Dual Feedback Streams and Laminar Integration of Long-range Inter-areal Processes in the Early Visual System

大脑皮层反馈在知觉-认知整合和脑功能的主要假说中起着关键作用，包括预测编码理论。我们的目标是在一个将使用神经成像、电生理学和解剖学的多学科项目的框架内，研究已经在灵长类大脑皮层的区域间投射中识别的两个反馈通路的整合作用。颗粒上和颗粒下皮质层中的两条反馈通路显示出明显的地形特征：一条长距离、弥漫地投射在颗粒下层的通路和一条短距离通路，其投射更集中且局限于颗粒上层。重要的是，这两条通路的具体功能尚不清楚。目标1和目标2通过研究人类和非人类灵长类动物在执行需要长距离皮质相互作用的任务：图形/背景、运动一致性和空间与特征选择性注意时，在需要知觉整合和注意的认知任务中早期视觉区域的层流依赖活动来探索这些途径。目的1，在人体中，在7T下使用层流分辨率功能成像和fMRI来探索什么刺激条件产生颗粒上层和颗粒下层的不同激活，并建立因果模型来推断定向的区域间有效连接。我们将探讨三个任务：(1)背景效应对表面颜色知觉的影响：(1)反馈信号的视觉来源和(Ii)刺激可预测性；(2)运动连贯性和刺激期望对反馈到早期视觉区域的影响；(3)空间和特征选择性注意在活动层状轮廓中的作用。我们希望这些实验将揭示不同条件对两个反馈流的不同影响，从而告诉我们它们不同的功能角色。目的2，在绒猴中，使用多点深度电极评估层特异性激活模式，并通过两条反馈通路的层特异性光发生激活来定向区域间相互作用，以探讨它们之间的因果关系。我们期望研究结果能让我们了解这两条反馈通路在大脑皮层加工中的不同作用，从而在预测编码框架中开发出更准确的大脑皮层加工模型。目的3研究皮层、间质神经元和皮质之间的长距离抑制性联系的性质和频率，研究它们是否优先与特定的回路相关。这种抑制过程预计将通过对振荡和同步性的影响而对区域间加工产生深远的影响。我们预测，拟议的工作将有助于理解规范的皮质微电路及其在预测性编码框架中支持的计算，从而进一步理解精神障碍的神经元基础。

Cortical feedback plays a critical role in perceptual-cognitive integration and in major hypotheses on brain function, including predictive coding theory. We aim to investigate the integrative roles of two feedback pathways that have been identified in the inter-areal projections of primate cerebral cortex in the framework of a multidisciplinary project that will use neuroimaging, electrophysiology and anatomy. The two feedback pathways in supra- and infragranular cortical layers show distinct topographical features: a long-distance, diffusely projecting pathway in infragranular layers and a short-distance pathway whose projections are more focal and confined to supragranular layers. Importantly, the specific functions of these two pathways are unknown. Objectives 1 and 2 probes these pathways by studying laminar dependent activity in early visual areas during cognitive tasks requiring perceptual integration and attention in human and nonhuman primates while performing tasks requiring long-range cortical interaction: figure/ground, motion coherence and spatial vs feature selective attention. Objective 1, in human, uses laminar-resolution functional imaging with fMRI at 7T to explore what stimulus conditions generate differential activation of supra and infragranular layers and causal modeling to infer directed inter-areal effective connectivity. We will explore three tasks: (1) contextual effects on surface color perception that influence (i) the visual stream of origin of feedback signals and (ii) stimulus predictability; (2) the influence of motion coherence and stimulus expectation on feedback to early visual areas; (3) the role of spatial and feature selective attention on the laminar profile of activity. We expect that these experiments will reveal conditions that differentially affect the two feedback streams, thus, informing us about their different functional roles. Objective 2, in marmoset uses multi-site depth electrodes to assess layer-specific activation patterns and directed inter-areal interactions via layer-specific optogenetic activation of the two feedback pathways to probe their causal relevance. We expect that the results will inform us about the differential roles of the two feedback pathways in cortical processing, which will allow more accurate models of cortical processing to be developed in a predictive coding framework. Objective 3 addresses the nature and frequency of long-distance inhibitory connections between cortical areas and interstitial neurons and cortex, investigating if they are preferentially associated with a particular circuit. Such inhibitory processes are predicted to have profound impact on inter-areal processing through effects on oscillation and synchrony. We predict the proposed work will contribute to understanding the canonical cortical microcircuits and the computations they support in a predictive coding framework and thereby furthering understanding the neuronal basis of psychiatric disorders.