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

Automated Anatomical Labeling of Activations in SPM Using a Macroscopic Anatomical Parcellation of the MNI MRI Single-Subject Brain

The unity and diversity of executive functions and their contributions to complex "Frontal Lobe" tasks: a latent variable analysis.

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

▪ Abstract The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed

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An integrative theory of prefrontal cortex function

1. An oculomotor delayed-response task was used to examine the spatial memory functions of neurons in primate prefrontal cortex. Monkeys were trained to fixate a central spot during a brief presentation (0.5 s) of a peripheral cue and throughout a subsequent delay period (1-6 s), and then, upon the extinction of the fixation target, to make a saccadic eye movement to where the cue had been presented. Cues were usually presented in one of eight different locations separated by 45 degrees. This task thus requires monkeys to direct their gaze to the location of a remembered visual cue, controls the retinal coordinates of the visual cues, controls the monkey's oculomotor behavior during the delay period, and also allows precise measurement of the timing and direction of the relevant behavioral responses. 2. Recordings were obtained from 288 neurons in the prefrontal cortex within and surrounding the principal sulcus (PS) while monkeys performed this task. An additional 31 neurons in the frontal eye fields (FEF) region within and near the anterior bank of the arcuate sulcus were also studied. 3. Of the 288 PS neurons, 170 exhibited task-related activity during at least one phase of this task and, of these, 87 showed significant excitation or inhibition of activity during the delay period relative to activity during the intertrial interval. 4. Delay period activity was classified as directional for 79% of these 87 neurons in that significant responses only occurred following cues located over a certain range of visual field directions and were weak or absent for other cue directions. The remaining 21% were omnidirectional, i.e., showed comparable delay period activity for all visual field locations tested. Directional preferences, or lack thereof, were maintained across different delay intervals (1-6 s). 5. For 50 of the 87 PS neurons, activity during the delay period was significantly elevated above the neuron's spontaneous rate for at least one cue location; for the remaining 37 neurons only inhibitory delay period activity was seen. Nearly all (92%) neurons with excitatory delay period activity were directional and few (8%) were omnidirectional. Most (62%) neurons with purely inhibitory delay period activity were directional, but a substantial minority (38%) was omnidirectional. 6. Fifteen of the neurons with excitatory directional delay period activity also had significant inhibitory delay period activity for other cue directions. These inhibitory responses were usually strongest for, or centered about, cue directions roughly opposite those optimal for excitatory responses.(ABSTRACT TRUNCATED AT 400 WORDS)

Mnemonic coding of visual space in the monkey's dorsolateral prefrontal cortex

Cellular basis of working memory

The sections in this article are:


1
Essence of Prefrontal Function: Regulation of Behavior by Representational Knowledge
11
Subdivisions of Prefrontal Cortex

12
Global Nature of Prefrontal Syndrome in Humans

13
Animal Model for Prefrontal Function in Humans

14
Delayed-Response Tests and Varying Interpretations of Their Functional Significance

15
Distractability and Perseveration: Secondary Consequences of Basic Defect in Representational Memory

16
Representational Memory in Wisconsin Card Sort and Other Diagnostic Tests of Prefrontal Function in Humans

17
Localization of Delayed-Response Function: Principal Sulcus

18
Circuit Basis of Visuospatial Functions




2
Accessing and “On-Line” Processing of Representations in Visuospatial Domain: Parietal-Prefrontal Connections
21
Visuospatial Representational Memory in Humans

22
Spatial-Mnemonic Nature of Delayed-Response Deficit: Domain-Specific Memory Loss

23
Topography of Representational Memory in Prefrontal Cortex

24
Electrophysiological Evidence of Spatial-Mnemonic Processes in Principal Sulcus

25
Parietal-Prefrontal Connectivity

26
Columnar and Laminar Framework for Feedforward and Feedback Mechanisms

27
Functional Significance of Parietal-Prefrontal Collaboration




3
Long-Term Memory and “Off-Line” Processing: Prefrontal-Limbic Connections
31
Role of Hippocampus in Spatial Memory

32
Multiple Connections Between Principal Sulcus and Hippocampal Formation

33
Quadripartite Neural Network: Parietal-Temporal-Cingulate-Prefrontal Circuit

34
Limbic Contribution to Spatial Memory




4
Response Initiation and Inhibition: Projections to Striatum, Tectum, Thalamus, and Premotor Cortex
41
Motor-Control Functions of Prefrontal Cortex

42
Cortical-Striatal Pathway and Related Feedback Loops

43
Cortical-Tectal Pathway

44
Thalamic-Cortical Systems

45
Prefrontal-Premotor Connections: Anterior Supplementary Motor Cortex Relays

46
Functional Speculations




5
Modulatory Mechanisms: Brain Stem Catecholamine Projections
51
Activation of Cognitive Machinery

52
Concentration and Synthesis of Catecholamines in Primate Cortex

53
Brain Stem Innervation of Prefrontal Cortex

54
Delayed-Response Deficits and Recovery Produced by Catecholamine Loss and Replacement in Prefrontal Cortex

55
Circuit Basis for Neuromodulation in Principal Sulcus




6
Multiple Subsystems of Prefrontal Cortex: Unity or Diversity of Function
61
Unity or Diversity of Prefrontal Function

62
Frontal Eye Fields

63
Inferior Convexity

64
Orbital Prefrontal Cortices

65
Problem of Integration




7
Diseases Affecting Prefrontal Cortex
71
Schizophrenia: Loss of Corticocortical Processing and Regulation of Behavior by Representational Knowledge

72
Wernicke-Korsakoff Syndrome: Loss of Thalamocortical and Brain Stem Modulatory Mechanisms

73
Huntington's Chorea and Parkinson's Disease: Loss of Prefrontal-Striatal Mechanisms and Initiation or Inhibition of Motor Response

74
Overview of Neurobiology of Disease




8
Summary

Circuitry of Primate Prefrontal Cortex and Regulation of Behavior by Representational Memory

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Preface: Cerebral Cortex Has Come of Age

Dopamine has been implicated in the cognitive process of working memory but the cellular basis of its action has yet to be revealed. By combining iontophoretic analysis of dopamine receptors with single-cell recording during behaviour, we found that D1 antagonists can selectively potentiate the 'memory fields' of prefrontal neurons which subserve working memory. The precision shown for D1 receptor modulation of mnemonic processing indicates a direct gating of selective excitatory synaptic inputs to prefrontal neurons during cognition.

Patricia S. Goldman-Rakic

Papers

Mnemonic coding of visual space in the monkey's dorsolateral prefrontal cortex

Cellular basis of working memory

Circuitry of Primate Prefrontal Cortex and Regulation of Behavior by Representational Memory

Preface: Cerebral Cortex Has Come of Age

Modulation of memory fields by dopamine D1 receptors in prefrontal cortex.