Enhanced Valley Polarization of Bilayer MoSe2 with Variable Stacking Order and Interlayer Coupling.

In two-dimensional transitional metal dichalcogenides, tuning the spin-valley-layer coupling via changing layer numbers and stacking orders remains desirable for their application in valleytronics. Herein, six-point star-like MoSe2 nanoflakes simultaneously containing different atom registration regions from monolayer to bilayer with 2H and 3R stacking order were fabricated, and the valley polarizations were comparably investigated by circular polarized photoluminescent spectroscopy. The degree of valley polarization was detected to be about 12.5% in the monolayer and 10% in the 2H bilayer, but greatly upgraded to about 40% in the 3R bilayer MoSe2. This enhancement was attributed to the multiband spin splitting and generation of spin-dependent layer polarization for the 3R MoSe2 bilayer, which is well evidenced by our ab initio calculations of the energy band structures. Our results demonstrate that preparing TMD crystals with controllable stacking orders and interlayer coupling is a promising route to tune the valley index in TMDs for developing valleytronics technology.

An Event Recognition Method for Φ-OTDR Sensing System Based on Deep Learning.

Phase-sensitive optical time domain reflectometer (Φ-OTDR) based distributed optical fiber sensing system has been widely used in many fields such as long range pipeline pre-warning, perimeter security and structure health monitoring. However, the lack of event recognition ability is always being the bottleneck of Φ-OTDR in field application. An event recognition method based on deep learning is proposed in this paper. This method directly uses the temporal-spatial data matrix from Φ-OTDR as the input of a convolutional neural network (CNN). Only a simple bandpass filtering and a gray scale transformation are needed as the pre-processing, which achieves real-time. Besides, an optimized network structure with small size, high training speed and high classification accuracy is built. Experiment results based on 5644 events samples show that this network can achieve 96.67% classification accuracy in recognition of 5 kinds of events and the retraining time is only 7 min for a new sensing setup.

Prior Knowledge Guides Speech Segregation in Human Auditory Cortex.

Segregating concurrent sound streams is a computationally challenging task that requires integrating bottom-up acoustic cues (e.g. pitch) and top-down prior knowledge about sound streams. In a multi-talker environment, the brain can segregate different speakers in about 100 ms in auditory cortex. Here, we used magnetoencephalographic (MEG) recordings to investigate the temporal and spatial signature of how the brain utilizes prior knowledge to segregate 2 speech streams from the same speaker, which can hardly be separated based on bottom-up acoustic cues. In a primed condition, the participants know the target speech stream in advance while in an unprimed condition no such prior knowledge is available. Neural encoding of each speech stream is characterized by the MEG responses tracking the speech envelope. We demonstrate that an effect in bilateral superior temporal gyrus and superior temporal sulcus is much stronger in the primed condition than in the unprimed condition. Priming effects are observed at about 100 ms latency and last more than 600 ms. Interestingly, prior knowledge about the target stream facilitates speech segregation by mainly suppressing the neural tracking of the non-target speech stream. In sum, prior knowledge leads to reliable speech segregation in auditory cortex, even in the absence of reliable bottom-up speech segregation cue.

Behavioral oscillation in face priming: Prediction about face identity is updated at a theta-band rhythm.

In order to deal with external world efficiently, the brain constantly generates predictions about incoming sensory inputs, a process known as "predictive coding." Our recent studies, by employing visual priming paradigms in combination with a time-resolved behavioral measurement, reveal that perceptual predictions about simple features (e.g., left or right orientation) return to low sensory areas not continuously but recurrently in a theta-band (3-4Hz) rhythm. However, it remains unknown whether high-level object processing is also mediated by the oscillatory mechanism and if yes at which rhythm the mechanism works. In the present study, we employed a morph-face priming paradigm and the time-resolved behavioral measurements to examine the fine temporal dynamics of face identity priming performance. First, we reveal classical priming effects and a rhythmic trend within the prime-to-probe SOA of 600ms (Experiment 1). Next, we densely sampled the face priming behavioral performances within this SOA range (Experiment 2). Our results demonstrate a significant ~5Hz oscillatory component in the face priming behavioral performances, suggesting that a rhythmic process also coordinates the object-level prediction (i.e., face identity here). In comparison to our previous studies, the results suggest that the rhythm for the high-level object is faster than that for simple features. We propose that the seemingly distinctive priming rhythms might be attributable to that the object-level and simple feature-level predictions return to different stages along the visual pathway (e.g., FFA area for face priming and V1 area for simple feature priming). In summary, the findings support a general theta-band (3-6Hz) temporal organization mechanism in predictive coding, and that such wax-and-waning pattern in predictive coding may aid the brain to be more readily updated for new inputs.

Neural correlates of reflection on actual versus ideal self-discrepancy.

Subjective feelings of actual/ideal self-discrepancy vary across individuals and influence one's own affective states. However, the neural correlates of actual/ideal self-discrepancy and their genetic individual differences remain unknown. We investigated neural correlates of actual/ideal self-discrepancy and their associations with the serotonin transporter promoter polymorphism (5-HTTLPR) that moderates human affective states during self-reflection. We scanned short/short and long/long allele carriers of 5-HTTLPR, using functional MRI, during reflection on the distance between actual and ideal self in personality traits. We found that larger actual/ideal self-discrepancy was associated with activations in the ventral/dorsal striatum and dorsal medial and lateral prefrontal cortices. Moreover, these brain activities were stronger in short/short than long/long allele carriers and predicted self-report of life satisfaction in short/short carriers but trait depression in long/long carriers. Our findings revealed neural substrates of actual/ideal self-discrepancy and their associations with affective states that are sensitive to individuals' genetic makeup.

Change of MicroRNA-134, CREB and p-CREB expression in epileptic rat.

OBJECTIVE: To To investigate the changes of MicroRNA-134, CREB and p-CREB expression in epileptic rat brains in order to elucidate the molecular mechanisms of epilepsy, providing new ideas for clinical treatment. METHODS: Sixty-four Spraque-Dawley (SD) rats were divided into groups randomly, including control group, six hours after seizure group, 24-hour group, three-day group, one-week group, two-week group, four-week group, and eight-week group. All groups were placed under a pilocarpine-induced epilepsy model except the control group, and all rats were decapitated in different points of time. Brain specimens were taken for quantitative PCR experiments, immunohistochemistry and Western blot experiments. The results of the epilepsy model groups and the control group were compared. RESULTS: There were no significant differences between the six hours after seizure group, the 24-hour group and the control group about the MicroRNA-134 levels. MicroRNA-134 in the hippocampus tissue of the three-day group significantly reduced compared with the control group; same result was observed with the one-week, two-week, four-week and eight-week groups. The CREB and p-CREB levels in the three-day group's rat hippocampus significantly increased compared with the control group; and the high levels of CREB and p-CREB were constantly maintained in the one-week, two-week, four-week and eight-week groups. CONCLUSIONS: The MicroRNA-134 level of the epileptic rat hippocampus is significantly lower than normal after three days, and continues to maintain a low level; while CREB and p-CREB levels are rsignificantly increased after three days, and continue to remain at a high level. MicroRNA-134 plays a role in inhibiting synaptic plasticity by inhibiting CREB and p-CREB expressions.

Quantification of microRNA-210 in the cerebrospinal fluid and serum: Implications for Alzheimer's disease.

The aim of the present study was to investigate the potential clinical application of the genetic marker microRNA (miRNA)-210 in the cerebrospinal fluid (CSF) and serum of patients with Alzheimer's disease (AD). The enrolled patients were divided into the mild cognitive impairment (MCI) and AD groups. Healthy individuals were used as the controls. The mRNA and protein expression of vascular endothelial growth factor (VEGF) in the CSF and serum samples was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis, respectively. The expression of miRNA-210 in the CSF and serum was detected by RT-qPCR. The results revealed that the mRNA and protein expression levels of VEGF in the CSF and serum were decreased in the MCI and AD groups compared with those in the control group. The greater the severity of the dementia, the lower the mRNA and protein expression of VEGF. Similar to the trend observed for VEGF, the miRNA-210 expression in the CSF and serum decreased as the severity of the AD increased. miRNA-210 is thus not only indicative of AD pathogenesis, but may also provide novel insights into the prevention and treatment of the disease.