老年执行功能的认知可塑性和神经可塑性

执行衰退假说认为执行功能的特异性衰退是引起认知年老化的主要原因, 近年来越来越多的研究表明, 老年人的执行功能及其相关脑区(主要为前额叶)存在可塑性, 通过训练执行功能的衰退可得到缓解, 且相关脑区的激活水平、脑容量或神经递质都可发生改变; 部分研究还发现执行功能训练对其它认知能力有一定的迁移效应。这些发现对于认知年老化理论的继续探索和认知干预研究的实践应用都具有重要意义。     

早期听觉剥夺后的大脑可塑性：来自先天性听力障碍群体的证据

皮层功能的正常发展依赖于充分的外部感觉信息的输入。先天性听力障碍群体由于经历早期听觉剥夺, 皮层功能往往出现异常。具体表现为初级听皮层功能退化, 初级、次级听皮层的功能连接变弱, 次级听皮层出现跨通道功能重组; 在后天听力重建后听皮层功能重组仍然存在, 言语加工需要更多高级认知资源的补偿。已有研究在探讨听力重建后皮层的长期可塑性机制、复杂声学环境下言语加工机制、汉语言加工独特性等方面尚不深入, 值得进一步研究。     

Interindividual Variability in Use-Dependent Plasticity Following Visuomotor Learning: The Effect of Handedness and Muscle Trained

Motor learning has been linked with increases in corticospinal excitability (CSE). However, the robustness of this link is unclear. In this study, changes in CSE associated with learning a visuomotor tracking task were mapped using transcranial magnetic stimulation (TMS). TMS maps were obtained before and after training with the first dorsal interosseous (FDI) of the dominant and nondominant hand, and for a distal (FDI) and proximal (biceps brachii) muscle. Tracking performance improved following 20 min of visuomotor training, while map area was unaffected. Large individual differences were observed with 18%–36% of the participants revealing an increase in TMS map area. This result highlights the complex relationship between motor learning and use-dependent plasticity of the motor cortex.     

New Advances in Understanding Sensitive Periods in Brain Development

ABSTRACT— Is a dog ever too old to learn new tricks? We review recent findings on sensitive periods in brain development, ranging from sensory processing to high-level cognitive abilities in humans. We conclude that there are multiple varieties of, and mechanisms underlying, these changes. However, many sensitive periods may be a consequence of the basic processes underlying postnatal functional brain development.     

视觉表象扫描加工可塑性水平的研究

本研究通过两个实验分别检测20名飞行员和10名老年被试及其相应控制组的表象扫描加工水平,旨在探讨表象扫描这一典型视觉空间认知加工所表现出的可塑性水平。研究结果表明,表象扫描加工水平既没有因外界系统的训练而发生功能增强的练习效应,也未出现随年老化过程所表现出的功能显著下降的年龄效应。研究提示,由于受大脑神经细胞活动特性改变的影响,表象扫描加工能力更多地表现出了其认知加工的相对稳定性或可塑性较低的认知特性。     

习得性长时程突触增强在学习各阶段中的变化

应用慢性埋植技术以电生理学结合行为学的方法,观察大鼠海马CA_3区锥体细胞在明暗辨别反应的建立、巩固、消退和再建立的连续过程中,突触效应的变化规律。结果:在条件反应的建立过程中,产生突触效应长时程增强(LTP);在条件反应的巩固过程中,LTP继续保持;在条件反应的消退过程中,LTP消退;在条件反应的再建立过程中,再次产生LTP。而这种习得性LTP的发展和变化超前于习得性行为的产生和改变。这是在同一动物身上实现了以往多项工作的连贯性观察,表明在动物学习活动的连贯的迅速改变的各个阶段,海马CA_3区有相应的对条件性行为有制约作用的习得性LTP的发生和改变。它为论证习得性LTP可能是学习和记忆的神经基础之一,提供了新的有力证据。     

Effect of neurofeedback on hemispheric word recognition

We applied SMR/theta neurofeedback (NF) training at central sites of 20 Israeli children aged 10-12 years, half boys and half girls. Half of the subjects received C3 training and the other half C4 training, consisting of 20 half-hour sessions. We assessed the effects of training on lateralized lexical decision in Hebrew. The lateralized lexical decision test reveals an independent contribution of each hemisphere to word recognition (Barnea, Mooshagian, & Zaidel, 2003). Training increased accuracy and sensitivity. It increased left hemisphere (LH) specialization under some conditions but it did not affect interhemispheric transfer. Training did affect psycholinguistic processing in the two hemispheres, differentially at C3 and C4. Training also increased hemispheric independence. There were surprising sex differences in the effects of training. In boys, C4 training improved LH accuracy, whereas in girls C3 training improved LH accuracy. The results suggest that the lateralized NF protocol activates asymmetric hemispheric control circuits which modify distant hemispheric networks and are organized differently in boys and girls.     

Visuomotor Adaptation and Proprioceptive Recalibration

ABSTRACT

Motor learning, in particular motor adaptation, is driven by information from multiple senses. For example, when arm control is faulty, vision, touch, and proprioception can all report on the arm's movements and help guide the adjustments necessary for correcting motor error. In recent years we have learned a lot about how the brain integrates information from multiple senses for the purpose of perception. However, less is known about how multisensory data guide motor learning. Most models of, and studies on, motor learning focus almost exclusively on the ensuing changes in motor performance without exploring the implications on sensory plasticity. Nor do they consider how discrepancies in sensory information (e.g., vision and proprioception) related to hand position may affect motor learning. Here, we discuss research from our lab and others that shows how motor learning paradigms affect proprioceptive estimates of hand position, and how even the mere discrepancy between visual and proprioceptive feedback can affect learning and plasticity. Our results suggest that sensorimotor learning mechanisms do not exclusively rely on motor plasticity and motor memory, and that sensory plasticity, in particular proprioceptive recalibration, plays a unique and important role in motor learning.