An amygdaloreticular pathway promotes motor programs of ingestion

Abstract

Despite internal cues signaling fullness, animals can continue eating when motivated by context or palatability. The neural pathways and signals enabling the override of these fullness cues remain unclear. Here, we examine a collateralized amygdaloreticular network, focusing on central amygdala (CeA) projections to the parabrachial nucleus (PBN) and adjacent pontine- and medullary-premotor fields controlling orofacial movements. Activity in the pontine terminals of this pathway correlates with the animal's licking behavior but is unaffected by metabolic need or palatability cues. Optogenetic stimulation causes animals to overeat, consume nearby non-edible objects, or exhibit ingestion-like behaviors—licking, chewing, and grasping—even without a target. Depending on training and context, stimulation elicits either licking or pellet consumption, suggesting that CeA projections promote a flexible, context-dependent, consummatory-like motor state by recruiting a distributed amygdaloreticular motor network rather than simply suppressing satiety signals. These findings highlight how forebrain-brainstem interactions re-engage feeding behavior beyond homeostatic need.