Neural networks in the brain involved in memory and recall

On the basis of the evidence, it is suggested that the CA3 stage acts as an autoassociation memory that enables episodic memories to be formed and stored for an intermediate term in the CA3 network, and that subsequently the extensive recurrent collateral connectivity allows for the retrieval of a whole representation to be initiated by the activation of some small part of the same representation (the cue). Therefore, this chapter performs quantitative analyses of the storage and retrieval processes in the CA3 network. Previous formal models of autoassociative memory is extended by analyzing a network with graded response units, so as to represent more realistically the continuously variable rates at which neurons fire, and with incomplete connectivity. By calculating the amount of information that would end up being carried by a CA3 firing pattern produced solely by the perforant path input and by the effect of the recurrent connections, it is shown that an input of the perforant path type, alone, is unable to direct efficient information storage