Investigation of empathy-like behavior in social housing

Abstract

The sensation of pain in the human body has been very well defined. Emotional loci in the brain have also been researched and uncovered. Literature and observed human behavior strongly suggests a link between the neural mechanisms of pain and emotion. The perception of pain to an individual is unique to a specific set of circumstances, with regards to environmental, genetic, and social factors despite the concise sensory system. This phenomenon combined with the expanding comprehension of mirror neurons leads to the conclusion that emotion plays an important role in the perception of pain. Specifically, empathy, or the ability to relate to the emotional experiences of another, may alter the perception of pain. Because recent literature has shown that rodents are able to demonstrate empathy, and knowledge that rats and humans exhibit high similarity in neural structures pertaining to emotion and nociception, an experimental model assessing the influence of empathy on pain-related behavior was created. Empathy was hypothesized to influence nociception in socially-housed versus isolated rats, through the use of a localized inflammatory model. Animals were randomly housed in isolation or socially, in cages of 4. Depending on treatment group, each animal was injected with Complete Freund’s Adjuvant or sterile saline in the left hindpaw. Three parameters were measured- body weight to quantify overall well-being, paw thickness to measure edema, and paw withdrawal latency, as a quantification of pain-like behavior. Behavior was also qualitatively reported. Data were collected weekly for 8 weeks following injection and a series of inferential analyses were conducted. No significant difference between any isolated or socially housed group was found, although many trends were uncovered to suggest value in the original hypothesis.