Fig. 6.

Functional block diagram for a control-theoretic view of allostasis. In contrast to Fig. 5, this diagram shows a closed-loop control system design for autonomous regulation of the body. An experimenter’s desired “task behavior” is replaced by the allostatic capacity estimator, which sends predictions of capacity curves to the interoceptive state estimator and receives prediction errors with which to update its estimates. The updated estimates are issued as a reference signal to the visceromotor controller. This diagram shows a formal logical structure, at a conceptual level; the hypothesis depicted is constrained by the inferred anatomical structures in Barrett (2017) but the boxes and arrows do not map one-to-one onto the anatomy of the brain or nervous system (Lee, Ferreira-Santos, & Satpute, 2021).