The (Un)surprising Empathic Abilities of Rodents

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Regrettably, it has taken a very long time for psychologists and neuroscientists to take the leap towards investigating empathy in non-primate mammals. Of course, why should sociobiology get in the way of politics and religion?

The study that had perhaps the biggest impact in this field, was conducted by Langford et al. (2006), entitled "Social modulation of pain as evidence of empathy in mice". The simple yet ingenious design included placing two mice, which were either strangers or cage mates, into transparent Plexiglas cylinders, such that they could see one another. Either one or both mice received an injection of 0.9% acetic acid into the stomach cavity and their pain response (writhing behavior) was measured. Remarkably, mice appeared to be in more pain when they saw another mouse also in pain, but only when that mouse was their cage mate or sibling, not when it was a stranger. Their pain was amplified by seeing familiar individuals in pain.

Molecular Underpinnings of Sexual Dimorphism in the CNS

Sexual dimorphism, as a topic, has been investigated extensively by neuroscientists at the level of brain structures, but the molecular underpinnings of these sex differences have received much less attention. Below is a short post summarizing the state of affairs in this regard. The information is derived from an excellent 2010 review by Jazin & Cahill published in Nature Reviews: Neuroscience.

Perhaps the most fascinating development in molecular studies of CNS sexual dimorphism is the focus on sex-biased gene expression. Gene expression differences which appear to be independent of hormone action have been found in rodents and in certain invertebrates, notably the fruitfly, D. melanogaster, and the nematode, C. elegans. In the latter two, there are even sex-specific neuronal networks governing mating/courtship behaviors.