从神经可塑性的视角看压力与疾病的关系

压力致病是一个复杂的过程,涉及到与多种致病因素的相互作用、多个器官系统的激活和反馈、不同发育阶段对疾病的易感性等。这个过程中,神经可塑性起着重要的调节作用。本文以神经可塑性为切入点,阐述了压力、发育阶段、个人发展、疾病发生之间的关系。     

年龄、作业难度和训练对成人记忆的影响

采用“联想学习”、“图象自由回忆”和“附加联想”三项目,对９０例成人（分为青年、老年和老老年组各３０例）进行记忆测查和训练,目的为探讨年龄,作业难度和训练对记忆的影响。结果表明：青年组记忆成绩明显高于老年和老老年组,后两组无显著差异;无关联想的年龄差异大于有关联想,作业难度扩大了年龄差异;各年龄组训练后记忆得到明显改善,并且训练扩大了年龄和作业易难的差异。由此可见,记忆受年龄、作业难度和训练三因素的相互作用,也再次证实了老年认知功能具有一定的可塑性。     

The import of infancy for individual, family, and societal development: commentary on the special section: does infancy matter?

Across their life spans humans actualize a rich potential for cognitive and behavioral plasticity, a set of developmental changes that require regulation of organism-context relations on the part of both the individual and society. An individual’s action on the context must be started in infancy and maintained in subsequent periods of life for adaptive functioning to occur across ontogeny. The process of the individual acting as an agent of his or her own development is continuous, although the particular ways in which such control is manifested will change in developmentally appropriate ways. As demonstrated by the papers in this special issue, the significance of infancy for the rest of the life-span rests on an integration of this continuity and discontinuity within the person-context developmental system.     

反应抑制的训练:内容、效果与机制

近期的研究发现,个体的反应抑制能力具有一定的可塑性。研究者多采用双盲随机对照实验设计,训练的对象包括儿童、成人和特殊群体,研究者通过Go/Nogo、Stop-signal等任务进行为期1周至3周,45至7200试次不等的抑制控制能力训练,并结合行为、脑电以及脑成像等技术对训练效果进行评估,研究结果发现,接受了抑制控制训练的个体其抑制能力得到提升,并伴随脑神经活动的变化。另外,研究者发现,抑制控制能力的训练效果还可以迁移至个体日常生活中的表现。但是,也有些研究并未发现抑制控制训练的效果。训练任务的设置,评估任务的选择以及被试反应策略的差异等因素可能会影响训练的效果。抑制控制训练引发行为与大脑活动的变化可能是由于训练导致了个体建立了自上而下有意识的抑制控制模式和自下而上的自动抑制模式。反应抑制和冲突抑制可塑性的比较,儿童与老年人抑制功能的训练以及训练效果的追踪研究将成为该领域日后研究的重点问题。     

脑功能可塑性与灾后心理功能康复

神经系统具有惊人的可塑性,这种可塑性可以终生保留。大脑不仅可因个体的经验与行为而改变,也可因内在思维、放松和注意的不同而发生改变。如汶川地震这样的大型自然灾害,因其突发性和巨变性,可使身临其境的人大脑功能状态在瞬间就发生持久的改变,从而表现为认知、情感等心理功能的改变。反过来,利用有关神经可塑性的认识,同样可使受损的大脑得以修复,使发育障碍的个体增强功能,亦可使由各种内外因素导致的心灵扭曲重新舒展开来。利用放松、修复、重建的3R脑功能重塑技术,可望解决包括地震灾后心理健康重建在内的各种神经和心理问题,具有广泛的应用前景     

自动情绪调节的神经机制及其可塑性

自动情绪调节无需意识决定、注意加工及有意控制, 改变着情绪轨迹。迄今为止, 研究仅限于证实其确能低耗高效地改变情绪过程, 尚未对其如何改变情绪过程进行研究。以自动情绪调节的神经机制作为研究对象具有可操作性, 可从行为和心理生理层面, 对自动情绪调节改变情绪过程的机制进行实验研究。研究问题包括：1)通过EEG技术检验自动情绪调节是否影响预备阶段行为反应倾向; 2)自动情绪调节对注意的注意觉醒、注意朝向和注意执行三个阶段的作用机制; 3)自动情绪调节对评价和反应的作用机制; 4)自动情绪调节的可塑性在脑活动上的体现。最终确定自动情绪调节的加工规律, 构建其预备-注意-评价-反应模型, 并为有效控制情绪紊乱和研究出高效的情绪调节干预方案提供理论和实证依据。     

Memory Maintenance

ABSTRACT— Change in the synaptic communication between neurons—known as synaptic plasticity—plays a key role in learning and memory. It is not yet clear, however, whether the properties of synaptic plasticity are sufficient to account for long-term-memory maintenance. Recent studies have revealed that synaptic plasticity can indeed persist for weeks or months, as might be expected of a long-term-memory mechanism. However, memories encoded by neural systems are not static; they continue to evolve as new learning occurs. Furthermore, neural-network modeling has shown that synapses must be able to reconfigure their connection strengths during new learning if old information is to be preserved. Recent tests confirm that synapses, once modified, retain their capacity for further modification, indicating that they can indeed operate in the manner predicted to be necessary for memory maintenance in a dynamic learning network.     

Susceptibility to induction of long-term depression is associated with impaired memory in aged Fischer 344 rats

The current study employed aged and young male Fischer 344 rats to examine the relationship between long-term depression (LTD), age, and memory. Memory performance was measured on two tasks that are sensitive to hippocampal function; inhibitory avoidance and spatial discrimination on the Morris water maze. The slope of the extracellular excitatory postsynaptic field potential was recorded from CA3-CA1 synapses in hippocampal slices. Low frequency stimulation (LFS) induced a modest LTD only in aged animals under standard recording conditions. The decrease in synaptic transmission examined only in aged animals correlated with memory scores on the spatial task and LTD was not observed in aged animals with the highest memory scores. LTD induction was facilitated by increasing the Ca(2+)/Mg(2+) ratio of the recording medium or employing a paired-pulse stimulation paradigm. Age differences disappeared when LFS was delivered under conditions of elevated Ca(2+)/Mg(2+) in the recording medium. Using multiple induction episodes under conditions which facilitate LTD-induction, no age-related difference was observed in the maximum level of LTD. The results indicate that the increased susceptibility to LTD induction is associated with impaired memory and results from a shift in the induction process. The possible relationship between LTD and memory function is discussed.     

Environmental enrichment improves behavioral performance and auditory spatial representation of primary auditory cortical neurons in rat

Environmental enrichment (EE) has an important role in brain plasticity. Early research has shown that EE increases the response strength of neurons in the auditory cortex, but it remains unknown whether EE can influence the process of spatial localization in the auditory system. In this study, we raised rats in enriched and standard conditions from postnatal day 10 to day 56. By testing behavioral tasks via auditory cues, we have shown that EE improved the number of correct scores, but decreased the reaction time and azimuth deviation in behavioral performance of sound-azimuth discrimination. By in vivo extracellular recording, we have shown that EE enhanced the directional sensitivity of neurons in the primary auditory cortex. For example, EE rats had a smaller spatial receptive field, sharper frequency tuning curve and directional selective curve of auditory neurons compared with normal rats. Our findings indicate that early exposure to EE increases directional sensitivity. These results provide an insight into developmental plasticity in the auditory system.