Neural projections subserving the initiation of a specific motivated behavior in the rat: new projections from the subfornical organ.

The activation of neurons in the subfornical organ (SFO) by angiotensin II in the blood is known to stimulate thirst. The projections of these neurons were examined with anterograde and retrograde axonal transport methods, and were found to end in specific parts of the prefrontal cortex, septal region, substantia innominata, medial preoptic area, zona incerta and lateral hypothalamic area. These regions in turn are thought to be involved in arousal, somatomotor control and cognitive functions, essential components of the initiation and procurement phases of motivated behavior.