Common Neural Mechanisms Underlying Reversal Learning by Reward and Punishment

Impairments in flexible goal-directed decisions, often examined by reversal learning, are associated with behavioral abnormalities characterized by impulsiveness and disinhibition. Although the lateral orbital frontal cortex (OFC) has been consistently implicated in reversal learning, it is still unclear whether this region is involved in negative feedback processing, behavioral control, or both, and whether reward and punishment might have different effects on lateral OFC involvement. Using a relatively large sample (N = 47), and a categorical learning task with either monetary reward or moderate electric shock as feedback, we found overlapping activations in the right lateral OFC (and adjacent insula) for reward and punishment reversal learning when comparing correct reversal trials with correct acquisition trials, whereas we found overlapping activations in the right dorsolateral prefrontal cortex (DLPFC) when negative feedback signaled contingency change. The right lateral OFC and DLPFC also showed greater sensitivity to punishment than did their left homologues, indicating an asymmetry in how punishment is processed. We propose that the right lateral OFC and anterior insula are important for transforming affective feedback to behavioral adjustment, whereas the right DLPFC is involved in higher level attention control. These results provide insight into the neural mechanisms of reversal learning and behavioral flexibility, which can be leveraged to understand risky behaviors among vulnerable populations.     

莲花山云南柳莺的孵卵行为

20 0 2年 6～ 7月 ,在甘肃省莲花山自然保护区对云南柳莺的孵卵行为进行了研究。结果表明 ,雌鸟孵卵的日活动期为 (80 0 5± 42 8)min (n =1 5 ) ,每天离巢 (3 2 7± 3 9)次 (n =1 5 ) ,每次离巢时间 (6 6±1 8)min (n =5 99) ,每次坐巢时间 (1 8 4± 9 2 )min (n =5 83 ) ,坐巢率为 (73 1± 1 9) %。雌鸟每次坐巢时间和离巢时间的长度均与气温显著相关。日活动期雌鸟在巢的平均卵温为 3 2 3℃ ,夜晚的平均卵温为3 2 7℃。整个孵卵期卵温在发育临界值 2 8℃以上的时间比例为 92 7%。在孵卵后期卵温有逐渐上升的趋势。     

黑河下游柽柳种群地上生物量及耗水量的空间分布

以黑河下游柽柳(Tamarixramosissima)种群为研究对象,通过野外观测,建立柽柳地上生物量与简便易测因子间的关系;利用研究区的高分辨率影像(QuickBird)进行决策树分类,提取出柽柳易测因子的空间分布,估算研究区柽柳生物量的空间分布;在此基础上,借助于柽柳的蒸腾系数(300)计算出整个研究区内柽柳的耗水量.结果表明:研究区柽柳地上生物量为69644.7 t,单位面积生物量为0.78 kg.m-2;河岸边柽柳生境适宜,生物量较大;研究区柽柳蒸散的总水量为2.1×107m3,多年平均耗水量的空间分布范围在30～386 mm.     

Tissue-specific mutagenesis by N-butyl-N-(4-hydroxybutyl)nitrosamine as the basis for urothelial carcinogenesis

Bladder cancer is one of the few cancers that have been linked to carcinogens in the environment and tobacco smoke. Of the carcinogens tested in mouse chemical carcinogenesis models, N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) is one that reproducibly causes high-grade, invasive cancers in the urinary bladder, but not in any other tissues. However, the basis for such a high-level tissue-specificity has not been explored. Using mutagenesis in lacI (Big Blue?) mice, we show here that BBN is a potent mutagen and it causes high-level of mutagenesis specifically in the epithelial cells (urothelial) of the urinary bladder. After a 2-6-week treatment of 0.05% BBN in the drinking water, mutagenesis in urothelial cells of male and female mice was about two orders of magnitude greater than the spontaneous mutation background. In contrast, mutagenesis in smooth muscle cells of the urinary bladder was about five times lower than in urothelial tissue. No appreciable increase in mutagenesis was observed in kidney, ureter, liver or forestomach. In lacI (Big Blue?) rats, BBN mutagenesis was also elevated in urothelial cells, albeit not nearly as profoundly as in mice. This provides a potential explanation as to why rats are less prone than mice to the formation of aggressive form of bladder cancer induced by BBN. Our results suggest that the propensity to BBN-triggered mutagenesis of urothelial cells underlies its heightened susceptibility to this carcinogen and that mutagenesis induced by BBN represents a novel model for initiation of bladder carcinogenesis.     

Enhanced antitumor efficacy of gemcitabine by evodiamine on pancreatic cancer via regulating PI3K/Akt pathway

Evodiamine has therapeutic potential against cancers. This study was designed to investigate whether combination therapy with gemcitabine and evodiamine enhanced antitumor efficacy in pancreatic cancer. In vitro application of the combination therapy triggered significantly higher frequency of pancreatic cancer cells apoptosis, inhibited the activities of PI3K, Akt, PKA, mTOR and PTEN, and decreased the activation of NF-κB and expression of NF-κB-regulated products. In vivo application of the combination therapy induced significant enhancement of tumor cell apoptosis, reductions in tumor volume, and inhibited activation of mTOR and PTEN. In conclusion, evodiamine can augment the therapeutic effect of gemcitabine in pancreatic cancer through direct or indirect negative regulation of the PI3K/Akt pathway.     

叶序角的最优性分析

提出了互生叶序的叶序角和最优叶序角2πω^2。的概念,并对2πω^2的最优性进行了讨论,得到了用2πω^2在圆周上作插分得到任意n个分点并将圆周分为n个角时,最小角与最大角之比或为ω,或为ω^2,即至少是ω^2,还得到了用任意一个角α去分割圆周,其最小角与最大角之比的最小值不会大于ω^2,从而初步证明了最优叶序角对植物生长的最优性。     

Ac/Ds(GUS)结构介导的水稻启动子捕获系统的建立

构建了基于Activator/Dissociation(β-glucuronidase)[简称Ac/Ds(GUS)]结构的捕获质粒p13B,用于分离水稻基因启动子.以此质粒用衣杆菌介导的方法转化粳稻品种中花11的胚性愈伤组织,对获得的18个独立转化株的T2代植株进行了抗除草剂筛选,从141个抗除草剂转基因植株中用PCR方法检测到其中37株是Ds因子发生了转座的植株,而且这种转座到新位置上的Ds因子是遗传的.初步观察到其中5株的GUS染色呈阳性.     

塔拉多糖的脱色工艺化研究

塔拉多糖是一种半乳甘露聚糖胶,对于我们具有非常重要的应用价值。本实验主要对塔拉提取物中的塔拉多糖进行脱色工艺化研究;在单因素实验的基础上,对活性炭颗粒质量、脱色时间、脱色温度以及脱色次数这四种因素进行正交优化实验,其最佳脱色实验参数为：活性炭颗粒0.6 g,脱色45 min,脱色温度45℃脱色次数3次,脱色率可以达到50.21%,同时多糖类保留率为90.39%。     

中国柳莺属分类现状

柳莺属Phylloscopus一直是中国鸟类分类学中问题最多,研究最不完善的类群。在上世纪末的10年中,新增加了12种柳莺,包括新发现的3种和亚种被提升到种地位的9种。本文回顾和介绍了我国柳莺属分类研究概况,包括四川柳莺P.sichuanensis,海南柳莺P.hainanus和峨眉柳莺P.emeiensis3个新发现种。黄腰柳莺青藏亚种P.proregulus chloronotus和甘肃亚种P.p.kansuensis,黄腹柳莺P.affinis subaffinis亚种。黄腰柳莺青藏亚种P.proregulus chloronotus和甘肃亚种和P.c.sindianus亚种,黄眉柳莺P.inormatus humei亚种等的分类地位已由亚种升为种,但黑眉柳莺P.ricketti goodsoni亚种分类地位仍存在着争议,最后提出了目前我国柳莺属分类上尚存在的一些问题。