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）确定如何通过反馈（正面或负面）等因素调节学习。在过去的一年中，我们同样专注于这两个目标。 1）学习对大脑结构和功能的影响（NCT00001360） 在过去的几年中，我们一直对参与者进行长期纵向研究，以学习不同的任务（例如运动序列，空间布局），以确定大脑的结构特性如何随着时间而变化。在四个星期的时间里，参与者接受了两项不同的任务培训，我们在培训过程中收集了广泛的功能和结构MRI数据。 尽管以前的研究已经确定了与学习相关的结构变化，即使在几个小时的过程中，我们的初步发现突出了潜在的混杂，在此类研究中需要考虑到。具体而言，我们发现，使用MRI获得的结构测量根据一天中的时间波动，灰质厚度降低和心室体积的增加。这些波动似乎与大脑脑脊液的变化有关，并且可能反映了每日昼夜节律的影响。 有趣的是，这些波动似乎是通过培训来调节的，我们正在尝试确定培训超过这些时间的效果，培训发生了哪些其他结构和功能变化。通过运动序列任务，我们发现，在训练之后，感觉运动网络显示其功能连接的变化。相反，随着空间布局任务，海马网络发生了变化。这些发现表明，特定网络中特定于任务的变化是昼夜节律波动所引起的任何变化的基础。 2）反馈对学习的影响（NCT00001360） 我们正在研究反馈（正，负）对运动学习的影响。对参与者组的两种不同运动任务之一进行了培训，并提供了正面，负或中性（非信息）反馈。训练发生在MRI扫描仪中，我们在训练之前，之中和之后测量了fMRI活动。 从行为上讲，我们发现反馈的影响取决于任务。在序列学习任务中，我们发现惩罚提高了在线表现，但我们观察到纯粹的摩尔力追踪任务的效果相反。 在大脑活动方面，我们发现惩罚与内侧颞叶和海马的变化更加相关，而奖励与小脑变化更相关。这些发现表明，可以利用奖励和惩罚影响的神经机制解离，这些神经机制可能用于增强训练。 建立成人皮层中可塑性的性质，程度和后果，为神经系统受伤或功能障碍后的康复脑疗法的潜力提供了重要的见解。