Memory influences on hippocampal and striatal neural codes: effects of a shift between task rules

Interactions with neocortical memory systems may facilitate flexible information processing by hippocampus. We sought direct evidence for such memory influences by recording hippocampal neural responses to a change in cognitive strategy. Well-trained rats switched (within a single recording session) between the use of place and response strategies to solve a plus maze task. Maze and extramaze environments were constant throughout testing. Place fields demonstrated (in-field) firing rate and location-based reorganization [Leutgeb, S., Leutgeb, J. K., Barnes, C. A., Moser, E. I., McNaughton, B. L., & Moser, M. B. (2005). Independent codes for spatial and episodic memory in hippocampal neuronal ensembles. Science, 309, 619-623] after a task switch, suggesting that hippocampus encoded each phase of testing as a different context, or episode. The task switch also resulted in qualitative and quantitative changes to discharge that were correlated with an animal's velocity or acceleration of movement. Thus, the effects of a strategy switch extended beyond the spatial domain, and the movement correlates were not passive reflections of the current behavioral state. To determine whether hippocampal neural responses were unique, striatal place and movement-correlated neurons were simultaneously recorded with hippocampal neurons. Striatal place and movement cells exhibited a response profile that was similar, but not identical, to that observed for hippocampus after a strategy switch. Thus, retrieval of a different memory led both neural systems to represent a different context. However, hippocampus may play a special (though not exclusive) role in flexible spatial processing since correlated firing amongst cell pairs was highest when rats successfully switched between two spatial tasks. Correlated firing by striatal cell pairs increased following any strategy switch, supporting the view that striatum codes change in reinforcement contingencies.     

GENETIC AND REPRODUCTIVE TECHNOLOGIES IN THE LIGHT OF RELIGIOUS DIALOGUE

Since the gene splicing debates of the 1980s, the public has been exposed to an ongoing sequence of genetic and reproductive technologies. Many issue areas have outcomes that lose track of people's inner values or engender opposing religious viewpoints defying final resolution. This essay relocates the discussion of what is an acceptable application from the individual to the societal level, examining technologies that stand to address large numbers of people and thus call for policy resolution, rather than individual fiat, in their application. A major source of guidance is the “Genetic Frontiers” series of professional dialogues and conferences held by the National Conference for Community and Justice from 2002 to 2004. Genetic testing, human gene therapy, genetic engineering of plants and animals, and stem cell technology are examined. While differences in perspective on the beginning of life persist, a stepwise approach to the examination of genetic testing reveals areas of general agreement. Stewardship of life, human co‐creativity with the divine, and social justice help define the bounds of application of genetic engineering and therapy; compassionate care plays a major role in establishing stem cell policy. Active, sustained dialogue is a useful resource for enabling sharing of religious values and crystallization of policies.     

Evolutionary Pluralism: A New System of Systems Philosophy

When Darwin wrote his ‘On the origin of species…” (1859) he focused on evolution as a property of living organisms in interaction with abiotic and biotic elements in the world. This viewpoint is still dominant amongst biologists. For particle physicists and cosmologists evolution refers to a larger scale, ranging from quarks and atoms to galaxies, stars and planets (i.e. Pagels 1985, Hawking 1988). To close the gap between such different viewpoints, a wide range of perspectives on an interdisciplinary understanding of system development has been published (i.e. Teilhard de Chardin 1966, von Bertalanffy 1968, Varela 1979, Prigogine and Stengers 1984, Laszlo 1996). As an integrative concept, the construction of nature from a hierarchy of system layers forms a central tenet in general system research and the stepwise construction of this layered hierarchy can be regarded as an interdisciplinary evolution theory. Surprisingly, the literature offers no unequivocal rules to recognise a multilayer hierarchy in nature. This presents an obstacle for interdisciplinary approaches to evolution.

Searching a solution to part of the above hierarchy problem, the present paper is dedicated to the analysis of a special kind of layering in natural systems, which is based on transitions between ‘building block’ systems. To identify these building blocks, and the transitions from building block x at level A, to building block y at level B, the focus of this study is further limited to ‘hypercydic dynamics’ and ‘containment’. On the basis of these criteria, a hierarchy is created which shows no possibilities for ‘bypasses’. It connects hadrons to atoms, atoms to cells, and cells to neural networks. Implications of this hierarchy for system studies and evolution are discussed.     

Dissociating word stem completion and cued recall as a function of divided attention at retrieval

The aim of this study was to investigate the widely held, but largely untested, view that implicit memory (repetition priming) reflects an automatic form of retrieval. Specifically, in Experiment 1 we explored whether a secondary task (syllable monitoring), performed during retrieval, would disrupt performance on explicit (cued recall) and implicit (stem completion) memory tasks equally. Surprisingly, despite substantial memory and secondary costs to cued recall when performed with a syllable-monitoring task, the same manipulation had no effect on stem completion priming or on secondary task performance. In Experiment 2 we demonstrated that even when using a particularly demanding version of the stem completion task that incurred secondary task costs, the corresponding disruption to implicit memory performance was minimal. Collectively, the results are consistent with the view that implicit memory retrieval requires little or no processing capacity and is not seemingly susceptible to the effects of dividing attention at retrieval.     

神经营养素3在小儿哮喘中表达的临床意义

神经营养素3（NT-3）参与了神经系统的发育和功能发挥.最近研究发现它在呼吸系统疾病,尤其是哮喘的发病中也发挥重要作用.本课题采用酶联免疫吸附实验（ELISA）检测哮喘各组和正常对照组血清中NT-3的表达水平;用NT-3体外刺激正常人外周血单核细胞（PBMC）,采用ELISA法检测培养上清中IL-6和TNFα的表达水平.结果显示,与对照组相比,在哮喘组血清中NT-3的表达水平明显增高;并且它在哮喘发作期和缓解期中的表达量也要高于正常组;另外,NT-3可以显著促进PBMC分泌IL-6和TNFα.以上结果提示,可以将NT-3在小儿哮喘患者血清中的表达水平作为诊断病变过程的标记物,并且NT-3在维持气道高反应性方面也起到一定作用.     

脂肪干细胞复合脂肪颗粒促血管化的实验研究

本研究探讨脂肪干细胞复合脂肪颗粒对裸鼠皮下血管化的影响。将12只裸鼠身上标记三个点,将三组试剂分别注射,分析结果如下：肉眼观察：取材时,裸鼠背部注射部皮下有一团状组织块,脂肪组织形状不规则,大小不一。微血管密度：A组明显高于B组、C组,且差异有统计学意义（P〈0．01）;B组明显高于c组,且差异有统计学意义（P〈0．01）。存活率比较：A组明显高于B组、C组,且差异有统计学意义（P〈0．01）;B组明显高于C组,且差异有统计学意义（P〈0．01）。脂肪颗粒作为生物支架可加速脂肪干细胞的促血管化作用,从而促进移植物的存活与生长。     

复述、提取抑制与有意遗忘的实验研究

有意遗忘是关于记忆研究的另一种实验范式,对于在实验中出现的要求遗忘的学习项目的记忆成绩差于要求记忆的项目的结果,目前主人存在着两种理论解释：基于编码的理论和基于提取抑制的理论。该实验运用单字提示方式,采用控制较为严密的补笔测验方法和加入所谓的“无关项”,对有意遗忘的心理过程进行进一步的探讨,实验表明：在单了提示方式下,被试在进行有意遗忘的过程中,既对记忆项进行了有意的复述又对遗忘项产生了提取抑制。     

干细胞治疗的系统观

当前干细胞治疗面临着不少的技术难关和争议,需要运用现代系统论观点,从患者的整体上确定治疗目标,摸索出各种疾病所需的最佳干细胞类型和输注数量、最佳治疗时机、最佳输注途径,以发挥最佳效果。     

干细胞治疗糖尿病及外周血管病变研究进展

本文综述干细胞移植治疗糖尿病及外周血管病变研究进展,各国学者在该领域的经验及现状新途径等。关于干细胞移植治疗糖尿病的临床有效性及安全性等方面,各国学者仍然存在争议。总结目前临床应用研究中所存在的相关问题及经验教训,各国学者在开展后续临床研究时,应该避免重要的方案参数之间存在明显差异。更值得一提的是,干细胞移植的长期安全性尚待评估,其潜在的致瘤风险已受到关注。近期,中华医学会糖尿病学分会撰写了《中华医学会糖尿病学分会关于干细胞治疗糖尿病的立场声明》和《中华医学会糖尿病学分会关于干细胞治疗糖尿病外周血管病变的立场声明》,就是希望能够为阻止当前临床医生和患者在认识上和就医行为上的混乱局面发挥作用,使我国的干细胞临床研究和应用在健康的轨道上发展。     

Epistemological and Moral Conflict Between Religion and Science

Debates about religion and educational attainment often assume that members of certain religious groups do not seek out knowledge of science because they are opposed to the use of the scientific method. Using the science module of the 2006 General Social Survey, the analysis indicates that no religious group differs from the nonreligious comparison group in its propensity to seek out scientific knowledge. A more subtle epistemological conflict may arise when scientists make claims that explicitly contradict theological accounts. Findings indicate that Protestants and Catholics differ from the comparison group only on the very few issues where religion and science make competing claims. A third possible source of conflict may not be epistemological, but rather derives from opposition to what is understood as the public moral agenda of scientists. Findings indicate that conservative Protestants are opposed to scientific influence in public affairs due to opposition to the scientists’ moral agenda.