Neuronal correlates of association learning and memory in the carrion crow

动物的许多习得的适应性行为依赖于刺激物之间的任意关联。为此，来自不同感觉器官的行为相关刺激需要跨越时间和方式进行关联。刺激联想对行为的引导既需要跨越时间间隔的短期记忆，也需要学习关系的长期记忆储存。在非人类灵长类动物中，这种综合脑功能通常分配给前额皮质的工作。然而，鸟类没有六层的新皮层，并且显示出非常不同的组织结构。相反，被称为nidopallium caudolaterale （NCL）的联想端脑区与鸟类的高级认知处理有关。这个大脑区域在高智商的鸦科鸣禽中尤为突出。本研究的目的是了解NCL神经元的神经元活动是否以及如何促进感觉刺激之间的记忆表征。我们将通过训练腐尸鸦（Corvus corone）来学习联想感官刺激来解决这个问题，然后我们将比较乌鸦在练习新联想时的表现与它们在熟悉（单模态和跨模态）联想时的表现。同时，记录斑马鱼NCL神经元群的活动。我们将研究在联想学习过程中神经元记忆信号是如何出现的，它们是如何被来自多种感觉模式的输入激活的，以及它们是如何规避或抑制干扰刺激的。这将使我们能够比较乌鸦与非人类灵长类动物在联想记忆的神经元基础上的预期差异和共性。这些见解将有助于我们理解鸟类大脑是如何在趋同进化的基础上产生联想的短期和长期记忆的，以及智能脊椎动物大脑的设计存在哪些进化限制。

Many of the learned, adaptive behaviors of animals depend on arbitrary associations between stimuli. To that aim, behaviorally relevant stimuli from different sense organs need to be related across time and modalities. The guiding of behavior by stimulus associations requires both short-term memory to bridge time intervals, as well as long-term memory storage of learnt relationships. In nonhuman primates, such integrative brain functions are typically assigned to the workings of the prefrontal cortex. Birds, however, lack a six-layered neocortex and show a very differently organized endbrain. Instead, the associative telencephalic brain area termed nidopallium caudolaterale (NCL) has been related to high-level cognitive processing in birds. This brain area is particularly prominent in highly intelligent corvid songbirds. The purpose of the proposed research project is to understand if and how neuronal activity of NCL neurons contributes to memory representations between sensory stimuli. We will approach this issue by training carrion crows (Corvus corone) to learn to associate sensory stimuli and later we will compare the crows performance while practicing novel associations with their performance on familiar (uni-modal and cross-modal) associations. At the same time, the activity of populations of neurons in the corvid NCL will be recorded. We will study how neuronal memory signals emerge during associative learning, how they can be activated by input from multiple sensory modalities, and how they may circumvent or suppress distractor stimuli. This will allow us to compare expected differences and commonalities of the neuronal basis of association memory in crows to findings in nonhuman primates. Such insights will foster our understanding of how bird brains give rise to associative short- and long-term memories based on convergent evolution, and which evolutionary constraints exist for the design of intelligent vertebrate brains.