“The Brain Senses Touch beyond the Body”
by Richard Sima
Scientific American, October 16, 2019
(Note from the writer: I had previously cold-pitched something to Dean Visser at Scientific American that was not accepted, but he was very generous in his feedback and encouraged me to send more pitches. I emphasized my neuroscience training somewhat because the technical details of the experiments were complex.)
Hope you are doing well.
I have a fascinating story about how our brains sense touch beyond our bodies, essentially treating the tools we use as a sensory extension of our selves.
This idea is actually quite old, though has not been traditionally investigated by researchers. Descartes (way back in the 17th century) discussed the ability of blind persons to sense their surroundings through the tip of their walking canes, but scientists have only recently begun studying how humans use tools to detect properties of the environment.
In a 2018 Nature paper, the neuroscientist Alessandro Farne’s research group reported that humans were able to accurately sense where an object contacts a wooden rod, just as they were able to on their own skin.
The same authors followed up on this study in a paper published yesterday in Current Biology, where they used EEGs to record neural activity of the subjects’ somatosensory (touch) cortices while subjects reported where on a tool they detected a touch. The researchers found that the cerebral cortex rapidly processed where the tool was touched. They also found that similar neural processing for touch locations on the subjects’ arms as touch locations on the tool. From these results, the researchers propose that the human brain uses similar neural processing for sensing with tools as with our body.
For this story, I plan to interview Luke Miller (the first author on both papers), Alessandro Farne (senior author on both papers), and Scott Johns-Frey (a cognitive neuroscientist who researches human tool use).
I think this news story has many facets that SciAm readers would enjoy: the novel research demonstrating how tools expand the sensory boundaries of our body on a neural level; the implications on how tool-use has perhaps impacted human evolution; and the potential applications to developing more effective prosthetic limbs. These findings have not yet been covered in any other outlet.
A bit about me: I studied neurobiology as an undergraduate at Harvard and recently received my PhD in neuroscience from Johns Hopkins. I am now writing about science full-time, both as a freelancer and for the International Arts + Mind Lab at Johns Hopkins (which is not affiliated with this story). You can find samples of my recent clips here: https://richardsima.com/portfolio
Please let me know what you think and if you have any questions.
Richard Sima, Ph.D.