FMRI STUDIES; VISUAL EXPERIENCE AND NEURONAL CHANGES

描述(摘自申请者的摘要)：在过去的十年中， 越来越多的动物模型研究表明， 视觉经验可以改变视觉皮层神经元的选择性。 然而，人们对期间发生的更具全球性的变化知之甚少 学习。例如，几乎没有关于哪些基础的信息 视觉学习过程中涉及到神经元回路。匮乏 这类信息的部分原因是全球覆盖率不高 由单电池记录提供。现在可以使用以下方法来填补这一空白 成像技术，如功能磁共振成像，提供出色的全球覆盖。 到目前为止，功能磁共振成像已经被广泛用于研究人脑，但 将它应用到猴子身上还有一个额外的好处，那就是它可以组合在一起 与其他侵入性技术，如单细胞记录和药理学。 我们建议在猴子身上使用功能磁共振成像来表征视觉的影响 有参与视觉处理的大脑皮层回路的经验。具体来说，我们 将分析早期可视区域地形组织的变化，作为 视觉体验的功能。更改将跨单个 记录麻醉动物和清醒动物的实验过程。最初， 在第一个映射阶段，对视觉刺激的反应放置在 将在早期视觉区域测量不同的视网膜位置 例如V1、V2、V4和MT。随后将进行培训阶段，在此期间， 随后将呈现原始映射刺激的组合， 另一个与第一个相同的映射阶段将应用于 描述由最近的视觉体验引起的任何变化。一批 这样的训练阶段将用不同的刺激组合进行 在一次实验课的过程中。我们提出的培训范式 是由Hebb提出的众所周知的假设所激发的，在Hebb中，学习是 反映在神经元之间联系的加强上。据认为， 当相互连接的单元同时被激活时，则 它们之间的联系得到了加强，因此， 神经元INS以一种反映时间关联的方式进行修改 环境中的刺激。

DESCRIPTION(adapted from applicant's abstract): Over the last decade, an increasing number of studies using animal models have shown that the selectivity of visual cortical neurons can be modified by visual experience. However, not much is known about the more global changes that take place during learning. For instance, there is little information as to which underlying neuronal circuits are involved during the course of visual learning. The lack of this sort of information has been partly due to the poor global coverage provided by single cell recording. It is now possible to fill this gap by using imaging techniques such as fMRI, which provides excellent global coverage. Until now, fMRI has been extensively used to study the human brain, but applying it to monkeys has the additional advantage that it can be combined with other invasive techniques such as single cell recording and pharmacology. We propose to use fMRI on monkeys to characterize the effects of visual experience on cortical circuits involved in visual processing. Specifically, we will analyze changes in the topographic organization of early visual areas as a function of visual experience. Changes will be identified across single recording sessions both in anesthetized and awake-behaving animals. Initially, during the first mapping phase, the responses to visual stimuli placed at different retinotopic locations will be measured across the early visual areas such as V1, V2, V4 and MT. A training phase will follow during which specific combinations of the original mapping stimuli will be presented Subsequently, another mapping phase identical to the first one will be applied to characterize any changes induced by the recent visual experience. A number of such training phases with different combinations of stimuli will be carried out during the course of one experimental session. The training paradigm we propose is motivated by the well known hypothesis originated by Hebb, where learning is reflected in the strengthening of connections among neurons. It is thought that when cells, connected to each other are activated at the same time, then the connections between them are strengthened and therefore the selectivity of neurons ins modified in a way that reflects the temporal associations of stimuli in the environment.