Neural correlates of the emergence of consciousness of thirst.
Proceedings of the National Academy of Sciences of the United States of America December 9, 2003 Gary Egan, Tim Silk, Frank Zamarripa et al.
Thirst was induced in humans by intravenous infusion of hypertonic saline. PET imaging revealed blood flow changes in ancient brain regions similar to those seen when thirst is maximal, while fMRI additionally showed activation in the anterior wall of the third ventricle, a region central to thirst generation in animals. Strong fMRI activations also appeared in the anterior cingulate, parahippocampal gyrus, frontal gyri, insula, and cerebellum. Drinking water to satiation immediately reduced thirst and caused a sharp decline in anterior cingulate activation, but the third ventricle activation remained unchanged, consistent with the time needed for plasma sodium to change after water absorption.