We developed an experimental task to examine the mirror system in rats, because previous studies of the mirror system have been limited to primates, despite that the mirror system in the brain is considered to be a neural basis of sociality. Here, we show that a rat could reach to a pellet and then grasp and eat it in front of another rat that was observing the reaching. This situation is similar to that in the study of the mirror system in primates. The success rate of reaching was about 60%, rate of "face to face" situation was about 20%, rate of "not paying attention" did not change during the training sessions (6 days). Moreover, we show that the meaning in the rat social context is equal to that in the human social context, which confirms the validity of our developed task for examining the rat mirror system. Our next task is to explore the rat mirror system. More detailed mechanisms of the mirror system will be revealed because many neuroscience approaches such as direct neural recording, lesions in specific brain area, micro-injection of neural transmitter antagonist or agonist in a local brain region, behavioral experiments in genetically modified mice, and molecular biological methods, are possible in rodent.
Acknowledgements:CREST(Core Research for Evolutional Science and Technology)funding program of the Japan Science and Technology Agency supported this work.