilateral microinjections of ibotenic acid in the thalamic reticular nucleus on delta oscillations and sleep in freely-moving rats.

The thalamic reticular nucleus (NRT) consists of a large pool of GABAergic neurons located on each side on the anterior, lateral, and ventral surfaces of the dorsal thalamus. The NRT is divided up into sectors. The aim of this study was to investigate the effects of bilateral lesions of the NRT on sleep and sleep oscillations. Only the results concerning delta oscillations will be reported here. As a first step we produced stereotaxically placed electrolytic lesions. The rats presented continuous circling behavior with electroencephalographic (EEG) theta and delta activity and subsequent sudden death. To avoid disruption of the bundles of fibers that pass through the NRT to and from the cerebral cortex, we used the excitotoxic ibotenic acid. Given its high toxicity, we concentrated on the rostral pole of the NRT, which is believed to have powerful effects on the synchronization of oscillatory activity during sleep. Immediately after surgery, the rats fell into a deep sleep during which there was an increase in EEG slow-wave activity and no spindles. On postoperative day 2, corresponding to the destruction period, the sleep/wake cycle partially recovered, but NREM sleep was quantitatively diminished and showed abnormalities (increased latency to sleep onset, sleep fragmentation, gradual elimination of the delta rhythm). It is concluded that the rostral pole of the NRT contributes to normal and pathological EEG synchronization and the organization of sleep in rats.

Animals↗