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

We review evidence for partially segregated networks of brain areas that carry out different attentional functions. One system, which includes parts of the intraparietal cortex and superior frontal cortex, is involved in preparing and applying goal-directed (top-down) selection for stimuli and responses. This system is also modulated by the detection of stimuli. The other system, which includes the temporoparietal cortex and inferior frontal cortex, and is largely lateralized to the right hemisphere, is not involved in top-down selection. Instead, this system is specialized for the detection of behaviourally relevant stimuli, particularly when they are salient or unexpected. This ventral frontoparietal network works as a 'circuit breaker' for the dorsal system, directing attention to salient events. Both attentional systems interact during normal vision, and both are disrupted in unilateral spatial neglect.

Control of goal-directed and stimulus-driven attention in the brain

https://surfer.nmr.mgh.harvard.edu/ftp/articles/desikan06-parcellation.pdf

An automated labeling system for subdividing the human cerebral cortex on MRI scans into gyral based regions of interest.

https://surfer.nmr.mgh.harvard.edu/ftp/articles/dale99-recon1.pdf

Cortical surface-based analysis. I. Segmentation and surface reconstruction

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

This article discusses the evolution of primate cortex. It covers the development of different cortical visual areas and the techniques used to map visual cortex across different species. The article emphasizes a systems approach to these studies in order to account for differences and similarities in the cortical maps in different species.

Visual Cortex: Evolution of Maps and Mapping

Most developmental studies of visual system functional organization have concentrated, quite sensibly, on areas in which the adult organization was already well understood. In vertebrates, these include the ocular dominance, orientation and retinotopic maps in mammalian visual cortex, and the retinotopy (and in experimental preparations, the ocular segregation) in frog optic tectum. Developmental aspects of these topics are covered elsewhere in this volume. Here we review the wealth of new data on the functional architecture of monkey visual cortex, a system particularly ripe for future developmental enquiry.

Columnar Organization of Primate Visual Cortex

250 words Introduction: 654 words Results: 3119 words Discussion: 1535 words Online Methods: 3270 words Main Figures: 12 Supplementary Figures: 7 Supplementary Tables: 2

Columnar Encoding of Personal Space and Visual Space in Human Parietal Cortex

FEF Microstimulation modulates visually driven activity in cortex: evidence from awake behaving monkey fMRI

Introduction: Variations in population receptive field (pRF) size are crucially related to the sensitivity to spatial frequency (SF) across visual cortex, across both cortical areas, and across the representation of retinotopic eccentricity in each area. For instance, cortical sites that represent peripheral (compared to central) visual fields have larger pRF sizes and respond more strongly to stimuli with lower SFs. However, within a given retinotopic representation, it remains unknown whether pRF size differs with variations in columnar sensitivity (e.g. color, disparity, motion, etc.). Here we tested this hypothesis, partly by leveraging a prior finding: we found a stronger response to low SF stimuli in V2/V3 thick stripes, compared to thin stripes (Tootell and Nasr, 2017). Methods: Using high-resolution fMRI (7T; voxel size: 1 mm isotropic), in 4 human subjects, we measured the pRF size by presenting moving bars at multiple orientations and motion directions. In two individuals, we also measured the reproducibility of the results by scanning them on two different days. In all subjects, we also independently localized V2/V3 thin vs. thick stripes (Tootell and Nasr, 2021). Results: Consistent with previous studies, in all individuals, we found a larger pRF in peripheral vs. central representations, and a progressively larger pRF size in V1<V2<V3<V3A. The pRF sizes were reproducible across sessions, in both deep and superficial cortical layers (r>0.39). Here, we found that average pRF size in V2/V3 was significantly larger in thick compared to thin stripes, even when the measurements were confined to iso-eccentric (3˚<r<10˚) representations. In all subjects, this effect was observed within both deep and superficial layers, consistent with a columnar organization. Conclusion: Our results show primary evidence for a heterogeneous, column-based distribution of pRF sizes at iso-eccentric sites. This supports the hypothesis that pRF size co-varies with column-scale variations in sensitivity to SF. 

Roger B. H. Tootell

Papers

Visual Cortex: Evolution of Maps and Mapping

Columnar Organization of Primate Visual Cortex

Columnar Encoding of Personal Space and Visual Space in Human Parietal Cortex

FEF Microstimulation modulates visually driven activity in cortex: evidence from awake behaving monkey fMRI

Population receptive field size varies between thin vs. thick stripes in cortical areas V2/V3