经导管射频消融术发展史及对医学教育的启示

自20世纪未,经导管射频消融术成功用于治疗快速心律失常,取得了瞩目的成就,本文回顾这一技术的发展史,认为它是理工科和医学高度结合的产物,提出医学教育与科研应该有理工医结合的环境。     

Towards a computational theory of experience

A standing challenge for the science of mind is to account for the datum that every mind faces in the most immediate – that is, unmediated – fashion: its phenomenal experience. The complementary tasks of explaining what it means for a system to give rise to experience and what constitutes the content of experience (qualia) in computational terms are particularly challenging, given the multiple realizability of computation. In this paper, we identify a set of conditions that a computational theory must satisfy for it to constitute not just a sufficient but a necessary, and therefore naturalistic and intrinsic, explanation of qualia. We show that a common assumption behind many neurocomputational theories of the mind, according to which mind states can be formalized solely in terms of instantaneous vectors of activities of representational units such as neurons, does not meet the requisite conditions, in part because it relies on inactive units to shape presently experienced qualia and implies a homogeneous representation space, which is devoid of intrinsic structure. We then sketch a naturalistic computational theory of qualia, which posits that experience is realized by dynamical activity-space trajectories (rather than points) and that its richness is measured by the representational capacity of the trajectory space in which it unfolds.     

Sleep EEG changes during adolescence: An index of a fundamental brain reorganization

Delta (1–4 Hz) EEG power in non-rapid eye movement (NREM) sleep declines massively during adolescence. This observation stimulated the hypothesis that during adolescence the human brain undergoes an extensive reorganization driven by synaptic elimination. The parallel declines in synaptic density, delta wave amplitude and cortical metabolic rate during adolescence further support this model. These late brain changes probably represent the final ontogenetic manifestation of nature’s strategy for constructing nervous systems: an initial overproduction of neural elements followed by elimination. Errors in adolescent brain reorganization may cause mental illness; this could explain the typical age of onset of schizophrenia. Longitudinal studies of sleep EEG are enhancing our knowledge of adolescent brain maturation. Our longitudinal study of sleep EEG changes in adolescence showed that delta power, which may reflect frontal cortex maturation, begins its decline between ages 11 and 12 years and falls by 65% by age 17 years. In contrast, NREM theta power begins its decline much earlier. Delta and theta EEG frequencies are important to sleep theory because they behave homeostatically. Surprisingly, these brain changes are unrelated to pubertal maturation but are strongly linked to age. In addition to these (and other) maturational EEG changes, sleep schedules in adolescence change in response to a complex interaction of circadian, social and other influences. Our data demonstrate that the daytime sleepiness that emerges in adolescence is related to the decline in NREM delta as well as to altered sleep schedules. These longitudinal sleep data provide guideposts for studying cognitive and behavioral correlates of adolescent brain reorganization.     

Neuroimaging and neuroenergetics: Brain activations as information-driven reorganization of energy flows

There is increasing focus on the neurophysiological underpinnings of brain activations, giving birth to an emerging branch of neuroscience – neuroenergetics. However, no common definition of “brain activation” exists thus far. In this article, we define brain activation as the information-driven reorganization of energy flows in a population of neuroglial units that leads to an overall increase in energy utilization in this population. On the basis of this definition, the key aspects of modern biochemical and biophysical approaches to neuroenergetics are considered from the perspective of the links between these approaches within the context of the free energy minimization principle and the neurophysiological conception of deviance detection. In this light, we consider brain basal activity as subserving internal representations of the environment (predictive coding), and brain activation as reflecting the level of deviance from predictive coding.     

HUMAN CLONING THROUGH THE EYES OF MUSLIM SCHOLARS: THE NEW PHENOMENON OF THE ISLAMIC INTERNATIONAL RELIGIOSCIENTIFIC INSTITUTIONS

In the wake of the February 1997 announcement that Dolly the sheep had been cloned, Muslim religious scholars together with Muslim scientists held two conferences to discuss cloning from an Islamic perspective. They were organized by two influential Islamic international religioscientific institutions: the Islamic Organization of Medical Sciences (IOMS) and the International Islamic Fiqh Academy (IIFA). Both institutions comprise a large number of prominent religious scholars and well-known scientists who participated in the discussions at the conferences. This article gives a comprehensive analysis of these conferences, the relation between science and religion as reflected in the discussions there, and the further influence of these discussions on Muslims living in the West. Modern discussions on Islamic bioethics show that formulating an Islamic perspective on these issues is not the exclusive prerogative of religious scholars. Formulating such perspectives has become a collective process in which scientists play an essential role. Such a collective approach strengthens the religious authority of Muslim scholars and makes it more influential rather than undermining it.     

THE FUTURE OF THE BUDDHIST PAST: A RESPONSE TO THE READERS

I respond to comments offered by Peter Harrison and Thupten Jinpa on my book Buddhism and Science: A Guide for the Perplexed (2008). I report briefly on the reception of the book thus far and provide a summary of its contents before responding individually to the essays of Harrison and Jinpa.     

肝脏X受体研究在心血管疾病中的应用展望

肝脏X受体(Liver X Receptor,LXR)是新近研究比较深入的一个热点话题,LXR主要参与胆固醇代谢和转运、脂肪代谢、糖原异生和炎症等过程。本文在LXR的结构、功能、其激动剂及其可能的临床作用、未来的研究方向等多个方面进行了详细的阐述。     

A New View of Language, Emotion and the Brain

Linguistic theory since the Cognitive Revolution has followed one of the premises of that revolution by largely sidelining the issue of emotions and concentrating on those aspects of language that are more strictly cognitive. However, during the last two decades research in cognitive science, especially in neuropsychology, has begun to fill in the gaps left by the exclusion of emotions from cognitive research. This article proposes a model for applying the fruits of this new research in emotion to our understanding of language itself. Building on Karl Pribram`s integrated model of emotions and motivations, the presentation it offers a propositional explanation for how the emotions may have contributed to the emergence of symbolic formation and, ultimately, to every aspect of language from lexis to literature.

Seeing is believing: the effect of brain images on judgments of scientific reasoning

Brain images are believed to have a particularly persuasive influence on the public perception of research on cognition. Three experiments are reported showing that presenting brain images with articles summarizing cognitive neuroscience research resulted in higher ratings of scientific reasoning for arguments made in those articles, as compared to articles accompanied by bar graphs, a topographical map of brain activation, or no image. These data lend support to the notion that part of the fascination, and the credibility, of brain imaging research lies in the persuasive power of the actual brain images themselves. We argue that brain images are influential because they provide a physical basis for abstract cognitive processes, appealing to people's affinity for reductionistic explanations of cognitive phenomena.     

METANEXUS 2007: THE CHALLENGE AHEAD

This essay is William Grassie's valedictory remarks at the Metanexus Institute's 2007 Annual Conference. Grassie asks what is wrong with religion, what is wrong with science, and why the constructive engagement of the two holds the key to setting things right. He cites Sir John Templeton and others to make his case and proposes a new curriculum for general science education that uses the history of nature as a mnemonic and context for promoting better science literacy and the incorporation of science into our cultural traditions.