Slow oscillation

Oscillations in the EEG of between 0.5 and 4 Hz, sometimes also called delta activity. SWA is a hallmark of the sleeping brain, and is most prevalent in the deepest sleep stages (stages 3 4). The slow oscillations arise from widespread synchrony of neuronal firing, particularly in the thalamocortical circuits. 

Woo TU, Whitehead RE, Melchitzky DS, Jewis DA (1998) A subclass of prefrontal GABA axon terminals are selectively altered in schizophrenia. Proc Natl Acad Sci U S A 95 5341-5346 Zhang Y, Perez Velazquez JL, Tian GE, Wu CP, Skinner FK, Caslen PL, Zhang L (1998) Slow oscillations (< 1 Hz) mediated by GABAergic interneuronal networks in rat hippocampus. J Neurosci 18 9256-9268... 

Cerebral cortex has an intrinsic oscillating field in the extracellular fluid, the EEG. It appears to originate principally in the enormously branched dendrites that characterize cerebral neurons. Measured over cellular dimensions, the EEG has a typical gradient of 50 mV/cm (20, 21), and a frequency spectrum from 1 to 100 Hz, with most energy in the band from 1 to 20 Hz. Records from intracellular microelectrodes in many but not all cerebral neurons display large slow oscillations up to 15 mV in amplitude that resemble the EEG from the same cortical region in spectral analyses. However, with an amplitude of 20-50 uV, the EEG is less than 1.0 percent of the amplitude of the intracellular neuronal waves from which it is derived, due to its attenuation in the neuronal membrane. 

Hence, the competition between the two subsystems of slow oscillations and fast event generation seems to play a major role for physiologically and pathophysi-... 

Figure 12.2b shows such a power spectrum for the tubular pressure variations depicted in Fig. 12.2a. This spectrum demonstrates the existence of two main and clearly separated peaks a slow oscillation with a frequency fsiow 0.034 Hz that we identify with the TGF-mediated oscillations, and a significantly faster component at ffasl 0.16 Hz representing the myogenic oscillations of the afferent arteriole. Both components play an essential role in the description of the physiological control system. The power spectrum also shows a number of minor peaks on either side of the TGF peak. Some of these peaks may be harmonics (/ 0.07 Hz) and subharmonics (/ 0.017 Hz) of the TGF peak, illustrating the nonlinear character of the limit cycle oscillations.

In a recent study [34], we made use of wavelet and double-wavelet analysis to examine the relative occurrence of various states of synchronization in pairs of interacting nephrons. We showed that both full and partial synchronization occur for normotensive as well as for hypertensive rats, and that the partial synchronization can involve only the slow oscillations or only the fast oscillations. We also used... 

Figure 4.38 shows the measured magnetization at T = 0.5 K for a field applied perpendicular to the conducting planes [372]. Clearly two different dHvA frequencies are visible in the signal. A slow oscillation of 730 T is superimposed on a dominant high frequency of 4170T. These frequencies correspond to FS areas which are more consistent with the band-structure calculation for the orthorhombic unit cell (Fig. 4.37a) but are in disagreement with the predicted band structure for the monoclinic cell (Fig. 4.37b). 

Successive high-resolution AMRO experiments shown in Fig. 4.39 verified the proposed FS in an impressive way [376]. As mentioned in Sect. 3.3, 0-(ET)2l3 was one of the first compounds where AMRO, i. e., resistance oscillations periodic in tan (9, were observed [258]. These results, which were reproduced later [377], are understood by the warped FS model explained above. The period of the oscillations is related to the Fermi wave vector via (3.18). In the experimental data shown in Fig. 4.39 not only the previously reported fast AMROs but also slow ones (indicated by small dashes) were observed [376]. The insets of Fig. 4.39 show the peak numbers of the (a) fast and (b) slow oscillation frequency vs tan O. From the slopes for different field rotation planes fcr(0) could be constructed. The resulting two ellipsoidal FSs are in good agreement with the proposed topology of Fig. 4.37c with respect to both form and area. 

Fig. 4.39. The main panel shows the angular dependence of the resistance of 0-(ET)2l3 in B = 13T for field rotation in the cb plane (orthorhombic notation). Two superimposed AMROs are visible. The insets show the peaks of (a) the fast and (b) the slow oscillation vs tan0. Prom [376]...

In order to have slow oscillations during and immediately after the laser source being switched on, e is written in terms of the maximum amplitude e0 and the switch-on time t as... 

The rotating wave approximation (RWA) is a useful simplification [465] which contains most of the features of coherent excitation it consists in assuming that only exp(iwt) terms are present (counter rotating terms are neglected), in which case the amplitudes Oi(t) and o/(t) experience only slow oscillations at the frequency Aw, according to the differential equations ... 

Destexhe, A., A. Babloyantz T.J. Sejnowski. 1993. Ionic mechanisms for intrinsic slow oscillations in thalamic relay neurons. Biophys. J. 

Ermentrout, G.B. N. Kopell. 1986. Parabolic bursting in an excitable system coupled with a slow oscillation. SIAM J. Appl. Math. 46 233-53. 

Harmonic and transient relaxation experiments for dodecyl dimethyl phosphine oxide solutions were performed with the elastic ring method by Loglio [240]. This methods allows oscillation experiments in the frequency range from about 0.5 to 0.001 Hz and is suitable for comparatively slow relaxing systems. Slow oscillation experiments can be performed much easier now with the pendent drop apparatus [186]. Both techniques are also able to perform transient relaxation experiments. The two types of experiments have a characteristic frequency defined in the same way by Eq. (4.110). 

The instrument shown schematically in Fig. 26 is suitable for slow oscillation experiments, as it was performed for the first time by Miller et al. in 1993. The frequency limit of the oscillations is given by the condition for the liquid meniscus shape, which has to be Laplacian. Under too fast deformations this condition is not fulfilled and hence the method does not provide reliable results. To reach higher frequencies of oscillation, the above mentioned oscillating drop or bubble experiments are suitable, because the shape of the menisci is spherical due to the small diameter. The instrument of Fig. 26 can be designed such that a pressure sensor and piezo translator are built in and the video system serves as optical control and determines the drop/bubble diameter accurately. 

A complete theory of the hierarchical mechanism of dynamic synaptic activity would require the study of co-operation and competition among the three oscillators. Here only one model, established for explaining the slow oscillation will be presented. The isolated model shows periodic behaviour. 

The skeleton model of the slow oscillation in free acetylcholine can be formulated in terms of mass-action kinetics (Csaszar et al., 1983). In principle, instead of setting up a lumped, skeleton model, a more complex model could be defined to take into account the details of subprocesses (synthesis, storage and release of ACh, cleft processes, transmitter-receptor interaction, diffusion, re-uptake). Experimental information, however, certainly would not be sufficient to parametrise such kinds of models. 

The measurement on the Dg-line in Fig. shows fast beats at 9.2 GHz and only one period of slow oscillation at 200 MHz, which is due to the hyperfine splitting frequencies of the 6p P3 -state. 

The 5-line spectrum may be considered due to slow oscillation about each stable... 

Abstract The physical and experimental technique of gas adsorption measurements by slow oscillations of a rotational pendulum or, hkewise, the relaxational motion of a freely floating rotator are described. Combinations of the pendulum with either gravimetric or volumetric measurements are outhned. These especially are suited to measure the absorption or solubility of gases in non-rigid or swelling sorbent materials like polymers. Pros and cons of these methods are discussed in brief. List of symbols. References. 

MEASUREMENT OF PURE GAS ADSORPTION EQUILIBRIA (N=l) BY SLOW OSCILLATIONS OF A ROTATIONAL PENDULUM... 

The drop and bubble shape tensiometer allows one to perform oscillation experiments. However, in contrast to similar studies with small spherical drops it is limited to slow oscillations. Depending on the hydrodynamic conditions, mainly the rheological behaviour of the bulk phases, oscillation from a certain frequency onwards do not provide drops or bubbles with a Laplacian shape, so that the data analysis will fail and yield unrealistic data. Even for liquids of high grade of purity interfacial tension changes are simulated and hence misinterpretations can be the consequence. Thus, the use of high speed video technique is not really relevant for shape analysis tensiometry (although provided by several companies), as the hydrodynamic relaxation can take much time to yield Laplacian menisci. 

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