抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Principles of Neural Science

The Reorienting System of the Human Brain: From Environment to Theory of Mind

Semantic memory refers to knowledge about people, objects, actions, relations, self, and culture acquired through experience. The neural systems that store and retrieve this information have been studied for many years, but a consensus regarding their identity has not been reached. Using strict inclusion criteria, we analyzed 120 functional neuroimaging studies focusing on semantic processing. Reliable areas of activation in these studies were identified using the activation likelihood estimate (ALE) technique. These activations formed a distinct, left-lateralized network comprised of 7 regions: posterior inferior parietal lobe, middle temporal gyrus, fusiform and parahippocampal gyri, dorsomedial prefrontal cortex, inferior frontal gyrus, ventromedial prefrontal cortex, and posterior cingulate gyrus. Secondary analyses showed specific subregions of this network associated with knowledge of actions, manipulable artifacts, abstract concepts, and concrete concepts. The cortical regions involved in semantic processing can be grouped into 3 broad categories: posterior multimodal and heteromodal association cortex, heteromodal prefrontal cortex, and medial limbic regions. The expansion of these regions in the human relative to the nonhuman primate brain may explain uniquely human capacities to use language productively, plan, solve problems, and create cultural and technological artifacts, all of which depend on the fluid and efficient retrieval and manipulation of semantic knowledge.

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Where Is the Semantic System? A Critical Review and Meta-Analysis of 120 Functional Neuroimaging Studies

Mindfulness meditation is a complex psychological process that involves emotional, attentional and awareness practices. In this work, we predict the years of meditation experience of Buddhist monks using Multivariate Pattern Regression and functional connectivity analysis. 12 Buddhist monks underwent a meditation session according to two meditation styles while BOLD fMRI at 1.5 T was recorded. Functional connectivity matrices were calculated between functionally subdivided ROIs. Correlations were used as features for a Support Vector Regression with target the monks’ experience. Regression weights highlighted prominent connections and differentiated meditation styles.

Prediction of meditation experience using fMRI functional connectivity and multivariate pattern analysis

The effects of intensive meditation practices on the functional and structural organization of the human brain have been addressed by a growing number of neuroscientific studies. However, the different modulations of meditation expertise and of ageing, in the underlying brain areas and networks, have not yet been fully elucidated. These effects should be distinguished in order to clarify how long-term meditation can modulate the connectivity between brain areas. To address this issue, we tested whether meditation expertise and age can be predicted from the multivariate pattern of functional Magnetic Resonance Imaging connectivity, in Theravada Buddhist monks with long-term practice in two different meditation forms: Focused Attention (FA) and Open Monitoring (OM). We found that functional connectivity patterns in both meditation forms can be used to predict expertise and age of long-term meditators. Our findings suggest that meditation expertise is associated with meditation-specific brain networks modulations, while age-related modifications are general and independent from the meditation type. Specifically, expertise modulated patterns during FA meditation include nodes and connections implicated in focusing, sustaining and monitoring attention, while the predictive patterns during OM meditation include nodes associated with cognitive and affective monitoring. Thus, the two forms of meditation may differentially contribute to counteract the effects of neurocognitive decline with ageing by neuroplasticity of brain networks.

/pdf/disentangling-functional-connectivity-effects-of-age-and-dgxcxilbcx.pdf

Disentangling functional connectivity effects of age and expertise in long-term meditators

1. Abstract Tying the hands behind the back has detrimental effect of sensorimotor perceptual tasks. Here we provide evidence that beta band oscillatory activity in a resting state condition might have a crucial role in such detrimental effects. EEG activity in a resting state condition was measured from thirty participants in two different body posture conditions. In one condition participants were required to keep their hands freely resting on the table. In the other condition, participants were required to keep the hands tied behind their back. Increased beta power was observed in the left inferior frontal gyrus (l-IFG) during the tied hands condition compared to the free hands condition. A control study ruled out alternative explanations including muscle tension that might have affected the EEG data. Our findings provide new insight on how body postural manipulations impact on perceptual tasks and intrinsic brain activity.

/pdf/the-impact-of-body-posture-on-intrinsic-brain-activity-the-3754hnb59p.pdf

The impact of body posture on intrinsic brain activity: the role of beta power at rest

The perception of the internal milieu is thought to reflect beliefs and prior knowledge about the expected state of the body, rather than only actual interoceptive states. This study investigated whether heartbeat perception could be illusorily distorted towards prior subjective beliefs, such that threat expectations suffice to induce a false perception of increased heartbeat frequency. Participants were instructed to focus on their cardiac activity and report their heartbeat, either tapping along to it (Experiment 1) or silently counting (Experiment 2) while ECG was recorded. While completing this task, different cues provided valid predictive information about the intensity of an upcoming cutaneous stimulation (high- vs. low- pain). Results showed that participants expected a heart rate increase over the anticipation of high- vs. low-pain stimuli and that this belief was perceptually instantiated, as shown by their interoceptive reports. Importantly, the perceived increase was not mirrored by the real heart rate. Perceptual modulations were absent when participants executed the same task but with an exteroceptive stimulus (Experiment 3). The findings reveal, for the first time, an interoceptive illusion of increased heartbeats elicited by threat expectancy and shed new light on interoceptive processes through the lenses of Bayesian predictive processes, providing tantalizing insights into how such illusory phenomena may intersect with the recognition and regulation of people’s internal states.

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Mauro Gianni Perrucci

Papers

Prediction of meditation experience using fMRI functional connectivity and multivariate pattern analysis

Disentangling functional connectivity effects of age and expertise in long-term meditators

The impact of body posture on intrinsic brain activity: the role of beta power at rest

Heart Is Deceitful Above All Things: threat expectancy induces the illusory perception of increased heartrate

The impact of cardiac phases on multisensory integration