Continuously Decoding Visual Perception and Working Memory

描述(申请人提供)：早期视觉区域通过基于特征的编码对详细的视觉输入进行编码，从而提供用于表示视觉刺激之间的细微差别的特定代码。例如，V1中的神经元对特定的视网膜位置、方向、空间频率、颜色、运动方向和双眼畸形做出选择性反应。我们已经从神经生理学研究中学到了许多关于这些功能调节特性的知识。最近，利用模式分类技术的功能磁共振研究已经允许检查人类视觉系统中的特征调节特性。在这些研究中，研究人员训练一名fMRI活动分类员，以区分与一小部分刺激条件相关的活动模式，而识别准确率提供了一种衡量这些区域传递了多少关于刺激条件的信息的指标。例如，可以从V1的fMRI活动模式中辨别参与者正在观看的八个方向中的哪一个，类似的方法已经成功地识别了其他基于特征的反应模式。然而，感兴趣的刺激维度，如方向、运动或颜色，通常是连续变量，可以在某个范围内呈现任何值。此外，与这些刺激变量相关的皮质反应模式可能在一个连续体上有所不同。这项提议的目标是开发一种方法，说明功能磁共振激活模式与某一特征在某一维度上的实际值之间的关系，而不是在一小部分值之间进行区分。这种连续解码方法的存在将提供一套比目前可能的更丰富的实验范例，允许对视觉皮质中特征是如何表示的进行新的研究。目标1的目标是使用连续解码从人类视觉皮质中提取有关方位选择反应的细粒度信息。目标2的目的是通过在视觉错觉体验过程中应用连续解码来研究这些方位选择反应与方位知觉之间的关系。目标3的目的是研究在没有视觉刺激的情况下，工作记忆任务中的行为表现与记忆特征的皮质表征之间的关系。该奖学金的总体目标是培训申请者使用功能磁共振成像，重点是解码方法。此外，申请者将通过定向阅读、每周研讨会和范德比尔特视力研究中心教员授课的课程工作，接受视觉科学领域的培训。这项培训将使申请者成为一名独立研究人员的长期目标成为可能，开发新的功能成像数据分析技术，并利用它们来加深我们对视觉感知和高阶认知的神经基础的理解。

DESCRIPTION (provided by applicant): Early visual areas encode detailed visual input through feature-based coding, thereby providing an ecient code for representing ne-grained dierences between visual stimuli. For example, neurons in V1 respond selectively to particular retinotopic locations, orientations, spatial frequencies, colors, motion directions, and binocular dis- parities. We have learned a great deal regarding these feature-tuning properties from neurophysiology studies. More recently, fMRI studies utilizing pattern classication techniques have allowed for the examination of feature- tuning properties in the human visual system. In these studies, researchers train a classier on fMRI activity to discriminate between activity patterns associated with a small set of stimulus conditions, and discrimination accuracy provides a measure of how much information those areas convey about the stimulus conditions. For example, it is possible to discern which of eight orientations a participant is viewing from fMRI activity patterns in V1, and similar approaches have been successful in identifying other feature-based response patterns. However, the stimulus dimensions of interest, such as orientation, motion or color are typically continuous variables that can take on any value within some range. Moreover, the cortical response patterns associated with these stimulus variables likely vary on a continuum. The goal of this proposal is to develop methods that account for relationships between fMRI activation patterns and the actual value of a feature experienced on some dimension, rather than discriminating between a small set of values. The existence of such continuous decoding methods will provide for a far richer set of experimental paradigms than are currently possible, allowing for novel investigations into how features are represented in visual cortex. The goal of Aim 1 is to use continuous decoding to extract ne-grained information about orientation-selective responses from the human visual cortex. The goal of Aim 2 is to inves- tigate the relationship between these orientation-selective responses and perceptions of orientation by applying continuous decoding during experiences of visual illusions. The goal of Aim 3 is to study relationships between behavioral performance on a working memory task and cortical representations of the remembered features in the absence of visual stimulation. The overall objective of this fellowship is to train the applicant in the use o fMRI, with an emphasis on decoding methods. In addition, the applicant will be trained in the eld of vision science through directed reading, weekly seminars, and course work taught by faculty in the Vanderbilt Vision Research Center. This training will make possible the applicant's long-term goal of becoming an independent researcher, developing novel analytic techniques for functional imaging data and using them to further our understanding of the neural bases of visual perception and higher-order cognition.