Individual differences in affective processing and implications for animal welfare: a reaction norm approach

每个人看待世界的方式不同。有些人对未来或模棱两可的情况的结果比其他人更乐观。有些人对令人愉快或有益的刺激更敏感。有些人更容易受到不愉快的事情的影响。这些差异会影响个人如何应对生活中的机遇或挑战，并对他们的总体健康和对抑郁症等情感（情绪）障碍的脆弱性产生连锁反应。这不仅仅是人的问题。在动物身上，越来越多的证据表明，在决定一个模糊的信号是预示着积极还是消极的结果时，个体在“乐观”/“悲观”方面存在差异，一些证据表明，这些个体或个性特征预测了他们科普挑战的能力。该项目的目的是全面调查这些个体差异及其对动物福利的影响。我们将使用在我们的实验室开发的认知任务，旨在测量“乐观”或“悲观”的反应，作为一个标记，分别是积极或消极的情感状态的模糊线索。这项任务已被用于160多项研究，涉及范围广泛的哺乳动物和鸟类，有证据表明，“乐观”的个性差异会影响动物对压力的脆弱性。此外，通过对该任务的数据进行计算建模，我们还可以得出个体对愉快和不愉快事件的敏感度。在本项目中，我们将首先量化广泛使用的实验室动物大鼠在这些特征（个性差异）的平均表达方面的个体差异。我们还将量化个体在重复测试中表达特征的稳定性（可变性或可预测性）以及在不同背景下测试时他们的反应有多灵活（可塑性）。这将为我们提供一个比以前更详细的画面，在“乐观”和敏感性的个体差异愉快和不愉快的事件，然后我们将评估不同类型的个体如何应对变化的机会或挑战，在他们的家庭笼子环境中，例如，通过丰富他们的笼子或引入一些不可预测的事件。我们将测量他们的福利指标，并使用与上述相同的分析方法来确定每个人在不同背景下的平均福利，特别是在充满机会的环境中福利改善的程度或在更具挑战性的环境中变得更穷的程度。因此，我们将能够测试，例如：是否更“乐观”的个人，特别是那些表现出可预测的，而不是可变水平的“乐观”，更好地科普挑战;是否个人谁是更敏感的愉快的事件受益于机会的增加;是否个人谁表现出更大的敏感性不愉快的事件更强烈的影响，挑战。因此，我们将绘制个体特征与福利增强或福利挑战环境中的鲁棒性或脆弱性之间的联系，然后我们将询问是否可以通过让个体在复杂环境中与其他动物玩耍来改变个体特征并提高鲁棒性。越来越多的人对利用玩耍作为改善实验室动物福利的实用方法感兴趣，我们将系统地评估这种可能性，如果得到支持，可以为动物管理实践提供信息。此外，如果游戏体验导致标准行为测试中个体反应的更大稳定性（例如焦虑样状态，认知能力），尽管家庭环境发生了变化，这不仅表明它在面对挑战时保持了福利，而且还表明它可以增强测试的跨背景再现性，这是现代科学的一个重要目标。

Individuals differ in how they view the world. Some are more optimistic than others about the future or the outcome of ambiguous situations. Some are more sensitive to stimuli that are pleasant or rewarding. And some are more strongly affected by unpleasant things. These differences impact how individuals respond to opportunities or challenges in their lives with knock-on effects for their general wellbeing and vulnerability to affective (emotional) disorders such as depression. This is not just the case for people. In animals there is growing evidence that individuals vary in 'optimism' / 'pessimism' when deciding whether an ambiguous signal heralds a positive or negative outcome, and some evidence that these individual, or personality, characteristics predict how well they cope with challenge. The aim of this project is to comprehensively investigate these individual differences and their implications for animal welfare. We will use a cognitive task developed in our lab and designed to measure 'optimistic' or 'pessimistic' responding to ambiguous cues as a marker of, respectively, positive or negative affective states. This task has been used in more than 160 studies across a wide range of mammalian and bird species, and there is evidence of personality differences in 'optimism' that can influence an animal's vulnerability to stress. Furthermore, computational modelling of data from this task also allows us to derive measures of an individual's sensitivity to pleasant and unpleasant events.In this project, we will first quantify individual differences in the average expression of these characteristics (personality differences) in a widely used lab animal, the rat. We will also quantify how individuals differ in their stability of expression of the characteristics across repeated tests (variability or predictability), and in how flexible their responses are when tested across different contexts (plasticity). This will provide us with a more detailed picture than before of individual differences in 'optimism' and sensitivity to pleasant and unpleasant events.We will then evaluate how different types of individual respond to changes in the presence of opportunities or challenges in their home cage environments, for example by enriching their cages or introducing some unpredictable events. We will measure markers of their welfare and use the same analysis approach as above to establish each individual's average welfare across contexts and, in particular, the extent to which its welfare improves when in an opportunity-filled environment or becomes poorer in more challenging environments. We will thus be able to test, for example: whether more 'optimistic' individuals, especially those showing predictable rather than variable levels of 'optimism', cope better with challenge; whether individuals who are more sensitive to pleasant events benefit more from an increase in opportunities; whether individuals who show greater sensitivity to unpleasant events are more strongly affected by challenge. We will thus map links between individual characteristics and robustness or vulnerability in welfare-enhancing or welfare-challenging environments.We will then ask whether we can alter individuals' characteristics and improve robustness by exposing them to experience of play in complex environments with other animals. There is growing interest in the use of play as a practical way of improving welfare in lab animals, and we will systematically evaluate this possibility which, if supported, could inform animal management practices. Moreover, if play experience results in greater stability of individual responses in standard behavioural tests (e.g. of anxiety-like states, cognitive ability) despite changes to home environments, this will not only indicate that it acts to maintain welfare in the face of challenge, but also that it can enhance cross-context reproducibility of testing, an important goal in modern science.