 The standard example of levels of mechanisms is the case of spatial memory and long-term potentiation (LTP; Craver 2007: 165–170). In the spatial memory mechanism, four levels of mechanisms can be identified: the level of spatial memory, the level of spatial map formation, the cellular-electrophysiological level, and finally the molecular level. In this hierarchy, entities at each lower level are components in the higher-level mechanism. For example, an NMDA receptor at the molecular level is a component of the LTP mechanism at the cellular level, and the LTP mechanism is in turn a component of the hippocampal mechanism of memory consolidation (at the level of spatial map formation). The hippocampal mechanism of memory consolidation then contributes to the overall mechanism at the level of spatial memory, which is the highest level and includes things such as the mouse performing behavioral tasks (e.g., navigating a water maze).