Voluntary versus spontaneous swallowing in man

Area of Science:

• Neuroscience
• Physiology
• Gastroenterology

Background:

• Voluntary swallows (VS) are initiated by the desire to eat or drink.
• Spontaneous swallows (SS) occur unconsciously due to saliva or food residue.
• Both swallow types involve distinct oral and pharyngeal phases.

Purpose of the Study:

• To review clinical and neurophysiological differences between voluntary and spontaneous swallows.
• To clarify the distinct roles and mechanisms of VS and SS.
• To differentiate the pharyngeal phase from spontaneous swallowing.

Main Methods:

• Literature review of clinical and neurophysiological evidence.
• Comparative analysis of muscle activation patterns in VS and SS.
• Examination of central pattern generator (CPG) and corticobulbar input roles.

Main Results:

• VS involves orderly oral muscle activation; SS often bypasses the oral phase.
• The pharyngeal phase is a protective reflex common to both VS and SS.
• Differences exist in corticobulbar input influencing VS and SS.

Conclusions:

• VS and SS, while sharing CPG dependence, exhibit significant neurophysiological distinctions.
• Understanding these differences is crucial for diagnosing and treating swallowing disorders.
• Further research into corticobulbar pathways may reveal therapeutic targets.