Unraveling the brain's GPS
Being able to navigate in an environment is a matter of survival for animals. Remarkably, in total darkness, thus in the absence of landmarks, many animals, including rodents, are able to return to their starting point. The network of brain structures that allows such computation is of extraordinary complexity and the underlying fundamental principles have only recently begun to be unveiled.
The vestibular organs record movements of the head, and this information eventually gives rise to the so-called head-direction (HD) cells. As a population HD cells act as a compass: they provide the brain’s navigation system with an estimate of the current direction of the head, even in darkness. The navigation system continuously integrates inertial information, such as their head direction and traveling speed, to track the animal’s current position. This position is encoded in a ‘cognitive map’, located in the hippocampus where each neuron fire for a given location of the animal in its environment, the so-called 'place cells'.
In the lab, we address the core question of how the brain signals coding for space are generated, how different sensory modalities (in particular visual and vestibular) are combined as the system does not know a priori where is 'north' and how these signals are maintained when external sensory information are missing.