FMRI STUDIES; VISUAL EXPERIENCE AND NEURONAL CHANGES

描述（改编自申请人的摘要）：在过去的十年中， 越来越多的使用动物模型的研究表明， 视觉皮层神经元的选择性可以通过视觉体验来改变。 然而，人们对发生在地球上的更全球性的变化知之甚少。 学习例如，很少有信息表明， 视觉学习过程中涉及神经元回路。缺乏 这类信息的部分原因是全球覆盖率低 由单细胞记录提供。现在可以通过使用 成像技术，如功能性磁共振成像，它提供了良好的全球覆盖范围。 到目前为止，fMRI已被广泛用于研究人类大脑，但 将其应用到猴子身上还有一个额外的好处， 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， 在视觉处理中涉及的皮层回路方面的经验。我们特别 将分析早期视觉区域地形组织的变化， 视觉体验的功能。变更将在单个 在麻醉和清醒的动物中记录会话。起初， 在第一映射阶段，对视觉刺激的反应被放置在 将测量跨越早期视觉区域的不同视网膜位置 例如V1、V2、V4和MT。随后将进行培训， 将呈现原始映射刺激的组合随后， 将应用与第一映射阶段相同的另一映射阶段 描述由最近的视觉体验引起的任何变化。一些 将进行具有不同刺激组合的这种训练阶段 在一次实验中我们提出的训练模式 是由著名的假设起源于赫布，其中学习是 这反映在神经元之间的连接加强上。人们认为 当彼此连接的细胞同时被激活时， 它们之间的联系得到加强，因此， 神经元以一种反映时间关联的方式被修改， 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.