The hippocampus is known as the core of memory system in the brain. However, how hippocampus works is not clear. In this paper, to estimate function of brains memory system based on studies and damage examples and examine the possibilities of generating one-shot learning and making episode memory. I focus on the Papez circuit which is a circuit related to the hippocampus and memory and I estimated that part contributes to the generation of time-series information. In addition, I discuss how self- learning can be realized by combination of memory system and expressing system about pleasant and unpleasant.