Mental stress-induced physiological changes in the human masseter muscle

Area of Science:

• Physiology
• Neuroscience
• Biomedical Engineering

Background:

• The impact of prolonged mental stress on masticatory muscle hemodynamics remains unexplored.
• Mental stress is linked to sympathetic nervous system activation, which can influence muscle function.

Purpose of the Study:

• To investigate hemodynamic and electromyographic changes in jaw-closure muscles during a sustained mental stress task.
• To explore the relationship between sympathetic nervous system activity and masticatory muscle responses to stress.

Main Methods:

• Healthy adult females underwent a two-hour mental stress task.
• Electromyographic activity of temporalis and masseter muscles was recorded.
• Masseter muscle hemodynamics were measured non-invasively, and autonomic function was assessed via heart rate spectral analysis.

Main Results:

• Temporalis muscle activity increased with sympathetic nervous system activity, but masseter muscle activity did not significantly change.
• Despite minimal changes in electromyography, the masseter muscle exhibited significant hemodynamic alterations during stress.
• Heart rate spectral analysis confirmed increased sympathetic nervous activity during the stress task.

Conclusions:

• Jaw muscle hemodynamics are sensitive to mental stress.
• Stress-induced hemodynamic changes in masticatory muscles may play a role in the development of jaw muscle dysfunction.
• Further research is warranted to elucidate the mechanisms linking mental stress, muscle hemodynamics, and jaw dysfunction.