Mechanisms of visuomotor transformations in the primate frontal cortex

大脑是一个复杂的器官，它接收感官信号，然后根据有机体的内部目标发出命令，移动执行动作的肌肉。这个从感觉到运动的转变过程是复杂的，理解不同大脑区域在其不同步骤中的作用一直是一个挑战。先前对猴子的研究通过识别大脑中几乎完全编码感觉和运动信号的区域（例如，感觉和运动皮质），解开了转换过程中感觉和运动端的一些基本机制。其他人已经确定了包含感觉和运动信号的大脑区域，主要是在对视觉目标进行注视运动（扫视）时。特别令人感兴趣的是额叶的区域，它也可能在学习中发挥作用。视觉信号是如何在这些区域转化为凝视指令的，我们仍然知之甚少。目前的提案继续我们在之前的发现基金中进行的研究。我们的目标是额叶皮层的一个区域，额叶眼场（FEF）作为在复杂任务中执行视觉运动转换的候选对象。我们将检验两个主要假设。首先，视觉信息到达FEF内的视觉神经元，然后被转移到视觉运动神经元，最后将信息传递给运动神经元。其次，我们将检验FEF在视觉运动联想学习中起重要作用的假设。我们预计，一些FEF神经元对携带关联意义的视觉线索具有选择性，当这些单元加强与编码预期跳眼运动位置的运动神经元的连接时，学习就发生了。我们将使用多电极阵列记录和行为测量在清醒的猴子执行视觉运动任务的组合。这将使我们能够表征反应，并利用相关性和格兰杰因果分析探索FEF内不同神经元类型之间的相互作用。我们的研究结果将揭示灵长类动物额叶视觉运动转化的机制以及视觉运动学习的神经基础。

The brain is a complex organ that received sensory signals and then produces according to the organism internal goals commands to move the muscles that execute actions. This process of sensory-to-motor transformation is complex and it has been challenging to understand the role of different brain areas in its various steps. Previous studies in monkeys have disentangled some of the basic mechanisms at the sensory and motor ends of the transformation, by identifying brain areas in which sensory and motor signals are almost exclusively encoded (e.g., sensory and motor cortices). Others have identified brain areas that contain a mix of sensory and motor signals, mainly during the execution of gaze movements (saccades) towards visual targets. Of particular interest are areas of the frontal lobe that may also play a role in learning. How are visual signals transformed into gaze commands within these areas remains poorly understood. The current proposal continues the research we have undertaken in the previous Discovery grant. We have targeted an area of the frontal cortex, the Frontal Eye Fields (FEF) as candidate for performing visuomotor transformations for gaze during complex tasks. We will test two main hypotheses. First, that visual information reaches visual neurons within the FEF, and then is transferred to visuomovement neurons that finally pass the information to movement neurons. Second, we will test the hypothesis that the FEF plays an important role in the learning of visuomotor associations. We anticipate that some FEF neurons become selective for visual cues carrying the meaning of the association and that learning occurs when these units strengthen their connectivity with movement neurons encoding the location of the intended saccadic eye movement. We will use a combination of multielectrode array recordings and behavioural measurements in awake monkeys performing visuomotor tasks. This will allow us to characterize the response and explore interactions amongst the different neuronal types within the FEF using correlation and Granger causality analyses. Our results will reveal the mechanisms of visuomotor transformation as well as the neural substrates of visuomotor learning in the primate frontal lobe.