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Се-doped (Pb,Gd)3(Al,Ga)5O12 single crystalline garnet films were grown using liquid-phase epitaxy from four series of supercooled PbO–B2O3-based melt solutions on Gd3Ga5O12 and Gd3Al2.26Ga2.74O12 single crystal substrates. The optical and scintillation properties of the epitaxial garnet films were studied. The 5d-4f emission of Ce3+ ions within 450–650 nm was observed. The highest pulsed cathodoluminescence yield and scintillation yield values under 133Ba excitation for the Pb0.01Ce0.02Gd2.97Al3.13Ga1.87O12 film were 43,100 photons/MeV and 20,000 photons/MeV, respectively. The pulsed cathodoluminescence decay times of the film were 1.8 (1%), 24 (25%), and 60 ns (74%), and the scintillation decay times were 3.9 (7%) and 43.6 ns (93%). Because of the rapid decay and high light yield, Се-doped (Pb,Gd)3(Al,Ga)5O12 garnet films can be used in X-ray scintillators for different applications, such as homeland security.

The Xenopus tadpole model offers many advantages for studying the molecular, cellular and network mechanisms underlying neurodevelopmental disorders. Essentially every stage of normal neural circuit development, from axon outgrowth and guidance to activity-dependent homeostasis and refinement, has been studied in the frog tadpole, making it an ideal model to determine what happens when any of these stages are compromised. Recently, the tadpole model has been used to explore the mechanisms of epilepsy and autism, and there is mounting evidence to suggest that diseases of the nervous system involve deficits in the most fundamental aspects of nervous system function and development. In this Review, we provide an update on how tadpole models are being used to study three distinct types of neurodevelopmental disorders: diseases caused by exposure to environmental toxicants, epilepsy and seizure disorders, and autism.

The neural circuits in the optic tectum of Xenopus tadpoles are selectively responsive to looming visual stimuli that resemble objects approaching the animal at a collision trajectory. This selectivity is required for adaptive collision avoidance behavior in this species, but its underlying mechanisms are not known. In particular, it is still unclear how the balance between the recurrent spontaneous network activity and the newly arriving sensory flow is set in this structure, and to what degree this balance is important for collision detection. Also, despite the clear indication for the presence of strong recurrent excitation and spontaneous activity, the exact topology of recurrent feedback circuits in the tectum remains elusive. In this study we take advantage of recently published detailed cell-level data from tadpole tectum to build an informed computational model of it, and investigate whether dynamic activation in excitatory recurrent retinotopic networks may on its own underlie collision detection. We consider several possible recurrent connectivity configurations and compare their performance for collision detection under different levels of spontaneous neural activity. We show that even in the absence of inhibition, a retinotopic network of quickly inactivating spiking neurons is naturally selective for looming stimuli, but this selectivity is not robust to neuronal noise and is sensitive to the balance between direct and recurrent inputs. We also describe how homeostatic modulation of intrinsic properties of individual tectal cells can change selectivity thresholds in this network, and qualitatively verify our predictions in a behavioral experiment in freely swimming tadpoles.

In the developing mammalian brain, gamma-aminobutyric acid (GABA) is thought to play an excitatory rather than an inhibitory role due to high levels of intracellular Cl(-) in immature neurons. This idea, however, has been questioned by recent studies which suggest that glucose-based artificial cerebrospinal fluid (ACSF) may be inadequate for experiments on immature and developing brains. These studies suggest that immature neurons may require alternative energy sources, such as lactate or pyruvate. Lack of these other energy sources is thought to result in artificially high intracellular Cl(-) concentrations, and therefore a more depolarized GABA receptor (GABAR) reversal potential. Since glucose metabolism can vary widely among different species, it is important to test the effects of these alternative energy sources on different experimental preparations. We tested whether pyruvate affects GABAergic transmission in isolated brains of developing wild type Xenopus tadpoles in vitro by recording the responsiveness of tectal neurons to optic nerve stimulation, and by measuring currents evoked by local GABA application in a gramicidin perforated patch configuration. We found that, in contrast with previously reported results, the reversal potential for GABAR-mediated currents does not change significantly between developmental stages 45 and 49. Partial substitution of glucose by pyruvate had only minor effects on both the GABA reversal potential, and the responsiveness of tectal neurons at stages 45 and 49. Total depletion of energy sources from the ACSF did not affect neural responsiveness. We also report a strong spatial gradient in GABA reversal potential, with immature cells adjacent to the lateral and caudal proliferative zones having more positive reversal potentials. We conclude that in this experimental preparation standard glucose-based ACSF is an appropriate extracellular media for in vitro experiments.

Highlights: [•] Films of Ce-doped Gd3(Al x Ga1−x )5O12 were grown using liquid-phase epitaxy method. [•] The emission of Ce3+ is observed only when Al3+ ions are incorporated into the films. [•] Gradual shift of Ce3+ levels into the bandgap occurs with the increase of x value. [•] The garnet's bandgap energy rises with increasing Al3+ concentration. [ABSTRACT FROM AUTHOR]

An invariable interest in mechanisms of synaptic plasticity gave birth to several specific methods of evoked postsynaptic responses analysis: quantal analysis, component analysis, nonstationary fluctuation analysis (NSFA) etc. The major part of these methods are not standardized yet however, that can lead to obtaining different (and even contradictory) results in similar experiments performed by different scientific groups. This paper issues the experiments for revealing pre- or postsynaptic location of the synaptic plasticity mechanisms during the early phases of the long-term potentiation (LTP). On a model we analyse how an estimation of the single-channel current made by the NSFA is influenced by changes in the evoked postsynaptic currents shape variability. A hypothesis is made that the apparent increase in the AMPA-receptor single-channel current, reported in some works for early LTP stages, could be concerned with the increase in the postsynaptic response shape variability rather then with real increase in AMPA-receptor channels conductivity. The shape of the postsynaptic responses can become more variable after LTP-associated unsilencing of the previously silent synapses. A new method of independent component analysis (ICA) is introduced to check this hypothesis first on model and than on physiological data. The results of the experiments in general agree with the hypothesis suggested.