Ben-Ami Bartal I, Decety J, and Mason P (2011) Empathy and pro-social behaviour in rats. Science 334: 1427-30.
The first demonstration of empathy driven helping behaviour in rodents. This paper now serves as the basis for all current experiments in the laboratory.
Ben-Ami Bartal I, Rodgers D, Bernanrdez Saria M, Mason P (2014) Pro-social behavior in rats is modulated by social experience. eLife 2014;3:e01385
Building upon the work of the last paper, this one delves further into the idea of pro-social behavior. In this case, two different strains of rats were used. Rats that would only consistently open for rats of the same strain they were raised in, even if they weren't born of the same strain.
Mason P and Bartal IB (2010) How the social brain experiences empathy: summary of a gathering. Soc Neurosci 6:1-5.
This review describes a variety of perspectives on empathy from the point of view of biology, anthropology, medicine, and psychology.