Peter Longstaff is a painter, pig farm owner, and father. He was also born with no arms and creates his art by grasping the brush between his toes, dipping it in paint and swiping it across the canvas in an incredible feat of foot dexterity.
Now, researchers have scanned the brains of Longstaff and Tom Yendell, another foot artist, to see if their brains differ in measurable ways from the handed population. And indeed they do – these individuals have "toe maps" in the brain similar to the "finger maps" of the control group. The finding is published in the journal Cell Reports.
"For almost all people, each of our fingers is represented by its own little section of the brain, while there's no distinction between brain areas for each of our toes," said the study's lead author, PhD student Daan Wesselink, from UCL Institute of Cognitive Neuroscience and University of Oxford, in a statement.
"But in other non-human primate species, who regularly use their toes for dextrous tasks like climbing, both the toes and fingers are specifically represented in their brains. Here, we've found that in people who use their toes similarly to how other people use their fingers, their toes were represented in their brains in a way never seen before in people."
The team studied two of three foot artists in the UK, both of whom use one foot for object manipulation and the other for stabilization. Using ultra high-resolution fMRI, they tapped the participants’ toes to see which areas of the brain lit up with activity.
For the painters, each individual toe brightened in the scanner in the brain region reserved for feet, but for the handed controls no such specificity was found. These artists, they found, have separate, defined regions for each of their toes next to each other – essentially "toe maps" in the brain. Not only that, but the artists’ stabilizing foot showed less pronounced activity than their dexterous foot. The activity also expanded to the region of the brain usually reserved for hands.
"The body maps we have in our brains are not necessarily fixed – it appears as such because they are very consistent across almost all people, but that's just because most people behave very similarly," said co-lead author Dr Harriet Dempsey-Jones.
However, there is a critical period of plasticity early in life when change seems to be the most possible. This doesn't mean plasticity in the adult brain isn't possible (it most definitely is), but that our early years are the most plastic. It’s also important to note there were only two foot participants and that the artists were born without hands, meaning such mapping could be different in those born with hands.
"It could be that our artists were learning to use their toes when they were children during this time of maximal brain plasticity," said Wesselink. "We know the adult brain is more fixed once the critical period of plasticity closes. It may be that once that happens you can't really change the brain in a major way, such as this."
"Whether it's the hand or toe, or any body part, we want to understand more about how the brain copes with these different types of changes," added Dempsey-Jones. "Mapping out finger and toe activity in the brain can help advance brain-machine interface technology where the brain learns how to control each digit of a prosthetic."