Stereotypy and perseveration in captive European starlings: consequences for decision-making

重复和不变的行为，如北极熊在动物园围栏中的踱步或实验室笼子里的老鼠的盘旋，在圈养动物中很常见。这些没有明显功能的神秘行为模式被统称为刻板印象，对它们的解释一直是一个争论不休的话题。它们是否具有让动物科普不适当的人工环境的功能，或者它们是潜在精神疾病的行为症状？支持后一种假设的证据正在开始积累。对笼中鸟类的实验在将圈养动物的刻板行为与患有精神分裂症等精神疾病的人类的类似行为模式联系起来方面发挥了重要作用。刻板印象中的鸟类和人类在一个被称为赌博任务的电脑游戏中表现出非常相似的行为，在这个游戏中，他们必须选择两个按钮中的哪一个会提供奖励。与非刻板印象的个体相比，刻板印象者表现出重复做出相同选择的倾向，这种现象被称为固执。刻板和固执都可能是负责行为模式排序的大脑系统功能障碍的症状。具体来说，人们认为，具有这些症状的人类和动物对参与停止电流反应并允许生物体切换到不同反应的途径有损伤。这一假设对广泛使用实验室动物作为正常人类行为的模型具有令人担忧的影响。在实验室动物身上进行的许多标准行为任务可能会受到持续行为的影响，然而，在这一点上，我们几乎不知道这个问题可能有多大。因此，我们研究的目的是探索刻板行为和用于评估正常适应行为的一些标准行为任务的表现之间的联系。我们选择研究圈养的欧洲椋鸟有两个原因：第一，因为现有的证据表明笼中刻板印象和持续性之间的联系主要来自鸟类，第二，因为野生捕获的鸟类对实验室中的适应行为研究很重要。因此，特别重要的是要知道，当他们形成陈规定型观念时，他们的行为可能会发生多大的变化。我们将创造不同程度的刻板性，他们表现出的发展历史和目前的笼子里使用的操纵鸟类群体。从野外捕获的成年鸟和圈养在大笼子里的鸟应该表现出最低水平的刻板印象，而从巢中取出的小鸟，人工饲养，然后圈养在小笼子里的鸟应该表现出最高水平。我们将通过分析鸟类行为的录像带来测量刻板印象，既可以用手，也可以用计算机软件自动跟踪笼子里的鸟的位置并寻找其行为模式。此外，我们将测试鸟类在一些计算机控制的任务：赌博任务类似于上面提到的一个，一个时间任务，和一个任务，测试敏感性的风险。我们之所以选择后两个任务，是因为它们通常用于行为研究。最后，我们将寻找一只鸟表现出的刻板印象程度与它在任务中的行为之间的联系。我们的研究将提供第一批数据，探索实验室动物的刻板行为如何影响一系列常见任务的正常行为。这些数据将使我们能够评估研究具有刻板印象的动物的潜在科学成本。如果这些成本是显着的，我们的研究结果将提供强有力的支持，进一步改善实验室动物的笼子环境，以防止他们发展刻板印象。

Repetitive and unvarying behaviour, such as the pacing of a polar bear in a zoo enclosure or the circling of a mouse in a laboratory cage, is common in captive animals. These mysterious behaviour patterns with no obvious function are collectively known as stereotypies, and their explanation has been a topic of much debate. Do they have a function in allowing animals to cope with their inadequate artificial environments, or are they behavioural symptoms of underlying psychiatric disease? Evidence supporting the latter hypothesis is beginning to accumulate. Experiments with caged birds have played an important role in linking stereotypies in captive animals with similar behaviour patterns in humans with psychiatric illness such as schizophrenia. Stereotyping birds and humans both show very similar behaviour on a computer game, known as the gambling task, in which they have to choose which of two buttons will provide reward. In comparison to non-stereotyping individuals, stereotypers show a tendency to repeatedly make the same choice, a phenomenon known as perseveration. Both stereotypy and perseveration are likely to be symptoms of dysfunction in the brain systems responsible for the sequencing of behaviour patterns. Specifically, it is believed that humans and animals with these symptoms have damage to the pathways involved in stopping the current response and allowing the organism to switch to a different one. This hypothesis has worrying implications for the widespread use of laboratory animals as models of normal human behaviour. Many of the standard behavioural tasks performed on laboratory animals are likely to be affected by perseveration, however, at this point we have very little idea how big this problem is likely to be. The aim of our research is therefore to explore the links between stereotypic behaviour and performance on some standard behavioural tasks used to assess normal, adaptive behaviour. We have chosen to study captive European starlings for two reasons: first because the existing evidence for a link between cage stereotypies and perseveration comes mainly from birds, and second because wild-caught birds are important for the study of adaptive behaviour in the lab. It is therefore particularly important to know how much their behaviour might be altered when they develop stereotypies. We will create groups of birds differing in the degree of stereotypy they exhibit by using manipulations of both developmental history and current caging. Birds that are caught from the wild as adults and housed in large cages should show the lowest levels of stereotypy, whereas birds taken from their nests as chicks, hand raised and then housed in small cages should show the highest levels. We will measure stereotypies by analysing videotapes of the birds' behaviour, both by hand, and by using computer software that automatically tracks the position of a bird in a cage and looks for patterns in its behaviour. In addition, we will test birds on a number of computer-controlled tasks: a gambling task similar the one mentioned above, a timing task, and a task that tests sensitivity to risk. We have chosen these latter two tasks because they are commonly used in studies of behaviour. Finally, we will look for links between the degree of stereotypy an individual bird exhibits and its behaviour on the tasks. Our study will provide the first data exploring how stereotypic behaviour in laboratory animals affects normal behaviour on a range of common tasks. These data will allow us to assess the potential scientific costs of studying animals with stereotypies. If these costs are significant, our findings will provide strong support for further improving the cage environments of laboratory animals in order to prevent them from developing stereotypies.