Tuberomammillary nucleus activation anticipates feeding under a restricted schedule in rats.

We used FOS-immunoreactivity to map changes in the neuronal activity of brain nuclei related to the state of arousal, in rats under a restricted feeding schedule. Our main finding was the outstanding activation of the tuberomammillary nucleus 24h after a meal, and its steep deactivation, which was independent of actually having the meal. The time course of FOS activation and deactivation indicated a burst of tuberomammilary nucleus activity in close temporal relation with the increased locomotor activity shown by rats in anticipation of the next meal.