Cortical Substrates of Working Memory for Visual Motion

项目摘要/摘要 视觉工作记忆的研究--目标定向过程中信息的维持和操作过程 行为，通常涉及跨越时间和空间的视觉刺激的比较。这类任务要求受试者识别这些 刺激，将它们保留在记忆中，并在比较时检索它们。因此，作为此类任务基础的电路必须 涉及皮层区域，次级服务于感觉的处理、维持、注意和决策。对于我们的研究 视觉工作记忆，我们选择了涉及记忆引导的视觉运动比较的任务，因为 这个维度和处理过程中涉及的大脑皮层区域已经被详细研究过了。出于这个原因，我们 聚焦于两个相互关联的区域，在视觉运动处理中起关键作用的区域，MT区， 还有与注意力、记忆和执行控制相关的外侧前额叶皮质(LPFC)。我们的病变和单细胞 录音研究将这两个区域与记忆视觉动作的能力联系起来。具体地说，LPFC或 MT导致视觉运动记忆障碍。此外，录音研究揭示了大脑中的运动信号 LPFC可能由MT提供，MT中的存储器和比较信号可能反映LPFC的影响 神经元。我们假设MT和LPFC的记忆相关活动的内容和动力学是 两个区域的神经元之间的相互作用，在此期间它们处理和交换产生的运动信号 在任务期间。在此续订申请中，我们将通过同时记录以下活动来直接解决这一假设 两个区域的多个神经元，重点是每个区域代表的记忆相关信号和动态 在比较由延迟隔开的两个运动刺激的方向时，它们之间的相互作用。在我们的分析中 我们将关注在记忆过程中从多个MT和LPFC神经元同时记录的活动的性质 在任务的比较阶段，并检查这两个区域神经元之间的相互作用(目标1)。 我们还将可逆地停用LPFC中的局部位置，以检查LPFC对内存相关活动的影响 在工作记忆任务期间记录在MT区(目标2)。揭示记忆相关信号的本质和它们的 在两个领域的互动中，我们将重点放在记忆延迟和任务的比较阶段。我们将研究 在逐个试验的基础上在每个区域中同时记录神经元的活动，应用种群解码算法， 在操作刺激位置和任务时检查神经元间和区域间噪声的相关性和同步性 要求。对MT-LPFC网络中同时记录的神经元活动的关注代表了一种 重点从单个神经元到皮质功能更具协同性的观点的重要转变。这一焦点的改变 使用最先进的技术将使我们能够识别网络动态和代码，这些代码是内存和 运动方向辨别任务中的比较加工。

Project Summary/Abstract Studies of visual working memory, the process of maintenance and manipulation of information during goal directed behaviors, often involve comparisons of visual stimuli across time and space. Such tasks require subjects to identify these stimuli, retain them in memory and retrieve them at the time of comparison. Thus, the circuitry underlying such tasks must involve cortical regions sub-serving sensory processing, maintenance, attention and decision-making. For our studies of visual working memory we chose tasks involving memory-guided comparisons of visual motion since the neural code of this dimension and the cortical areas involved in its processing have been examined in some detail. For that reason, we focused on two reciprocally interconnected regions, the area playing a key role in processing of visual motion, area MT, and the lateral prefrontal cortex (LPFC), linked to attention, memory and executive control. Our lesion and single cell recording studies linked both areas to the ability to remember visual motion. Specifically, the damage of either LPFC or MT resulted in deficits in remembering visual motion. Furthermore, recording studies revealed motion signals in the LPFC likely to be supplied by MT and memory and comparison signals in MT likely to reflect influences from LPFC neurons. We hypothesize that the content and the dynamics of memory-related activity in MT and LPFC is a product of the interactions between neurons in the two areas during which they process and exchange motion signals generated during the task. In this renewal application we will address this hypothesis directly by simultaneously recording activity of multiple neurons in both areas, with the focus on memory-related signals represented in each area and on dynamic interactions between them during comparisons of directions of two moving stimuli separated by a delay. In our analysis we will focus on the nature of activity recorded simultaneously from multiple MT and LPFC neurons during the memory delay and during the comparison phase of the task and examine the interactions between neurons in the two areas (Aim 1). We will also reversibly inactivate localized sites in the LPFC, to examine LPFC influences on memory-related activity recorded in area MT during working memory tasks (Aim 2). To reveal the nature of memory-related signals and their interactions in the two areas we will focus on the memory delay and the comparison stage of the task. We will examine activity of simultaneously recorded neurons in each area on a trial-by-trial basis, apply population decoding algorithms, examine inter-neuronal and inter-areal noise correlations and synchrony while manipulating stimulus locations and task demands. The focus on the activity of simultaneously recorded neurons across the MT-LPFC network represents an important shift of emphasis from individual neurons to a more synergistic view of cortical function. This change of focus and the use of state-of-the-art techniques will allow us to identify network dynamics and codes that underlie memory and comparison processes during motion direction discrimination tasks.