A genetically defined pontine nucleus essential for ingestion in mice

Area of Science:

• Neuroscience
• Motor Control
• Feeding Behavior

Background:

• Feeding involves complex orofacial muscle coordination for biting and chewing.
• The precise neural circuits controlling these actions, particularly in the hindbrain reticular formation, remain poorly understood.

Purpose of the Study:

• To identify and characterize specific neuron groups in the brainstem involved in regulating orofacial motor patterns during feeding.
• To elucidate the role of the Phox2b-expressing nucleus in the supratrigeminal area (Sup5Phox2b) in feeding control.

Main Methods:

• Characterization of excitatory reticular interneurons expressing Phox2b in the supratrigeminal area.
• Investigation of neural inputs to the Sup5Phox2b nucleus from sensory and cortical regions.
• In vivo analysis of Sup5Phox2b neuronal activity during different feeding behaviors (lapping, biting, chewing).
• Optogenetic manipulation (activation/inhibition) of Sup5Phox2b neurons to assess their role in volitional feeding.

Main Results:

• Identified Sup5Phox2b as a premotor nucleus receiving sensory, motor cortex, and satiation-related inputs.
• Demonstrated that Sup5Phox2b activity differentially correlates with lapping, biting, and chewing.
• Showed that optogenetic activation or inhibition of Sup5Phox2b disrupts feeding sequences.

Conclusions:

• Sup5Phox2b is a critical, genetically and topologically defined subcortical node in the neural control of the oral phase of feeding.
• This nucleus plays an obligatory role in coordinating orofacial motor patterns essential for food intake in mice.