Unfolding the Folding Problem of the Cerebral Cortex: Movin’ and Groovin’

The development of reproducible folding in the gyrencephalic cerebral cortex is a topic of great interest to neuroscientists. In a recent paper in Cell, del Toro et al. (2017) show that changing the adhesive properties of neurons in the normally lissencephalic mouse cortex leads to the formation of stereotyped folding.Stem Cell and Regenerative Biolog

Structural Connectivity of the Anterior Cingulate Cortex, Claustrum, and the Anterior Insula of the Mouse

The claustrum is a narrow subcortical brain structure that resides between the striatum and insular cortex. The function of the claustrum is not fully described, and while our previous work supports a role for the claustrum in top-down cognitive control of action, other evidence suggests the claustrum may be involved in detecting salient changes in the external environment. The anterior cingulate cortex (ACC) and the anterior insular (aINS) are the two major participants in the salience network of human brain regions that activate in response to salient stimuli. While bidirectional connections between the ACC and the claustrum exist from mouse to non-human primate, the aINS connectivity with claustrum remains unclear, particularly in mouse. Here, we explored structural connections of the aINS with the claustrum and ACC through adeno-associated virus neuronal tract tracer injections into the ACC and aINS of the mouse. We detected sparse projections from the claustrum to the aINS and diffuse projections from the aINS to the borders of the claustrum were observed in some cases. In contrast, the insular cortex and endopiriform nucleus surrounding the claustrum had rich interconnectivity with aINS. Additionally, we observed a modest interconnectivity between ACC and the aINS. These data support the idea that claustrum neuron responses to salient stimuli may be driven by the ACC rather than the aINS

Mechanismen der Neuroligin- Funktion in inhibitorischer postsynaptischer Differenzierung

Die Ausbildung von akuraten synaptischer Übertragungswegen ist Grundlage für die Informationsprozessierung in neuronalen Netzwerken und für die Funktion des gesamten neuronalen Systems. Das geordnete Aufstellen eines spezialisierten synaptischen Apparates ist ein entscheidender zellulärer Vorgang, bei der die Übertragungseigenschaften der Synapse gestaltet werden. Jedoch sind die molekularen Prozesse, die an der Ausbildung der Synapse beteiligt sind, noch weitgehend unbekannt. Die vorliegende Arbeit hat sich mit der Rolle von Neuroliginen bei diesen Vorgängen beschäftigt. Bei Neuroliginen handelt sich dabei um eine Familie von postsynaptischen Zelladhäsionsproteinen, die entscheidend zur Differenzierung von inhibitorischen Postsynapsen, sowohl GABAergen als auch glycinergen, beitragen.Es konnte gezeigt werden, dass die Aufgabe von Neuroligin 2 durch eine Interaktion mit Gephyrin, einem Markerprotein für inhibitorische Postsynapsen, vermittelt wird. Zusätzlich erfolgt dabei eine spezifische Aktivierung des Signalmoleküls Collybistin. Neuroligin 2 ist sogar entscheidend für eine korrekte Aufstellung des postsynaptischen Gerüsts in Neuronen. Zusammen mit Gephyrin und Collybistin ist Neuroligin 2 ausreichend für die korrekte Anordnung von GABA-A Rezeptoren.Darüber hinaus konnte ein neuartiges, für die Neuroliginfamilie kennzeichnendes, Gephyrin-Bindungsmotiv identifiziert werden. Da alle verschiedenen Neuroligine die Fähigkeit haben Gephyrin zu binden, erscheint es möglich, daß die verschiedenen Neuroliginisoformen zusätzliche Aufgaben an der inhibitorischen Postsynapse ausüben. Dafür spricht, dass Neuroligine, wie in dieser Arbeit gefunden wurde, sowohl Hetero- als auch Homodimere ausbilden. Es wurden auch zelluläre Mechanismen aufgedeckt, die die Ausbildung und den Transport von Neuroliginoligmeren regulieren und des Weiteren wurden Hinweise gefunden, die eine Beteiligung von Neuroliginen an der Ausbildung von Autismus nahelegen

Subcellular transcriptomes and proteomes of developing axon projections in cerebral cortex

Subcellular RNA-Proteome Mapping dataset for manuscript Poulopoulos A, Murphy AM,... Macklis JD, 2018 "Subcellular transcriptomes and proteomes of developing axon projections in cerebral cortex

On the Quantum Confinement Effects in Ultrathin PdO Films by Experiment and Theory

Radio frequency magnetron sputtering conducted in a high vacuum with a base pressure of 1×10−6 mbar was used to deposit ultrathin palladium films on Corning glass. The thickness of these films ranged from 0.4 to 13 nanometers. PdO films were produced after being post-annealed in a furnace at temperatures of 530 degrees Celsius in the presence of air. The results of an atomic force microscopy study showed that the material possessed a high crystalline quality with a low roughness. When looking at Tauc plots to determine the position of the direct optical band gap, the thicker films show a value that is relatively close to 2.2 eV. When the film thickness was reduced all the way down to 0.7 nm, a significant “blue shift” of more than 0.5 eV was observed. In order to provide a more in-depth understanding of the experiment, theoretical calculations based on the Hartree–Fock approximation as applied to an electron-hole system were performed in the framework of the effective mass approximation. The findings are regarded as empirical proof of the existence of quantum confinement effects

On the Localized Surface Plasmonic Resonances of AgPd Alloy Nanoparticles by Experiment and Theory

Ag/Pd multilayers and AgPd alloyed ultrathin films were deposited on Corning glass by magnetron sputtering. After being annealed in a furnace in air at 460 °C, self-assembled nanoparticles were formed. Localized surface plasmon resonances were observed only for the Ag-rich samples in the full range of the visible light spectrum. The resonance position was found to depend on the initial film thickness. In order to gain further physical insight, rigorous theoretical calculations were carried out via the rigid coupled-wave analysis method for the entire compositional range between Ag and Pd. Theoretical calculations were proven to be in suitable agreement with the experimental results

Band Gap Measurements of Nano-Meter Sized Rutile Thin Films

Thin Titanium films were fabricated on quartz substrates by radio frequency magnetron sputtering under high vacuum. Subsequent annealing at temperatures of 600 ∘C in air resulted in single-phase TiO2 with the structure of rutile, as X-ray diffraction experiment demonstrates. Atomic-force microscopy images verify the high crystalline quality and allow us to determine the grain size even for ultrathin TiO2 films. Rutile has a direct energy band gap at about 3.0–3.2 eV; however, the transitions between the valence and conduction band are dipole forbidden. Just a few meV above that, there is an indirect band gap. The first intense absorption peak appears at about 4 eV. Tauc plots for the position of the indirect band gap show a “blue shift” with decreasing film thickness. Moreover, we find a similar shift for the position of the first absorbance peak studied by the derivative method. The results indicate the presence of quantum confinement effects. This conclusion is supported by theoretical calculations based on a combination of the effective mass theory and the Hartree Fock approximation

A Study of Quantum Confinement Effects in Ultrathin NiO Films Performed by Experiment and Theory

Ultrathin NiO films in the thickness range between 1 and 27 nm have been deposited on high-quality quartz substrates by direct magnetron sputtering under a rough vacuum with a base pressure of 2 × 10−2 mbar. The sputtering target was metallic Ni; however, due to the rough vacuum a precursor material was grown in which most of Ni was already oxidized. Subsequent short annealing at temperatures of about 600 °C in a furnace in air resulted in NiO with high crystallinity quality, as atomic force microscopy revealed. The images of surface morphology showed that the NiO films were continuous and follow a normal grain growth mode. UV-Vis light absorption spectroscopy experiments have revealed a blue shift of the direct band gap of NiO. The band gap was determined either by Tauc plots (onset) or by the derivative method (highest rate of absorbance increase just after the onset). The experimental results are interpreted as evidences of quantum confinement effects. Theoretical calculations based on Hartree Fock approximation as applied for an electron-hole system, in the framework of effective mass approximation were carried out. The agreement between theory and experiment supports the quantum confinement interpretation

Magnetic Aspects and Large Exchange Bias of Ni0.9Co0.1/NiCoO Multilayers

Ultrathin films of Ni0.9Co0.1 were grown by radio frequency magnetron sputtering. By means of a periodic natural oxidation procedure they were transformed into Ni0.9Co0.1/NiCoO multilayers. Room temperature hysteresis loops recorded via the magneto-optic Kerr effect have revealed over all in-plane magnetic anisotropy due to magnetostatic anisotropy. Mild thermal annealing at 250 °C enhanced a tendency for perpendicular magnetic anisotropy, mainly due to an increase of the uniaxial volume anisotropy term. Spin reorientation transition, exchange bias larger than 700 Oe, and strong coercivity enhancement were observed via a superconducting quantum interference device at low temperatures after field cooling