Abstract
Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, using two different handling methods, as previous studies have shown that standard tail handling of mice increases physiological and behavioural measures of anxiety compared to cupped handling. Therefore, we hypothesised that tail handled mice would display a negative cognitive bias. We handled 28 female CD-1 mice for 16 weeks using either tail handling or cupped handling. The mice were then trained in an eight arm radial maze, where two adjacent arms predicted a positive outcome (darkness and food), while the two opposite arms predicted a negative outcome (no food, white noise and light). After six days of training, the mice were also given access to the four previously unavailable intermediate ambiguous arms of the radial maze and tested for cognitive bias. We were unable to validate this test, as mice from both handling groups displayed a similar pattern of exploration. Furthermore, we examined whether maze exploration is affected by the expression of stereotypic behaviour in the home cage. Mice with higher levels of stereotypic behaviour spent more time in positive arms and avoided ambiguous arms, displaying a negative cognitive bias. While this test needs further validation, our results indicate that it may allow the assessment of affective state in mice with minimal training—a major confound in current cognitive bias paradigms.
Highlights
Assessment of the subjective component of animal welfare has mostly relied on physiological [1,2] and behavioural [3,4,5] measures
Once the discrimination is learned, the animal is presented with one or more ambiguous stimuli to assess whether it expects a positive outcome, suggesting the animal is in a positive affective state, or whether it expects a negative outcome, suggesting it is in a negative affective state [6]
Mice were trained on a radial arm maze to discriminate between positively cued arms and negatively cued arms and were tested for exploration of positive and negative arms as well as intermediate ambiguous arms that had not been accessible during training
Summary
Assessment of the subjective component of animal welfare has mostly relied on physiological [1,2] and behavioural [3,4,5] measures. Based on evidence that cognitive processes such as attention, judgement and memory are biased by the valence of an individual’s affective state [7,8,9], measures of cognitive bias have recently been implemented as proxy measures of affective valence in the study of animal welfare [6,10]. Among tests probing such cognitive biases, the most commonly used type is a decision making paradigm which uses judgement biases to infer animals’ affective state. Once the discrimination is learned, the animal is presented with one or more ambiguous stimuli to assess whether it expects a positive outcome, suggesting the animal is in a positive affective state, or whether it expects a negative outcome, suggesting it is in a negative affective state [6]
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