For many decades, mice have been used as subjects in scientific research. This is the case even though the majority of research pertains to the wellbeing of humans and the pursuit of scientific knowledge. Drawing from novel research findings about mice, I will discuss how these findings may affect the ethical use of mice in research.
Research by Sweis and colleagues (2018) have demonstrated that mice are capable of learning regret. Over a longitudinal period of 70 days, Sweis and colleagues evaluated the decision-making processes of mice. This design consisted of stations that offered different flavors of pellets. Referred to as restaurants, these stations were characterized as either an offer zone or a wait zone. In the offer zone, mice were trained to learn that if they waited a certain amount of time, they would obtain food. Mice were able to learn this by the specific pitch of tone; during each block of wait time and food availability, a specific tone was associated. Mice eventually learned to distinguish the amount of wait time given the tone frequency. If the mice chose to pursue the pellet, they would go to the wait zone and stay until the tone terminated. If the mice successfully stayed in the wait zone, they would be rewarded with the pellet. Importantly, this study was the only opportunity for mice to eat over the 70 day period, and only an hour per day was allocated to earn food.
The significance of this study is that it shows the ability of non-human subjects to learn and alter their behavior over a long-term period. Previous studies have shown that non-human subjects are capable of demonstrating regret in the short-term, but not the long-term. Specifically, this research shows that mice demonstrated strategic decision-making processes and planned ahead for upcoming offer zones. In particular, mice showed that from previous experience, they had learned to skip an expensive zone rather than waste time by entering and then shortly leaving the wait zone. This study also shows that mice learned to reduce the amount of decision changes during the wait zone. Put otherwise, the mice learned that to maximize pellet earnings, planning ahead for the next offer zone reaped more benefits than leaving the wait zone before the pellet was earned. Lastly, this study found that mice are able to adjust decision-making processes regardless of whether it increased the pellet reward rate. This shows the depth of which mice can learn. As noted in the paper, mice did not have to learn how to deal with regret. Rather, they learned how to avoid regret all together by basing decisions on past experiences.
Moving on, regret can manifest as an action where behavior is changed, but more commonly, regret can manifest as an emotion. When people think of their experience of regret, they will often use the word feel as a description. With this said, several questions arise from this research: if mice can demonstrate regret behaviorally, can they also experience emotional relatives of regret such as pain? If this is the case, what does this imply about current animal-testing procedures in scientific research?
To elaborate on regret manifesting as an emotion, research by Smith and colleagues (2017) have demonstrated that through auditory, visual, and olfactory exchange, mice are able to empathize with other mice. The purpose of this study was to determine if hyperalgesia, experienced by drug withdrawn mice, would transfer to the bystander mice, those not experiencing withdrawal. These two groups of mice were housed in the same area. Hyperalgesia is a condition that increases sensitivity to pain and it can be induced by drug withdrawal. The primary finding was that bystander mice demonstrated hyperalgesia due to living in the same area as the drug withdrawn mice. This shows that mice are capable of empathy, an ability that many think is restricted to humans or closely related species, but even more importantly, that mice feel pain.
As a whole, these studies have demonstrated that mice are able to learn regret by altering decision-making processes and behavior, and that mice can feel the pain experienced by other mice. These findings suggest that mice are more similar to humans than is credited. The implications of this are serious and should prompt us to critically think. If mice can empathize with other mice and experience their emotional state, what implications does this have for use of mice in research testing?
References
Smith, M., Walcott, A., Heinricher, M., Ryabinin, A. (2017). Anterior cingulate cortex contributes
to alcohol withdrawal-induced and socially transferred hyperalgesia. Journal of Society for Neuroscience, 4(4), 1-10. https://doi.org/10.1523/ENEURO.0087-17.2017
Sweis, B., Thomas, M., Reddish, D. (2018). Mice learn to avoid regret. Journal Plos Biology,
16(6), 1-21. https://doi.org/10.1371/journal.pbio.2005853
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