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Rhythmic Oscillations (rhythmic + oscillation)
Selected AbstractsOral compression activity on a surrogate nipple in the newborn rat: Nutritive and nonnutritive suckingDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2003Andrey P. Kozlov Abstract Newborn rats, 3 hr after birth and before any experience in suckling, were exposed for 10 min to a surrogate nipple providing milk. One hour later, they were exposed to an empty nipple for another 10-min period. The basic characteristics of oral behavior (oral compression activity, OCA) were assessed by recording intranipple pressure during the pups' first attachment to a nipple. The peculiarities of milk-induced changes of OCA were examined with three modes of milk delivery (milk infusions, and intermittent and continuous milk deliveries). The pattern of OCA exerted by the newborn pups on a surrogate nipple consisted of rhythmic oscillations within a frequency range of 0.4 to 1.0 Hz, superimposed on slow (frequency,<,0.2 Hz), irregular intranipple pressure fluctuations. Oral behavior during the first minute after oral capture of the nipple differed significantly from that during any subsequent 1-min interval in terms of frequency content of OCA. The pattern of OCA changes induced by milk infusions or intermittent milk delivery included an abrupt rise in intranipple pressure, accompanied or followed by a burst of fast nipple compressions (bites). Our data suggest that newborn rats attached to a surrogate nipple demonstrate patterns of oral behavior that simulate, in terms of basic frequency characteristics, patterns of nutritive and nonnutritive suckling observed in more mature pups on the maternal nipple. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 43: 290,303, 2003. [source] Persistent rhythmic oscillations induced by nicotine on neonatal rat hypoglossal motoneurons in vitroEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2006Nerijus Lamanauskas Abstract Patch-clamp recording from hypoglossal motoneurons in neonatal Wistar rat brainstem slices was used to investigate the electrophysiological effects of bath-applied nicotine (10 µm). While nicotine consistently evoked membrane depolarization (or inward current under voltage clamp), it also induced electrical oscillations (3,13 Hz; lasting for , 8.5 min) on 40% of motoneurons. Oscillations required activation of nicotinic receptors sensitive to dihydro-,-erythroidine (0.5 µm) or methyllycaconitine (5 nm), and were accompanied by enhanced frequency of spontaneous glutamatergic events. The slight voltage dependence of oscillations and their block by the gap junction blocker, carbenoxolone, suggest they originate from electrically coupled neurons. Network nicotinic receptors desensitized more slowly than motoneuron ones, demonstrating that network receptors remained active longer to support heightened release of the endogenous glutamate necessary for enhancing the network excitability. The ionotropic glutamate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and the group I metabotropic receptor antagonist, (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA), suppressed oscillations, while the NMDA receptor antagonist, d -amino-phosphonovaleriate (APV), produced minimal depression. Nicotine-evoked oscillations constrained spike firing at low rates, although motoneurons could still generate high-frequency trains of action potentials with unchanged gain for input depolarization. This is the first demonstration that persistent activation of nicotinic receptors could cause release of endogenous glutamate to evoke sustained oscillations in the theta frequency range. As this phenomenon likely represented a powerful process to coordinate motor output to tongue muscles, our results outline neuronal nicotinic acetylcholine receptors (nAChRs) as a novel target for pharmacological enhancement of motoneuron output in motor dysfunction. [source] Tetanic stimulation of Schaffer collaterals induces rhythmic bursts via NMDA receptor activation in rat CA1 pyramidal neuronsHIPPOCAMPUS, Issue 4 2002Christian Bonansco Abstract Exploring the principles that regulate rhythmic membrane potential (Vm) oscillations and bursts in hippocampal CA1 pyramidal neurons is essential to understanding the , rhythm (,). Recordings were performed in vitro in hippocampal slices from young rats, and a group of the recorded CA1 pyramidal cells were dye-filled with carboxifluorescein and immunolabeled for the R1 subunit of the NMDA receptor. Tetanic stimulation of Schaffer collaterals (SCs) and iontophoresis of glutamate evoked rhythmic Vm oscillations and bursts (,10 mV, ,7 Hz, 2,5 spikes per burst) in cells (31%) placed close to the midline ("medial cells"). Rhythmic bursts remained under picrotoxin (10 ,M) and Vm oscillations persisted with tetrodotoxin (1.5 ,M), but bursts were blocked by AP5 (25 ,M) and Mg2+ -free solutions. Depolarization and AMPA never induced rhythmic bursts. The rest of the neurons (69%), recorded closer to the CA3 region ("lateral cells"), discharged rhythmically single repetitive spikes under SC stimulation and glutamate in control conditions, but fired rhythmic bursts under similar stimulation, both when NMDA was applied and when non-NMDA receptors were blocked with CNQX (20 ,M). Medial cells exhibited a larger NMDA current component and a higher NMDAR1 density at the apical dendritic shafts than lateral cells, suggesting that these differences underlie the dissimilar responses of both cell groups. We conclude that the ",-like" rhythmic oscillations and bursts induced by glutamate and SC stimulation relied on the activation of NMDA receptors at the apical dendrites of medial cells. These results suggest a role of CA3 pyramidal neurons in the generation of CA1 , via the activation of NMDA receptors of CA1 pyramidal neurons. Hippocampus 2002;12:434,446. © 2002 Wiley-Liss, Inc. [source] Gonadotrophin-Releasing Hormone Pulse Generator Activity in the Hypothalamus of the GoatJOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2009S. Ohkura Pulsatile release of gonadotrophin-releasing hormone (GnRH) is indispensable to maintain normal gonadotrophin secretion. The pulsatile secretion of GnRH is associated with synchronised electrical activity in the mediobasal hypothalamus (i.e. multiple unit activity; MUA), which is considered to reflect the rhythmic oscillations in the activity of the neuronal network that drives pulsatile GnRH secretion. However, the cellular source of this ultradian rhythm in GnRH activity is unknown. Direct input from kisspeptin neurones in the arcuate nucleus (ARC) to GnRH cell bodies in the medial preoptic area or their terminals in the median eminence could be the intrinsic source for driving the GnRH pulse generator. To determine whether kisspeptin signalling could be responsible for producing pulsatile GnRH secretion, we studied goats, measured plasma levels of luteinising hormone (LH) and recorded MUA in the posterior ARC, where the majority of kisspeptin neuronal cell bodies are located. Rhythmic volleys of MUA were found to be accompanied by LH pulses with regular intervals in the ARC, where kisspeptin neuronal cell bodies were found. Exogenous administration of kisspeptin stimulated a sustained increase in LH secretion, without influencing MUA, suggesting that the GnRH pulse generator, as reflected by MUA, originated from outside of the network of GnRH neurones, and could plausibly reflect the pacemaker activity of kisspeptin neurones, whose projections reach the median eminence where GnRH fibres project. These observations suggest that the kisspeptin neurones in the ARC may be the intrinsic source of the GnRH pulse generator. [source] Bridging Mucosal Vessels Associated with Rhythmically Oscillating Blood Flow in Murine ColitisTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2008Aslihan Turhan Abstract Oscillatory blood flow in the microcirculation is generally considered to be the result of cardiopulmonary influences or active vasomotion. In this report, we describe rhythmically oscillating blood flow in the bridging vessels of the mouse colon that appeared to be independent of known biological control mechanisms. Corrosion casting and scanning electron microscopy of the mouse colon demonstrated highly branched bridging vessels that connected the submucosal vessels with the mucosal plexus. Because of similar morphometric characteristics (19 ± 11 ,m vs. 28 ± 16 ,m), bridging arterioles and venules were distinguished by tracking fluorescent nanoparticles through the microcirculation using intravital fluorescence videomicroscopy. In control mice, the blood flow through the bridging vessels was typically continuous and unidirectional. In contrast, two models of chemically induced inflammation (trinitrobenzenesulfonic acid and dextran sodium sulfate) were associated with a twofold reduction in flow velocity and the prominence of rhythmically oscillating blood flow. The blood oscillation was characterized by tracking the bidirectional displacement of fluorescent nanoparticles. Space,time plots and particle tracking of the oscillating segments demonstrated an oscillation frequency between 0.2 and 5.1 cycles per second. Discrete Fourier transforms demonstrated a power spectrum composed of several base frequencies. These observations suggest that inflammation-inducible changes in blood flow patterns in the murine colon resulted in both reduced blood flow velocity and rhythmic oscillations within the bridging vessels of the mouse colon. Anat Rec, 291:74,82, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||