Principal investigator(s): Mark Humphries, Alexandre Hyafil, Boris Gutkin
If the hippocampus stores internal maps of an animal environment, then who reads the map and decides where to go? The prefrontal cortex is the natural candidate for such a role of selecting actions based on the rewards they are supposed to lead to. Yet how communication between hippocampus and prefrontal cortex takes place at decision points remain mysterious. Recent evidence collected by Karim Benchenane and colleagues shows that neural activity in rat prefrontal cortex is shaped by hippocampus theta oscillations (4-8 Hz). Theta oscillations in hippocampus are known to encapsulate short sequences representing the rat trajectories (theta phase precession). Crucially this phase-locking of prefrontal neurons is enhanced at the time when rats make correct decisions in a maze, and this effect is most probably due to the release of dopamine that is known to take place at such decision points.
We have initiated a project that aims at understanding how the physiological effects of dopamine on prefrontal neurons may induce this change in hippocampus-prefrontal cortex coupling. At a second stage, we plan to investigate how this improved inter-area communication may improve the encoding and selection of trajectories leading to rewards.