Learning and plasticity in the human brain

人脑的学习和可塑性

基本信息

批准号：
7735212
负责人：
Christopher Baker
金额：
$ 27.95万
依托单位：
NATIONAL INSTITUTE OF MENTAL HEALTH
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

项目摘要

The goal of this research is to establish the extent to which the adult brain is plastic even in adulthood and to determine the functional consequences of such plasticity. Over the past year we have focused on plasticity following the loss of input to particular regions of the brain, including visual and somatosensory cortex. People with macular degeneration lose central vision due to damage of the retina. But what happens to the parts of the brain that are specifically involved in processing central visual stimuli? Do those parts of the brain simply become inactive or can they take on new function? Using functional magnetic resonance imaging (fMRI), we have previously shown in two participants with macular degeneration that the parts of the brain specifically involved in processing central vision become responsive to visual stimuli in peripheral vision. We have now extended these findings to three new participants with macular degeneration and further shown that the change in functional properties occurs only when there is complete loss of central vision: in two participants with severely disrupted central vision but with some residual vision, we found no evidence for activation by peripheral stimuli of brain areas selective for central vision. Having shown brain reorganization following loss of visual input, we are now addressing the functional consequences of that reorganization. Following limb amputation, the majority of people report phantom sensations in their missing limb, often painful sensations. One current theory is that the phantom limb pain arises as a result of cortical reorganization. We are currently monitoring brain activation with fMRI in unilateral limb amputees over a period of four weeks while they undergo therapy to treat the phantom limb pain. The therapy being used is mirror therapy: each day the participants view their intact limb in a mirror giving the impression of their amputated limb moving. In particular we are trying to establish whether the presence of phantom limb pain correlates with cortical reorganization in the somatosensory cortex (similar to that observed in our participants with macular degeneration) and whether the therapy works by reducing the extent of cortical reorganization. Establishing the degree and consequences of plasticity in the adult cortex provides important insights into the potential for rehabilitative brain therapies.

这项研究的目的是确定成年大脑在成年期的塑性程度，并确定这种可塑性的功能后果。在过去的一年中，我们一直关注对大脑特定区域（包括视觉和体感皮质）输入输入后的可塑性。黄斑变性的人由于视网膜的损害而失去了中央视力。但是，专门处理中央视觉刺激的大脑部分会发生什么？大脑的那些部分只是不活跃还是可以采用新功能？使用功能性磁共振成像（fMRI），我们以前在两名具有黄斑变性的参与者中表明，大脑的部分专门参与处理中心视力，对外周视觉中的视觉刺激有反应。现在，我们将这些发现扩展到了三名具有黄斑变性的新参与者，并进一步表明，仅当中央视力完全丧失时，功能性能的变化才会发生：在两个严重破坏中心视觉的参与者中，有一些残留的视力，但我们没有发现大脑区域外围刺激可用于选择中心视觉的表面激活的证据。在视觉输入丢失后显示出脑重组后，我们现在正在解决该重组的功能后果。肢体截肢后，大多数人在肢体缺失的情况下报告了幻影感觉，通常是痛苦的感觉。当前的一种理论是，幻影肢体疼痛是由于皮质重组而引起的。目前，我们在四个星期内通过单侧肢体截肢者在单侧肢体上监测大脑的激活，同时他们接受了治疗幻影肢体疼痛的治疗。所使用的疗法是镜像疗法：每天参与者在镜子里看到自己的完整肢体，给人以截肢的肢体移动的印象。特别是我们试图确定幻影肢体疼痛的存在是否与体感皮质中的皮质重组相关（类似于在黄斑变性的参与者中观察到的）以及该治疗方法是否通过减少皮质重组程度来起作用。建立成人皮层可塑性的程度和后果，为康复性脑疗法的潜力提供了重要的见解。