20Humans and other animals make decisions in order to satisfy their goals. However, it remains 21 unknown how neural circuits compute which of multiple possible goals should be pursued (e.g. 22 when balancing hunger and thirst) and combine these signals with estimates of available reward 23 alternatives. Here, humans undergoing functional magnetic resonance imaging (fMRI) 24 accumulated two distinct assets over a sequence of trials. Financial outcomes depended on the 25 minimum cumulate of either asset, creating a need to maintain "value homeostasis" by 26 redressing any imbalance among the assets. BOLD signals in the dorsal anterior cingulate 27 cortex (dACC) tracked the level of homeostatic imbalance among goals, whereas the 28 ventromedial prefrontal cortex (vmPFC) signalled the level of homeostatic redress incurred by 29 a choice, rather than the overall amount received. These results suggest that a network of medial 30 frontal brain regions compute a value signal that maintains homeostatic balance among internal 31 goals. 32 33 3Canonical models in psychology, economics, and machine learning assume that decisions are 34 made in order to maximise expected reward. One popular view proposes that estimates of 35 reward for distinct stimuli or attributes (e.g. price and quality) are collapsed into a common 36 value signal that motivates reward-based decisions 1-3 . In humans, BOLD signals 4-6 in the 37 medial orbitofrontal cortex (OFC) and ventromedial prefrontal cortex code for food items 7,8 , 38 money 9,10 and social stimuli 11 , suggesting the existence of a domain-general value code in this 39 region. In non-human primates and rodents, neuronal firing rates 12-14 in lateral and central 40 orbitofrontal cortex (OFC) encode value signals for primary reinforcers. Moreover, humans 41 and primates with medial OFC lesions fail to integrate multiple attributes of a stimulus when 42 making decisions, implying that the OFC plays an active role in constructing composite value 43 estimates for available stimuli [15][16][17][18] . 44 However, in natural environments, survival depends on the minimum level of any one of a 45 number of competing internal needs. For example, a hungry animal needs food more than 46 water, whereas the reverse is true for a thirsty animal. As the world changes dynamically, 47 distinct internal assets (e.g. satiety or hydration) are continuously being depleted and 48 replenished, so that homeostasis among internal resource levels needs to be monitored and 49 maintained in neural circuits for valuation and choice [19][20][21] . The OFC is likely to play a role in 50 evaluating stimuli in the context of internal goal states (e.g. satisfy hunger or quench thirst), 51 because animals with OFC lesions continue to choose actions that lead to devalued outcomes, 52 as if they were failing to maintain or follow currently active goals 18,22 . However, a key open 53 question is how the brain evaluates which of multiple possible goals should be pursued at any 54 one time, and how it dynamically upda...