In our real life, it is well known that our cognitive process is always influenced by our environment. It is called as “context dependency” of the cognition. In this paper, we propose a memory model “PATON” that is based on a macroscopic structure of a cortico-hippocampal memory system; it has three components of a symbolic layer, a pattern layer, and an attentional system. The attentional system sends signals to control a change of the model's structure dynamically. The change induces a modulation of metric between memorized items. Computer simulation shows an association process dependent upon a context based on the modulation.