Learning and plasticity in the human brain

人脑的学习和可塑性

基本信息

批准号：
7969454
负责人：
Christopher Baker
金额：
$ 22.28万
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 continued to focus 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 that the parts of the brain deprived of input start to respond to visual stimuli in other regions of the visual field, as if they are taking on new function. But what drives this reorganization of visual processing? We investigated whether the observed plasticity is use-dependent (affecting only the peripheral part of the retina, the preferred retinal locus or PRL, used for fixation in patients with macular degeneration), or whether it reflects a more passive process that affects input through all parts of the retina. We found that the part of the brain deprived of visual input responded to visual stimuli both at PRL and non-PRL locations, suggesting passive rather than use-dependent plasticity. We have also investigated the functional consequences of deprivation of visual input, by patching one eye in participants with full vision. We found that depriving visual input produced very rapid perceptual distortions, suggesting that changes in visual processing, such as those observed in patients with macular degeneration, may reflect the unmasking of exisiting connections rather than any new anatomical changes. 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 continuing to recruit participants and to monitor 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 nature, degree and consequences of plasticity in the adult cortex provides important insights into the potential for rehabilitative brain therapies following damage to the nervous system.

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，我们继续专注于对大脑特定区域（包括视觉和体感皮质）输入的投入后，我们一直专注于可塑性。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），我们先前已经表明，剥夺输入的大脑部分开始响应视野其他区域的视觉刺激，就好像它们正在扮演新功能一样。但是，是什么推动了视觉处理的重组？我们研究了观察到的可塑性是否依赖于使用（仅影响视网膜的周围部分，首选的视网膜基因座或PRL，用于黄斑变性患者的固定），或者它是否反映了一个更具被动过程，该过程会影响通过视网膜所有部位的输入影响输入。我们发现，剥夺了视觉输入的大脑部分对PRL和非PRL位置的视觉刺激做出了反应，这表明被动而不是使用依赖性可塑性。我们还通过对具有全视力的参与者进行修补，研究了视觉输入剥夺的功能后果。我们发现，剥夺视觉输入会产生非常快速的感知扭曲，这表明视觉处理的变化（例如在黄斑变性患者中观察到的变化）可能反映出透露给出的连接，而不是任何新的解剖学变化。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。我们将继续招募参与者，并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。建立成人皮层中可塑性的性质，程度和后果为损害神经系统损害后的康复性脑疗法的潜力提供了重要的见解。