Diversity of fear responses : investigating a broader fear behaviour repertoire in mice

The prevalence of post-traumatic stress disorder (PTSD) among surveyed Australians is 5.6% in 2022. (Australian Bureau of Statistics, 2022). This debilitating disorder can cause a variety of physical, behavioural, and psychological symptoms. As a result, research into fear and its underlying mechanisms is a crucial area of study. A typical methodology employed in fear research involves introducing rodents to frightening stimuli and measuring their fear responses (Colom-Lapetina et al., 2019). The most widely utilised measure is freezing, which is a robust, well-researched measure that can be recorded and analysed by computer software. However, emerging studies suggest that the tendency of studies to use freezing as the sole behavioural measure dismiss the complexity of fear (Gruene et al., 2015a). This investigative paper explored the fear responses of 12 male mice, to investigate potential new measures of fear. The findings reveal that 12.62% of total fear response time was occupied by fear-related behaviours other than freezing, suggesting that a portion of potentially informative animal data may be neglected in favour of an oversimplified approach. The paper makes suggestions on ways that these other fear behaviours may be incorporated into emerging research software.