Details, gist and schema: hippocampal-neocortical interactions underlying recent and remote episodic and spatial memory

Memories are complex and dynamic, continuously transforming with time and experience. In this paper, we review evidence of the neural basis of memory transformation for events and environments with emphasis on the role of hippocampal-neocortical interactions. We argue that memory transformation from detail-rich representations to gist-like and schematic representation is accompanied by corresponding changes in their neural representations. These changes can be captured by a model based on functional differentiation along the long-axis of the hippocampus, and its functional connectivity to related posterior and anterior neocortical structures, especially the ventromedial prefrontal cortex (vmPFC). In particular, we propose that perceptually detailed, highly specific representations are mediated by the posterior hippocampus and neocortex, gist-like representations by the anterior hippocampus, and schematic representations by vmPFC. These representations can co-exist and the degree to which each is utilized is determined by its availability and by task demands.