How good is a sixth finger?

sixth finger

People born with more than five fingers or toes have a condition called Polydactyly. New research has studied the movement abilities of such people for the first time. A joint collaboration of a team of researchers from the University of Freiburg, the University Hospital of Lausanne, Imperial College London and EPFL have zeroed in on motor skills and sensorimotor brain areas of people with polydactyly.

According to the research, an extra finger can add to manipulation abilities and skills. Polydactyly also encourages movements with one hand, whereas people with five fingers need both hands. This augmented motor ability is a result of dedicated sensorimotor brain areas, which are allegedly blueprinted for the development of additional artificial limbs that extend motor ability.

The research was published in the journal Nature Communications and for the study subjects with an extra finger between thumb and the forefinger were examined. The researchers asked the subjects to perform several behavioral experiments, during which the experts recorded their brain activity by using functional magnetic resonance imaging (fMRI).

“We wanted to know if the subjects have motor skills that go beyond people with five fingers and how the brain is able to control the additional degrees of freedom,” says Prof. Dr. Carsten Mehring from the University of Freiburg and the Bernstein Center Freiburg.

The results concluded that the extra fingers were moved by their own muscles which allowed the subjects to move their additional fingers as far and as independently as possible. This made the manipulation versatile and skillful, concluding that the brain had enough capacity to control the degrees of freedom caused by the additional finger. Furthermore, scientists recorded no disadvantage was caused to people with extra fingers.

The implementation of fMRI also led to new discoveries to the group of scientists. “We found dedicated neural resources that control the sixth finger, and the somatosensory and motor cortex are organized exactly to allow for the additional motor skills observed,” records Prof. Dr. Andrea Serino and Dr. Michael Akselrod, who carried out the neuroimaging studies at EPFL and Lausanne University Hospital.

This research of polydactyly has laid foundation work for research in the development of additional artificial limbs. “The additional extremities have been trained in the subjects since birth. This does not necessarily mean that similar functionality can be achieved when artificial limbs are supplemented later in life. Yet, people with polydactyly provide a unique opportunity to analyze the neuronal control of extra limbs and the possibilities of sensorimotor skills,” the team adds in connection to the futuristic possibilities of the study.