Gamma oscillations in V1 are correlated with GABA(A) receptor density: A multi-modal MEG and Flumazenil-PET study.

High-frequency oscillations in the gamma-band reflect rhythmic synchronization of spike timing in active neural networks. The modulation of gamma oscillations is a widely established mechanism in a variety of neurobiological processes, yet its neurochemical basis is not fully understood. Modeling, in-vitro and in-vivo animal studies suggest that gamma oscillation properties depend on GABAergic inhibition. In humans, search for evidence linking total GABA concentration to gamma oscillations has led to promising -but also to partly diverging- observations. Here, we provide the first evidence of a direct relationship between the density of GABA(A) receptors and gamma oscillatory gamma responses in human primary visual cortex (V1). By combining Flumazenil-PET (to measure resting-levels of GABA(A) receptor density) and MEG (to measure visually-induced gamma oscillations), we found that GABA(A) receptor densities correlated positively with the frequency and negatively with amplitude of visually-induced gamma oscillations in V1. Our findings demonstrate that gamma-band response profiles of primary visual cortex across healthy individuals are shaped by GABA(A)-receptor-mediated inhibitory neurotransmission. These results bridge the gap with in-vitro and animal studies and may have future clinical implications given that altered GABAergic function, including dysregulation of GABA(A) receptors, has been related to psychiatric disorders including schizophrenia and depression

Kak's three-stage protocol of secure quantum communication revisited: Hitherto unknown strengths and weaknesses of the protocol

Kak's three-stage protocol for quantum key distribution is revisited with special focus on its hitherto unknown strengths and weaknesses. It is shown that this protocol can be used for secure direct quantum communication. Further, the implementability of this protocol in the realistic situation is analyzed by considering various Markovian noise models. It is found that the Kak's protocol and its variants in their original form can be implemented only in a restricted class of noisy channels, where the protocols can be transformed to corresponding protocols based on logical qubits in decoherence free subspace. Specifically, it is observed that Kak's protocol can be implemented in the presence of collective rotation and collective dephasing noise, but cannot be implemented in its original form in the presence of other types of noise, like amplitude damping and phase damping noise. Further, the performance of the protocol in the noisy environment is quantified by computing average fidelity under various noise models, and subsequently a set of preferred states for secure communication in noisy environment have also been identified.Comment: Kak's protocol is not suitable for quantum cryptography in presence of nois

Qualitative study of supramolecular assemblies of β-cyclodextrin and cholecalciferol and the cobalt (II), copper (II) and zinc (II) ions

A 13C NMR in DMSO-d6 as solvent, diffuse reflectance spectra and X-ray powder diagram study of the inclusion of vitamin D in β-cyclodextrin and of the ternary assemblies with β-cyclodextrin, vitamin D and metal ions (e.g. Co(II), Cu(II) and Zn(II)) was carried out to determine the structure of these associations in which the molecular ratios (β-cyclodextrin:vitamin D:metal ions) were 5:1:1 or 10:1:1

11 nm hard X-ray focus from a large-aperture multilayer Laue lens

The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone width and 4.2 mm focal length at 12 keV was characterized with X-rays using ptychography method. The reconstructed probe shows a full-width-at-half-maximum (FWHM) peak size of 11.2 nm. The obtained X-ray wavefront shows excellent agreement with the dynamical calculations, exhibiting aberrations less than 0.3 wave period, which ensures the MLL capable of producing a diffraction-limited focus while offering a sufficient working distance. This achievement opens up opportunities of incorporating a variety of in-situ experiments into ultra high-resolution X-ray microscopy studies

Supramolecular assemblies of Al3+ complexes with vitamin D3 (cholecalciferol) and phenothiazine. Encapsulation and complexation studies in β-cyclodextrin

Ternary assemblies of β-cyclodextrin with cholecalciferol (or vitamin D3) or phenothiazine and Al3+ ions were studied. The stability constants of aluminium binary complexes with cholecalciferol or phenothiazine and of ternary assemblies (β-cyclodextrin, cholecalciferol or phenothiazine and Al3+) were determined using potentiometric titrations at 25 °C (I = 0.100 M). The 13C NMR spectra of the supramolecular structures in the solid state showed that ternary supramolecular structures associating β-cyclodextrin, cholecalciferol or phenothiazine and aluminium(III) ions were obtained. Finally, X-ray powder diffraction patterns showed that the ternary assemblies with phenothiazine are channel type inclusion complexes

Multimodality hard-x-ray imaging of a chromosome with nanoscale spatial resolution

We developed a scanning hard x-ray microscope using a new class of x-ray nano-focusing optic called a multilayer Laue lens and imaged a chromosome with nanoscale spatial resolution. The combination of the hard x-ray's superior penetration power, high sensitivity to elemental composition, high spatial-resolution and quantitative analysis creates a unique tool with capabilities that other microscopy techniques cannot provide. Using this microscope, we simultaneously obtained absorption-, phase-, and fluorescence-contrast images of Pt-stained human chromosome samples. The high spatial-resolution of the microscope and its multi-modality imaging capabilities enabled us to observe the internal ultra-structures of a thick chromosome without sectioning it

On the importance of long-term functional assessment after stroke to improve translation from bench to bedside

Despite extensive research efforts in the field of cerebral ischemia, numerous disappointments came from the translational step. Even if experimental studies showed a large number of promising drugs, most of them failed to be efficient in clinical trials. Based on these reports, factors that play a significant role in causing outcome differences between animal experiments and clinical trials have been identified; and latest works in the field have tried to discard them in order to improve the scope of the results. Nevertheless, efforts must be maintained, especially for long-term functional evaluations. As observed in clinical practice, animals display a large degree of spontaneous recovery after stroke. The neurological impairment, assessed by basic items, typically disappears during the firsts week following stroke in rodents. On the contrary, more demanding sensorimotor and cognitive tasks underline other deficits, which are usually long-lasting. Unfortunately, studies addressing such behavioral impairments are less abundant. Because the characterization of long-term functional recovery is critical for evaluating the efficacy of potential therapeutic agents in experimental strokes, behavioral tests that proved sensitive enough to detect long-term deficits are reported here. And since the ultimate goal of any stroke therapy is the restoration of normal function, an objective appraisal of the behavioral deficits should be done