A frontal cortical world model shapes inference of causal relationships in hippocampus

Causal reasoning, inferring what leads to what, is the foundation upon which animals and humans build their understanding of the world. Yet causal relations are rarely fully revealed; they must be inferred from incomplete and ambiguous observations. We propose that such causal inference operates through the integration of two complementary models of the environment: a relational structure, encoding cause-effect relationships, and an abstract world model, encoding the generative principles that govern how causal relations are formed and interpreted. To dissociate these two processes, we developed a novel one-shot causal inference paradigm. Combining both neural recording and intervention methods, we reveal that the two proposed models are neurally dissociable yet functionally coordinated: the hippocampus instantiates the relational structure by building a map of causal relations, a process controlled by the inferior frontal sulcus (IFS), which is critically involved in inferring unobserved causal relations through its encoding of the abstract world model.