HAND BRAIN HANDLES TOOLS
the part of the brain dealing with images of hands also processes how to grab cutlery & the differences between grabbing cutlery & rods. hands & tools inter-digitate in the visual brain
original article: Knights et al., 2021 (Journal of Neuroscience), reported in: Twitter by James Rosen-Birch on 13th May 2021 image source
this story was in episode 11 #hand #tool #FMRI #visual #grasp #decode
the error bar says
the life of a volunteer inside a brain scanner is not easy
strapped into a dark, noisy tube, a plastic spoon is lit up for a quarter of a second. it's grabbed between finger & thumb. this happens four more times. after 10 seconds' reprieve it happens again. now a strange rod. next grabbing a plastic knife blade, then a pizza cutter, then another rod. again & again & again for an hour
20 volunteers' brains were scanned each for about 2 hours while they viewed then grasped different items of cutlery & unfamiliar rods & while they just looked at similar images
the researchers in Cambridge & Norwich, UK, found that brain areas thought to be for processing visual images of hands also contain information on the orientation of spoons, knives & pizza-cutters, but not about unfamiliar rods
reports on social media suggested that we finally understand how the brain interprets tools as if they were literally a part of the body
does the brain bit for hands also do tools?
yes
this is a good news story. it is a technical achievement just to adapt the brain scanner to do this work successfully & the researchers clearly spent a lot of time with each of their volunteers to get really good data over multiple sessions inside the torture tube, err, the brain scanner
figure 2 in the paper is a masterpiece in efficiency & clarity of data reporting - everything you need to know is right there
and like all good studies, it raises more questions
first, two overlapping parts of brain - for hands and tools respectively - showed quite different responses. the separate areas were defined independently - which is the right way to do it - so it raises the possibility that these brain areas can be defined in a different way and that could even give better results
second, like most studies of this kind, the statistical effects were really very small - signals in the brain areas distinguished typical from atypical grasps, or cutlery from rods, only about 55 to 60 percent of the time, with chance being just 50%. this study was powerful enough to find these tiny signals in the brain, but these are needles-in-haystacks
while the excitement on social media is justified by this study's quality, we still have a lot to learn about how the brain deals with tools