Bakst Leah, Fleuriet Jérome, Mustari Michael J
Graduate Program in Neuroscience, University of Washington, Seattle, Washington.
Washington National Primate Research Center, University of Washington, Seattle, Washington.
J Neurophysiol. 2017 May 1;117(5):1987-2003. doi: 10.1152/jn.00786.2016. Epub 2017 Feb 15.
Neurons in the smooth eye movement subregion of the frontal eye field (FEFsem) are known to play an important role in voluntary smooth pursuit eye movements. Underlying this function are projections to parietal and prefrontal visual association areas and subcortical structures, all known to play vital but differing roles in the execution of smooth pursuit. Additionally, the FEFsem has been shown to carry a diverse array of signals (e.g., eye velocity, acceleration, gain control). We hypothesized that distinct subpopulations of FEFsem neurons subserve these diverse functions and projections, and that the relative weights of retinal and extraretinal signals could form the basis for categorization of units. To investigate this, we used a step-ramp tracking task with a target blink to determine the relative contributions of retinal and extraretinal signals in individual FEFsem neurons throughout pursuit. We found that the contributions of retinal and extraretinal signals to neuronal activity and behavior change throughout the time course of pursuit. A clustering algorithm revealed three distinct neuronal subpopulations: was defined by a higher sensitivity to eye velocity, acceleration, and retinal image motion; had greater activity during blinks; and had significantly greater eye position sensitivity. We also performed a comparison with a sample of medial superior temporal neurons to assess similarities and differences between the two areas. Our results indicate the utility of simple tests such as the target blink for parsing the complex and multifaceted roles of cortical areas in behavior. The frontal eye field (FEF) is known to play a critical role in volitional smooth pursuit, carrying a variety of signals that are distributed throughout the brain. This study used a novel application of a target blink task during step ramp tracking to determine, in combination with a clustering algorithm, the relative contributions of retinal and extraretinal signals to FEF activity and the extent to which these contributions could form the basis for a categorization of neurons.
已知额叶眼区平滑眼动亚区（FEFsem）中的神经元在自愿性平滑跟踪眼动中起重要作用。该功能的基础是向顶叶和前额叶视觉联合区以及皮层下结构的投射，所有这些区域在平滑跟踪的执行中都起着至关重要但不同的作用。此外，FEFsem已被证明携带多种信号（例如，眼速度、加速度、增益控制）。我们假设FEFsem神经元的不同亚群负责这些不同的功能和投射，并且视网膜和视网膜外信号的相对权重可以构成单位分类的基础。为了研究这一点，我们使用了带有目标眨眼的阶梯斜坡跟踪任务，以确定在整个跟踪过程中视网膜和视网膜外信号在单个FEFsem神经元中的相对贡献。我们发现，在跟踪的时间过程中，视网膜和视网膜外信号对神经元活动和行为的贡献会发生变化。一种聚类算法揭示了三个不同的神经元亚群：一个亚群对眼速度、加速度和视网膜图像运动具有更高的敏感性；另一个亚群在眨眼期间具有更大的活动；还有一个亚群具有明显更高的眼位敏感性。我们还与内侧颞上神经元样本进行了比较，以评估这两个区域之间的异同。我们的结果表明，诸如目标眨眼之类的简单测试在解析皮层区域在行为中的复杂和多方面作用方面具有实用性。已知额叶眼区（FEF）在意志性平滑跟踪中起关键作用，携带分布于整个大脑的多种信号。本研究在阶梯斜坡跟踪期间使用了目标眨眼任务的新应用，结合聚类算法，来确定视网膜和视网膜外信号对FEF活动的相对贡献，以及这些贡献在多大程度上可以构成神经元分类的基础。
