Kids with extra fingers on their hands usually have them removed soon after birth, but some get to keep them into adulthood. This condition, known as polydactyly, is usually looked upon as a disability that has to be studied and addressed. Researchers at the University of Freiburg in Germany, Imperial College London, and the Université de Lausanne and École polytechnique fédérale de Lausanne in Switzerland, wanted to evaluate how the extra fingers are handled by the brain and whether this could mean anything for the development of prosthetic devices.
Normally, prosthetic devices are designed to mimic what is missing. This is because it is assumed that the brain will have an easier time adjusting to something that it is already basically familiar with. But what if a prosthetic is fundamentally different to the original anatomy it is intended to replace?
The researchers recruited two participants with polydactyly, a mother and son with both hands having six fully developed and independent fingers. MRI scans were performed to study the anatomy of their hands and functional MRI, which detects brain activity, was employed to see how the brain functions when different fingers are being used.
It was discovered that in both of the subjects, extra brain regions in the motor cortex were responsible for the extra fingers. Moreover, it gave the mother and son pretty impressive abilities, such as tying shoelaces with one hand, that the rest of us would be jealous of.
What this means for the field of prosthetics is that assistive devices can probably be designed with novel forms and configurations that don’t have to necessarily copy native anatomy. The brain should be able to adjust and take advantage of the new capabilities, potentially giving amputees some interesting superpowers that they wouldn’t have with boring and old-fashioned five fingered hands.
Here’s a quick video that demonstrates what six fingers per hand can achieve:
Study in journal Nature Communications: Augmented manipulation ability in humans with six-fingered hands