Psychiatry related information on Theta Rhythm

• Central nicotinic receptors have been implicated in Alzheimer's disease, seizure activity, the generation of slow-wave theta rhythm in the hippocampus and the potential abuse liability of nicotine [1].
• PLC-beta1(-/-) mice also have somewhat disrupted theta activity during paradoxical sleep but do have an atropine-resistant component of theta rhythm [2].

High impact information on Theta Rhythm

• Here we show that mice harboring a phospholipase C (PLC)-beta1(-/-) mutation (PLC-beta1(-/-) mice) lack one subset of theta rhythms normally observed during urethane anesthesia, alert immobility, and passive whole-body rotation [2].
• We show that a single burst of five pulses at 200 Hz given on the positive phase of tail pinch-triggered theta rhythm reliably induced LTP in the stratum radiatum of the hippocampus of urethane-anesthetized rats [3].
• Effects of 5-HT3 receptor antagonism on hippocampal theta rhythm, memory, and LTP induction in the freely moving rat [4].
• Unilateral fimbria lesions left theta rhythm and AChE staining essentially unaltered in ipsilateral DHPC and MEC but depleted AChE in ipsilateral ventral hippocampus (VHPC) and ventral lateral entorhinal cortex (LEC) [5].
• A lesion of the dorsal fornix at the level of the hippocampal flexure left ipsilateral DHPC theta rhythm and AChE stain unaltered while causing a substantial reduction in theta rhythm and depletion of AChE in ipsilateral MEC [5].

Biological context of Theta Rhythm

• Intraventricular (i.c.v.) AMPA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX, 5-10 microg) decreased the commissural evoked potential and the amplitude of the hippocampal EEG, including the theta rhythm [6].
• The faster changes in synaptic potentials caused by GABA could cause changes within each cycle of the theta rhythm, rapidly switching between encoding and retrieval dynamics during exploration [7].
• Fifty-six percent of the cells in this sample were termed theta (theta)-related, i.e., they exhibited membrane potential oscillations of 5-28 mV and rhythmic spike discharges related to the carbachol-induced extracellular theta-rhythm [8].

Anatomical context of Theta Rhythm

• Each rat served as its own control and the properties of the hippocampal theta rhythm were studied before and after ibotenic acid and control saline infusion into the medial septal area [9].
• The coherence and the phase of the theta rhythm at the CA1 apical dendrites, with respect to a superficial electrode, also declined significantly after ibotenic acid lesion [9].
• In the urethane-anesthetized rat, it was found that procaine injections attenuated both the frequency and amplitude of theta rhythm elicited by stimulation of the pontine reticular formation [10].
• Pharmacological suppression of the median raphe nucleus with serotonin1A agonists, 8-OH-DPAT and buspirone, produces hippocampal theta rhythm in the rat [11].
• The most intense NCAM PSA immunoreactivity was observed in the medial and triangular septal nuclei, regions that regulate hippocampal theta rhythm during memory consolidation [12].

Associations of Theta Rhythm with chemical compounds

• These results suggest tha MSA paces MEC theta rhythm and that the presumed cholinergic projection which mediates this function travels in the dorsal fornix [5].
• MEASUREMENTS AND RESULTS: In artificially ventilated rats, carbachol injections repeatedly elicited cortical activation and hippocampal theta rhythm [13].
• These results suggest a role of interactions between NMDA conductance and intrinsic membrane properties in generating the CA1 theta-rhythm [14].
• Hippocampal theta rhythm in behaving rats following ibotenic acid lesion of the septum [9].
• A constant impulse flow in the septohippocampal GABA pathway is essential for the generation of theta rhythm [15].

Gene context of Theta Rhythm

• However, in mice, inhibition of ERK activation blocked LTP induced by two LTP induction paradigms that mimicked the endogenous theta rhythm [16].
• The pronounced theta rhythm characteristic of unanesthetized mocha mice was not observed in these chloral-hydrate anesthetized mice, whereas spike discharge activity was frequently present in the recordings [17].
• A frontal midline theta rhythm increased in magnitude with increased memory load [18].
• Intrahippocampal injection of NMDA receptor antagonist D-2-amino-5-phosphonovaleric acid (D-APV, 2.5 microg) decreased the amplitude of the theta rhythm and, less consistently, the gamma EEG [6].
• Opposite effects of oxytocin and vasopressin on avoidance behaviour and hippocampal theta rhythm in the rat [19].

Analytical, diagnostic and therapeutic context of Theta Rhythm

• The activity of 72 neurons recorded in the reticularis pontis oralis nucleus (RPO) was examined in anesthetized and curarized rats during hippocampal theta (theta) rhythm elicited by either sensory stimulation or carbachol microinjections [20].
• Brainstem carbachol injections in the urethane anesthetized rat produce hippocampal theta rhythm and cortical desynchronization: a comparison of pedunculopontine tegmental versus nucleus pontis oralis injections [21].
• Hippocampal and entorhinal cortex glucose metabolism were studied by 14C-2-deoxyglucose (2-DG) autoradiography in anesthetized rats with and without continuous theta rhythm (theta) [22].
• When these subjects were reexamined, the rate of appearance of the frontal midline theta rhythm which appears during light drowsiness was 87.2% in the theta group and 0% in the control group [23].

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