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

As humans, we perceive feelings from our bodies that relate our state of well-being, our energy and stress levels, our mood and disposition. How do we have these feelings? What neural processes do they represent? Recent functional anatomical work has detailed an afferent neural system in primates and in humans that represents all aspects of the physiological condition of the physical body. This system constitutes a representation of 'the material me', and might provide a foundation for subjective feelings, emotion and self-awareness.

How do you feel? Interoception: the sense of the physiological condition of the body.

Functional neuroimaging studies have started unravelling unexpected functional attributes for the posteromedial portion of the parietal lobe, the precuneus. This cortical area has traditionally received little attention, mainly because of its hidden location and the virtual absence of focal lesion studies. However, recent functional imaging findings in healthy subjects suggest a central role for the precuneus in a wide spectrum of highly integrated tasks, including visuo-spatial imagery, episodic memory retrieval and self-processing operations, namely first-person perspective taking and an experience of agency. Furthermore, precuneus and surrounding posteromedial areas are amongst the brain structures displaying the highest resting metabolic rates (hot spots) and are characterized by transient decreases in the tonic activity during engagement in non-self-referential goal-directed actions (default mode of brain function). Therefore, it has recently been proposed that precuneus is involved in the interwoven network of the neural correlates of self-consciousness, engaged in self-related mental representations during rest. This hypothesis is consistent with the selective hypometabolism in the posteromedial cortex reported in a wide range of altered conscious states, such as sleep, drug-induced anaesthesia and vegetative states. This review summarizes the current knowledge about the macroscopic and microscopic anatomy of precuneus, together with its wide-spread connectivity with both cortical and subcortical structures, as shown by connectional and neurophysiological findings in non-human primates, and links these notions with the multifaceted spectrum of its behavioural correlates. By means of a critical analysis of precuneus activation patterns in response to different mental tasks, this paper provides a useful conceptual framework for matching the functional imaging findings with the specific role(s) played by this structure in the higher-order cognitive functions in which it has been implicated. Specifically, activation patterns appear to converge with anatomical and connectivity data in providing preliminary evidence for a functional subdivision within the precuneus into an anterior region, involved in self-centred mental imagery strategies, and a posterior region, subserving successful episodic memory retrieval.

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The precuneus: a review of its functional anatomy and behavioural correlates.

http://www.brainresearch.us/cognitive.pdf

The cognitive control of emotion.

In this study, we investigated the level of visual processing at which surface colour information improves the naming of colour diagnostic and noncolour diagnostic objects. Continuous electroencephalograms were recorded while participants performed a visual object naming task in which coloured and black-and-white versions of both types of objects were presented. The black-and-white and the colour presentations were compared in two groups of event-related potentials (ERPs): (1) The P1 and N1 components, indexing early visual processing; and (2) the N300 and N400 components, which index late visual processing. A colour effect was observed in the P1 and N1 components, for both colour and noncolour diagnostic objects. In addition, for colour diagnostic objects, a colour effect was observed in the N400 component. These results suggest that colour information is important for the naming of colour and noncolour diagnostic objects at different levels of visual processing. It thus appears that the visual system us...

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Electrophysiological evidence for colour effects on the naming of colour diagnostic and noncolour diagnostic objects

Trial-by-trial coupling of concurrent EEG and fMRI identifies BOLD correlates of the N400

Is there a relation between socioeconomic factors and aphasia severity and recovery? Connor, Obler, Tocco, Fitzpatrick, and Albert (2001) describe correlations between the educational level and socioeconomic status of aphasic subjects with aphasia severity and subsequent recovery. As stated in the introduction by Connor et al. (2001), studies of the influence of educational level and literacy (or illiteracy) on aphasia severity have yielded conflicting results, while no significant link between socioeconomic status and aphasia severity and recovery has been established. In this brief note, we will comment on their findings and conclusions, beginning first with a brief review of literacy and aphasia research, and complexities encountered in these fields of investigation. This serves as a general background to our specific comments on Connor et al. (2001), which will be focusing on methodological issues and the importance of taking normative values in consideration when subjects with different socio-cultural or socio-economic backgrounds are assessed. 2003 Elsevier Science (USA). All rights reserved.

Notes and Discussion Educational level, socioeconomic status and aphasia research: A comment on Connor et al. (2001)—Effect of socioeconomic status on aphasia severity and recovery

Language Comprehension: The Interplay between Form and Content Vasiliki Folia a,b,c (vasiliki.folia@fcdonders.ru.nl) Christian Forkstam a,b,c (christian.forkstam@ki.se) Peter Hagoort a,c (peter.hagoort@fcdonders.ru.nl) Karl Magnus Petersson a,b,c,d (karl-magnus.petersson@mpi.nl) a Max Planck Institute for Psycholinguistics, Nijmegen, the Netherlands b Stockholm Brain Institute, Karolinska Institutet, Stockholm, Sweden c Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, the Netherlands d Cognitive Neuroscience Research Group, Universidade do Algarve, Faro, Portugal Abstract In a 2x2 event-related FMRI study we find support for the idea that the inferior frontal cortex, centered on Broca’s region and its homologue, is involved in constructive unification operations during the structure-building process in parsing for comprehension. Tentatively, we provide evidence for a role of the dorsolateral prefrontal cortex centered on BA 9/46 in the control component of the language system. Finally, the left temporo-parietal cortex, in the vicinity of Wernicke’s region, supports the interaction between the syntax of gender agreement and sentence-level semantics. Keywords: FMRI; syntax; semantics; language comprehension; Broca’s region; Wernicke’s region; inferior parietal region Introduction Humans encounter many new and unexpected sentences in everyday life and typically interpret them without cognitive effort. This ability is grounded in a peculiar biological system, part of the human brain, called the faculty of language. Most current models of language processing agree that different types of constraints are rapidly utilized in on- line sentence processing (Hagoort, 2005). Constraints on how words can be structurally combined operate interactively and in parallel with qualitatively distinct constraints on the combination of word meanings, the grouping of words into phonological phrases, and their referential binding in discourse models (Jackendoff, 2007). Most models make a distinction between retrieval and combinatorial/compositional processes, implying that sentences have internal structure. Retrieval entails lexical selection from the mental lexicon, a specific long-term memory store. Lexical representations include knowledge about lexical form, syntactic properties (e.g., constituent class, syntactic gender etc.), and lexical meaning. The creative aspect of language is in part captured by its generative structure-building processes which create sentence-internal structure that represents for example who did what to whom and how. A recent trend in theoretical linguistics suggests that the separation between lexical items and traditional rules of grammar is fading and increasing support for these so-called lexicalized models have accumulated. In lexicalized models of parsing, the properties of words needed for sentence level integration are retrieved from the mental lexicon in the form of structured primitive representations (e.g., treelet) and only relatively generic structure building operations like unification (Vosse & Kempen, 2000), unify-pieces (Culicover & Jackendoff, 2005), or merge (Chomsky, 2005) are necessary to complete the on-line combinatorial integration process. Vosse and Kempen (2000) proposed a computationally explicit lexicalist unification space model that accounts for a large range of empirical findings in the parsing- and neuropsychological aphasia literature. According to this unification space model, every incoming word retrieves lexical frames (elementary syntactic trees) that specify possible structural environments for input words. When retrieved, these lexical frames enter the unification space in a sequential fashion and are integrated interactively and in parallel in a unification process in which lexical frames are dynamically linked and various constraints, like agreement and linear order constraints, are applied (Kempen & Harbusch, 2002). A key question in our understanding of language is whether and where in the human brain the different levels are localized and processed as well as whether and where they interact. Understanding where, how, and when the linguistic subcomponents are interacting in order to provide a coherent interpretation is a fundamental challenge in the neurobiological study of the language faculty (Chomsky, 2005). It is well-accepted that large regions within the frontal, temporal, and temporo-parietal cortices are involved in language processing. The temporal and temporo-parietal cortices play a central role in both short-term verbal memory (e.g., Petersson et al., 2009), storage and retrieval of lexical information, that has been encoded during language acquisition (Indefrey & Cutler, 2005). Based on a meta-analysis of syntactic processing (Indefrey, 2004), Hagoort (2005) suggested that the left posterior temporal cortex is involved in the retrieval of lexical frames that form the building blocks for syntactic unification, which he argued, is supported by the left inferior frontal cortex (LIFC). Functional magnetic resonance imaging (FMRI) evidence support the role of the LIFC in the unification operations that are performed at the structural/syntactic (Petersson et al., 2004; Snijders et al., 2008) and

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Language comprehension: The interplay between form and content

The aim of the present study was to investigate whether reading failure in the context of an orthography of intermediate consistency is linked to inefficient use of the lexical orthographic reading procedure. The performance of typically developing and dyslexic Portuguese-speaking children was examined in a lexical decision task, where the stimulus lexicality, word frequency and length were manipulated. Both lexicality and length effects were larger in the dyslexic group than in controls, although the interaction between group and frequency disappeared when the data were transformed to control for general performance factors. Children with dyslexia were influenced in lexical decision making by the stimulus length of words and pseudowords, whereas age-matched controls were influenced by the length of pseudowords only. These findings suggest that non-impaired readers rely mainly on lexical orthographic information, but children with dyslexia preferentially use the phonological decoding procedure--albeit poorly--most likely because they struggle to process orthographic inputs as a whole such as controls do. Accordingly, dyslexic children showed significantly poorer performance than controls for all types of stimuli, including words that could be considered over-learned, such as high-frequency words. This suggests that their orthographic lexical entries are less established in the orthographic lexicon.

/pdf/lexical-and-phonological-processes-in-dyslexic-readers-10vu0h1pv8.pdf

Karl Magnus Petersson

Papers

Electrophysiological evidence for colour effects on the naming of colour diagnostic and noncolour diagnostic objects

Trial-by-trial coupling of concurrent EEG and fMRI identifies BOLD correlates of the N400

Notes and Discussion Educational level, socioeconomic status and aphasia research: A comment on Connor et al. (2001)—Effect of socioeconomic status on aphasia severity and recovery

Language comprehension: The interplay between form and content

Lexical and phonological processes in dyslexic readers: evidence from a visual lexical decision task.