Theta frequency

Rapid eye movement sleep. Sleep stage characterized by rapid movements of the eyes and asynchronous EEG activity in the theta-frequency (5-10Hz) range. Counterpart is slow wave sleep, characterized by other electrophysiological (synchronized low frequency l-2Hz, large amplitude EEG and neuronal sharp wave-ripple oscillations) and endocrine (growth hormone surge) activities. 

Wess J (2004) Muscarinic acetylcholine receptor knockout micemovel phenotypes and clinical implications. Ann Rev Pharmacol Toxicol 44 423-50 Winder DG, Martin KC, Muzzio IA, Rohrer D, Chruscinski A, Kobilka B, Kandel ER (1999) ERK plays a regulatory role in induction of LTP by theta frequency stimulation and its modulation by 3-adrenergic receptors. Neuron 24 715-26... 

Ang CW, Carlson GC, Coulter DA. 2005. Hippocampal CA1 circuitry dynamically gates direct cortical inputs preferentially at theta frequencies. J Neurosci 25 9567-9580. 

In GABAa /13 receptor subunit-deficient mice, functional expression of GC GABAa receptors was almost eliminated, amplitudes of mitral/tufted cell miniature IPSPs, theta-frequency oscillations, and /-frequency oscillations were increased, and discrimination of closely related mixtures of alcohols after training was poor relative to normal mice (Nusser et al., 2001). These results provide functional evidence for the importance of both GC and mitral/tufted cell GABAa receptors in olfaction. 

Hayar A, Kamup S, Shipley MT, Ennis M. 2004a. Olfactory bulb glomeruli External tufted cells intrinsically burst at theta frequency and are entrained by patterned olfactory input. J Neurosci 24 1190-1199. 

DAngelo, E., T. Nieus, A. Maffei, S.A.R Rossi, V. TagHetti, A. Fontana, and G. Naldi (2001). Theta-frequency bursting and resonance in cerebellar granule cells experimental evidence and modehng of a slow K+-dependent mechanism. /. Neurosci. 21,759-770. 

The results showed that the participants became less vigilant and reported more TUITs over the course of the session. The measures of absolute power in the alpha, beta, and theta frequency bands did not show any differences across the pre-TUIT and post-TUTT intervals. However, significant increases fiom pre-to post-TUIT in the value of two of the power band ratios, beta/(alpha +theta) and beta/alpha, were observed for all parietal lobe sites (Pz, P3, and P4). Cunningham etal. (in press) concluded power band ratios may provide a more sensitive measure of fluctuations in attention than more Iradilional measures of absolute power within any individual frequency band. 

There are two parts to the EEG analysis in Huang, et al. s research (2008). At first, the researchers analyzed the EEG data to make sure that the participants emotional responses really were induced. The EEG data from task C (neutral affect) was the baseline of the EEG waveform for individual participants. If the participants showed more positive than neutral affect, the power value of the alpha frequency band would be higher. In contrast, if the participants showed more negative than neutral affect, the power value of the alpha frequency band would be lower (Huang et al., 2008). The data which did not reflect the expected emotions were rejected. Second, the data which were accepted were analyzed to identify changes in the power value of the theta frequency band. The theta frequency band is always identified as the indicator to assess creativity. 

Dose-related shifts in predominant EEG frequency for PCP and several phencyclinoids are shown in figure 3. For all 10 compounds tested, there was a shift in predominant EEG frequency into the theta range across the lower doses, associated primarily with increased locomotor activity and stereotyped behaviors. With further increases in dose, PCP and all of its analogues produced shifts to lower predominant frequencies, which typically fell between 2 and 4 Hz. As the dose was incremented geometrically, the lower frequency EEG waves were associated first with ataxia, then with dyskinetic movements, catalepsy, and possibly seizure activity. SKF-10,047 also produced ataxia, but was unique in that it did not cause a shift to a lower predominant frequency and produced only EEG theta activity at all subconvulsant doses. 

Administration of HA and its effect on sleep-wakefulness Local application of HA (5, 30 and 60 pg) in the TMN region of cats increased the latency to sleep, increased arousal, and reduced NREM sleep in a site-specific, dose-dependent manner. The highest dose produced the maximal effect, which lasted for 6 h. The HA-induced arousal was completely blocked when the cats were pretreated intraperitoneally with the Hi receptor antagonist mepyramine (Lin et at, 1986, 1988). In rats, intraventricular administration of HA blocked the increase in delta and theta activity (0-6 Hz) in the EEG induced by repeated low-frequency stimulation of the midbrain reticular formation. This effect was blocked if specific thalamic nuclei were lesioned (Tasaka et at, 1993) or by simultaneous administration of an Hi receptor antagonist, but not by an H2 receptor antagonist (Tasaka et at, 1989). Application of HA... 

These data thus confirm our initial hypothesis that mGlu2/3 receptors are tonically active in lowering the level of brain arousal. Thus, antagonizing these receptors increases arousal as evidenced by the increase in waking and the stimulation of high-frequency EEG power. The striking increase in theta power was unexpected but is also consistent with increased arousal. 

Electrophysiological Tobacco smoking produces cortical activation on the EEG. Broadly, it reduces slow-wave activity (theta and delta) and increases activity in alpha and beta frequency bands (Knott et al. 1998 Pritchard et al. 1999). Other studies have found more isolated effects in alpha frequencies (Domino and Matsuoka 1994 Foulds et al. 1994). 

Regarding EEG frequencies outside the delta band, several micro-architectural sleep EEG characteristics of depression have been sought in both the remitted and the symptomatic state [Armitage 1995]. Based on preliminary data, certain computerized sleep EEG patterns appear to be relatively specific to depression [e.g., an elevated fast frequency activity on the right hemisphere and a reduced beta and theta interhemispheric coherence] [Armitage et al. 1991, 1992c, 1993]. The consistency of all these findings, however, has not yet been established. 

Chlorpromazine and clozapine at low doses lead to an increase in slow (delta, theta) waves and a decrease in alpha activity in the pharmaco-EEG of healthy subjects. Findings regarding beta activity are less uniform. Rohloff et ul. (1992) reported on an increase in slow frequency components and a decrease of alpha and beta activity after 4.0 mg of haloperidol. Low doses of amisulpride (up to 50 mg) were reported to display an alertness-enhancing effect (Rosenzweig et ul., 2002). 

As can be seen from Fig. 30-32, neurons send "trains" of spikes down their axons. These form synapses with dendrites, usually on dendritic spikes, of a postsynaptic cell.593,1007-1009 However, each such cell typically receives input from thousands of other neurons. At any moment most of these are probably "silent," but others are sending trains of impulses. Among the important questions are "How does the postsynaptic neuron know whether to fire or not " and "What kinds of information, if any, are encoded in the trains of impulses both in the presynaptic inputs and in the output of the postsynaptic neuron "10101011 Part of the answer to the first question is probably that firing occurs if two or more input impulses arrive synchronously,10101012-1014 and if there are not too many inhibitory impulses that damp the response. In the hippocampus a network of neurons electrically coupled via gap junctions may be synchronized to the theta and gamma brain rhythms by high-frequency (150-200 Hz) oscillations.988 See also Fig. 30-15. 

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