心理旋转研究的新进展

心理旋转是一种空间表征转换形式,也是认知心理学家关注的热点问题。文章结合实证研究,分析了心理旋转加工的大脑机能一侧化问题,阐释了心理旋转能力的个体差异性,探讨了基于心理旋转能力可塑性的提高空问智能的有效途径。并在此基础上．对未来心理旋转领域的研究加以展望。     

The Occipital Cortex in the Blind

ABSTRACT— Studying the brains of blind individuals provides a unique opportunity to investigate how the brain changes and adapts in response to afferent (input) and efferent (output) demands. We discuss evidence suggesting that regions of the brain normally associated with the processing of visual information undergo remarkable dynamic change in response to blindness. These neuroplastic changes implicate not only processing carried out by the remaining senses but also higher cognitive functions such as language and memory. A strong emphasis is placed on evidence obtained from advanced neuroimaging techniques that allow researchers to identify areas of human brain activity, as well as from lesion approaches (both reversible and irreversible) to address the functional relevance and role of these activated areas. A possible mechanism and conceptual framework for these physiological and behavioral changes is proposed.     

脑信号导向蛋白Semaphorins3F与难治性癫痫

在神经发育过程中Semaphorins为轴突导向和神经细胞的迁移提供导向信息。这些导向分子通过抑制自发的或异常的轴突生长来维持己建立的神经连接,并参与突触可塑性以及中枢神经受损后抑制神经再生与神经细胞的死亡。目前,虽然对Semaphorins在神经发育、成熟及受损不同阶段中的功能己有初步的了解,但Semaphorins其受体多样,尚无法预测Sema-phorins与其受体的结合将产生的生物学效应以及Semaphorins在神经系统中起作用的分子机制。进一步研究Semaphorins对癫痫、精神分裂、老年痴呆症等神经系统性疾病的治疗具有深远意义。     

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。     

前额叶在老年阶段的可塑性及相关机制

大量研究表明, 前额叶的结构和功能更容易受年老化影响; 然而, 近年来的研究发现, 前额叶的结构和功能在老年阶段具有一定的可塑性。对老年人进行认知训练, 能够延缓前额叶皮层厚度的萎缩, 提高白质完整性, 改善神经网络的功能连接和分化, 并可能通过调节多巴胺系统的活动改变前额叶皮质和皮质下结构的功能激活模式。有氧锻炼能够改善心脑血管功能, 保护和促进神经元的存活和生长, 引起前额叶灰质、白质体积的增加及功能激活的变化。认知训练与有氧锻炼等相结合的整合性训练不仅引起前额叶及相关认知功能的改变, 而且具有更好的生态学效度, 使老年人日常认知能力和生活质量得到提高。未来研究应采用多种技术手段, 从多个层面理解老年阶段前额叶的可塑性及相关机制; 加强对与前额叶关系密切的多种认知功能可塑性神经机制的研究; 并重视与整合性训练有关的前额叶可塑性。     

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.     

Global VOR gain adaptation during near fixation to foveal targets

Long-term rotational vestibulo-ocular (VOR) adaptation occurs during systematic dysmetria between visual and vestibular afferents, adjusting eye-rotation angular velocity to re-establish retinal stability of the visual field. Due to translational motion of the eyes during head rotation, VOR gain is higher when fixating near objects. The current study measures VOR in humans before and after 6 min of exposure to a foveal near-target during sinusoidal whole-body rotation at 0.45 Hz. All of six participants showed post-exposure increases in open-loop VOR gain after fixating near targets, demonstrating a mean modulation increase of open-loop VOR gain from 0.86 before adaptation to 1.2 after adaptation. We discuss a number of theoretical and applied implications.     

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.