Design and Test of Spatial Cognitive Training and Evaluation System Based on Virtual Reality Head-Mounted Display With EEG Recording.

The field of spatial cognitive training and evaluation has rapidly evolved. However, the low learning motivation and engagement of the subjects hinder the widespread use of spatial cognitive training. This study designed a home-based spatial cognitive training and evaluation system (SCTES), which aimed to train subjects on spatial cognitive tasks for 20 days, and compared the brain activities before and after the training. This study also evaluated the feasibility of using a portable all-in-one prototype for cognitive training that combined a virtual reality (VR) head-mounted display with high-quality electroencephalogram (EEG) recording. During the course of training, the length of the navigation path and the distance between the starting position and the platform position revealed significant behavioral differences. In the testing sessions, the subjects showed significant behavioral differences in the time it took to complete the test task before and after training. After only four days of training, the subjects demonstrated significant differences in the Granger causality analysis (GCA) characteristics of brain regions in the δ , θ , α1 , ß2 , and γ frequency bands of the EEG, as well as significant differences in the GCA of the EEG in the ß1 , ß2 , and γ frequency bands between the two test sessions. The proposed SCTES used a compact and all-in-one form factor to train and evaluate spatial cognition and collect EEG signals and behavioral data simultaneously. The recorded EEG data can be used to quantitatively assess the efficacy of spatial training in patients with spatial cognitive impairments.

Electrophysiological Correlates of Processing Warning Signs With Different Background Colors: An Event-Related Potentials Investigation.

Warning signs, as a type of safety signs, are widely applied in our daily lives to informing people about potential hazards and prompting safe behavior. Although previous studies have paid attention to the color of warning signs, they are mostly based on surveys and behavioral experiments. The neural substrates underlying the perception of warning signs with different background colors remain not clearly characterized. Therefore, this research is intended to address this gap with event-related potentials (ERPs) technique. Warning signs with three different background colors (i.e., white, yellow, and blue) were used in the experiment. The results showed that the perceptual differences between different warning signs were present in the form of differential ERPs components (P1, N1, P2, N2, and P3) though subjects were not required to explicitly attend to the warning signs.

The EEG Signal Analysis for Spatial Cognitive Ability Evaluation Based on Multivariate Permutation Conditional Mutual Information-Multi-Spectral Image.

This study aims to find an effective method to evaluate the efficacy of cognitive training of spatial memory under a virtual reality environment, by classifying the EEG signals of subjects in the early and late stages of spatial cognitive training. This study proposes a new EEG signal analysis method based on Multivariate Permutation Conditional Mutual Information-Multi-Spectral Image (MPCMIMSI). This method mainly considers the relationship between the coupled features of EEG signals in different channel pairs and transforms the multivariate permutation conditional mutual information features into multi-spectral images. Then, a convolutional neural networks (CNN) model classifies the resultant image data into different stages of cognitive training to objectively assess the efficacy of the training. Compared to the multi-spectral image transformation method based on Granger causality analysis (GCA) and permutation conditional mutual information (PCMI), the MPCMIMSI led to better classification performance, which can be as high as 95% accuracy. More specifically, the Theta-Beta2-Gamma-band combination has the best accuracy. The proposed MPCMIMSI method outperforms the multi-spectral image transformation methods based on GCA and PCMI in terms of classification performance. The MPCMIMSI feature in the Theta-Beta2-Gamma band is an effective biomarker for assessing the efficacy of spatial memory training. The proposed EEG feature-extraction method based on MPCMIMSI offers a new window to characterize spatial information of the noninvasive EEG recordings and might apply to assessing other brain functions.

A colorimetric and surface-enhanced Raman scattering dual-signal sensor for Hg2+ based on Bismuthiol II-capped gold nanoparticles.

The addition of Bismuthiol II to the gold nanoparticles (AuNPs) solution led to the aggregation of AuNPs with a color change from red to blue. As a result, hot spots were formed and strong surface-enhanced Raman scattering (SERS) signal of Bismuthiol II was observed. However, the Bismuthiol II-induced aggregation of AuNPs could be reversed by Hg(2+) in the system, accompanied by a remarkable color change from blue to red. As evidenced by UV-vis and SERS spectroscopy, the variation in absorption band and SERS intensity was strongly dependent on the concentration of Hg(2+), suggesting a colorimetric and SERS dual-signal sensor for Hg(2+). The sensor had a high sensitivity, low detection limits of 2nM and 30nM could be achieved by UV-vis spectroscopy and by SERS spectroscopy, respectively. Other environmentally relevant metal ions did not interfere with the detection of Hg(2+). The method was successfully applied to detect Hg(2+) in water samples. It was simple, rapid and cost-effective without any modifying or labeling procedure.

Synthesis of a ß-cyclodextrin-modified Ag film by the galvanic displacement on copper foil for SERS detection of PCBs.

A mono-6-thio-ß-cyclodextrin-modified silver film was synthesized via galvanic displacement on copper foil. The prepared silver films could enrich non-polar polychlorinated biphenyls (PCBs) molecules from hydrophilic phase using thiolate ß-cyclodextrins (SH-ß-CDs) as receptors. The components of as-prepared Ag-coated-Cu (Ag-Cu) film were confirmed by powder X-ray diffraction (XRD). Both surface-enhanced Raman spectroscopy (SERS) and energy dispersive X-ray spectroscopy (EDS) measurements gave strong evidences that the thiolated ß-cyclodextrins (SH-ß-CDs) had been immobilized on the surface of silver film. Compared to the substrates prepared in the absence of SH-ß-CD, the surface morphology of the CD-modified Ag films was obviously changed. The interfacial enrichment and the capability of substrates to form inclusion complexes with PCBs molecules were tested by using PCB-15 (4,4'-dichlorobiphenyl) as the probe molecules via SERS technique. The measured SERS spectra could distinguish the PCB-15 molecules at micro-molar level according to the most intense CCC bending in-plane mode of PCBs. The enhancement factor (EF) of the SERS substrates for PCB-15 was 1.2×10(5), which was comparable with a number of previous reports.

Preparative isolation and purification of polymethoxylated flavones from Tangerine peel using high-speed counter-current chromatography.

Several polymethoxylated flavones including nobiletin, 3,5,6,7,8,3',4'-heptamethoxyflavone, tangeretin and 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone were separated from Tangerine peel (Juhong in Chinese) by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.8:1:1, v/v). Then, 26 mg of nobiletin, 6 mg of 3,5,6,7,8,3',4'-heptamethoxyflavone, 35 mg of tangeretin and 11 mg of 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone could be obtained from 150 mg crude extracts and their purities were 98.6%, 95.9%, 99.8% and 96.8%, respectively. All these constituents were identified by EI-MS and 1H NMR.

Application of preparative high-speed counter-current chromatography for separation and purification of arctiin from Fructus Arctii.

Following an initial clean-up step on the AB-8 resin (polystyrene resin, 0.3-1.25 mm: NanKai Chemical Factory, Tianjin, China), high-speed counter-current chromatography (HSCCC) was used to purify an arctiin from an extract of the fruits of the Arctium lappa L. Arctiin is a major lignan compound in the traditional Chinese medicinal herb A. lappa L. The two-phase solvent system used was composed of ethyl acetate-n-butanol-ethanol-water at an optimized volume ratio of 5:0.5:1:5 (v/v/v/v). The upper phase was used as the mobile phase in the head to tail elution mode. A total amount of 159 mg of arctiin at 98% purity was obtained from 350 mg of the crude extract (containing 49% arctiin) with 91% recovery. The preparative isolation and purification of arctiin by HSCCC was completed in 5 h in a separation. Identification of the target compound was performed by LC-electrospray ionization MS and 13C-NMR. The structure of the product was further confirmed by comparison with authentic sample (National Institute of the Control of Pharmaceutical and Biological Products, Beijing, China).