Neuronal correlates of association learning and memory in the carrion crow

动物的许多习得的、适应性的行为依赖于刺激之间的任意联系。为此，来自不同感官的行为相关刺激需要在不同的时间和方式之间联系起来。通过刺激联想来引导行为，既需要短期记忆来跨越时间间隔，也需要长期记忆存储学习的关系。在非人类灵长类动物中，这种整合的大脑功能通常被分配给前额叶皮质的工作。然而，鸟类缺乏一个六层的新大脑皮层，并表现出非常不同的组织终脑。相反，被称为尾侧尼多利姆(NCL)的联合端脑区域与鸟类的高级认知处理有关。这一大脑区域在高智商的乌鸦鸣禽中尤为突出。该研究项目的目的是了解NCL神经元的神经元活动是否以及如何对感觉刺激之间的记忆表征做出贡献。我们将通过训练腐肉乌鸦(Corvus Corone)学习关联感觉刺激来解决这个问题，稍后我们将比较乌鸦在练习新奇联想时的表现与它们在熟悉的(单模式和跨模式)联想上的表现。同时，记录下丘脑中央核神经元群的活动情况。我们将研究神经记忆信号是如何在联想学习中出现的，它们如何被来自多个感觉模式的输入激活，以及它们如何绕过或抑制分心刺激。这将使我们能够比较乌鸦与非人类灵长类动物的联想记忆神经元基础的预期差异和共性。这样的见解将有助于我们理解鸟类的大脑如何基于收敛进化产生联想的短期和长期记忆，以及智能脊椎动物大脑的设计存在哪些进化限制因素。

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.