Abstract
The prefrontal cortex (PFC) and hippocampus (Hip) are important brain regions for learning and memory. The anatomical connection between both regions is well known. The aim of this study was to investigate relationship between these regions based on the correlation of neuronal activities. Under urethane anesthesia, the recording electrodes were implanted into PFC and Hip according to anatomical data reported previously. After that, multiple unit activities (MUAs) of both regions were recorded simultaneously. Analysis of cross-correlograms (CCs) between MUAs revealed significant peaks. They had lags mainly from Hip to PFC. The peaks of those CCs (MUA-based CCs) could reflect relationship between individual spikes and/or population of spikes. To evaluate contribution of these factors, we calculated CCs based on spike density function (SDF), which mainly reflects function of population of spikes. There were no significant differences in lags between MUA-based CCs and SDF-based CCs. These results suggest that relationships between population of spikes not individual spikes contribute to our observed peaks of CCs. Significant information may be conveyed by population of spikes at least in Hip-PFC communication. Such a communication based on population of spikes between Hip and PFC could provide some gates for information flow between these regions. [J Physiol Sci. 2008;58 Suppl:S143]
