Behavioral and immunohistochemical assessment of selected cognitive functions in elasmobranch fishes (Chiloscyllium griseum)

鲨鱼、鳐鱼和嵌合体组成了软骨鱼纲（约1200种），它们代表了现存最古老的有颌脊椎动物，因此在理解脊椎动物大脑进化的系统发育中占有关键地位。虽然这一群体以前被认为是具有原始大脑的原始鱼类，但过去几十年的研究提供了越来越多的证据，表明鲨鱼和鳐鱼表现出复杂的行为，具有复杂的生物学，并配备了完全适应水下生活的感觉系统。然而，尽管进行了详细的研究，这一群体的认知程度在很大程度上仍然是未知的。基于先前的研究，我们的假设是板鳃类动物有（选择的）认知能力，与许多硬骨鱼或其他脊椎动物非常相似。本研究旨在提供先前缺乏的关于1.的选定认知功能的信息。2.对象分类；3.虚幻轮廓的识别；4.空间学习的方方面面。的记忆力。为了补充行为研究，将进行即时早期基因分析（IEGA），以确定参与学习和高级认知任务的神经元基质(5)。主要靶部位是端脑。实验将在灰竹鲨（Chiloscyllium griseum）上进行，这是一种大约70厘米的小型底栖动物。所有被提出的实验对被测试的物种都有生态意义：个体生活在复杂的环境中，如珊瑚礁、泻湖和近海地区，可能是有领土的，因此会受益于使用认知空间地图（实验3）、空间记忆（实验3、4）和视觉分类能力（实验1）来寻找和记住藏身之处和食物区，以及识别和记住同质物、捕食者和猎物。错觉轮廓是大脑对视觉信息的误读，表明大脑对视觉世界有一定的先入之见，并将其应用于传入的感官信息（Kandel et al. 1991）。确定鲨鱼的大脑在这方面是否与其他脊椎动物使用相同的基本规则将是非常有趣的（实验2）。时空学习有助于提高觅食效率或成功避开捕食者（实验3）。依赖全局线索而不是局部线索（信标）提供了更大的灵活性，因为单个地标可能会消失或改变外观（实验3）。到目前为止，还没有对鲨鱼进行过IEG研究。因此，本研究旨在确定学习特定任务诱导的神经元活动是否会导致端脑或其特定区域c-fos和egr-1表达上调（实验5）。

Sharks, rays and chimaeras comprise the class Chondrichthyes (about 1200 species), which represents the oldest extant jawed vertebrates and thereby holds a key phylogenetic position to understanding vertebrate brain evolution. While this group was formerly known as primitive fish with primitive brains, research over the last few decades has provided increasing evidence that sharks and rays show sophisticated behaviour, have a complex biology and are equipped with sensory systems perfectly adapted to life underwater. However, despite elaborate research, the extent of cognition within this group is still largely unknown. Based on previous research, our hypothesis is that elasmobranchs have (selected) cognitive abilities that closely match those of many teleosts or other vertebrates. This study aims to provide previously lacking information on selected cognitive functions regarding 1. object categorization, 2. recognition of illusionary contours, 3. aspects of spatial learning and 4. memory retention. To complement the behavioural work, immediate early gene analyses (IEGA) will be performed to determine the neuronal substrates involved in learning and higher cognitive tasks (5). The primary target site is the telencephalon. Experiments will be conducted on the grey bamboo shark (Chiloscyllium griseum), a small, benthic of about 70 cm. All proposed experiments have an ecological significance to the species tested: individuals live in complex environments such as coral reefs, lagoons and inshore areas, are probably territorial, and would therefore benefit from using cognitive spatial maps (experiment 3), spatial memory (Experiments 3, 4) as well as visual categorization abilities (experiment 1) to find and remember hiding places and food patches as well as to recognize and remember con-specifics, predators and prey. Illusionary contours are misreadings of visual information by the brain and demonstrate that the brain has certain preconceptions about the visual world that it applies to the incoming sensory information (Kandel et al. 1991). It would be extremely interesting to determine if the shark brain uses the same basic rules in this regard as other vertebrates (experiment 2). Spatiotemporal learning would provide benefits in regards to foraging efficiency or successful predator avoidance (experiment 3). Relying on global cues instead of local cues (beacons) provides more flexibility, as individual landmarks may disappear or change appearance (experiment 3). So far, no IEG studies have been performed in sharks. The study therefore aims to determine if neuronal activity induced by learning specific tasks induces up-regulation of expression of c-fos and egr-1 in the telencephalon or specific regions thereof (experiment 5).