Cortico-hippocampal interactions for memory
Francesco Battaglia, PhD, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen

Memory representations are evolving objects through the lifetime of a memory. The recording of large groups of neurons from behaving animals has been instrumental for investigating brain network dynamics supporting memory encoding consolidation and retrieval. Classically, upon memory encoding during active behavior, hippocampal activity is dominated by theta oscillations. During inactivity, hippocampal neurons burst synchronously, constituting sharp waves, which can propagate to other structures, theoretically supporting memory consolidation. The PFC is one prominent target. This ‘two-stage’ model has been updated by new data from high-density electrophysiological recordings in animals that shed light on how information is encoded and exchanged between hippocampus and PFC. I will present an overview of this field focusing on results from my lab on cortico-hippocampal dynamics, including new theoretical and experimental developments.  I will show how functional connectivity reconstruction based on Maximum Entropy methods can uncover changes in the prefrontal neural network that are linked to learning, and how these cortical functional network responds to hippocampal sharp waves.  The link between cortical functional networks and hippocampal sharp waves correlates with animal’s performance in the behavioral task. In order to better delineate this link, we designed a novel behavioral task, the “object-space” task, which allows to compare episodic-like memory acquisition, with memory acquired by accumulation across multiple episodes, while the basic behavioral sequence is very similar and comparable across conditions.