The brain, sensing the internal & external milieu, & consulting its database, predicts what is likely to be needed; it computes the best response; it rewards a better-than-predicted result with a pulse of dopamine, encouraging learning

Allostasis: A Brain-Centered, Predictive Mode of Physiological Regulation. Jay Schulkin, Peter Sterling. Trends in Neurosciences, September 2 2019. https://doi.org/10.1016/j.tins.2019.07.010

Highlights
.    Allostasis – brain-centered predictive regulation – starts with a hypothalamic clock that synchronizes clocks in every tissue.

.    On this diurnal cycle of metabolic variation, the brain superimposes an episodic rest–activity cycle that coordinates change in key systems (respiration, heart rate, blood pressure, body temperature, and physical activity).

.    The brain predicts upcoming needs for food, water, salt, warmth, or cooling and satisfies them by adjusting physiology and behavior to prevent errors that would require homeostatic correction.

.    The brain rewards a better-than-predicted result with a pulse of dopamine, thereby encouraging the organism to learn effective regulatory behaviors.

Abstract: Although the concept of allostasis was proposed some 30 years ago, doubts persist about its precise meaning and whether it is useful. Here we review the concept in the context of recent studies as a strategy to efficiently regulate physiology and behavior. The brain, sensing the internal and external milieu, and consulting its database, predicts what is likely to be needed; then, it computes the best response. The brain rewards a better-than-predicted result with a pulse of dopamine, thereby encouraging the organism to learn effective regulatory behaviors. The brain, by prioritizing behaviors and dynamically adjusting the flows of energy and nutrients, reduces costly errors and exploits more opportunities. Despite significant costs of computation, allostasis pays off and can now be recognized as a core principle of organismal design.