INFORMATION-FLOW BETWEEN HIPPOCAMPUS AND RELATED STRUCTURES DURING VARIOUS TYPES OF RATS BEHAVIOR

The relationships among the CA1 field of hippocampus, the entorhinal-p iriform area, the subiculum and the lateral septum were studied in var ious behavioral states in the rat. The EEG signals recorded simultaneo usly from chronically implanted electrodes were analyzed by means of a multichannel autoregressive (AR) model. Power spectra, ordinary, mult iple and partial coherences, and directed transfer functions were calc ulated. The method of analysis which took into account all signals sim ultaneously, not pair-wise, made it possible to estimate the spectral characteristics and the directions of the EEG flow between structures. The pattern of the EEG activity propagation depended on the type of b ehavior, difficulty of the task performed by the animal, and the phase of the trial. Our results not only confirmed the existence of connect ions between analyzed structures, but also showed that these connectio ns may have different strengths during various types of behavior. (C) 1997 Elsevier Science B.V.