Functional subdivisions of the hypothalamus using areal parcellation and their signal changes related to glucose metabolism.

The hypothalamus consists of numerous nuclei, and is regarded as the highest center for various autonomic functions. Although each hypothalamic nucleus implements a distinct function, it remains difficult to investigate the human hypothalamus at the nucleus level. In the present high-resolution functional MRI study, we utilized areal parcellation to discriminate individual nuclei in the human hypothalamus based on areal profiles of resting-state functional connectivity. The areal parcellation detected ten foci that were expected to represent hypothalamic nuclei, and the locations of the foci were consistent with those of the hypothalamic nuclei identified in previous histological studies. Regions of interest (ROI) analyses revealed contrasting brain activity changes following glucose ingestion: decrease in the ventromedial hypothalamic nucleus and increase in the lateral hypothalamic area in parallel with blood glucose increase. Moreover, decreased brain activity in the arcuate nucleus predicted future elevation of blood insulin during the first 10 min after glucose ingestion. These results suggest that the hypothalamic nuclei can putatively be determined using areal parcellation, and that the ROI analysis of the human hypothalamic nuclei is useful for future scientific and clinical investigations into the autonomic functions.