A unified model of cortico-hippocampal interactions through neural field theory

Functional interactions between cortex and hippocampus play a central role in cognition and are disrupted in major neurological disorders, but the mechanisms underlying coordinated cortico-hippocampal dynamics are poorly understood. We address this challenge using neural field theory, a biophysically-grounded framework for modelling large-scale neural dynamics. We first show how the autonomous activity of cortex and hippocampus emerge from corticothalamic and hippocampo-septal feedback loops, respectively, giving rise to cortical alpha and hippocampal theta rhythms. We next integrate these two systems through topologically and topographically informed coupling between cortex and hippocampus. Weak coupling yields spatially precise correlations between cortical and hippocampal activity, consistent with neurophysiological recordings. Stronger coupling pushes both the cortex and the hippocampus toward criticality, triggering state transitions and mode mixing, such that activity propagates across spatial scales and reorganizes both cortical and hippocampal dynamics. These disruptive, unstable processes also provide an explanation for the frequent involvement of the hippocampus in seizures. This prediction is validated using intracranial electroencephalographic data from human patients with focal onset epilepsy. Together, these results establish a geometrically and biophysically grounded framework that gives a unifying account of large-scale cortico-hippocampal dynamics and provides a physically principled foundation for studying other distributed brain systems.