Magnetic polarons reach a hundred thousand Bohr magnetons.

The ability of light to manipulate fundamental interactions in a medium is central to research in optomagnetism and applications in electronics. A prospective approach is to create composite quasiparticles, magnetic polarons, highly susceptible to external stimuli. To control magnetic and transport properties by weak magnetic and electric fields, it is important to find materials that support photoinduced magnetic polarons with colossal net magnetic moments.

Irisin/BDNF signaling in the muscle-brain axis and circadian system: A review.

In mammals, the timing of physiological, biochemical and behavioral processes over a 24-h period is controlled by circadian rhythms. To entrain the master clock located in the suprachiasmatic nucleus of the hypothalamus to a precise 24-h rhythm, environmental zeitgebers are used by the circadian system. This is done primarily by signals from the retina the retinohypothalamic tract, but other cues like exercise, feeding, temperature, anxiety, and social events have also been shown to act as non-photic zeitgebers.

Automatic thermal conductivity measurements with 3-omega technique.

This article describes an improvement of the 3-omega thermal conductivity measurement system facilitating automatic mode measurement. The use of the electrical circuit with negative feedback to compensate the first harmonic in the voltage signal on the heater-thermometer eliminates manual resistance tuning. To test the procedure, measurements of the thermal conductivity of single crystal sapphire AlO were made.

[THE EFFECT OF NEUROPEPTIDE Y ON SPIKE ACTIVITY OF NEURONS IN THE SUPRACHIASMATIC NUCLEUS OF RAT IN VITRO].

In the experiments on sagittal hypothalamic slices of male Wistar rats, the effect of 10 nM neuropeptide Y on the electrical activity of the suprachiasmatic nucleus neurons and spike information coding parameters were studied. Applications of neuropeptide Y induced a reduction of action potential frequency in 35 of 81 tested neurons, in 8 cells an increase in the parameter was observed; the remaining 38 neurons did not change their spike activity level. The decrease in spike frequency generation by neurons of the suprachiasmatic nucleus accompanied by an increase in both entropy of interspike interval distribution and mutual information between adjacent interspike intervals.

Activation of glycine receptor phase-shifts the circadian rhythm in neuronal activity in the mouse suprachiasmatic nucleus.

In mammals, the master clock in the suprachiasmatic nucleus (SCN) of the hypothalamus is composed of numerous synchronized oscillating cells that drive daily behavioural and physiological processes. Several entrainment pathways, afferent inputs to the SCN with their neurotransmitter and neuromodulator systems, can reset the circadian system regularly and also modulate neuronal activity within the SCN. In the present study, we investigated the function of the inhibitory neurotransmitter glycine on neuronal activity in the mouse SCN and on resetting of the circadian clock.

Local GABAergic modulation of the activity of serotoninergic neurons in the nucleus raphe magnus.

Experiments on rat brainstem sections in membrane potential clamping conditions addressed the effects of serotonin and GABA on serotoninergic neurons in the nucleus raphe magnus. Local application of serotonin stimulated inhibitory postsynaptic currents (IPSC) in 45% of the serotoninergic neurons studied. This response was not seen in the presence of the fast sodium channel blocker tetrodotoxin.

Mechanisms of the respiratory activity of leptin at the level of the solitary tract nucleus.

Acute experiments on anesthetized laboratory rats were performed to study the effects microinjections of 10(-4) M leptin into the solitary tract nucleus on the extent of the Hering-Breuer inflation reflex in ventilatory reactions to hypercapnia. Local administration of leptin into this area led to inhibition of the Hering-Breuer reflex. The extent of ventilatory responses to hypercapnia, conversely, increased, which may provide evidence that leptin has a modulatory influence on central chemoreceptors.

Secretory cells of the supraoptic nucleus have central as well as neurohypophysial projections.

Conventional neuroanatomical methods may fail to demonstrate the presence of axons that are finer than 1 microm in diameter because such processes are near or below the limit of resolution of the light microscope. The presence of such axons can, however, be readily demonstrated by recording. The most easily interpreted type of recording for this purpose is the demonstration of antidromic activation of the cell body following stimulation of the region through which the axon passes.

Orexin A modulates neuronal activity of the rodent suprachiasmatic nucleus in vitro.

In mammals, as in rats and mice used in the present study, the major internal timekeeping mechanism is located in the suprachiasmatic nucleus (SCN). It is composed of a complex tissue of multiple, individual oscillator cells that drive numerous physiological and endocrine processes via an electrical and humoral output. Several afferent input systems can interact with the clock mechanism and lead to phase-resetting actions.

Leptin modulates spike coding in the rat suprachiasmatic nucleus.

The mammalian circadian pacemaker, the suprachiasmatic nucleus (SCN), contains receptors to the adipose tissue hormone leptin. In the present study, the effects of leptin on the electrophysiological activity of the SCN cells were characterised in vitro in rat brain slices. During extracellular recording, application of 20 nm leptin (n = 36) decreased mean spike frequency (Wilcoxon signed rank test, z = -3.

Respiratory responses to microinjections of leptin into the solitary tract nucleus.

The regulatory peptide leptin has a respiratory stimulating effect along with its well known hypothalamic effects. The present study, performed on anesthetized rats, addressed respiratory responses to microinjections of 10(-10)-10(-4) M leptin into the solitary tract nucleus, which contains a high concentration of leptin receptors. Injections of 10(-8)-10(-4) M leptin led to stimulation of respiration, inducing a dose-dependent increase in the level of pulmonary ventilation and an increase in respiratory volume, accompanied by an increase in bioelectrical activity in the inspiratory muscles; 10(-6) M leptin also induced a transient increase in respiratory rate due to shortening of inhalation and exhalation.

Effects of leucine-enkephalin on potassium currents in neurons in the rat respiratory center in vitro.

Experiments to identify the neuronal mechanisms underlying the respiratory activity of the opioid peptide leucine-enkephalin were performed on transverse slices of the rat brainstem in voltage-clamped conditions; studies addressed the effects of this peptide (10 nM-1 microM) on the potassium A current and the inward potassium current of neurons in two areas of the respiratory center: the ventrolateral area of the solitary tract nucleus and the pre-Bötzinger complex. The parameters of the A current assessed in all respiratory center neurons studied showed no change in the presence of leucine-enkephalin. At the same time, leucine-enkephalin produced reversible increases in the amplitude of the inward potassium current.

Melatonin modulates spike coding in the rat suprachiasmatic nucleus.

The effects of the application of melatonin in vitro on the electrophysiological activity of suprachiasmatic neurones were characterised using novel measures of coding based on the analysis of interspike intervals. Perfusion of 1 nM melatonin in vitro (n = 53) had no consistent effect on mean spike frequency (Wilcoxon's sign rank, z = -0.01, P = 0.

Pharmacological imposition of sleep slows cognitive decline and reverses dysregulation of circadian gene expression in a transgenic mouse model of Huntington's disease.

Transgenic R6/2 mice carrying the Huntington's disease (HD) mutation show disrupted circadian rhythms that worsen as the disease progresses. By 15 weeks of age, their abnormal circadian behavior mirrors that seen in HD patients and is accompanied by dysregulated clock gene expression in the circadian pacemaker, the suprachiasmatic nucleus (SCN). We found, however, that the electrophysiological output of the SCN assayed in vitro was normal.

The effects of leucine-enkephalin on the membrane potential and activity of rat respiratory center neurons in vitro.

Studies of transverse slices of Wistar rat brainstem using a patch clamp technique addressed the effects of the opioid peptide leucine-enkephalin (10 nM-1 microM) on the membrane potential and pattern of spontaneous activity of neurons in two parts of the respiratory center: the ventrolateral area of the solitary tract nucleus and the pre-Bötzinger complex. Leucine-enkephalin induced membrane hyperpolarization of respiratory center neurons and decreased the level of spike activity in spontaneously active cells. In pre-Bötzinger complex neurons showing a burst pattern of activity, leucine-enkephalin decreased the burst frequency, and two cells showed a transition from burst activity to tonic activity.

Respiratory reactions to microinjection of bombesin into the solitary tract nucleus and their mechanisms.

Acute experiments were performed on urethane-anesthetized adult laboratory rats to investigate the effects of microinjections of 10(-13)-10(-4) M bombesin into the solitary tract nucleus on measures of respiration. Bombesin microinjections were found to stimulate respiration, inducing significant increases in the level of pulmonary ventilation, increases in respiratory volume, and increases in the bioelectrical activity of the inspiratory muscles. The most marked respiratory reactions were seen after intermediate peptide doses (10(-10)-10(-7) M).

Spike coding during osmotic stimulation of the rat supraoptic nucleus.

Novel measures of coding based on interspike intervals were used to characterize the responses of supraoptic cells to osmotic stimulation. Infusion of hypertonic NaCl in vivo increased the firing rate of continuous (putative oxytocin) cells (Wilcoxon z= 3.84, P= 0.

Thyroliberin blocks the potassium A-current in neurons in the respiratory center of adult rats in vitro.

Thyroliberin is a neuropeptide with marked respiratory activity. The neuronal mechanisms underlying this activity were addressed in experiments on transverse slices of brainstem from adult rats in conditions of membrane potential clamping to study effect effects of thyroliberin (10 nM) on the potassium A-current in neurons of two areas of the respiratory center--the ventrolateral areas of the solitary tract nucleus and the pre-Betzinger complex. The A-current, seen in all study neurons in the respiratory center, was partially and reversibly blocked by thyroliberin.

Rhythmic changes in spike coding in the rat suprachiasmatic nucleus.

The suprachiasmatic nucleus is regarded as the main mammalian circadian pacemaker but evidence for rhythmic firing of single units in vivo has been obtained only recently. The present study was undertaken to determine if rhythms could be seen using measures of activity in addition to the mean spike frequency. We investigated whether there were changes in the irregularity of cell activity measured by the disorder of the interspike interval distribution for neurones recorded in vivo and in vitro.

Effects of thyroliberin on membrane potential and the pattern of spontaneous activity of neurons in the respiratory center in in vitro studies in rats.

Patch-clamp experiments on transverse brainstem slices from rats were performed to study the effects of thyroliberin (10(-8) M) on the membrane potential and spontaneous activity of neurons in two areas of the respiratory center: the ventrolateral area of the solitary tract nucleus and the pre-Botzinger complex. Thyroliberin induced membrane depolarization of neurons in the respiratory center and increased their spike activity. The pattern of activity of neurons in the pre-Botzinger complex showed decreases in the time intervals between the beginnings of bursts in response to thyroliberin.

Assessment of spike activity in the supraoptic nucleus.

Novel approaches to the characterization of coding carried by spike trains are discussed. Measuring firing frequency alone may only partially reflect spike patterning, and can only quantify changes of the most obvious kind. We have devised a method that combines probabilistic and information approaches to quantify the variability of the interspike intervals in a way that is independent of spike frequency.

Comparative characteristics of respiratory pattern responses to microinjection of kainic acid into different parts of the nucleus ambiguus.

Experiments on anesthetized rats were performed using local chemical exclusion of neurons with kainic acid to study the relative roles of the rostral, intermediate, and caudal parts of the nucleus ambiguus in the mechanisms controlling respiration. The characteristics of the respiratory rhythm and pattern responses to chemical exclusion of different parts of this nucleus were observed. In particular, sequential exclusion of the left and right rostral parts of the nucleus ambiguus reproducibly induced significant decreases in the respiration rate and respiratory volume in the first minutes; in 83% of experiments, there was also irreversible respiratory arrest.

Amygdalofugal modulation of Hering-Breuer inspiration-inhibiting reflex.

Acute experiments on rats showed that the central nucleus of the amygdaloid complex modulates realization of the Hering-Breuer inspiration-inhibiting reflex. It is hypothesized that amygdalobulbar interrelations are realized via modulation of respiratory reflexes by the amygdala. This interaction is mediated by the GABAergic system of the amygdala.

Respiratory effects of sensorimotor cortex and their mechanisms in rats.

Acute experiments on anesthetized rats showed differential effect of various areas of the sensorimotor cortex on activity of the respiratory center. It is hypothesized that GABAergic structures of the solitary tract nucleus play an important role in the mechanisms of respiratory effects of the sensorimotor cortex.

The pre-Bötzinger complex participates in generating the respiratory effects of thyroliberin.

Experiments on anesthetized rats were performed to study the effects of microinjection of thyroliberin (10 fM-100 microM) into the area of the pre-Bötzinger complex on respiratory and circulatory parameters. Thyroliberin dose-dependently increased respiration frequency, with shortening of inspiration and expiration. Tidal volume and the amplitude of the integrated EMG recorded from the inspiratory muscles decreased after administration of concentrated solutions.