Spatial memory is an important cognitive process that relies on extensive neural networks throughout the brain. The hippocampus (HC) is important for the formation of these memories but over time, in a process referred to as consolidation, recall becomes increasingly reliant on other brain areas. The anterior cingulate cortex (ACC), a region within the medial prefrontal cortex, is important for spatial learning, spatial working memory, and remote memory recall, but the mechanisms underlying recall processes are still unknown. To better understand the role of the ACC and HC during memory recall, we introduced rodents into a series of spatially and texturally unique environments at differing delay periods (day 1 (learning), day 11 (recent), and day 18 (remote)) while simultaneously recording local field potentials (LFPs) from both areas. We found significant increases in theta band coherence between ipsilateral ACC and HC LFPs during remote memory recall but not recent memory recall. In addition to these changes, directional analysis revealed a reversal in signal initiation, such that during the learning and recent recall condition, hippocampal theta oscillations led ACC theta oscillations. However, during the remote recall condition, the direction changed, and ACC theta led hippocampal theta activity. This experiment provides evidence of time-dependent changes in ACC – hippocampal network interactions, and illustrates a possible mechanism that describes how the ACC mediates recall of remote spatial memories
