Complex Activity and Stochastic Resonance in the Hippocampus

Evidence for chaos in the brain has been provided using CA3 slices of the rat hippocampus. It has also been reported that a CA3 network model developed on the basis of physiological knowledge reproduces complex activity including chaos. Complex CA3 activity is projected to CA1 through Schaffer collaterals, and integrated EPSPs evoked in CA1 pyramidal cells are noisy. On the other hand, perforant path signal projected to CA1 from the entorhinal cortex is weak and causes subthreshold oscillation in CA1 pyramidal cells. In this paper, we will first show that stochastic resonance (SR) takes place in the hippocampus using CA3-CA1 network model. Secondly, we will show that SR is a possible mechanism of memory recall in the hippocampus. Key-Words: Hippocampus, Network model, Chaos, Complex activity, Stochastic resonance, Memory recall