Mechanisms of Perceptual Learning in Primary Visual Cortex

初级视觉皮层知觉学习的机制

• 批准号: 7533774
• 负责人: Andreas Tolias
• 金额: $ 38.38万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7533774
• 关键词: Amblyopia; Animals; Architecture; Area; Behavioral; Brain; Brain Injuries; Bypass; Chronic; Complex; Condition; Data; Depth; Discrimination; Fire - disasters; Implant; Individual; Laboratories; Learning; Macaca; Maps; Measures; Methods; Monitor; Monkeys; Neurons; Noise; Perceptual learning; Performance; Population; Positioning Attribute; Process; Property; Public Health; Rate; Recovery; Retinal; Sensory; Specificity; Sports; Staging; Stimulus; Structure; Techniques; Testing; Thinking; Time; Training; Vision Disorders; Visual; Visual system structure; Week; area V1; area striata; awake; day; extracellular; extrastriate visual cortex; improved; in vivo; member; neural circuit; orientation selectivity; preference; research study; response; theories; visual process; visual processing

DESCRIPTION: There are many types of learning realized in different brain areas but the basic mechanisms underlying different forms of learning may be quite similar. One of the most widely studied forms of learning is perceptual learning in the visual system, defined as the permanent improvement in performance as a result of training on a sensory task. Training improves the ability to perceive simple as well as complex visual attributes such as depth defined with a random-dot stereogram, pop-out of a stimulus, and bomb outlines visualized though x-ray machines. Studying perceptual learning in the visual system is advantageous for understanding mechanisms of learning since it is thought to involve early stages of visual processing where the most is known about the properties of single units and cortical architecture. In addition, perceptual learning paradigms are used in the treatment of visual disorders (such as amblyopia) and in the enhancement of reorganization and behavioral recovery after brain injury, underscoring the importance of understanding the underlying mechanisms. A prerequisite for understanding learning mechanisms is to characterize how the response properties of individual neurons as well as their interactions change during the course of learning. A major impediment for realizing this has been the inability to record from the same individual neurons chronically, in vivo, during the course of learning. We now, for the first time, bypassed this limitation by developing a method using chronically implanted tetrode arrays that allows us to record from the same neurons across multiple consecutive days and weeks in awake, behaving macaques. We plan to study perceptual learning in an orientation discrimination task associated with improved performance in the discrimination of the orientation of a stimulus as a result of practice. Learning in this paradigm is specific to the trained retinal position and is therefore thought to reflect plasticity in early visual areas like the primary visual cortex (V1). We will study this process in area V1 of the macaque. First, we will measure how variable orientation tuning functions are across days and weeks during periods of no training (Specific Aim 1). Determining the stability of baseline orientation maps in V1 is an essential first step for studying how learning can modify them. Moreover, the information contained in the activity of a population of neurons also depends on the pair wise interactions between these neurons in addition to their individual properties. A good analogy is the performance of a team which does not only depend on the capabilities of its individual members but also in the way players interact with each other. Therefore, in order to quantify the information content of neural circuits before and after learning it is essential to also measure the strength of correlations between the neurons (Specific Aim 2). In Specific Aim 3, we will record chronically from the same neurons in V1 while animals are being trained in an orientation discrimination task. This is very exciting since for the first time we are now able to record from individual neurons during the course of learning and characterize the associated changes in neural circuits. PUBLIC HEALTH RELEVANCE One of the most widely studied forms of learning is perceptual learning in the visual system, defined as the permanent improvement in performance as a result of extensive training on numerous sensory tasks. Perceptual learning paradigms are used in the treatment of visual disorders such as amblyopia and using learning paradigms has great potential in the enhancement of reorganization and behavioral recovery after brain injury, underscoring the importance of understanding learning mechanisms. We will study perceptual learning while recording from the same neurons chronically during the course of learning.

描述：在不同的大脑领域实现了许多类型的学习类型，但是不同形式的学习形式的基本机制可能非常相似。研究最广泛的学习形式之一是视觉系统中的感知学习，这定义为在感官任务上培训的导致性能的永久改善。训练可以提高感知简单以及复杂的视觉属性的能力，例如用随机点立体图，弹性弹出的深度以及炸弹概述了可视化X射线机器的轰炸。在视觉系统中学习感知学习对于理解学习机制是有利的，因为它被认为涉及视觉处理的早期阶段，其中最了解单个单元和皮质体系结构的特性。此外，感知学习范例用于治疗视觉疾病（例如弱视），以及在脑损伤后的重组和行为恢复的增强中，强调了理解潜在机制的重要性。理解学习机制的先决条件是表征单个神经元及其相互作用在学习过程中的反应特性如何变化。意识到这一点的主要障碍是在学习过程中无法长期从体内记录相同的单个神经元。现在，我们首次通过使用长期植入的四极阵列开发一种方法来绕过这一限制，该方法使我们能够在醒着中连续多个天和几周从同一神经元记录相同的神经元，表现出猕猴。我们计划在与实践导致刺激方向相关的方向歧视任务中研究感知学习。在此范式中学习是特定于训练有素的视网膜位置的，因此被认为反映了早期视觉区域（如主视觉皮层（V1））的可塑性。我们将在猕猴的V1区域研究此过程。首先，我们将衡量在没有培训期间的几天和几周内可变方向调谐功能的多变（特定目标1）。确定V1中基线方向图的稳定性是研究学习如何修改它们的重要第一步。此外，神经元人群活性中所含的信息还取决于这些神经元之间的对相互作用，除了它们的各个特性。一个很好的类比是团队的表现，不仅取决于其个人成员的能力，而且还取决于玩家相互互动的方式。因此，为了量化学习前后神经回路的信息含量，必须测量神经元之间相关性的强度（特定目标2）。在特定目标3中，我们将在V1中的同一神经元中长期记录动物在方向歧视任务中训练时。这是非常令人兴奋的，因为在学习过程中，我们现在第一次能够从单个神经元中记录并表征神经回路的相关变化。公共卫生相关性研究最广泛的学习形式之一是视觉系统中的感知学习，这定义为由于对众多感官任务的广泛培训，性能的永久改善。感知学习范例用于治疗诸如弱视和学习范式之类的视觉障碍，在增强脑损伤后重组和行为恢复的可能性很大，强调了理解学习机制的重要性。在学习过程中，我们将长期从同一神经元记录同一神经元时研究感知学习。