Organization of a primitive memory: olfaction.

I present a tentative, and schematic, picture of the olfaction storage system in early mammalians: (i) how the excitation trains from the olfactory bulb excite selectively N types of cells in the piriform cortex and (ii) how these cells transfer their information to a storage area. Simple size and connectivity requirements impose that each odor is stored in a very small cluster of approximately 3 neurons. This surprising result holds even if the model parameters are strongly altered (e.g., if N = 10(3) rather than 10(2)).