To this aim, recent human and animal neurophysiological data enlightened many facets of how these sub-processes are carried out and led to the arousal of various computational models. Among these evidences, first, hippocampal rhythms have been demonstrated to play significant roles in memory tasks (theta rhythms for memory formation/recall and sharp waves for memory consolidation to cortical areas). Then, spatial memory in rodents received a lot of attention with the discovery of hippocampal "place cells" firing at specific locations in an environment (observed also in humans) and more recently of entorhinal cells firing according to a grid like pattern. Furthermore, a temporal code has been found in the firing patterns of hippocampal and entorhinal cells in term of "theta phase precession".

In this talk, I will mainly focus on a recent computational model I developed explaining how hippocampal "place fields" can emerge from the firing pattern of entorhinal "grid cells" which are located one synapse upstream the hippocampus and which conveys the majority of its cortical inputs. My model demonstrated that the temporal code of entorhinal grid neurons firing with "theta phase precession" provides selectivity in input integration of dentate neurons and may be necessary for the emergence of place fields. More generally this indicates a critical role of temporal coding for space computation in the entorhinal-hippocampal system. I will discuss the implications/predictions of this model and will show how they can be validated by ongoing experimental results from tetrode recordings of rats during exploratory behavior.

Hopefully, the discussion will continue on other facets involved in memory processing, as how these place fields could create a cognitive map, then, how the behavioral events can be replayed in a compressed form during sleep or awake inactivity sharp waves for memory transfer to cortical areas for long term storage.