Differential functional connectivity between hippocampus and prefrontal cortex is associated with heterogeneity in open field exploration

A common paradigm in behavioral neuroscience involves recording neural activity from freely moving rodents as they forage in an open field. This procedure is often used in studies investigating spatial navigation, where recording is conducted in regions such as the hippocampus and entorhinal cortex. It is usually assumed that there is no systematic variation in behavior in this paradigm, thereby allowing spatial representations to be examined without the confounding effects of behavior change. Here we show that the behavior of rats in this paradigm can be algorithmically divided into at least two distinct modes, and that the transitions between these modes is marked by distinct differences in theta and gamma band power in the hippocampus, as well as transition-associated communication between hippocampus and prefrontal cortex, with information strongly flowing from hippocampus to prefrontal cortex during the transition period. Moreover, we show that following a maternal immune activation intervention, intra-regional changes in power are preserved, but communication between hippocampus and prefrontal cortex is impaired. These findings demonstrate that animals in the open field perform distinct behaviors that are accompanied by marked changes in brain activity and regional communication.