Gender-, side- and site-dependent variations in human perioral spatial resolution

Area of Science:

• Neuroscience
• Human Sensory Perception
• Biophysics

Background:

• Facial sensory perception is crucial for functions like speech and eating.
• Understanding spatial resolution differences across the face can inform clinical assessments and prosthetics.
• Previous research has not comprehensively mapped facial spatial resolution with standardized methods.

Purpose of the Study:

• To investigate and quantify spatial resolution thresholds across multiple facial sites.
• To compare tactile spatial sensitivity between males and females.
• To explore the relationship between objective sensory measurements and subjective self-ratings of facial sensitivity.

Main Methods:

• Utilized an adaptive psychophysical tracking procedure to determine two-point discrimination thresholds.
• Employed a method-of-limits procedure for clinical comparison.
• Collected subjective ratings on overall facial sensitivity and proprioceptive abilities of the lips, cheeks, and chin.

Main Results:

• Significant differences in spatial resolution were found based on facial site (p < 0.001) and gender (p < 0.04).
• Females demonstrated significantly higher spatial sensitivity than males, with smaller average threshold separations.
• The upper lip vermilion showed the highest sensitivity (2.4 mm), while preauricular skin had the lowest (20.9 mm).

Conclusions:

• Facial tactile spatial resolution is not uniform, with marked sensitivity gradients from the mouth outwards.
• Gender influences facial spatial resolution, with females being more sensitive.
• Subjective reports of sensory discrimination ability correlate with objective measures of tactile sensitivity.