Jing Luo

An fMRI Study on the Time-Limited Role of the Medial Temporal Lobe in Long-Term Topographical Autobiographic Memory

The time-limited role of the medial temporal lobe (MTL) in human long-term memory is well known. However, there is still no direct neuroimaging evidence to confirm it. In this fMRI study, nine subjects were scanned while asked to recall the places they visited more than seven years ago (remote memories); and the places they visited recently (recent memories). We observed robust and dominant MTL activity peaking in the left parahippocampal gyrus when recent memories were contrasted with remote memories. This result provided direct evidence for the time-limited role of the MTL in long-term topographical autobiographic memory. Further analysis revealed that this MTL activity was not due to the fact that the retrieval of recent memories was accompanied by more details. When detailed recent memories were contrasted with detailed remote memories, there was still MTL activity peaking in the left parahippocampal gyrus. The effects of details in remote memories are also discussed.

Immune-related gene expression in response to H5N1 avian influenza virus infection in chicken and duck embryonic fibroblasts

Chicken and ducks are important hosts in responses to highly pathogenic avian influenza virus (HPAIV) H5N1 infection. In ducks, avian influenza (AI) generally causes an asymptomatic and long-lasting infection, whereas clinical apparent and transient disease is often observed in chickens. Using real-time quantitative PCR, we examined the expression of immune-related genes in response to H5N1 infection in chicken embryo fibroblasts (CEF) and duck embryo fibroblasts (DEF). While in CEF IL-6 expressed at high levels similar to mammalian species, in DEF expression levels were minimal. Similarly, duck IFN-β expression were slightly upregulated, whereas chicken expressions were highly upregulated. Chronologically, the mRNA levels of both IFN-alpha and IFN-gamma, which belong to type I and type II interferon, respectively, were unregulated in a similar fashion in chickens than in ducks. IL-2 and TLR-7 were elevated from the beginning of the infection in both CEF and DEF to the end of the experiment. Chicken MHC class I expression was almost unaffected while duck expression were downregulated. DEF and CEF MHC class II expression were downregulated. Chemokine IL-8 expression was upregulated in both species. The IL-8 levels closely parallel the IL-1β induced IL-6 levels in the same samples. These results show distinct embryo fibroblasts expression patterns of pro-inflammatory cytokines and IFNs between species.

Perceptual contributions to problem solving: Chunk decomposition of Chinese characters

Chunk decomposition is the decomposing of familiar patterns into their component elements so that they can be regrouped in another meaningful manner. Such a regrouping is sometimes critically required in problem solving because during initial encoding the problem elements become automatically grouped into familiar chunks and this may prohibit finding a novel or efficient solution to problems [G. Knoblich, S. Ohlsson, H. Haider, D. Rhenius, Constraint relaxation and chunk decomposition in insight problem solving, J. Exp. Psychol. Learn. Mem. Cogn. 25 (1999) 1534-1556]. In order to elucidate the brain mechanisms underlying the process of chunk decomposition, we developed a task that uses Chinese character as materials. Chinese characters are ideal examples of perceptual chunks. They are composed of radicals, which in turn, are composed of strokes. Because radicals are meaningful chunks themselves but strokes are not meaningful in isolation, it is much easier to separate a character by its radicals than to separate a character by its strokes. By comparing the stroke-level decomposition and the radical-level decomposition, we observed activities in occipital, frontal, and parietal lobes. Most importantly, during the moment of chunk decomposition, we found the early visual cortex showed a tendency of negative activation whereas the higher visual cortex showed a tendency of positive activation. This suggests that in order to successfully decompose a chunk, the higher visual areas must at least partly be disconnected from the input provided by early visual processing in order to allow simple features to be rearranged into a different perceptual chunk. We conclude that early perceptual processes can crucially affect thinking and problem solving.

Phylogenetic analysis and molecular characteristics of seven variant Chinese field isolates of PRRSV

BackgroundPorcine reproductive and respiratory syndrome (PRRS) has now been widely recognized as an economically important disease. The objective of this study was to compare the molecular and biological characteristics of porcine reproductive and respiratory syndrome virus (PRRSV) field isolates in China to those of the modified live virus (MLV) PRRS vaccine and its parent strain (ATCC VR2332).ResultsFive genes (GP2, GP3, GP4, GP5 and NSP2) of seven isolates of PRRSV from China, designated LS-4, HM-1, HQ-5, HQ-6, GC-2, GCH-3 and ST-7/2008, were sequenced and analyzed. Phylogenetic analyses based on the nucleotide sequence of the ORF2-5 and NSP2 showed that the seven Chinese isolates belonged to the same genetic subgroup and were related to the North American PRRSV genotype. Comparative analysis with the relevant sequences of another Chinese isolate (BJ-4) and North American (VR2332 and MLV) viruses revealed that these isolates have 80.8-92.9% homology with VR-2332, and 81.3-98.8% identity with MLV and 80.7-92.9% with BJ-4. All Nsp2 nonstructural protein of these seven isolates exhibited variations (a 29 amino acids deletion) in comparison with other North American PRRSV isolates. Therefore, these isolates were novel strain with unique amino acid composition. However, they all share more than 97% identity with other highly pathogenic Chinese PRRSV strains. Additionally, there are extensive amino acid (aa) mutations in the GP5 protein and the Nsp2 protein when compared with the previous isolates.ConclusionsThese results might be useful to study the genetic diversity of PRRSV in China and to track the infection sources as well as for vaccines development.

In search of the 'Aha!' experience: Elucidating the emotionality of insight problem-solving.

UNLABELLEDnAlthough the experience of insight has long been noted, the essence of the Aha! experience, reflecting a sudden change in the brain that accompanies an insight solution, remains largely unknown. This work aimed to uncover the mystery of the Aha! experience through three studies. In Study 1, participants were required to solve a set of verbal insight problems and then subjectively report their affective experience when solving the problem. The participants were found to have experienced many types of emotions, with happiness the most frequently reported one. Multidimensional scaling was employed in Study 2 to simplify the dimensions of these reported emotions. The results showed that these different types of emotions could be clearly placed in two-dimensional space and that components constituting the Aha! experience mainly reflected positive emotion and approached cognition. To validate previous findings, in Study 3, participants were asked to select the most appropriate emotional item describing their feelings at the time the problem was solved. The results of this study replicated the multidimensional construct consisting of approached cognition and positive affect. These three studies provide the first direct evidence of the essence of the Aha!nnnEXPERIENCEnThe potential significance of the findings was discussed.

Multivalent DNA vaccine induces protective immune responses and enhanced resistance against Cryptosporidium parvum infection.

The aim of this work was to evaluate efficiency as well as the type of immune response, Th1 or Th2, induced by multivalent DNA vaccinations in C57BL/6 interleukin-12p40 (IL-12p40) knockout (KO) mice. A recombinant pVAX-15-23 plasmid DNA was constructed by inserting surface glycoprotein (cp15- and p23)-encoding DNA into the pVAX1 expression vector. Various parameters including antibody and cytokine responses, proliferation assay and oocyst shedding were used to evaluate the type of immune response and the level of protection against challenge infection. Obtained results indicated that plasmid pVAX-15-23 induced strong protective immune response against C. parvum characterized by dominance of IgG2a, high level of INF-γ and lower level of the oocysts shedding after challenge infection. Moreover, co-immunization with the multivalent DNA and pMEM12R plasmid encoding IL-12 can further enhance these responses compared with the multivalent DNA alone. The obtained results suggest that multivalent pVAX-15-23 DNA vaccine may be a candidate as a generic approach to C. parvum immunization applicable to clinical practice.

Effects of local factors and climate on permafrost conditions and distribution in Beiluhe basin, Qinghai-Tibet Plateau, China

Beiluhe basin is underlain by warm and ice-rich permafrost, and covered by vegetation and soils characteristic of the Qinghai-Tibet Plateau. A field monitoring network was established to investigate permafrost conditions and to assess potential impacts of local factors and climate change. This paper describes the spatial variations in permafrost conditions from instrumented boreholes, controlling environmental factors, and recent thermal evolution of permafrost in the basin. The study area was divided into 10 ecotypes using satellite imagery based classification. The field investigations and cluster analysis of ground temperatures indicated that permafrost underlies most of the ground in swamp meadow, undisturbed alpine meadow, degrading alpine meadow, and desert alpine grassland, but is absent in other cover types. Permafrost-ecotope relations examined over a 2-year (2014-2016) period indicated that: (i) ground surface temperatures varied largely among ecotopes; (ii) annual mean ground temperatures ranged from -1.5 to 0°C in permafrost, indicating sensitive permafrost conditions; (iii) active-layer thicknesses ranged from 1.4m to 3.4m; (iv) ground ice content at the top of permafrost is high, but the active-layer soil is relatively dry. Long-term climate warming has driven thermal changes to permafrost, but ground surface characteristics and soil moisture content strongly influence the ground thermal state. These factors control local-scale spatial variations in permafrost conditions. The warm permafrost in the basin is commonly in thermal disequilibrium, and is sensitive to future climate change. Active-layer thicknesses have increased by at least 42cm and the mean annual ground temperatures have increased by up to 0.2°C in the past 10years over the basin. A permafrost distribution map was produced based on ecotypes, suggesting that permafrost underlies 64% of the study region.

Long-term thermal regimes of the Qinghai-Tibet Railway embankments in plateau permafrost regions

Ten years of ground temperature data (2003–2013) indicate that the long-term thermal regimes within embankments of the Qinghai-Tibet Railway (QTR) vary significantly with different embankment structures. Obvious asymmetries exist in the ground temperature fields within the traditional embankment (TE) and the crushed-rock basement embankment (CRBE). Measurements indicate that the TE and CRBE are not conducive to maintaining thermal stability. In contrast, the ground temperature fields of both the crushed-rock sloped embankment (CRSE) and the U-shaped crushed-rock embankment (UCRE) were symmetrical. However, the UCRE gave better thermal stability than the CRSE because slow warming of deep permafrost was observed under the CRSE. Therefore, the UCRE has the best long-term effect of decreasing ground temperature and improving the symmetry of the temperature field. More generally, it is concluded that construction using the cooling-roadbed principle meets the design requirements for long-term stability of the railway and for train transport speeds of 100 km h−1. However, temperature differences between the two shoulders, which exist in all embankments shoulders, may cause potential uneven settlement and might require maintenance.

Thaw-induced slope failures and susceptibility mapping in permafrost regions of the Qinghai–Tibet Engineering Corridor, China

With recent climatic warming and enhanced human activities, slope failures related to permafrost degradation are widespread along the Qinghai–Tibet Engineering Corridor. Assessment and mapping of the slope failures are necessary to mitigate hazards and plan engineering activities. According to our field investigations, the occurrence of slope failures is mainly controlled by the slope gradient, ground-ice content, permafrost temperatures, surficial deposits, and slope aspect. Modeling conducted in ArcGIS™ was used to produce a slope failure susceptibility map for a representative region along the Qinghai–Tibet Railway from Wudaoliang to Fenghuo Mountain Pass. The study region was divided into four classes based on slope failure susceptibility: (1) unlikely, (2) low, (3) moderate, and (4) high. Areas classified as unlikely accounted for 10.76xa0% of the study region, while low susceptibility areas comprised 44.51xa0%. The moderate and high susceptibility zones comprised 21.79 and 22.94xa0%, respectively. The actual distribution of slope failures in the region was consistent with the modeled results, which demonstrates the utility of the assessment method for future hazard management and engineering planning.

Thaw-induced slope failures and stability analyses in permafrost regions of the Qinghai-Tibet Plateau, China

The distribution of permafrost-related slope failures along the Qinghai-Tibet Highway from Wuddaoliang to Fenghuoshan correlates with ice content, slope gradient, and ground temperature. Slope failures are of two types. (1) Retrogressive thaw slumps result from icy permafrost being exposed by either man-induced excavation or fluvial-thermal erosion and undercutting of basal slopes. (2) Active-layer-detachment failures are caused by thaw of icy permafrost at the active layer-permafrost interface. After initial failure, active-layer-detachment failures can lead to retrogressive thaw-slumping and localized surficial landslide. Common trigger mechanisms for failure include high summer air temperatures and heavy summer precipitation. A third possible trigger mechanism for slope failure is earthquake occurrence. A geotechnical slope stability analysis was undertaken for an active-layer-detachment failure that had progressed into a retrogressive thaw slump. A safety factor (Fs) of 1.24 for the natural slope was determined using in situ tested strength parameters. However, the slope would lose stability when either the groundwater level over the permafrost table exceeded 1.42xa0m or seismic acceleration reached, or exceeded, 0.03u2009g.