Dynamic analysis of internal and external mental sweating by optical coherence tomography

Area of Science:

• Neuroscience
• Biomedical Engineering
• Dermatology

Background:

• Mental sweating, influenced by the sympathetic nervous system, is a key indicator of neural activity under stress.
• Optical coherence tomography (OCT) offers high-resolution, in vivo imaging of eccrine sweat glands.
• Previous methods could not visualize sweat dynamics within the gland lumen.

Purpose of the Study:

• To demonstrate dynamic OCT for imaging mental sweating in eccrine sweat glands.
• To quantitatively assess sweat dynamics and differentiate between internal and external sweating.
• To investigate the utility of internal sweating for evaluating sympathetic nerve activity.

Main Methods:

• Dynamic OCT was employed to capture time-sequential images of eccrine sweat glands on human fingertips.
• Sweating dynamics were tracked with one-second frame spacing.
• Quantitative analysis of sweat volume within the spiral lumen was performed on OCT images.

Main Results:

• Dynamic OCT successfully visualized the spiral lumen of eccrine sweat glands during mental stress.
• Internal sweating, without ejection to the skin surface, was observed and documented for the first time.
• Internal sweating occurred more frequently under mental stress and appears more indicative of sympathetic nerve activity than external sweating.

Conclusions:

• Dynamic OCT is a novel technique for visualizing and quantifying both internal and external sweating.
• Internal sweating represents a previously unrecognized physiological response.
• Internal sweating provides a more sensitive measure of sympathetic nerve activation compared to external sweating.