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

Part I. Experimental Studies: 2. Experiment in psychology 3. Experiments on perceiving III Experiments on imaging 4-8. Experiments on remembering: (a) The method of description (b) The method of repeated reproduction (c) The method of picture writing (d) The method of serial reproduction (e) The method of serial reproduction picture material 9. Perceiving, recognizing, remembering 10. A theory of remembering 11. Images and their functions 12. Meaning Part II. Remembering as a Study in Social Psychology: 13. Social psychology 14. Social psychology and the matter of recall 15. Social psychology and the manner of recall 16. Conventionalism 17. The notion of a collective unconscious 18. The basis of social recall 19. A summary and some conclusions.

Remembering. A Study in Experimental and Social Psychology, Cambridge (University Press) 1964.

The authors describe a model of autobiographical memory in which memories are transitory mental constructions within a self-memory system (SMS). The SMS contains an autobiographical knowledge base and current goals of the working self. Within the SMS, control processes modulate access to the knowledge base by successively shaping cues used to activate autobiographical memory knowledge structures and, in this way, form specific memories. The relation of the knowledge base to active goals is reciprocal, and the knowledge base "grounds" the goals of the working self. It is shown how this model can be used to draw together a wide range of diverse data from cognitive, social, developmental, personality, clinical, and neuropsychological autobiographical memory research.

The construction of autobiographical memories in the self-memory system

https://www.cell.com/trends/cognitive-sciences/pdf/S1364-6613(04)00053-1.pdf

Inhibition and the right inferior frontal cortex.

Three studies show that the retrieval process itself causes long-lasting forgetting. Ss studied 8 categories (e.g., Fruit). Half the members of half the categories were then repeatedly practiced through retrieval tests (e.g., Fruit Or ). Category-cued recall of unpracticed members of practiced categories was impaired on a delayed test. Experiments 2 and 3 identified 2 significant features of this retrieval-induced forgetting: The impairment remains when output interference is controlled, suggesting a retrieval-base d suppression that endures for 20 min or more, and the impairment appears restricted to high-frequenc y members. Low-frequency members show little impairment, even in the presence of strong, practiced competitors that might be expected to block access to those items. These findings suggest a critical role for suppression in models of retrieval inhibition and implicate the retrieval process itself in everyday forgetting. A striking implication of current memory theory is that the very act of remembering may cause forgetting. It is not that the remembered item itself becomes more susceptible to forgetting; in fact, recalling an item increases the likelihood that it will be recallable again at a later time. Rather, it is other items—items that are associated to the same cue or cues guiding retrieval—that may be put in greater jeopardy of being forgotten. Impaired recall of such related items may arise if access to them is blocked by the newly acquired strength of their successfully retrieved competitors (Blaxton & Neely, 1983; Brown, 1981; Brown, Whiteman, Cattoi, & Bradley, 1985; Roediger, 1974, 1978; Roediger & Schmidt, 1980; Rundus, 1973). This implication follows from three assumptions underlying what we herein refer to as strength-dependent competition models of interference: (a) the competition assumption—that memories associated to a common cue compete for access to conscious recall when that cue is presented; (b) the strengthdependence assumption—that the cued recall of an item will decrease as a function of increases in the strengths of its

Remembering can cause forgetting: retrieval dynamics in long-term memory

Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.

/pdf/neural-systems-underlying-the-suppression-of-unwanted-pwblc7lkgq.pdf

Neural Systems Underlying the Suppression of Unwanted Memories

Freud proposed that unwanted memories can be forgotten by pushing them into the unconscious, a process called repression1. The existence of repression has remained controversial for more than a century, in part because of its strong coupling with trauma, and the ethical and practical difficulties of studying such processes in controlled experiments. However, behavioural and neurobiological research on memory and attention shows that people have executive control processes directed at minimizing perceptual distraction2,3, overcoming interference during short and long-term memory tasks3,4,5,6,7 and stopping strong habitual responses to stimuli8,9,10,11,12,13. Here we show that these mechanisms can be recruited to prevent unwanted declarative memories from entering awareness, and that this cognitive act has enduring consequences for the rejected memories. When people encounter cues that remind them of an unwanted memory and they consistently try to prevent awareness of it, the later recall of the rejected memory becomes more difficult. The forgetting increases with the number of times the memory is avoided, resists incentives for accurate recall and is caused by processes that suppress the memory itself. These results show that executive control processes not uniquely tied to trauma may provide a viable model for repression.

Suppressing unwanted memories by executive control

Rethinking interference theory: Executive control and the mechanisms of forgetting.

Theories of cognition frequently assume the existence of inhibitory mechanisms that deactivate mental representations. Justifying this assumption is difficult because cognitive effects thought to reflect inhibition can often be explained without recourse to inhibitory processes. This article addresses the uncertain status of cognitive inhibitory mechanisms, focusing on their function in memory retrieval. On the basis of a novel form of forgetting reported herein, it is shown that classical associative theories of interference are insufficient as accounts of forgetting and that inhibitory processes must be at work. It is argued that inhibitory processes are used to resolve computational problems of selection common to memory retrieval and selective attention and that retrieval is best regarded as conceptually focused selective attention.

Michael C. Anderson

Papers

Remembering can cause forgetting: retrieval dynamics in long-term memory

Neural Systems Underlying the Suppression of Unwanted Memories

Suppressing unwanted memories by executive control

Rethinking interference theory: Executive control and the mechanisms of forgetting.

On the status of inhibitory mechanisms in cognition: Memory retrieval as a model case