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

A fundamental question in memory research is how our brains can form enduring memories. In humans, memories of everyday life depend initially on the medial temporal lobe system, including the hippocampus. As these memories mature, they are thought to become increasingly dependent on other brain regions such as the cortex. Little is understood about how new memories in the hippocampus are transformed into remote memories in cortical networks. However, recent studies have begun to shed light on how remote memories are organized in the cortex, and the molecular and cellular events that underlie their consolidation.

/pdf/the-organization-of-recent-and-remote-memories-3ix3ec7bmc.pdf

The organization of recent and remote memories

The role of nucleus accumbens dopamine in motivated behavior: a unifying interpretation with special reference to reward-seeking

Hippocampus: Cognitive Processes and Neural Representations that Underlie Declarative Memory

Is there a biology of intelligence which is characteristic of the normal human nervous system?" Here we review 37 modern neuroimaging studies in an attempt to address this question posed by Halstead (1947) as he and other icons of the last century endeavored to understand how brain and behavior are linked through the expression of intelligence and reason. Reviewing studies from functional (i.e., functional magnetic resonance imaging, positron emission tomography) and structural (i.e., magnetic resonance spectroscopy, diffusion tensor imaging, voxel-based morphometry) neuroimaging paradigms, we report a striking consensus suggesting that variations in a distributed network predict individual differences found on intelligence and reasoning tasks. We describe this network as the Parieto-Frontal Integration Theory (P-FIT). The P-FIT model includes, by Brodmann areas (BAs): the dorsolateral prefrontal cortex (BAs 6, 9, 10, 45, 46, 47), the inferior (BAs 39, 40) and superior (BA 7) parietal lobule, the anterior cingulate (BA 32), and regions within the temporal (BAs 21, 37) and occipital (BAs 18, 19) lobes. White matter regions (i.e., arcuate fasciculus) are also implicated. The P-FIT is examined in light of findings from human lesion studies, including missile wounds, frontal lobotomy/leukotomy, temporal lobectomy, and lesions resulting in damage to the language network (e.g., aphasia), as well as findings from imaging research identifying brain regions under significant genetic control. Overall, we conclude that modern neuroimaging techniques are beginning to articulate a biology of intelligence. We propose that the P-FIT provides a parsimonious account for many of the empirical observations, to date, which relate individual differences in intelligence test scores to variations in brain structure and function. Moreover, the model provides a framework for testing new hypotheses in future experimental designs.

/pdf/the-parieto-frontal-integration-theory-p-fit-of-intelligence-2kp9bfy1c3.pdf

The Parieto-Frontal Integration Theory (P-FIT) of intelligence: converging neuroimaging evidence.

The hippocampus is crucial for spatial memory formation, yet it does not store long-lasting memories By combining functional brain imaging and region-specific neuronal inactivation in mice, we identified prefrontal and anterior cingulate cortex as critical for storage and retrieval of remote spatial memories Imaging of activity-dependent genes also revealed an involvement of parietal and retrosplenial cortices during consolidation of remote memory Long-term memory storage within some of these neocortical regions was accompanied by structural changes including synaptogenesis and laminar reorganization, concomitant with a functional disengagement of the hippocampus and posterior cingulate cortices Thus, consolidation of spatial memory requires a time-dependent hippocampal-cortical dialogue, ultimately enabling widespread cortical networks to mediate effortful recall and use of cortically stored remote memories independently

https://science.sciencemag.org/content/sci/305/5680/96.full.pdf

Sites of Neocortical Reorganization Critical for Remote Spatial Memory

Memory-improving action of glucose: indirect evidence for a facilitation of hippocampal acetylcholine synthesis.

Raised glucose levels enhance scopolamine-induced acetylcholine overflow from the hippocampus: an in vivo microdialysis study in the rat.

Differential hippocampal and cortical cholinergic activation during the acquisition, retention, reversal and extinction of a spatial discrimination in an 8-arm radial maze by mice

Male mice of the BALB/c strain were given a solution of 12% v/v ethanol as their only source of fluid for 7 months. Memory performance was tested after ethanol was omitted from the diet for 3 to 9 weeks, and was compared with performance of control animals (no ethanol) which had been pair-fed or had received tap water. The spontaneous alternation task that was used consisted of two forced trials (acquisition) followed, at varying intervals ranging from 30 sec to 6 hr, by a free test trial (retention). Experimental subjects exhibited an accelerated rate of decay of spontaneous alternation, reaching chance level at 6 hours. All animals were then tested at this 6-hour interval following injections of either physostigmine or neostigmine that were given before both acquisition and retention (0.05 mg/kg IP). Results showed that physostigmine, but not neostigmine, dramatically improved performance of alcohol-treated subjects. Parallel neurochemical analysis showed that chronic ethanol treatment induced a slight (12%) but significant decrease in hippocampal sodium-dependent high affinity choline uptake. Though these findings suggest that the observed memory deficits (i.e., an accelerated rate of forgetting) might be related to a cholinergic dysfunction, alternative explanations are also proposed.

Thomas P. Durkin

Papers

Sites of Neocortical Reorganization Critical for Remote Spatial Memory

Memory-improving action of glucose: indirect evidence for a facilitation of hippocampal acetylcholine synthesis.

Raised glucose levels enhance scopolamine-induced acetylcholine overflow from the hippocampus: an in vivo microdialysis study in the rat.

Differential hippocampal and cortical cholinergic activation during the acquisition, retention, reversal and extinction of a spatial discrimination in an 8-arm radial maze by mice

On the involvement of the central cholinergic system in memory deficits induced by long term ethanol consumption in mice.