Learning and plasticity in the human brain

人脑的学习和可塑性

• 批准号: 9568270
• 负责人: Christopher Baker
• 金额: $ 33.02万
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9568270
• 关键词: Adult; Behavioral; Brain; Cerebellum; Cerebrospinal Fluid; Circadian Rhythms; Data; Development; Dissociation; Feedback; Functional Magnetic Resonance Imaging; Functional disorder; Goals; Hippocampus (Brain); Hour; Human; Injury; Learning; Longitudinal Studies; Magnetic Resonance Imaging; Measures; Medial; Motor; Nature; Nervous system structure; Participant; Performance; Property; Punishment; Rehabilitation therapy; Research; Rewards; Structure; Temporal Lobe; Thick; Time; Training; Ventricular; behavior measurement; gray matter; improved; insight; motor learning; neuromechanism; relating to nervous system; sequence learning; skills; white matter; white matter change

The primary goals of this research are i) to establish how learning impacts the structure and function of the brain, and ii) to determine how learning can be modulated by factors such as feedback (positive or negative). Over the past year we have focused equally on both of these goals. 1) Impact of learning on brain structure and function (NCT00001360) Over the past few years, we have been conducting a long-term longitudinal study of participants learning different tasks (e.g. motor sequences, spatial layout) to determine how structural properties of the brain (gray matter, white matter) change over time. Over a period of four weeks, participants were trained in two different tasks and we collected extensive functional and structural MRI data over the course of training. While previous studies have identified structural changes associated with learning, even over the course of a couple of hours, our initial findings have highlighted a potential confound that needs to be accounted for in such studies. Specifically, we have found that the structural measures obtained with MRI fluctuate according to the time of day, with decreases in gray matter thickness and increases in ventricular volume. These fluctuations appear to be related to changes in cerebrospinal fluid in the brain and may reflect the impact of the daily circadian rhythm. Interestingly, these fluctuation appear to be modulated by training and we are trying to establish what additional structural and functional changes occur with training above and beyond these time-of-day effects. With the motor sequence task we find that, following training, sensorimotor networks show changes in their functional connectivity. In contrast, with the spatial layout task, hippocampal networks change. These findings suggest task-specific changes in particular networks underlie learning above and beyond any changes due to circadian fluctuations. 2) Impact of feedback on learning (NCT00001360) We are investigating the impact of feedback (positive, negative) on motor learning. Groups of participants were trained on one of two different motor tasks and either provided with positive, negative or neutral (uninformative) feedback. Training occurred in the MRI scanner and we measured fMRI activity before, during and after training. Behaviorally, we found that the impact of feedback is dependent on the task. While in a sequence learning task we find that punishment improves online performance, we observe the opposite effect in a purely motoric force-tracking task. In terms of brain activity, we found that punishment was more associated with changes in the medial temporal lobe and hippocampus, while reward was more associated with changes in the cerebellum. These findings suggest a dissociation of the neural mechanisms underlying the impact of reward and punishment that might be utilized to enhance training. Establishing the nature, degree and consequences of plasticity in the adult cortex provides important insights into the potential for rehabilitative brain therapies following injury or dysfunction in the nervous system.

这项研究的主要目标是：i）确定学习如何影响大脑的结构和功能; ii）确定学习如何通过反馈（积极或消极）等因素进行调节。在过去一年中，我们同样注重这两个目标。 1)学习对大脑结构和功能的影响（NCT 00001360） 在过去的几年里，我们一直在对学习不同任务（例如运动序列，空间布局）的参与者进行长期的纵向研究，以确定大脑（灰质，白色物质）的结构特性如何随时间变化。在为期四周的时间里，参与者接受了两项不同任务的培训，我们在培训过程中收集了大量的功能和结构MRI数据。 虽然以前的研究已经确定了与学习相关的结构变化，即使是在几个小时的过程中，我们的初步研究结果强调了一个潜在的混淆，需要在这些研究中加以解释。具体来说，我们已经发现，与MRI获得的结构措施波动，根据一天中的时间，减少灰质厚度和增加心室容积。这些波动似乎与大脑中脑脊液的变化有关，并可能反映了每日昼夜节律的影响。 有趣的是，这些波动似乎受到训练的调节，我们正试图确定除了这些时间效应之外，训练还会发生什么额外的结构和功能变化。在运动序列任务中，我们发现，经过训练后，感觉运动网络的功能连接发生了变化。相反，在空间布局任务中，海马网络发生变化。这些发现表明，特定网络中的特定任务变化是学习的基础，而不是由于昼夜节律波动而引起的任何变化。 2)反馈对学习的影响（NCT 00001360） 我们正在研究反馈（积极的，消极的）对运动学习的影响。各组参与者接受两种不同运动任务之一的训练，并提供积极，消极或中性（无信息）反馈。训练在MRI扫描仪中进行，我们在训练前、训练中和训练后测量了fMRI活动。 行为上，我们发现反馈的影响取决于任务。虽然在序列学习任务中，我们发现惩罚提高了在线性能，但在纯粹的运动力跟踪任务中，我们观察到相反的效果。 在大脑活动方面，我们发现惩罚与内侧颞叶和海马体的变化更相关，而奖励与小脑的变化更相关。这些发现表明，潜在的奖励和惩罚的影响，可能被用来加强培训的神经机制的分离。 确定成人皮质可塑性的性质、程度和后果，为神经系统损伤或功能障碍后的康复性脑治疗提供了重要的见解。