Effect of change in levels of motor activity and innervation on basic and secondary rhythms of rat heart rate and respiration in ontogenesis

Changes in the heart basic rhythm, its rhythmical variations on periodograms, and level of spontaneos motor activity were studied on offspring of white rats from newborn to 3-week age at transition from the state of active wakefulness to narcosis as well as under conditions of blockade of M-cholinoreceptors with atropine. It is shown that the endogenous rhythmical activity can be regulated not only by a change in frequency of basic rhythms, but also by action on all parameters and properties of their rhythmical variations and secondary rhythms. The changes in power of the heart secondary rhythms exceed considerably the frequency oscillations of basic rhythms during blockade of cholinergic innervation or a change in the motor activity level that affects both the basic rhythm circulation and respiration and their variations--secondary rhythms. The atropine blockade of M-cholinoreceptors at the studied ages changes the heart beating rhythm within the limits of 10% of bradicardia in newborns to tachycardia in the 3-week old animals. At the same time, power of the cardiac rhythm secondary oscillations changes several times. These data indicate that the cholinergic mechanisms play the key role in formation of the secondary rhythms and their correlation with motor activity.     

Effect of change in levels of motor activity and innervation on basic and secondary rhythms of rat heart beatings and respiration in ontogenesis

Changes in the heart basic rhythm, its rhythmical variations on periodograms, and level of spontaneous motor activity were studied on offspring of white rats from newborn to 3-week age at transition from the state of active wakefulness to narcosis as well as under conditions of blockade of M-cholinoreceptors with atropine. It is shown that the endogenous rhythmical activity can be regulated not only by a change in frequency of basic rhythms, but also by action on all parameters and properties of their rhythmical variations and secondary rhythms. The changes in power of the heart secondary rhythms exceed considerably the frequency oscillations of basic rhythms during blockade of cholinergic innervation or a change in the motor activity level that affects both the basic rhythm circulation and respiration and their variations—secondary rhythms. The atropine blockade of M-cholinoreceptors at the studied ages changes the heart contraction rhythm within the limits of 10% of bradycardia in newborns to tachycardia in the 3-week old animals. At the same time, power of the cardiac rhythm secondary oscillations changes several times. These data indicate that the cholinergic mechanisms play the key role in formation of the secondary rhythms and their correlation with motor activity.     

The Circadian Rhythm of Cardiac Frequency in Crayfish: a Multioscillator System?

The aim of this work was to study the humoral regulation of the circadian rhythm of cardiac frequency in crayfish and explore the possibility that isolated heart has a circadian-like oscillation. Sinus glands are the main source of neurohormones in crayfish, and their excision dampens the rhythm, lengthens the period and induces high frequency oscillations. Isolated crayfish hearts show a circadian-like rhythm of frequency with two peaks. These results suggest the participation of several oscillators in the generation and/or expression of the circadian rhythm.     

The Circadian Rhythm of Cardiac Frequency in Crayfish: a Multioscillator System?

The aim of this work was to study the humoral regulation of the circadian rhythm of cardiac frequency in crayfish and explore the possibility that isolated heart has a circadian-like oscillation. Sinus glands are the main source of neurohormones in crayfish, and their excision dampens the rhythm, lengthens the period and induces high frequency oscillations. Isolated crayfish hearts show a circadian-like rhythm of frequency with two peaks. These results suggest the participation of several oscillators in the generation and/or expression of the circadian rhythm.     

Oscillatory processes in lymph microcirculation in the human skin

This study was the first to use laser Doppler flowmetry followed by wavelet analysis in order to estimate oscillations in lymph microcirculation in 30 subjects with (n = 13) or without (n = 17) edema of the distal part of the upper limb. Lymph flow in the human skin exhibited clear dominance of pacemaker phase oscillations in the frequency ranges of 0.021–0.042 and 0.016–0.035 Hz in the skin of the palm surface of the finger nail bone and in the skin of the forearm, respectively. Edema was associated with an increase in the peak frequencies and normalized maximum amplitudes (Al/Ml, where Al is the mean value of the maximum amplitude of phase oscillations, and Ml is the value of the averaged lymph flow expressed in perfusion units). Low-amplitude oscillations were recorded rarer in the myogenic, endothelial, and respiratory ranges. We did not find any cardiac pulse rhythm in the wavelet spectrum of the lymph flow. We did not find any interaction between the Al/Ml value and the skin temperature. In the group of subjects without edema, under physiological conditions only, we found a negative correlation between the Al/Ml value and the amplitudes of myogenous proper blood flow oscillations, which reflected the number of functional capillaries and activity of oxidative metabolism in the tissue. In the group with edema, we did not find any correlations between the indices of lymph flow and blood flow. The values of normalized amplitude and frequency of phase oscillations may be used as efficient diagnostic tools in the studies on lymph microcirculation.     

Cardiac Rhythm Variability: Approaches to Mechanisms

Physiological mechanisms of cardiac rhythm variability (CRV) are reviewed. The results of original experiments are discussed together with the history of the problem and data available from the literature. Special emphasis is placed on the spectral analysis of cardiac rhythm. Various mechanisms of the generation of periodic and aperiodic components of CRV are considered. Although the variability of cardiac rhythm has been studied for many years in many laboratories worldwide, fine mechanisms of CRV remain obscure. However, a number of specific features of CRV are presently widely recognized. Periodic CRV components isolated from short-term records in patients at rest are represented by high-frequency, low-frequency, and very low-frequency oscillations. Fourier-transform spectral analysis of cardiac rhythm is the most appropriate method of the detection of these oscillations. High-frequency components are associated with respiration and represent the effects of the parasympathetic nervous system on myocardium. Low-frequency components are due to the activity of the postganglionic sympathetic fibers and represent the processes of cardiac rhythm modulation by the sympathetic nervous system. Genesis of very low-frequency oscillations is still uncertain. Most probably, these oscillations are associated with the effects of suprasegmental (primarily, hypothalamic) centers of autonomic regulation. Aperiodic CRV components represent random events associated with the reflex regulation of the heart rate by external or internal factors. Because aperiodic components significantly modify the results of the CRV analysis, the effects of these factors should be eliminated. It is concluded that because many problems associated with cardiac rhythm variability remain to be solved, extensive research in this direction should be continued.     

Phase synchronization of skin blood flow oscillations in humans under asymmetric local heating

The hypothesis is proposed that an external local stimulus may cause a change in the phase relationships of oscillations in the peripheral skin blood flow of contralateral extremities. To test this assumption, the wavelet phase coherence of skin blood flow oscillations of the left and right forearms of 18 healthy volunteers of both sexes at rest and in response to unilateral local heating was investigated. An area of the skin of the left forearm was exposed to heat and the native blood perfusion in an area of the skin of the right forearm was recorded simultaneously. It was shown that an asymmetric local change of skin perfusion led to a significant change in the phase relationships of the blood flow oscillations in all the analyzed frequency ranges. A significant reduction of phase synchronization of oscillations of skin blood flow in the range of endothelial, neurogenic, and myogenic activity, as well as in the range of respiratory rhythm was revealed. In contrast, in the range of the cardiac rhythm, a significant increase in phase synchronization of the oscillations of the blood flow of contralateral skin areas of the forearm was detected.     

Oscillations in calcium-cyclic AMP control loops form the basis of pacemaker activity and other high frequency biological rhythms.

In this paper theoretical and experimental evidence is presented which indicates that oscillations in internal calcium and cyclic AMP concentrations due to an instability in their common control loops are possible and indeed may be widespread. Further, it is demonstrated that fluctuations in various cellular properties, in particular membrane potential, are a direct consequence of these second messenger oscillations. Given the central importance of calcium and cyclic AMP to the regulation of metabolism, these oscillations would influence most metabolic processes especially rhythmic behaviour. We propose that these oscillations form the basis of several biological rhythms including, potential oscillations in cardiac pacemaker cells, neurones and insulin secreting β-cells, the minute rhythm in smooth muscle, cyclic AMP pulses in Dictyostelium, rhythmical cytoplasmic streaming in Physarum and transepitheliel potential oscillations in Calliphora salivary gland. This model makes possible an explanation of the frequency and amplitude effects of hormones.     

Treatment of a depressive disorder patient with EEG-driven photic stimulation

This study examined the effects of electroencephalographic-(EEG-) driven photic stimulation on a case of depressive disorder, as measured by a psychometric test of mood states, EEG parameters, and several autonomic indices. The EEG-driven photic stimulation enhances the alpha rhythm of brain waves using photic signals, the brightness of which is modulated by a subject's own alpha rhythm. The patient was a 37-year-old businessman, who was treated for depression with medication during the 13 months prior to his first visit to our hospital. He underwent two sets of inpatient treatment sessions, comprising first 16 and then 18 treatment sessions. The treatments brought about the following changes: an improvement in general mood state, alpha rhythm increase, cardiac parasympathetic suppression, and increased skin conductance level. In addition, significant correlations between alpha rhythm increase and cardiac parasympathetic suppression or cardiac sympathetic predominance were observed with each inpatient treatment. Significant correlations between alpha rhythm increase, cardiac parasympathetic suppression, or cardiac sympathetic predominance and the improvement of general mood state were also observed. Thus, from these observations, it was concluded that the alpha enhancement induced by EEG-driven photic stimulation produced an improvement in the patient's depressive symptomatology connected with cardiac parasympathetic suppression and sympathetic predominance.     

Simulation of the hippocampal theta rhythm

Centre of Theoretical and Computational Neuroscience, University of Plymouth, UK Basing on the hypothesis about the mechanisms of the theta rhythm generation, the article presents mathematical and computational models of theta activity in the hippocampus. The problem of the theta rhythm modeling is nontrivial because the slow theta oscillations (about 5 Hz) should be generated by a neural system composed of frequently firing neural populations. We studied a model of neural pacemakers in the septum. In this model, the pacemaker follows the frequency of the external signal if this frequency does not deviate too far from the natural frequency of the pacemaker, otherwise the pacemaker returns to the frequency of its own oscillations. These results are in agreement with the experimental records of medial septum neurons. Our model of the septal pacemaker of the theta rhythm is based on the hypothesis that the hippocampal theta appears as a result of the influence of the assemblies of neurons in the medial septum which are under control of pacemaker neurons. Though the model of the pacemaker satisfies many experimental facts, the synchronization of activity in different neural assemblies of the model is not as strong as it should be. Another model of the theta generation is based on the anatomical data about the existence of the inhibitory GABAergic loop between the medial septum and the hippocampus. This model shows stable oscillations at the frequency of the theta rhythm in a broad range of parameter values. It also provides explanation to the experimental data about the variation of the frequency and the amplitude of the theta rhythm under different external stimulations of the system. The role of the theta rhythm for information processing in the hippocampus is discussed.     

Quantitative estimation of connection of the heart rate rhythm with motor activity in rat fetuses

In rat fetuses over E17-20 with preserved placental circulation with use of mathematical analysis there were revealed value and character of connections of slow wave oscillations of the heart rhythm with motor activity for 30 min of observation. In the software PowerGraph 3.3.8, normalization and filtration of the studied signals were performed in three frequency diapasons: D1-0.02–0.2 Hz (5–50 s), D2-0.0083-0.02 Hz (50 s-2 min), and D3-0.0017–0.0083 Hz (2–10 min). The EMG curves filtrated by diapasons or piezograms were compared with periodograms in the corresponding diapasons of the heart rhythm variations. In the software “Origin 8.0”, quantitative estimation of the degree of intersystemic interrelations for each frequency diapason was performed by Pearson correlation of coefficient, by the correlation connection value, and by the time shift of maximum of cross-correlation function. It has been established that in the frequency D1, regardless of age, the connection of heart rhythm oscillations with motor activity is expressed weakly. In the frequency diapason D2, the connection in most cases is located in the zone of weak and moderate correlations. In the multiminute diapason (D3), the connection is more pronounced. The number of animals that have a significant value of the correlation connection rises. The fetal motor activity fires in the decasecond diapason in all age groups are accompanied by short-time decelerations of the heart rhythms. In the minute diapason, there is observed a transition from positive connections in E17 and E18 to the negative ones in E19-20. Results of the study are considered in association with age-related changes of ratios of positive and negative oscillations of the heart rhythm change depending on the character of motor activity.     

Serotonin modulates oscillation parameters of the membrane potential in isolated spinal neurons in the lamprey

The 5-HT was shown to depolarize branch cells (supposedly motoneurones and interneurones) by 2-6 mV, inducing, however, no MP oscillations. In case the MP oscillations were present (induced by the NMDA, for instance), the 5-HT altered their parameters: increased the amplitude of all types of oscillations, frequency of irregular oscillations, and duration of the depolarising plateau with the AP discharges. This modulation of the induced oscillations may enhance activity of neuronal locomotor network and thus reinforce muscle contractions and increase the intensity of the animal's movements. Possible mechanisms of the receptor modulation, of the AP enhancement, and of the changes in locomotor rhythm parameters, are discussed.     

Locomotion-related oscillatory body movements at 6-12 Hz modulate the hippocampal theta rhythm

The hippocampal theta rhythm is required for accurate navigation and spatial memory but its relation to the dynamics of locomotion is poorly understood. We used miniature accelerometers to quantify with high temporal and spatial resolution the oscillatory movements associated with running in rats. Simultaneously, we recorded local field potentials in the CA1 area of the hippocampus. We report that when rats run their heads display prominent vertical oscillations with frequencies in the same range as the hippocampal theta rhythm (i.e., 6-12 Hz). In our behavioral set-up, rats run mainly with speeds between 50 and 100 cm/s. In this range of speeds, both the amplitude and frequency of the "theta" head oscillations were increasing functions of running speed, demonstrating that the head oscillations are part of the locomotion dynamics. We found evidence that these rhythmical locomotor dynamics interact with the neuronal activity in the hippocampus. The amplitude of the hippocampal theta rhythm depended on the relative phase shift with the head oscillations, being maximal when the two signals were in phase. Despite similarity in frequency, the head movements and LFP oscillations only displayed weak phase and frequency locking. Our results are consistent with that neurons in the CA1 region receive inputs that are phase locked to the head acceleration signal and that these inputs are integrated with the ongoing theta rhythm.     

Use of a Physiological Monitoring Model for Comprehensive Evaluation of Adaptive Capacities in Schoolchildren during Learning: I. Influence of Various Motor Activity Regimens on Cardiac Rhythm Indices in Junior Schoolchildren

The dynamics of changes in the indices of the autonomic regulation of cardiac rhythm was studied in junior schoolchildren during adaptation to physical exercise. An analysis of variation pulsometry parameters throughout the school year showed the role of the sympathetic and parasympathetic parts of the autonomic nervous system in the formation of body adaptive reactions to various motor activity regimens.     

Development of psychomotor tempó (tapping speed and stability) and EEG alpha frequency in 7 to 15-years-old children

The psychomotor tempo (tapping) and its relation to alpha frequency was investigated in 100 7- to 15-year-old children. The frequency of alpha rhythm increased in proportion to age, and the maximum and preferential tapping frequencies revealed an increasing tendency, too. Mainly the preferential tapping frequency correlated with the age-dependent increment of EEG alpha frequency. Simultaneously, the variability of the tapping frequency decreased. During a phase of relatively stable tapping performance regular fluctuations in the tapping frequency occurred with a period duration between 0.67 and 13.3 s. These oscillations of the motor activity developed during ontogenesis: The slow fluctuations were found in all groups, whereas those with shorter periods were best pronounced in the older children. The development of EEG and psychomotor indices are assumed to be based on the morphological and functional maturation of the developing brain. Therefore, they may be used as a tool to assess the normal and disturbed brain development.     

Temporal location of the cardiac rhythm frequency structure based on discrete wavelet transform

Application of discrete wavelet transform to the temporal location of the frequency structure of the cardiac rhythm is considered. A method for analysis of tachograms (TGs) consisting of signal preparation, discrete wavelet transform, and a variant of estimation of the relative contributions of the rhythm frequency components is suggested. The use of the method is exemplified by analysis of a TG containing recordings of transitional processes, including the moments of a fixed respiration rate test, Valsalva test, and orthostatic test. The detected characteristics of changes in the frequency components are demonstrated by comparing them with the changes in the integral index of the total regulatory effect on the sinus node, which forms the response to these functional tests.     

Role of sympathetic and parasympathetic mechanisms in formation of secondary cardiac rhythms in rats ontogenesis

In progeny of Wistar rats aged from birth to 3 week, there was studied participation of sympathetic and parasympathetic mechanisms in regulation of cardiac rhythm and its rhythmic oscillations (secondary cardiac rhythms), whose spectral composition was analyzed using rapid Fourier transformation. Consequences, which changed in the process of development, of blockade of -adrenoreceptors by propranolol, of -adrenoreceptors by phentolamine, and of muscarinic cholinoreceptors by atropine as well as of chronic desympathization by guanethidine (isobarine). It was found that due to heterochronia in establishment of functions of sympathetic and parasympathetic nervous systems, reactions to blockade of adreno- and cholinoreceptors for the first 3 weeks of postnatal ontogenesis changed not only quantitatively, but also qualitatively. Blockade of adrenoreceptors in newborn animals leads to an increase of power of the rhythm oscillations in all low-frequency diapasons. The baroreflex function of parasympathetic innervation is well expressed as early as in newborns. Tonic function with respect to frequency of heart rate and power of oscillations in the high-frequency diapason becomes evident only by the 3-week age.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 69–75.Original Russian Text Copyright © 2005 by Bursian, Sizonov, Semenova, Kulaev, Timofeeva, Polyakova, Dmitrieva.     

Age-related differences in the dynamics of the skin blood flow oscillations during postocclusive reactive hyperemia

Age-related changes in peripheral microcirculation were studied using laser Doppler flowmetry in 60 apparently healthy subjects. The response of microcirculation to short-term ischemia was studied using the occlusion test. Changes in the amplitude of the peripheral blood flow oscillations were determined using time-amplitude analysis based on continuous adaptive wavelet filtration. The oscillation amplitude in the frequency range of the heart rate was found to reach the maximum with a delay after the removal of the occlusion, whereas in the range of the respiratory rhythm, no delay was observed. The hyperemic response to short-term ischemia is assumed to develop under the predominant influence of the arterial-arteriolar component, whereas the dynamics of amplitude oscillations in the range of the respiratory rhythm is a result of the devastation of the venular component after removal of occlusion. In response to short-term ischemia, the maximum oscillation amplitudes of myogenic, neurogenic, and endothelial rhythms decreased with age, which demonstrates the restriction of the regulatory control of the peripheral blood flow by the corresponding systems.     

HIGH FREQUENCY OSCILLATIONS IN THE ACTIVITY OF PHOSPHOTYROSINE PHOSPHATASE IN MURINE ERYTHROLEUKAEMIC CELLS: ACTION OF INSULIN AND HEXAMETHYLENE BISACETAMIDE

We have previously reported oscillations in the activities of the phosphoamino acid phosphatases in murine erythroleukaemic cells. In keeping with our predictions we now show that the phosphotyrosine phosphatase activity rhythm has a much shorter period than originally seemed the case, being of the order of 10min and probably less. The periodic changes show evidence of rhythmic modulation of mean, period and amplitude as with all other cellular oscillations studied. Insulin decreases the frequency of the rhythm while the inducer of differentiation, hexamethylene bisacetamide (HMBA) decreases its amplitude. Current ideas on phosphorylation dynamics in relation to metabolism and mitosis may need to be revised in the light of the observations.     

Oscillatory Transpiration of Avena Plants: Perturbation Experiments Provide Evidence for a Stable Point of Singularity

Oscillatory plant water regulation of young Avena plants was studied. The period of the oscillations was around 40 min. Pulse perturbations were given to plants showing oscillations in the transpiration rate. Perturbations consisted in temporary irradiance changes of the leaf or in water potential changes around the root. The effect of the pulse perturbations on the amplitude of the oscillations was recorded. The oscillations could be permanently halted after a perturbation of suitable magnitude given at a suitable phase of The oscillations. A subsequent perturbation could restart the oscillations again. By means of simulations it was shown that a feedback model For the transpiration oscillations could explain the experimental outcome if a non finearity of a special kind was incorporated. The circadian eclosion rhythm of Drosophila pseudoobscura and the petal rhythm of Kalanchoe blossfeldiana show many features in common with the experiments reported. Biophysically the present results indicate that the transpiration oscillations of Avena plants have a stable point of equilibrium or a stable point of singularity.