Could Ultrasonic Vocalisations Provide The Elusive, Graded Measure Of Affective State Needed To Inform Refinements For The Laboratory Rat?

动物研究要求研究考虑3R(减少、改进和替换)。改进涉及到使用对动物造成最小痛苦的方法，这可能更具挑战性，以客观地评估。要达到精致，就需要有能力量化动物的情感或“情感”体验。尽管动物行为的公开变化可以提供一些信息，但这些信息并不能提供足够的敏感性来理解情绪影响。我们的研究开创了用客观方法测量动物情感状态的先河。通过翻译来自人类心理学的行为方法，我们开发并验证了新的分析方法，这些方法准确地测量了动物对不同干预措施的积极或消极的情感体验。我们使用了其中一种分析方法，情感偏差测试，来证明老鼠发出的高频呼叫提供了一种对它们个人情绪体验的分级测量。这增加了一种令人兴奋的可能性，即测量这些超声波发声可能提供一种简单易用的方法来评估精细化程度。我们的方法不需要昂贵的设备或专业知识，这意味着它可以很容易地设置并在任何动物研究设施中使用。以前的研究表明，成年大鼠在经历假定的积极事件或消极事件时分别发出50 khz或22 khz的叫声。尽管已经获得了支持这一观点的间接证据，但我们之前还没有可靠的客观方法来准确量化这些叫声和动物个体情感体验之间的关系。到目前为止，这些超声波发声与情感状态之间的直接相关性只在模拟人类玩耍或在老鼠身上挠痒痒的情况下进行了测试。情感偏向测试是一项简单的、基于奖励的任务，我们已经证明，它可以为大鼠在急性心理社会或药物干预期间的情感状态提供分级测量。这项任务测量了与联想学习和记忆相关的情感偏向。情感偏差描述了情绪状态对不同认知过程的影响，并被认为调节人类和非人类动物的学习、记忆和决策行为。认知的偏差可以是积极的，也可以是消极的，既受情绪状态的短期变化影响，也受类似情绪的核心情感变化的影响。使用我们的情感偏差测试，我们将检验这样一个假设，即超声波发声可以提供对动物情感状态的同样敏感的测量，但使用的方法可以在科学界广泛采用。我们的研究将呼叫与ABT中积极或消极情感状态的测量相关联，这将为该方法的有效性提供直接证据。我们还将测试一组动物，这些动物处于一种假定的类似抑郁症的状态，在这种状态下，我们发现负面的情感偏见被强化了。我们的目标是确定发声是否发生了类似的改变，从而为理解动物的核心情感状态提供了一种方法。这些验证研究将告诉我们，记录动物的叫声是否可以提供关于它们在急性体验期间的情绪状态的信息，以及与核心情感或“情绪”有关的信息。在我们的最终工作包中，我们将根据实验室常用的操作，将这种方法转化为在家庭笼子中以及在个人和群体层面上进行测试。我们还将测试两种改进方法，习惯于人类处理和一种新的笼子系统，旨在增加空间和社交互动，同时也实用于处理。该项目的成果将是使更多的研究人员能够研究改进的方法，并使机构能够使用简单、非侵入性和非专业的方法来监测其群体的情感状态。

Animal research requires that studies consider the 3Rs (Reduce, Refine and Replace). Refinement involves using methods which cause the least suffering to the animal, and this can be more challenging to assess objectively. To achieve refinement requires the ability to quantify the animals affective or 'emotional' experience. Although overt changes in the animal's behaviour can provide some information, these do not offer sufficient sensitivity to understand the emotional impacts. Our research has pioneered the development of objective methods to measure animals' affective state. By translating behavioural methods from human psychology, we have developed and validated novel assays which accurately measure animals positive or negative affective experience of different interventions. We have used one of these assays, the affective bias test, to demonstrate that high frequency calls emitted by rats provide a graded measure of their individual emotional experience. This raises the exciting possibility that measuring these ultrasonic vocalisations may provide a simple and easy to use method to evaluate refinements. Our approach will not require costly equipment or specialist expertise meaning it could be readily set-up and utilised within any animal research facility.Previous studies suggest that adult rats emit 50kHz or 22kHz calls when they experience putative positive or negative events, respectively. Although indirect evidence to support this idea has been achieved, we have not previously had a reliably objective method to accurately quantify the relationship between these calls and the animal's individual affective experience. Direct correlation between these ultrasonic vocalisations and affective state has so far only been tested in relation to human simulated play or 'tickling' in rats. The affective bias test is a simple, reward-based task which we have shown can provide a graded measure of the affective state of rats during acute psychosocial or pharmacological interventions. The task measures affective biases related to associative learning and memory. Affective bias describes the effect of emotional state on different cognitive processes and are known to modulate learning and memory and decision-making behaviour in human and non-human animals. Cognition can be biased in either a positive or negative direction influenced by both short-term changes in emotional state and arising from changes in core affect akin to mood. Using our affective bias test, we will test the hypothesis that ultrasonic vocalisations can provide an equally sensitive measure of animal's affective state but using a method which can be widely adopted across the scientific community. Our studies correlating calls with our measure of positive or negative affective state in the ABT will provide direct evidence of the validity of the approach. We will also test a cohort of animals in a putative depression-like state where we have found that negative affective biases are potentiated. Our aim is to establish whether vocalisations are similarly altered and hence provide a way of understanding animals core affective state. These validation studies will tell us whether recording animals calls can provide information about their emotional state both during acute experiences and in relation to core affect or 'mood'. In our final work package, we will translate the approach to testing in the home-cage and at an individual and populations level in response to manipulations commonly used the laboratory. We will also test two refinement methods, habituation to human handling and a novel caging system designed to increase space and social interactions whilst also being practical for handling. The outcomes of this project will be methods to enable many more researchers to study refinement and enable institutions to monitor the affective state of their colonies using a simple, non-invasive and non-specialist method.