胃肠道干细胞

胃肠道是人体内各系统细胞更新频率最高的器官,其干细胞的增生分化也很旺盛。尽管胃肠道干细胞本身未分化成熟,其细胞表型无法确认而不利于鉴别,但随着一些干细胞标志物的发现及对细胞信号传导通路的不断了解,我们对胃肠道干细胞的调控机制的认识正在不断加深。胃肠道干细胞的基本特征:(1)胃肠道干细胞的数量、定位和组织起源;(2)胃肠道干细胞的主要功能,包括分化转化成胃肠道各成熟的细胞系及维持组织的动态平衡和稳定;(3)从其他组织的干细胞获得胃肠组织细胞系用以胃肠道疾病的治疗;(4)胃肠道组织癌变的基因变化及形态学观察。     

学习困难儿童在工作记忆任务中抑制机制的研究

本研究的目的旨在探讨在WM任务中,LD儿童是否存在抑制机制缺陷。实验程序采用重复启动范式,设计“预期”和“目标”两种启动条件,随后通过间接测量的方式(内隐记忆测验)分别测得LD儿童和NLD儿童对预期词和目标词的启动量。结果表明,LD儿童对预期词的启动分数与目标词没有显著差异,NLD儿童对目标词的启动分数显著高于对预期词的启动分数。我们得出结论:在工作记忆任务中,LD儿童存在抑制机制缺陷。     

策略型学习者认知心理结构及其运行机制

高效率学习是现代社会发展的需要,也是适应信息量急增的社会变革需要的必然选择。从教育心理学的视角研究策略型学习者,对其高效率学习心理,特别是高效率学习认知心理结构及其运行机制进行研究,有助于教育理论与实践工作者准确把握这类特殊教育对象的心理特点与规律,为开展策略型学习者教育提供了心理学依据。     

双语者代码切换的认知与神经机制——从行为研究到脑成像研究

双语者代码切换的机制已引起心理语言学家和认知神经科学家的广泛关注。研究分别在行为层面和神经机制层面展开。发现,双语者在进行代码切换时会出现切换代价,切换代价来源于心理词典外部的语言任务图式之间的竞争,其机制可能与中央执行控制机制有密切联系,左侧额下回、双侧缘上回和背外侧前额叶等脑区参与了双语者的代码切换过程。文章还分析了在这一领域仍待研究的一些问题,并提出了进一步开展双语代码切换研究的建议。     

The "Perceptual Wedge Hypothesis" as the basis for bilingual babies' phonetic processing advantage: new insights from fNIRS brain imaging

In a neuroimaging study focusing on young bilinguals, we explored the brains of bilingual and monolingual babies across two age groups (younger 4-6 months, older 10-12 months), using fNIRS in a new event-related design, as babies processed linguistic phonetic (Native English, Non-Native Hindi) and nonlinguistic Tone stimuli. We found that phonetic processing in bilingual and monolingual babies is accomplished with the same language-specific brain areas classically observed in adults, including the left superior temporal gyrus (associated with phonetic processing) and the left inferior frontal cortex (associated with the search and retrieval of information about meanings, and syntactic and phonological patterning), with intriguing developmental timing differences: left superior temporal gyrus activation was observed early and remained stably active over time, while left inferior frontal cortex showed greater increase in neural activation in older babies notably at the precise age when babies’ enter the universal first-word milestone, thus revealing a first-time focalbrain correlate that may mediate a universal behavioral milestone in early human language acquisition. A difference was observed in the older bilingual babies’ resilient neural and behavioral sensitivity to Non-Native phonetic contrasts at a time when monolingual babies can no longer make such discriminations. We advance the “Perceptual Wedge Hypothesis” as one possible explanation for how exposure to greater than one language may alter neural and language processing in ways that we suggest are advantageous to language users. The brains of bilinguals and multilinguals may provide the most powerful window into the full neural “extent and variability” that our human species’ language processing brain areas could potentially achieve.     

Brain activity in adults who stutter: similarities across speaking tasks and correlations with stuttering frequency and speaking rate

Many differences in brain activity have been reported between persons who stutter (PWS) and typically fluent controls during oral reading tasks. An earlier meta-analysis of imaging studies identified stutter-related regions, but recent studies report less agreement with those regions. A PET study on adult dextral PWS (n = 18) and matched fluent controls (CONT, n = 12) is reported that used both oral reading and monologue tasks. After correcting for speech rate differences between the groups the task-activation differences were surprisingly small. For both analyses only some regions previously considered stutter-related were more activated in the PWS group than in the CONT group, and these were also activated during eyes-closed rest (ECR). In the PWS group, stuttering frequency was correlated with cortico-striatal-thalamic circuit activity in both speaking tasks. The neuroimaging findings for the PWS group, relative to the CONT group, appear consistent with neuroanatomic abnormalities being increasingly reported among PWS.     

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.     

The neural, evolutionary, developmental, and bodily basis of metaphor

We propose that there are four fundamental kinds of metaphor that are uniquely mapped onto specific brain “networks” and present preliterate (i.e., evolutionary, including before the appearance of written language in the historical record), prelinguistic (i.e., developmental, before the appearance of speech in human development), and extralinguistic (i.e., neuropsychological, cognitive) evidence supportive of this view. We contend that these basic metaphors are largely nonconceptual and entail (a) perceptual-perceptual, (b) cross-modal, (c) movement-movement, and (d) perceptual-affective mappings that, at least, in the initial stages of processing may operate largely outside of conscious awareness. In opposition to our basic metaphor theory (B_mT), the standard theory (S_mT) maintains that metaphor is a conceptual mapping from some base domain to some target domain and/or represents class-inclusion (categorical) assertions. The S_mT captures aspects of secondary or conceptual metaphoric relations but not primary or basic metaphoric relations in our view. We believe our theory (B_mT) explains more about how people actually recognize or create metaphoric associations across disparate domains of experience partly because they are “pre-wired” to make these links.     

Emergence from brain architectures: a new cognitive science?

The way in which artificial intelligence has developed over the last 50 years has had a major role in shaping cognitive science as it is today. This has generated computational models of behaviour. The connectionist revival of the 1980s added a tinge of neurodynamics to this. Here I suggest that some post-connectionist work in artificial intelligence is turning towards an understanding and formalisation of the mechanisms of brain architectures which contribute to an emergence of cognition providing a closer link between brain mechanisms and experienced brain states. This even addresses the neurological basis of consciousness.     

WHY I AM AN ACCOMMODATIONIST AND PROUD OF IT

There is a strong need of a reasoned defense of what was known as the “independence” position of the science–religion relationship but that more recently has been denigrated as the “accommodationist” position, namely that while there are parts of religion—fundamentalist Christianity in particular—that clash with modern science, the essential parts of religion (Christianity) do not and could not clash with science. A case for this position is made on the grounds of the essentially metaphorical nature of science. Modern science functions because of its root metaphor of the machine: the world is seen in mechanical terms. As Thomas Kuhn insisted, metaphors function in part by ruling some questions outside their domain. In the case of modern science, four questions go unasked and hence unanswered: Why is there something rather than nothing? What is the foundation of morality? What is mind and its relationship to matter? What is the meaning of it all? You can remain a nonreligious skeptic on these questions, but it is open for the Christian to offer his or her answers, so long as they are not scientific answers. Here then is a way that science and religion can coexist.