Aside from unique identifiers used in databases and law enforcement processes, fingerprints could also serve for a more acute sense of touch - according to a new study.
A team of researchers from the Department of Integrative Medical Biology at the Umeå University in Umeå, Sweden, have examined the sensory neurons in a fingertip, discovering that it is sensitive enough to detect impulses on the scale of a single fingerprint ridge - the curved lines that make up a person's fingerprint.
They detail their study and results in an article titled "Human touch receptors are sensitive to spatial details on the scale of single fingerprint ridges," appearing in the Journal of Neuroscience, March 15.
MANCHESTER, ENGLAND - NOVEMBER 16: Home Office minister Phil Woolas has his fingerprints and photograph scanned as he enrolls for the National Identity card at Manchester passport office on November 16, 2009, Manchester, England. Mr. Woolas, regional minister for the North West, is one of the first to enroll for the new biometric identity card, which goes live for a trial in Manchester on November 30th.
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Measuring Electrical Activity on Fingertips
The human hand alone is home to tens of thousands of sensory neurons, with each nerve tuned in to detect sensory inputs on a particular spot on your skin - with the area covered by each neuron called a "receptive field." Each neuron is responsible for the sense of touch - gathering information on changes to environmental stimuli like pressure, vibration, temperature, and more. While science has unveiled these sensory neurons' networks, a single neuron's precise sensitivity has not been examined until now.
Researchers Ewa Jarocka, J Andrew Pruszynski, and Roland S Johansson set out to measure the electrical activity in the human fingertips after stimulating the region with raised dots swept over the skin that part. Researchers then calculated the sensory neurons' detection areas or receptive fields, developing a mapping of these neurons over the fingerprint.
They then discovered that the detection area for a single sensory neuron matched those of a single fingerprint ridge width. Furthermore, these detection areas remained consistent, covering the same ridges even when scanned under varying scanning speeds and directions, suggesting that these neurons are actually fixed and anchored to the fingerprint ridges. Specific spots where receptive fields overlap with smaller detection areas, according to the researchers, explain how humans have such sensitive and accurate senses of touch.
In their paper, researchers additionally noted that the distal axon of some neuron types branches underneath the skins and innervates receptor organs associated with fingerprint ridges. This results in "heterogenous receptive fields" with a topography made up of many sensitive zones, or "subfields."
About the Human Fingerprint
The Encyclopedia Brittanica describes the fingerprint as an impression made by papillary ridges or friction ridges on the fingertips. They have been regarded as an infallible means of identification for humans since the ridge patterns are unique for every human.
The understanding that fingerprints are unique is generally attributed to British scientist Sir Francis Galton. However, his work heavily relies on Dr. Henry Faulds and the British magistrate's previous efforts based in India William Herschel. In 1858, William Herschel required native Indians to imprint their entire palms on contracts to ensure compliance and as proof of them agreeing to the contract. Several years later, in 1880, Faulds published his report on fingerprints and their potential as unique identifiers for every human being in the scientific journal "Nature."
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