Dynamic cultural modulation of neural responses to one's own and friend's faces

Long-term cultural experiences influence neural response to one''s own and friend''s faces. The present study investigated whether an individual''s culturally specific pattern of neural activity to faces can be modulated by temporary access to other cultural frameworks using a self-construal priming paradigm. Event-related potentials were recorded from British and Chinese adults during judgments of orientations of one''s own and friend''s faces after they were primed with independent and interdependent self-construals. We found that an early frontal negative activity at 220–340 ms (the anterior N2) differentiated between one''s own and friend''s faces in both cultural groups. Most remarkably, for British participants, priming an interdependent self-construal reduced the default anterior N2 to their own faces. For Chinese participants, however, priming an independent self-construal suppressed the default anterior N2 to their friend''s faces. These findings indicate fast modulations of culturally specific neural responses induced by temporary access to other cultural frameworks.     

Influence of molecular weight and concentration of carboxymethyl chitosan on biomimetic mineralization of collagen

The objective of the present study was to systematically investigate the influence of molecular weight (MW) and concentration of carboxymethyl chitosan (CMC), which served as non-collagenous protein (NCP) surrogates, on biomimetic mineralization of type I collagen. Supersaturated CMC-stabilized amorphous calcium-phosphate (CMC-ACP) dispersions containing different MWs (20 kDa, 60 kDa, 150 kDa) and concentrations (25, 50, 100, 200, 400 μg ml⁻¹) of CMC were prepared. After mineralization in the aforementioned dispersions for 7 days, the pattern and extent of biomimetic mineralization of collagen scaffolds were investigated. Our study showed that increasing CMC concentration resulted in increasing stability and decreasing particle size of CMC-ACP dispersions. Images from scanning and transmission electron microscopy revealed that intrafibrillar mineralization of collagen was obtained with 20k-200, 60k-100, 60k-200 and 150k-200 CMC-ACP dispersions, with hydroxyapatite (HAp) formation confirmed by Fourier transform infrared spectroscopy and X-ray diffraction measurements, whereas HAp formed extrafibrillar clusters in other collagen scaffolds. Thermogravimetric analysis showed that the combined effect of MW and concentration of CMC contributed to different extents of biomimetic mineralization, and was correlated with the stability and particle size of CMC-ACP dispersions, and the size-exclusion characteristics of type I collagen. The results of this work support the effective function of CMC as NCP analogs, and provide parameters of MWs and concentrations of CMC for applications in hard tissue engineering as well as insights into intersections of mechanisms in biomimetic mineralization.

The study systematically investigated the influence of molecular weight and concentration of CMC on CMC-ACP nanoparticles and biomimetic mineralization.     

Covalently functionalized graphene oxide wrapped by silicon–nitrogen-containing molecules: preparation and simultaneous enhancement of the thermal stability,flame retardancy and mechanical properties of epoxy resin nanocomposites

A novel functionalized graphene oxide (FGO) wrapped with Si–N-containing flame retardant (FR-fGO) was successfully synthesized via a chemical modification process and applied to enhance the thermal stability, fire resistance, and mechanical properties of epoxy resin (EP). Herein, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to explore the structure and morphology of FR-fGO to overcome the fact that the FGO cannot strongly bond with the polymer matrix. With the incorporation of FR-fGO into EP, the thermal stability improved and the total heat release decreased compared with pure EP. Meanwhile, FR-fGO composites significantly reduced the amount of flammable and toxic volatiles. A possible flame-retardant mechanism of FR-fGO was deduced from a theoretical analysis of the chemical bond energy and the experimental results of thermal decomposition: namely, well-dispersed FR-fGO nanosheets constituted a physical barrier, with an Si–N-containing synergy system forming a highly graphitized residual char with an Si-containing cross-linked network. The enhancement in mechanical properties demonstrated that the composites had remarkable compatibility. This study provides a novel modification strategy to improve the dispersion and flame retardance of graphene.

This study provided a modification strategy for improving the flame retardance of graphene and its derivatives in a polymer matrix.     

Dual responsive oligo(lysine)-modified Pluronic F127 hydrogels for drug release of 5-fluorouracil

Peptide-containing hydrogels have become a research hotspot due to their unique secondary structure and biocompatibility. Herein, we used amino-terminated F127 as a macroinitiator to initiate the ring-opening polymerization of l-lysine(z)-NCA, and the obtained oligo(lysine)-modified F127 (FL) had degrees of polymerization of lysine of 2, 5, and 8. The results showed that the FL hydrogels had reversible temperature-dependent sol–gel transitions, and the introduction of lysine increased the critical gel temperature. In the dilute solution of FL, the micelle size increased and aggregated as the pH increased; the micelle grew into a rod-like shape under alkaline conditions. Scanning electron micrographs showed that the interior of the FL hydrogel had a more complete porous structure. The FL-2 hydrogel loaded with 5-fluorouracil exhibited an approximately linear release trend within 12 h and has good biocompatibility. Therefore, FL hydrogels have potential applications in the field of biomedicine.

Oligo(lysine)-F127 hydrogels have a temperature-responsive sol–gel transition and pH-responsive micelle morphology.     

Intracerebroventricular administration of ouabain alters synaptic plasticity and dopamine release in rat medial prefrontal cortex

Intracerebroventricular (ICV) administration of ouabain, a specific Na–K-ATPase inhibitor, in rats mimics the manic phenotypes of bipolar disorder and thus has been proposed as one of the best animal models of mania. Bipolar mania has been known to be associated with dysfunctions of medial prefrontal cortex (mPFC), a brain area critically involved in mental functions; however, the exact mechanism underlying these dysfunctions is not yet clear. The present study investigated synaptic transmission, synaptic plasticity, and dopamine release in Sprague-Dawley rat mPFC following ICV administration of ouabain (5 μl of 1 mM ouabain). The electrophysiological results demonstrated that ouabain depressed the short- and the long-term synaptic plasticity, represented by paired-pulse facilitation and long-term potentiation, respectively, in the mPFC. These ouabain-induced alterations in synaptic plasticity can be prevented by pre-treatment with lithium (intraperitoneal injection of 47.5 mg/kg lithium, twice a day, 7 days), which acts as an effective mood stabilizer in preventing mania. The electrochemical results demonstrated that ICV administration of ouabain enhanced dopamine release in the mPFC, which did not be affected by pre-treatment with lithium. These findings suggested that alterations in synaptic plasticity and dopamine release in the mPFC might underlie the dysfunctions of mPFC accompanied with ouabain administration-induced bipolar mania.     

Down-regulation of beta1-adrenoceptors gene expression by short interfering RNA impairs the memory retrieval in the basolateral amygdala of rats

The influence of basolateral amygdala (BLA) on memory is known to depend critically on adrenergic neurotransmission. However, the roles of noradrenergic receptors on memory retrieval have been elusive and controversial. Here, we investigated the effect of beta(1)-adrenoceptor (beta(1)-AR) on auditory fear memory in the rat BLA. We attenuated the expression of beta(1)-AR by RNA interference, a popular means to specific suppress gene expression. Bilaterally microinjection of beta(1)-AR short interfering RNA (siRNA) could reach a satisfying transfection in the BLA: beta(1)-AR protein expression was reduced transiently by siRNA in vivo at day 3. The behavioral tests indicated that memory retrieval was impaired as beta(1)-AR protein expression was prevented, and the memory was restored when the beta(1)-AR protein got back to normal level. The results suggested that beta(1)-AR might be critical for the retrieval of auditory fear memory.     

Facial emotion perception abilities are related to grey matter volume in the culmen of cerebellum anterior lobe in drug-naïve patients with first-episode schizophrenia

Brain Imaging and Behavior - Impaired capability for understanding and interpreting the expressions on other people's faces manifests itself as a core feature of schizophrenia, contributing to...