June 3, Polydactyly is the extraordinary condition of someone being born with more than five fingers or toes. In a case study published in Nature Communications , researchers from the University of Freiburg, Imperial College London, the University Hospital of Lausanne, and EPFL have for the first time examined the motor skills and sensorimotor brain areas in people with polydactyly.
The results show that an extra finger can significantly extend the manipulation abilities and skill. It enables people with six fingers to perform movements with one hand where people with only five fingers would need two hands. The augmented motor abilities observed in the polydactyly subjects are made possible by dedicated areas in the sensorimotor brain areas.
These findings may serve as blueprint for the development of additional artificial limbs extending motor abilities. The case study of the researchers from Freiburg, London and Lausanne investigates for the first time the movement abilities of people with six fingers per hand. In the case of the two examined subjects, an additional finger between thumb and forefinger is fully formed on each hand. To find out the extent of their abilities, the researchers had the subjects perform several behavioural experiments, and their brain activity was monitored using functional magnetic resonance imaging fMRI.
The results show that the subjects' extra fingers are moved by own muscles. This allows the subjects to move their extra fingers as far as possible independently of all other fingers. For instance, in our experiments subjects can carry out a task with one hand, for which we normally need two hands," summarises Professor Mehring.
In a nutshell, it is amazing that the brain has enough capacity to do it without sacrificing elsewhere. That's exactly what our subjects do," says Prof. Etienne Burdet of Imperial College London. To understand how the brain of polydactyly subjects controls the additional fingers, the scientist used high-resolution functional magnetic resonance imaging fMRI. Andrea Serino and Dr. The study of these polydactyly hands could advance the development of additional artificial limbs to expand people's motor skills.
