According to new findings, it may be possible to tap into the brain's resources to control robotic extra limbs and digits.
All over the world, about one in every 500 babies are born with extra fingers and toes, a condition known as polydactyly. Mostly seen as a 'birth defect,' extra digits are usually removed shortly after birth.
Mostly, studies into polydactyly have focused on the genetic mutation behind it, but until now, nobody has studied how the brain and body make up for the extra workload when the extra digits are functional.
With the new study, researchers from the University of Freiburg in Germany, Imperial College London and University de Lausanne/EPFL in Switzerland, have discovered that the brain allocates dedicated areas to the extra digits, making them as useful as standard digits.
According to the authors, polydactyl brains could teach us how our brains adapt to extra workloads. The findings present an argument for keeping the extra toes or fingers with which some people are born if they are well-formed and functional.
How digits fit into this arrangement is all that the researchers wanted to discover. Professor Etienne Burdet, the senior author of the study from Imperial's Department of Bioengineering who carried out this study with his colleagues in Germany and Switzerland, said that extra fingers and toes are traditionally seen as a birth defect, so nobody has thought to study how useful they might be.
The study, published in Nature Communications, investigated two people, a 52-year-old woman, and her 17-year-old son, who both have six fingers on each of their hands with a well-formed extra finger between the thumb and forefingers.
Intending to study the potential benefits of their other fingers, the researchers have the subjects to explore objects with their hands, tie shoelaces, type on their phones, and play custom-made video games; movements classed as 'manipulation.'
The team analyzed and compared the movements to the movements of control subjects with five fingers on each hand. During manipulation, high-resolution functional magnetic resonance imaging (fMRI) monitored their brain activity.
They discovered that, like non-polydactyl fingers, the extra digits had their dedicated tendons, muscles, and nerves, as well as additional corresponding brain regions in the motor cortex.
Also, polydactyl participants performed better at many tasks than their non-polydactyl counterparts. For instance, they were able to execute some tasks, including tying shoelaces with only one hand, where two are usually needed.
The researchers believe that the results of the study might serve as a blueprint for developing artificial limbs and digits to expand our natural movement abilities. For example, giving a surgeon control over an extra robotic arm could enable them to operate without an assistant.