Mechanisms of visuomotor transformations in the primate frontal cortex

大脑是一个复杂的器官，它接收感觉信号，然后根据生物体的内部目标产生命令来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各个步骤中的作用一直是一个挑战。先前对猴子的研究已经解开了转换的感觉和运动端的一些基本机制，通过识别感觉和运动信号几乎完全编码的大脑区域（例如，感觉和运动皮层）。其他人已经确定了包含感觉和运动信号混合的大脑区域，主要是在对视觉目标进行凝视运动（扫视）期间。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。视觉信号如何在这些区域内转化为凝视命令仍然知之甚少。目前的提案继续了我们在以前的发现补助金中进行的研究。我们有针对性的额叶皮层的一个区域，额叶眼场（FEF）作为候选人执行视觉变换的凝视在复杂的任务。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，然后被传递到视觉运动神经元，视觉运动神经元最终将信息传递到运动神经元。第二，我们将检验这一假设，即FEF在视觉联想的学习中起着重要的作用。我们预计，一些FEF神经元成为选择性的视觉线索进行的意义的协会和学习发生时，这些单位加强其连接与运动神经元编码的位置的预期扫视眼球运动。我们将结合使用多电极阵列记录和行为测量在清醒的猴子执行视觉任务。这将使我们能够使用相关性和格兰杰因果关系分析来表征反应并探索FEF内不同神经元类型之间的相互作用。本研究结果将有助于揭示灵长类动物额叶的视觉转换机制和视觉学习的神经基础。

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.