Hypothalamic interaction with reward-related regions during subjective evaluation of foods

The reward system implemented in the midbrain, ventral striatum,
orbitofrontal cortex, and ventromedial prefrontal cortex evaluates and
compares various types of rewards given to the organisms. It has been
suggested that autonomic factors influence reward-related processing via
the hypothalamus, but how the hypothalamus modulates the reward system
remains elusive. In this functional magnetic resonance imaging study, the
hypothalamus was parcellated into individual hypothalamic nuclei
performing different autonomic functions using boundary mapping
parcellation analyses. The effective interaction during subjective
evaluation of foods in a reward task was then investigated between the
human hypothalamic nuclei and the reward-related regions. We found
significant brain activity decrease in the paraventricular nucleus (PVH)
and lateral nucleus in the hypothalamus in food evaluation compared with
monetary evaluation. A psychophysiological interaction analysis revealed
dual interactions between the PVH and (1) midbrain region and (2)
ventromedial prefrontal cortex, with the former correlated with the
stronger tendency of participants toward food-seeking. A dynamic causal
modeling analysis further revealed unidirectional interactions from the
PVH to the midbrain and ventromedial prefrontal cortex. These results
suggest that the PVH in the human hypothalamus interacts with the
reward-related regions in the cerebral cortex via multiple pathways (i.e.,
the midbrain pathway and ventromedial prefrontal pathway) to evaluate
rewards for subsequent decision-making.