An amygdalopontine pathway promotes motor programs of ingestion

Abstract

Despite internal cues that signal fullness, animals can continue eating when motivated by context or palatability. The neural pathways and signals that enable animals to override these fullness cues remain unclear. We examined a central amygdala (CeA) projection to the dorsolateral pons that targets the parabrachial nucleus, a well-established meal termination center, and the adjacent supratrigeminal nucleus, a region that controls orofacial movements. Activity in this CeApons pathway correlated with the animals licking behavior but was not modulated by metabolic need or palatability cues. CeApons stimulation caused animals to overeat, consume non-edible objects within reach, or exhibit ingestion-like behaviors--licking, chewing, and grasping--even when no target was present. Depending on training and context, stimulation elicited either licking or pellet consumption, suggesting that CeApons promotes a flexible, goal-directed ingestive state by recruiting consummatory motor circuits rather than simply suppressing satiety signals. These findings highlight how forebrain-brainstem interactions can re-engage feeding behavior beyond homeostatic need.