Generation of masticatory rhythm in the brainstem

Area of Science:

• Neuroscience
• Mammalian Physiology
• Oral-Facial Motor Control

Background:

• Mastication is a fundamental, rhythmical mammalian behavior.
• Motor commands for mastication originate from a brainstem neural network.
• This network, the central pattern generator (CPG), controls jaw, tongue, and facial muscles.

Purpose of the Study:

• To review the localization and activation of the central rhythm generator (CRG) for masticatory jaw movements.
• To discuss the neurochemical basis of trigeminal motoneuron activity and rhythm generation.
• To present findings on inducing fictive sucking movements in an in vitro preparation.

Main Methods:

• Review of existing evidence on CRG localization and premotor neuron pathways.
• Discussion of neurochemical mechanisms underlying masticatory rhythm.
• Experimental induction of neural activities simulating sucking behavior in vitro.

Main Results:

• Evidence suggests the masticatory CPG is functionally divided into CRG and pattern-generating neuronal groups.
• The CRG provides timing signals for jaw opening and closing.
• Neural activities mimicking sucking movements were successfully induced in vitro.

Conclusions:

• The masticatory CPG is a complex network involving distinct rhythm and pattern generators.
• Understanding the CRG's neurochemical basis is crucial for comprehending masticatory control.
• In vitro models offer a valuable tool for studying primitive oral behaviors like sucking.