Theta-Rhythmic Oscillation of Working Memory Performance

Representations held in working memory are crucial in guiding human attention in a goal-directed fashion. Currently, it is debated whether only a single representation or several of these representations can be active and bias behavior at any given moment. In the present study, 25 university students performed a behavioral dense-sampling experiment to produce an estimate of the temporal-activation patterns of two simultaneously held visual templates. We report two key novel results. First, performance related to both representations was not continuous but fluctuated rhythmically at 6 Hz. This corresponds to neural oscillations in the theta band, the functional importance of which in working memory is well established. Second, our findings suggest that two concurrently held representations may be prioritized in alternation, not simultaneously. Our data extend recent research on rhythmic sampling of external information by demonstrating an analogous mechanism in the cyclic activation of internal working memory representations.

Aspects of compactification on a linear dilaton background

We consider the most general Kaluza-Klein (KK) compactification on S1/ℤ2 of a five dimensional (5D) graviton-dilaton system, with a non-vanishing dilaton background varying linearly along the fifth dimension. We show that this background produces a Higgs mechanism for the KK vector coming from the 5D metric, which becomes massive by absorbing the string frame radion. The $$ \mathcal{N} $$ N = 2 minimal supersymmetric extension of this model, recently built as the holographic dual of Little String Theory, is then reinvestigated. An analogous mechanism can be considered for the 4D vector coming from the (universal) 5D Kalb-Ramond two-form. Packaging the two massive vectors into a spin-3/2 massive multiplet, it is shown that the massless spectrum arranges into a $$ \mathcal{N} $$ N = 1, D = 4 supersymmetric theory. This projection is compatible with an orbifold which preserves half of the original supersymmetries already preserved by the background. The description of the partial breaking $$ \mathcal{N} $$ N = 2 → $$ \mathcal{N} $$ N = 1 in this framework, with only vector multiplets and no hypermultiplets, remains an interesting open question which deserves further investigation.

Analogous mechanism regulating formation of neocortical basal radial glia and cerebellar Bergmann glia

Neocortical basal radial glia (bRG) and cerebellar Bergmann glia (BG) are basal progenitors derived from ventricular apical radial glia (aRG) that selectively lose their apical processes. bRG and BG have been implicated in the expansion and folding of the cerebrum and cerebellum, respectively. Here, we analyzed the molecular characteristics and development of bRG and BG. Transcriptomic comparison revealed striking similarity of the molecular features of bRG and BG. We found that heightened ERK signaling activity in aRG is tightly linked to the temporal formation and the relative abundance of bRG in human and mouse cortices. Forced activation of an FGF-ERK-ETV axis that is crucial to BG induction specifically induced bRG with canonical human bRG features in mice. Therefore, our data point to a common mechanism of bRG and BG generation, bearing implications to the role for these basal progenitors in the evolution of cortical folding of the cerebrum and cerebellum.

Structural deformation phenomenon of synthesized poly(isosorbide-1,4-cyclohexanedicarboxylate) in hot water

Water induced deformation phenomena of synthesized polyester including isosorbide shares analogous mechanism of solvent induced crystallization. This structural deformation is effected by pH, open-ring ISB and ester hydrolysis.

How decreasing oxygenase activity helps cells cope with hypoxia

The ability of our bodies to adapt to reduced oxygen availability (hypoxia) by increasing red blood cell formation was recognized in the 19th century, but almost 200 years passed before the molecular mechanism underlying this hypoxic response was revealed. In animals, hypoxia tolerance is enabled by turning on a plethora of genes, all under the control of the hypoxia inducible transcription factor protein, HIF. Crucially, levels of HIF are controlled by a set of enzymes, whose activity is exquisitely sensitive to oxygen availability. A low-oxygen response system is arguably more important for plants which, as sessile organisms, cannot employ behavioural responses to hypoxia, and recent findings reveal a distinct yet analogous mechanism. It seems that in plants as well as in animals, oxygen-dependent enzymes are the linchpins connecting oxygen availability with the cellular response to hypoxia.

Structural Insights into Bak Activation and Oligomerisation

Apoptotic stimuli activate and oligomerise the pro-apoptotic proteins Bak and Bax resulting in mitochondrial outer membrane permeabilisation and subsequent cell death. This activation can occur when certain BH3-only proteins directly interact with Bak and Bax. A recent crystal structure by Czabotar et al. (2013) revealed a novel conformational change for Bax upon activation by BH3-only peptides. Distinguishing characteristics of BH3-only proteins capable of directly activating Bax were also elucidated. Here we describe complementary studies on the related protein Bak. We identify specific BH3-only peptides capable of inducing Bak dimerisation and describe crystal structures that provide key insights into Bak activation and oligomerisation. These structures demonstrate that Bak undergoes similar conformational changes upon activation to those observed with Bax. Altogether our results confirm an analogous mechanism for activation and dimerization of Bak and Bax in response to BH3-only peptides.