A dynamical feedback mechanism for the generation of hippocampal field rhythms

Different rhythmic activities in CA1 characterize the neuronal correlate of several behavioral states. Recently, in an in vitro preparation of the who le hippocampus, spontaneous delta rhythms similar to hippocampal EEG seen i n behaving animals, have been recorded. Based on the experimental data and by using numerical simulations, we suggest a mechanism in which a dynamical feedback from populations of synchronized interneurons entrain an increasi ng and/or more synchronized activity in the pyramidal cell population. In t his scenario, the number of the excitatory cells as well as the excitabilit y of the interneurons determine the frequency and robustness of these slow rhythms. (C) 2001 Elsevier Science B.V. All rights reserved.