Spatial information processing in the avian hippocampus

空间认知（感知、操作和回忆空间环境信息的能力）对任何物种的生存都至关重要。因此，大量的研究调查了这种重要的认知形式，主要集中在哺乳动物身上。这项研究表明，海马体形成（HF）及其周围皮层结构对这种学习至关重要。鸟类还具有解决高级（例如，食物贮藏）和在许多情况下具有独特挑战性（例如，迁徙）的空间问题的能力。尽管可以在鸟类中观察到复杂的空间技能，但相对于哺乳动物，鸟类空间学习的神经基础知之甚少。虽然我们知道鸟类有心力衰竭，而且心力衰竭的损伤在两类动物中都会产生类似的空间处理缺陷，但在鸟类心力衰竭中如何处理空间信息在很大程度上仍然未知。这在一定程度上是因为鸟类HF缺乏其哺乳动物同类的许多定义特征，包括明确的三层结构和主要的单向三突触环。事实上，即使是禽流感的细分仍然是一个有争议的问题。我们也许可以根据功能而不是解剖学上的同源性来定义禽HF的区域，从而解决这个问题。哺乳动物心衰（即CA1、CA3和齿状回）的活动模式可以有许多不同的实验范式。在经过可比范例训练的鸟类中，探测禽类HF广泛区域的活动依赖基因表达可能为鸟类如何处理空间信息提供重要见解。

Spatial cognition (the ability to perceive, operate on, and recall information about spatial environments) is critical to the survival of any species. Accordingly, a wealth of research has investigated this vital form of cognition, focusing largely on mammals. This research shows that the hippocampal formation (HF) and surrounding cortical structures are critical for this kind of learning. Avian species also have the ability to solve advanced (e.g., food caching) and in many cases uniquely challenging (e.g., migration) spatial problems. Despite the sophisticated spatial repertoire that can be observed in birds, relatively little is known about the neural substrate of spatial learning in birds relative to mammals. While we know that birds have a HF and that lesions to the HF produce comparable deficits in spatial processing in both classes of animal, how spatial information is processed within the avian HF remains largely unknown. This is in part because the avian HF lacks many of the defining features of its mammalian counterpart, including clear trilaminar structure and a dominantly unidirectional tri-synaptic loop. In fact, even the subdivisions of the avian HF remain a matter of debate. We may be able to resolve this issue by defining the regions of the avian HF on the basis of their functional, rather than anatomical, homology. There are many experimental paradigms in which the pattern of activity in the HF of mammals (i.e., CA1, CA3, and the dentate gyrus) can be made to diverge. Probing activity-dependent gene expression across widespread regions of the avian HF in birds that are trained on comparable paradigms may provide critical insight into how avian species process spatial information.