Changes

There are substantial hormonal influences on behavior. For example, circulating hormones such as leptin and ghrelin act as satiety and hunger signals, reporting the status of body energy reserves (e.g. adipose tissue), energy requirements, and acute nutrient intake to hypothalamic and midbrain targets in the central nervous system that regulate feeding behavior<ref>Korotkova, Sergeeva, Eriksson et al., 2003</ref>. They also act on brain regions (in particular dopaminoceptive areas) implicated in human decision-making<ref>Hommel, Trinko, Sears et al., 2006</ref><ref>Krügel, Schraft, Kittner et al., 2003</ref>.  Metabolic state itself may thus directly affect the neural expression of preference, exemplified by findings that physiological state influence preferences for economic risk in humans<ref>Symmonds M, Emmanuel J, Drew M, Batterham R, Dolan R. Metabolic state alters economic decision-making under risk in humans. PLoS ONE. 2010b; 5: e11090.</ref>