I feel you: Emotional mirror neurons found in the rat -- ScienceDaily
On the basis of this, researchers formulated two speculations: (a) the cingulate cortex contains mirror neurons, i.e. neurons that trigger our own feeling of pain and are reactivated when we see the pain of others, and (b) that this is the reason why we wince and feel pain while seeing the pain of others. This intuitively plausible theory of empathy however remained untested because it is not possible to record the activity of individual brain cells in humans. Moreover, it is not possible to modulate brain activity in the human cingulate cortex to determine whether this brain region is responsible for empathy.
Rat shares emotions of others
For the first time, researchers at the Netherlands Institute for Neuroscience were able to test the theory of empathy in rats. They had rats look at other rats receiving an unpleasant stimulus (mild shock), and measured what happened with the brain and behavior of the observing rat. When rats are scared, their natural reaction is to freeze to avoid being detected by predators. The researchers found that the rat also froze when it observed another rat exposed to an unpleasant situation.
This finding suggests that the observing rat shared the emotion of the other rat. Corresponding recordings of the cingulate cortex, the very region thought to underpin empathy in humans, showed that the observing rats activated the very neurons in the cingulate cortex that also became active when the rat experienced pain himself in a separate experiment. Subsequently, the researchers suppressed the activity of cells in the cingulate cortex through the injection of a drug. They found that observing rats no longer froze without activity in this brain region.