Associative memory in a pair of cortical cell groups with reciprocal projections

We examine the functional hypothesis of bidirectional associative memory in a pair of reciprocally projecting cortical cell groups. Our simulation model features two-compartment neurons and synaptic weights formed by Hebbian learning of pattern pairs. After stimulation of a learned memory in one group we recorded the network activation. At high synaptic memory load (0.14 bit/synapse) we varied the number of cells receiving stimulation input (input activity). The network `recalleda patterns by synchronized regular gamma spiking. Stimulated cells also expressed bursts that fascilitated the recall with low input activity. Performance was evaluated for one-step retrieval based on monosynaptic transmission expressed after ca. 35 ms, and for bidirectional retrieval involving iterative activity propagation. One-step retrieval performed comparably to the technical Willshawmodel with small input activity, but worse in other cases. In 80% of the trials with low one-step performance iterative retrieval improved the result. It achieved higher overall performance after recall times of 60}260 ms. 2001 Elsevier Science B.V. All rights reserved.