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

In humans, visual stimuli can be perceived across an enormous range of light levels. Evidence suggests that different neural mechanisms process different subdivisions of this range. For instance, in the retina, stimuli presented at very low (scotopic) light levels activate rod photoreceptors, whereas cone photoreceptors are activated relatively more at higher (photopic) light levels. Similarly, different retinal ganglion cells are activated by scotopic versus photopic stimuli. However, in the brain, it remains unknown whether scotopic versus photopic information is: 1) processed in distinct channels, or 2) neurally merged. Using high-resolution functional magnetic resonance imaging at 7 T, we confirmed the first hypothesis. We first localized thick versus thin-type columns within areas V2, V3, and V4, based on photopic selectivity to motion versus color, respectively. Next, we found that scotopic stimuli selectively activated thick- (compared to thin-) type columns in V2 and V3 (in measurements of both overlap and amplitude) and V4 (based on overlap). Finally, we found stronger resting-state functional connections between scotopically dominated area MT with thick- (compared to thin-) type columns in areas V2, V3, and V4. We conclude that scotopic stimuli are processed in partially segregated parallel streams, emphasizing magnocellular influence, from retina through middle stages of visual cortex.

/pdf/scotopic-vision-is-selectively-processed-in-thick-type-1y9ts1s0og.pdf

Scotopic Vision Is Selectively Processed in Thick-Type Columns in Human Extrastriate Cortex.

Publisher Summary This chapter discusses the evidence for functional columns in man and lower primates. The visual world as imaged on the retina is two-dimensional; therefore, it seems sensible to preserve these spatial relationships in subsequent cortical maps. Only spatially unlimited two-dimensional axis runs parallel to the cortical layers, which is presumably why the cortical retinotopy and related maps are arranged parallel to the layers. A modular architecture permits several of these retinotopic maps representing different kinds of information to coexist in the same plane, while keeping intermap (vertical, cross-laminar) connections as short as possible. In a cortical module, different functional maps are accommodated within the same cortical area by cutting each map up into roughly equal-sized chunks and arranging them in a systematic array of stripes or dots. This preserves the original neighborhood relations as much as possible in the transformed map. A number of tracer studies have shown that functionally similar columns in different areas are often anatomically interconnected.

Roger B. H. Tootell

Papers

Scotopic Vision Is Selectively Processed in Thick-Type Columns in Human Extrastriate Cortex.

Columnar Organization in Visual Cortex in Non-Human Primates and Man

The ‘Parahippocampal Place Area’ responds selectively to high spatial frequencies in humans and monkeys

Areas involved in extracting structure from motion: an fMRI study in the awake fixating monkey

Retinotopic localization of novel picture encoding and relation to object recognition using fMRI at 3T