What is a memory schema? A historical perspective on current neuroscience literature.

The term "schema" has been used to describe vastly different knowledge structures within the memory neuroscience literature. Ambiguous terminology hinders cross-study comparisons and confounds interpretation of the suggested role of the ventromedial prefrontal cortex (vmPFC) in schema functions. Based on an extensive review of the psychological literature, we propose a framework for distinguishing memory schemas from other knowledge structures. The framework includes a definition of schema as possessing four necessary and sufficient features, and four additional features schemas are sensitive to, which are not required but do play a frequent and central role in schema functions. Necessary schema features are (1) an associative network structure, (2) basis on multiple episodes, (3) lack of unit detail, and (4) adaptability. Features schemas are sensitive to are (5) chronological relationships, (6) hierarchical organization, (7) cross-connectivity, and (8) embedded response options. Additionally, we suggest that vmPFC activity observed in studies of schemas corresponds with participants' coordination of existing schemas with ongoing task demands.