Three “models”: Freudian iceberg model of the human mind, modern neuropsychiatric control circuit model, and dynamical systems model of a control circuit. (A) An example of the typical conceptual models historically grounding psychiatry, Freud’s theories assume that behavior reflects unconscious influences provided by components of the mind, including drives (“id”). (B) Schematic of the cortico-basal ganglia-thalamo-cortical (CBGTC) loop, integrating data from multiple neuroimaging (MR-PET) modalities. Crucially, the CBGTC loop can be treated either as a heuristic (as per the Freudian iceberg mind) in which it functions more as a map than a true model—meaning that it cannot be operationalized to make predictions over time—with new inputs, or it can be treated as a graphical representation of a dynamical system of differential equations as per (Frank, 2005) and the PID control circuit shown in C. (C) The dynamical system model is distinguished by the fact that, when presented with time-series inputs, it produces simulation outputs. These output trajectories can be compared with new data to rigorously assess the model’s validity. Images adapted from (Maia and Frank, 2011) and Arturo Urquizo (CC-BY 3.0).