"Fingerprints Enhance Our Sense of Touch (Neuroscience News, March 15, 2021). Fingerprints usually come up in the context of forensics: identifying criminals by the unique patterns of ridges on their fingertips. But what do they do for us?
The hand contains tens of thousands of sensory neurons.
Each neuron tunes in to a small surface area on the skin — a receptive field — and detects touch, vibration, pressure, and other tactile stimuli. The human hand possesses a refined sense of touch, but the exact sensitivity of a single sensory neuron has not been studied before.
And just how sensitive is a single sensory neuron? Dr. Eva Jarocka et al. “measured the electrical activity of the sensory neurons in human fingertips when they stimulated with raised dots swept over the skin.”
They refined the data and mapped it onto images of a fingerprint. The result? “Human Touch Receptors Are Sensitive to Spatial Details on the Scale of Single Fingerprint Ridges.” This was the title of their paper in the Journal of Neuroscience, published 21 April 21.
Look at those ridges right now on a finger, using a magnifier if you have one. That’s amazingly precise. But why do we have fingerprint ridges?
Taken together, these results suggest that the internal
sensitivity topography of a neuron’s receptive field was largely conserved across scanning directions but could be influenced by direction-dependent shear deformations of the skin surface. In addition, most neurons retain the distinctiveness of the features of their receptive fields with reference to other neurons’ fields.
---This appears to mean that a fingertip, with its ridges and valleys, enhances the responsiveness of its underlying neurons.
Each neuron remembers its own response.
The brain puts together a map of the surface based on
thousands of inputs—a very advanced method of maximizing data input from
a field, similar to radar and other scanning algorithms." CEH
